 Welcome, everyone. My name is Kathy Kling, and I'm very pleased to welcome you to this virtual workshop of the Environmental Health Matters Initiative of the National Academy of Sciences. Today, we're going to be learning about and discussing issues related to reducing the health impacts of the nitrogen problem. As I said, my name is Kathy Kling, and I'm delighted to have the privilege of chairing the planning committee for this important workshop. A couple of housekeeping things to get us started. We encourage all of you to participate as much as you can in comments and questions. We're doing that through the use of a Slack channel. If you scroll down, you should be able to see on your screen a way to connect to our Slack channel, and we'd really love to have as much input and questions as possible. Those questions will be taking account of them and feeding those to some of the presenters throughout, so please take advantage of that. Also want to let you know that we are recording this, and it will be available later today on the website. Today is the first of five weeks of webinars all told on this topic. I'm going to provide an outline of those five workshops shortly, as well as a broad introduction to the issues associated with nitrogen moving through agriculture and into our environment. But first, I want to turn to Tom Burke, who's going to give you an introduction both about the role of the National Academies in work like this, and the Environmental Health Matters Initiative under the auspices of which we're running this webinar. Please take it away, Tom. Thanks so much Kathy. And if I can have the slides. So I want to welcome everyone to our workshop, reducing the health impacts of the nitrogen problem. Next slide. I'm here as the chair of the Environmental Health Matters Initiative to provide you with an overview. Next slide. So on behalf of the National Academy of Sciences and Engineering and Medicine, welcome. As you may know, the National Academies is a nonprofit organization with really a dual vision and a dual role founded by our President Abraham Lincoln to honor our nation's top scientists, but perhaps more importantly to all of us to serve as scientific advisors to the nation to provide independent objective scientific advice to inform decision making and public policy. So what we're doing here today to bring together experts to advise the government NGOs foundation business and the academic community. Next slide. Now I'm honored to chair the Environmental Health Matters Initiative. The EHMI is really a unique somewhat new approach for the academies to bring together the real resources of the three academies. One of the things we in the scientific community know about is we tend to be disciplined driven and and the EHMI founded in 2019 was really a new approach to take a broad lens to provide a neutral, nonpartisan place where stakeholders as well as scientists can share insights to provide leadership with a very experienced program development team, the resources and the staff of the academy plus the experts from government business and academia. Really, I consider the National Academies to be the most credible source with a long organizational history of working, not only in the environmental health field, but across medicine engineering and science. And then finally, the EHMI has a unique ability and now a growing track record of convening experts across the scientific disciplines and across sectors to solve our most challenging environmental health problems. Next slide. Just a little bit of history of our organization. So we are taking on some of the most challenging cross disciplinary cross sector environmental challenges that we have with face as a nation really that are global. Just to give you a little bit of the background of things we've already done and and these workshops and reports on them are available on the EHMI website. We've had workshops so far on the really vexing challenging issue of the fluorinated compounds and looking at opportunities to understand control and prevent exposures to PFAS. We've also taken on one of the nation's most challenging issues. High quality safe drinking water from every tap. More recently, as an emerging problem, and really to inform the very many debates about controlling the transmission of COVID, we held a very successful workshop on airborne transmission of COVID of SARS Coronavirus 2. And in July, we anticipate taking a broad lens to the issues of our new transportation approaches and new mobility options and their potential impact on our health. Next slide. And as you can tell from even today's topic, the issue of nitrogen in agriculture and the impacts on health. EHMI is focused on our most wicked environmental health problems, those problems that really show a strong connection between the quality of environment and our health. They're complex. They're affected by so many different interacting factors. They have various spatial scales and sometimes very long temporal scales. Many of these challenges have global implications like today agriculture. They're difficult to define and unstable socially complicated with no one clear solution. And most importantly, I think for the Academy and bringing folks together is that today's environmental health challenges really extend beyond the understanding of one discipline. And we have convened a great crew of speakers and participants to really share their disciplines together as we look for solutions. Next slide. Just a little overview of the many disciplines we're bringing together and the geography of our participation. It really is throughout the country. But as we look with this lens, this health lens at the issue of nitrogen in agriculture. We have expertise in epidemiology and public health, the broad range of environmental sciences, chemistry and biogeochemical cycles, agriculture, water. So much of this challenge is interrelated with water and water management, climate and weather and economic evaluation of ecosystems. And finally ecological risk management. So our intent here today is to give you these various disciplines to show the perspectives and report to you on the state of the science, the state of our knowledge as we move ahead. Next slide. Now we had an amazing and very hard working planning committee that has been hard at work for the past two months to bring us this webcast today and this workshop. And Kathy will say more about that committee in her presentation following me. Next slide. And I also want to thank the standing EHMI steering committee. As I mentioned, I'm honored to chair this committee and I wouldn't go through all the names, but we have tremendous representation from business, from foundations, from our NGO community. And I like to point out the very strong public health and environmental science background here and the expertise in this committee, including I think three deans of schools of public health. Next slide. Really important to EHMI as we look at that cross sector involvement are the EHMI liaisons. And I would go through the entire list here but just taking a look. We have the major federal agencies addressing environment addressing health that range from the Department of Defense to USGS and NOAA. And the strong sponsorship we've gotten from the Centers for Disease Control, the National Institute of Environmental Health Sciences, and EPA. But as you look across the membership of our liaisons, you also see a strong presence from the National Science Foundation and various foundations, including the business community with folks from industry, the chemical industry, and even Walmart. Next slide. So I'll finish up with the logos and a final word from our sponsor. One test of the importance and the impact of an initiative, I think, is who's willing to come to the table and support it. And as you can see, we've had tremendous support from the business community and tremendous support from the agencies across government and the broad intersection cooperation that we need to address these environmental challenges. So with that, I want to welcome you once again and I'll turn the baton over to Kathy again. Thank you, Tom. That was great. I really appreciate that overview of the Academy as a whole, as well as the important Environmental Health Matters initiative. So I'm going to kick us off right into today's topic. We're here in case you joined us late on a first of five webinars on reducing the health impacts of the nitrogen problem. So as you can see from the pictures that I've placed on my intro slide, our focus is going to be the agricultural component of contributions of nitrogen into the environment. And my goal here is to give sort of an overarching overview of some of the fundamental foundations that people need to have in order to really get this conversation going. Next slide, please. We have had an outstanding planning committee. My name again is Kathy Clang and I've been lucky enough to chair this committee and work with this group of individuals. Alina Austin from the University of Washington, Jerry Hatfield from USDA, the National Lab in Ames, Iowa, ARS, Jim Galloway, Jennifer McPartland, Robin Wilson, and Raj Khosla. All of these individuals you will see again, they will be helping to moderate. I really need to have a big shout out to our National Academy staff. Unfortunately, I don't have pictures of them. I should below. Carol Laney, who is a Senior Program Officer at the Academy on the Board on Ag and Natural Resources, and Sarah Harper, a program assistant associated with the Board on Chemical Sciences and Technology. They have done very heavy lifting, much of the detailed logistic work to put a huge effort together like this. And we simply could not have done it without them. Next slide, please. So let's get started. Today's webinar is the first of five to get us talking and thinking about opportunities in U.S. agriculture to reduce the public health risks of nitrogen in water. Tom Burke gave you some introduction to the goals of these kinds of webinars and I put them in three simple buckets here. One is we hope for information exchange. We have brought together experts from across a wide variety of sciences to provide a high level understanding of the state of the science. And as emphasized by Tom, we mean the natural science, the physical sciences, social sciences, economics, as well as the current policy landscape and realities of what life is like across these many actors in this problem space. So information exchange is really important on a basic scientific level. We also have a goal to use that foundation then for informed discussion. We in the Academy want to provide a platform to consider possible actions to address these issues. We mean producers, farmers, consumers, NGOs, state and federal government policies. All of those actors and decision makers are potentially part of the discussion, stakeholders in all realms. And finally, a goal of this workshop is to take important steps to accelerate progress in this important area. We're hopeful that these sorts of discussions will lead to new technologies, to discussions and possible changes in policy, behavioral changes in all the different actors and players related to these difficult challenges. Next, please. There are some products as well that we hope will come out of this webinar. First, a really important product and I think the most important one is a robust data and science driven communication, laying a foundation for system wide understanding that crosses public health experts, agricultural experts, economists, policymakers, everyone in the policy community to bring together these groups who often are too siloed in their discussion of these issues. For each to understand the science and state of knowledge in and across the aisle, so that we can better proceed to make progress in these problems. In the process, we hope and plan over the next five weeks to have discussion and synthesizing, identifying what we know about a variety of things and just as importantly, frankly, what we don't know, including the nature and extent of human health risks from an exposure, the contribution and pathways from agriculture into that exposure, changes in farming systems and land uses that can reduce that exposure. A geographic extent and intensity of change needed to really move the needle on some of these problems. We also hope to learn about the economic social costs and benefits of achieving these reductions, the ability of existing state and federal policies to reduce that human health risks. And as much as possible, we're hoping to spur and create discussions of new technologies on the horizon, as well as new changes that we can make policy governance approaches actions at NGOs can take as well as producers and consumers. I think it's important to mention that the workshop will not produce conclusions or recommendations. This is not a consensus study of the National Academies, but we will have a summary capturing presentations and discussions that will be available after the workshop ends. And again, I really encourage all of you to put comments as much as you can into the Slack channel, those will be captured and we will be thinking about those as part of our synthesis. Next please. I'm going to step now to a very brief and high level overview of some of the issues and context for the remaining five weeks. This picture was provided to me by our very own Jim Galloway, who I will be turning things over to moderate very soon. And it's adapted from a paper he and co authors published in bioscience, you can see the citation below, and it depicts the nitrogen cycle. On the left, you see three sources of human activity that create nitrogen anthropogenic sources of nitrogen release into our environment, energy production, food production, and people's consumption of food fiber and a variety of other activities. The arrows show you that there are multiple ways and media into which those nitrogen is released into the atmosphere, into terrestrial systems, and into water. This is a series of natural processes and processing occurs and that's depicted by movement within forests and grasslands through plants, the air particular matter and stratospheric effects in terms of dynamic movements and movements into water. It's more complicated than that, however, when we recognize that there are other intertwined systems that also have human health anthropogenic sources and impacts. Just a few of them are other nutrients like phosphorus and other externalities like sediment. Greenhouse gas emissions, carbon sequestration capturing carbon in soils in particular in soil health, and finally the ever present and important component of water movement. Next slide please. Those are complex interrelated systems that will not be the focus of this workshop. And furthermore, the full nitrogen cascade will not be the focus of this workshop. Rather, what will be the focus is what I've outlined in red in here, food production, agriculture, and how that contributes nitrogen into the system. And from there, how through water pathways, that nitrogen affects, agriculture affects nitrogen, and ultimately how all of that moves to human health. So we are picking off what is still a very large piece, but is more focused than the entire nitrogen cycle and nitrogen system. In no way do we mean to suggest that this is the most important or the only one of relevance, but it was a component that we felt needed and to be tackled and that we could address and make progress on. Next please. There are other important impacts of nitrogen that we will not be talking about. And again, all I'm doing here in this and in the next slide is to emphasize what we will be focused on and what we will not be focused on. This is a slide from the EPA that indicates that all 50 states are in fact impacted by nutrient pollution, and that of course includes nitrogen. States have identified about 15,000 water bodies that do not meet the intended use of those water bodies due to nutrients that's more inclusive than nitrates and nitrogen problems, but it certainly includes them. Unless those connect to human health, we will not have those as a focus of our discussions in the next five weeks. Next please. Likewise, a very important problem that also occurs simultaneously with human health impacts are hypoxic zones. This is a picture I took from NOAA. Unfortunately for hypoxic or dead zones as they are more colloquially referred to, global warming climate changes likely to impact and worsen those problems. This is a picture indicating by 2100 where it is expected we'll have some of the worst hypoxic zones along our coasts. We will not be addressing those in this workshop, despite their very important and real impact in the environment, except for the extent to which they may have human health impacts. Next slide please. The final thing I really want to try to provide an overview for before we kick off the rest of the workshop is an overview of some key federal regulations and policies that affect nitrogen. Most importantly or importantly at least is the Clean Water Act, which is of course the overarching federal regulation and policy of the government passed in 1972. The Clean Water Act regulates emissions into polluting waters of all types of externalities pollution into those waters. For industrial and municipal sources of water pollution, the Clean Water Act takes a direct regulatory approach. Limits are placed on those pollution sources and one must have a permit to allow one to emit into those waters. This is consistent with a very standard principle that's often discussed in the environmental literature of the Polluter Pays principle. This is the same kind of regulation and approach as the US takes for air pollution and a number of other environmental externalities. In the case of agriculture, many agricultural sources are in fact exempt from that direct regulation. An important exception is large animal feeding operations, which are in fact under that regulatory regime. Instead for agricultural sources that are exempt, the policy is to rely on voluntary actions by farmers and landowners. A second very important policy is the Safe Drinking Water Act, which was passed in 1974, and the purpose of that is to regulate sources of drinking water. This covers about 86% of US households drinking water. It establishes minimum standards to protect tap water, the water that we drink and cook with. All owners, operators of public water systems have to comply with a set of primary health related standards, and that's a requirement. It's regulatory. However, private wells which account for about 14% of households water consumption are not directly under the Safe Drinking Water Act. Instead, people are encouraged to test, but there are no required testing, and we're still learning a lot about how much testing actually gets done at the household level. Next slide, please. A couple other federal and state policies. One is the USDA Natural Resource Conservation, Federal Conservation Title. We will be hearing more about this in webinar, I think it's three, where we'll get an overview of those programs, as well as information on changes that might, ideas about changes in those programs that could better address nitrogen issues. But these are federal conservation programs that pay farmers or provide important cost share or information to farmers to help them adopt actions that reduce pollution. These fall under the terminology of voluntary. Remember that the approach in the United States is largely voluntary, but for some of these programs, farmers actually get paid. So it's kind of just a bit different use of the term voluntary here than I think we often use in typical language. But these all are called voluntary, even though there is payment in some cases. States also have a role. Indeed, some states have regulated agriculture, although the Clean Water Act forbids the federal government from doing so. States do not fall under that. They can regulate and indeed some have. There are a number of states who have winter bands on manure spreading. The Florida Everglades has had an important role, an important and really interesting example of permit farming for sugarcane, but voluntary approaches remain the primary state policy. Next slide. I want to show this slide just to give you a notion of the scale of the agricultural footprint in the U.S. We'll be hearing more about this. About 44% of total land in the United States is in farm land. That's a very large area, obviously that dark and light green are the areas that we're considering. Next slide, please. Finally, I want to show you the scale of the private drinking water aspect. This shows you, according to the USGS, where the private wells and people who drink from private wells are located. Red, green and yellow areas are all areas where there is at least some use of private water drinking wells. So that's the scale of that aspect. Next. And finally, before I turn it over to Jim Galloway to get us going on the rest of our webinar, I want to note the topics for the next five. Today, we're going to spend all of our time on really the foundations, what is the nitrogen problem. Next week, we're going to drill down into farm level actions that can be taken, that we know work. We're going to learn what we do know about the extent to the effectiveness of those approaches. Week three will be turning to landscape level actions and some innovative technologies that perhaps could be forward-looking and move us in better directions in the future. Section four will address policies and markets that could be created or that are in place that could move the needle as well as discussion of perhaps whole new things that are going to need to be brought to bear. And finally, we'll have reflection and synthesis in the final webinar on February 25. With that, I'm going to turn it now to Jim Galloway, one of our committee members, who is going to be monitoring the rest of the webinar for us. Jim, please take it away. Kathy, thank you very much for that great introduction, Tom. Thank you also. I'm very excited about this entire operation. So this is the first webinar on reducing the health impacts of the nitrogen problem. We've got five great speakers in this session. The session's title is What is the nitrogen problem? What a great place to start. Mary Ward is going to tell us about the health effects of nitrogen and drinking water. Craig Cox will tell us about where that drinking water is contaminated. And then we'll talk about the role of nitrogen in U.S. agricultural systems and the need for metrics that Matt Hilmer's is going to talk about the geographical scale of the nitrogen challenge in the United States. And then Eric Davidson will talk about these broader issues of leaky nitrogen in the environment. So it's now in my pleasure to introduce our first speaker, Mary Ward. She is a senior investigator in occupational and environmental epidemiology branch in the digital of cancer epidemiology. She is lost my note. She develops interdisciplinary collaborations to develop new methods of exposure assessment for epidemiological studies and cancer risk in relationship to drinking water contamination. What a perfect person to talk about this topic, health effects of nitrogen in drinking water. Mary, over to you. Hey, thank you. It's a pleasure to talk to everyone today. Whoops. I think I'm controlling my slide. So let me see if I can put it back in slide show. I'm, as Jim mentioned, I'll be talking about health effects of nitrogen mostly talking about nitrate, which is what we find is contaminate in our drinking water supplies. So just a brief overview of my talk, I'll be talking about the role of nitrate ingestion, the biology and how it is a precursor in the formation of nitroso compounds. And then giving a fairly brief overview of the health effects. I'm first starting with meth, hemoglobinemia, which is the health outcome that the regulatory limit for nitrate in public water supplies is based upon. And then covering the literature on adverse reproductive outcomes, cancer and thyroid disease. But first, just a little background. As you already know, nitrogen fertilizers and concentrated animal feeding operations are major contributors to nitrate and drinking water. And the regulatory limit in the United States is 10 milligrams for later as nitrate nitrogen that's roughly comparable to the EU limit, which is as nitrate the ion. The highest exposures are for residents in agricultural areas and in those areas, those are the areas in the USGS map here on the right that's shown in purple and red. The highest exposures in those agricultural areas are the populations on private wells. And as Kathy mentioned, these are not regulated and there's very sparse measurement data. So just briefly, I want to talk about nitrate in the diet. Nitrate is also found at high levels in certain vegetables. They contain leafy vegetables, celery and beets, but these vegetables also contain vitamin C, polyphenols and other antioxidants that inhibit the formation of nitroso compounds. And they have been a high nitrate diet through vegetable intake has been shown to have beneficial effects on the cardiovascular system by reducing hypertension through nitric oxide formation. For there is some marketing of supplements with high nitrate levels such as the juice which have not been evaluated in terms of their potentially detrimental effects of form forming higher levels of nitroso compounds. And you probably heard a lot about nitrate and nitrite are also added for in the curing process to process meats and higher intake of cured process meats are is linked definitively to increase risk of colorectal cancer and to some other cancers. So how does ingested nitrate form nitroso compounds. First of all, when we drink nitrate through our drinking water or our diet, it's concentrated in the saliva through an active transport system. And it's the oral bacteria or the oral microbiome that reduce nitrate to nitrite the very reactive compound, which then swallowed reacts with stomach acid to form nitrosating agents that can react with the means in a mid such as commonly found in our diet through consumption of protein. And this reaction of forming nitroso compounds is increased in the presence of heme iron such as found in red meat, also increased by the cyanate from smoking, and it's decreased in the presence of antioxidants like vitamin C. So about 5 to 8% of the nitrate that we ingest is reduced to nitrite by the oral bacteria. There's a direct relationship with between nitrate conversion to nitrite and the NOC concentrations measured in urine. And I'll point you to this figure to the on the right side of my slide that shows a direct this direct relationship and you can see that there was a range of about 10 to 30% of the nitrate reduced to nitrite in the mouth by the oral bacteria is is the individual variation in that oral bacteria is likely what's causing that range. And so it's an exciting area for future research because we can now measure the oral microbiome in our epidemiologic studies with a simple spit test spit sample. So, a few studies have looked at the concentration of drinking water nitrate and endogenous formation of nitrous of nitroso compounds. Two studies looked at nitrate concentrations that ranged above the maximum contaminant level of 10 milligrams per liter and saw that at levels above that MCL, there was an increased formation of nitroso compounds. But one study where levels were all below five milligrams for later saw no such increase in nitroso compounds. That's so nitroso compounds include nitrosamines and nitrosamids and the in animal studies they've been shown to cause cancer and birth defects over 300 have been tested in animals and 90% were carcinogenic. They cause cancer in every animal species that's been tested so it's unlikely that humans are not susceptible. They cause tumors at multiple organ sites, some of which are shown here. And in utero utero exposure causes congenital malformations, especially of the central nervous system and first trimester pregnancy exposure is most important because that's when organs are developing. So first I'll talk about methemoglobinemia, again, what the regulation is based on. An early report in the Journal of the American Medical Association in 1945 by a pediatrician in Iowa City, Iowa, reported cyanosis in infants caused by nitrates in well water. And this brought national attention to this issue of methemoglobinemia sometimes called blue baby syndrome. And what happens is that the nitrate that's reduced to nitrite binds to hemoglobin forming methemoglobin, which interferes with oxygen transport. Iowa City, Iowa reported cyanosis in infants caused by nitrates in well water. I'm getting some recording perhaps. Okay. So this happens when levels are over 20% and infants less than six months are most susceptible. So a few years later, there was an investigation of several hundred cases of blue baby syndrome in 14 US states, and it was found that there were no cases below 20 milligrams per liter. And that was really the basis of the regulatory limit. It was set at half that 20 more gram per liter at 10 milligrams per liter. And indeed there have been no cases reported below 10. However, fairly recent somewhat recently in the late 1990s, there was a case in Wisconsin attributed to high nitrate well water at about a little less than three times the limit. And certainly this is an ongoing health problem in places like Eastern Europe, the Gaza Strip in Morocco, where drinking water resources are highly contaminated with nitrate. So now turning to adverse reproductive outcomes. There've been, I'll talk first about spontaneous abortions and limited evidence there. And then most well studied are the congenital malformations, sometimes called birth defects. And there's really been very few studies of other outcomes like low birth weight or preterm birth. So for spontaneous abortions, it's known that a high maternal meth hemoglobin level can cause abortions in laboratory animals. And this has also been reported in livestock. In 1996, the CDC investigated a cluster of spontaneous abortions among women living in rural Indiana who were using private wells where the nitrate level was greater than 20 milligrams per liter. One of the women had had a live birth previously before moving to her residence with the high nitrate well water. After these women were switched to low nitrate water, they had healthy births. So this was kind of a compelling cluster investigation. Maybe not definitive, but in a small number of cases, but certainly pointed to a potential role for high nitrate water at least in spontaneous abortions. Another study in Massachusetts found no association with levels of nitrate in the drinking water, but levels were all below 5.5 milligrams per liter. So I mentioned that adverse reproductive outcomes or congenital malformations are the most well studied. There's been numerous studies of central nervous system malformations. There's been a total of six actually. And of these five studies occurring in Australia, Canada, California and Texas found a positive association with higher nitrate levels in drinking water and one or more malformation. CNS malformation. And in four of these studies, the levels were below the regulatory limit of 10 milligrams per liter. In the two studies by Brenda, the first one was in Texas where there was a two-fold increase in neural tube defects. The highest risk was found for women who had both high nitrate in their drinking water and also took prescription or over-the-counter drugs that can form nitroso compounds during the pregnancy. And so these are called nitrosatable drugs. In the second study by Brenda and colleagues that occurred in Texas and Iowa, they similarly found a two-fold increase risk. It was a larger study, so they were able to look at individual types of defects. And they found a two-fold increase risk of various defects all again, central nervous system malformations. And again, the highest risk was for women who had high total nitrate. They assessed both diet and drinking water sources as well as nitrosatable drug use during the pregnancy. So in summary, five of the six studies of these central nervous system malformations found positive associations with nitrate concentrations. And for four of them, these were at levels that were below the maximum contaminant level. So now I want to turn to cancer. In 2006, the International Agency for Research on Cancer, which is part of the WHO, convened an expert working group to evaluate the potential carcinogenicity of ingested nitrate and nitrite. And the working group concluded that nitrate and nitrite, when ingested under conditions favorable for endogenous nitrosation, which is the formation of these nitrosal compounds in the body, was probably carcinogenic. So that's their second highest rating, with one being a human carcinogen. So this was, rating was based on the animal studies, which I talked a little bit about, and very strong human mechanistic studies. But in terms of the epidemiology studies, there were no associations and studies that evaluated dietary nitrate intake, which is compatible with this conditions that would not be favorable to endogenous nitrosation. And for drinking water nitrate, it was considered that the evidence was inadequate, and that was because there were few studies of any particular cancer type. Exposures were generally low because the population was generally included only those using public water supplies, where there were measurement data available. Historical exposures were not always evaluated, and factors affecting endogenous nitrosation were not always considered in those studies. So this gives an overview of the case control or cohort studies of drinking water nitrate and cancer. And this is a study design where we had actual individual estimates of exposure, as opposed to just comparing rates in areas that are high versus low. So this shows the cancer site, the number of studies, and then in parentheses the number that were positive, and at least one subgroup in that study. So the strongest evidence is for colorectal cancer, there's been five studies and four of which were positive. In one of those positive studies, risk was only elevated in the subgroup who had either low vitamin C intake or high red meat intake, but that again is the group that would be expected to have higher endogenous nitrosation. For bladder cancer, two of the four studies were positive. And for kidney cancer, both studies showed a positive association with the nitrate level in the drinking water. Again, in one of those it was in the subgroup who had low vitamin C or high red meat intake. And both studies that have actually assessed the nitrate level in drinking water during pregnancy have found an increased risk for childhood brain tumors. So I want to just kind of take you through a well designed study and how we do the exposure assessment. And this is a cohort study of postmenopausal women in Iowa. Cohort studies are great because you can look at a number of different cancer sites. This cohort, which these women were enrolled in the late 80s from across Iowa, 73% use public water supplies, 25% use private wells. So for the women who are on public water supplies, we linked historical drinking water monitoring data about 30 years of data on nitrate to their residents to the city where they lived. Some of these are very small towns in Iowa. And we linked them by the duration that the women lived at that residence. And we computed two types of exposure metrics, a long-term average for nitrate, as well as we also looked at tri-hello-messains, which is a major type of disinfection byproduct. And we also calculated the years that they were living at the residence where the level was above half the maximum contaminant level. And this is a very stable population. About 82% of the women had used their water supply for 16 or more years. So in early results from the study, and these were included in that slide where I gave the overview of all cancers, but early results found an increased risk of ovarian cancer for women who had the highest quartile of average nitrate levels compared to the lowest, and a suggestion of an elevated risk for women who were using private wells. There were no measurements, but they were compared to the lowest quartile of women on public water. And for bladder cancer, there was almost three-fold increased risk for the highest quartile of average nitrate levels in public supplies, but no association for private well use. And then there were no associations for these other eight cancer sites that were evaluated. We did some updated analyses with additional years of follow-up. There's now well over 20 years of follow-up for this cohort and many more cancer cases. We saw a similar increased risk for ovarian and bladder cancer as was found in the first analysis of these data. We updated analysis for colon rectum pancreas cancer, which still showed no association with the nitrate level. But for kidney cancer, we saw that there was an increased risk in the very highest exposure group, which was those who had average levels above five milligrams per liter. And in this update, we improved the exposure assessment by taking into account trihalomethanes, which are moderately correlated with the nitrate concentrations in the water. And we also assessed dietary nitrate intake, and we looked at factors affecting nitrosome compound formation. So I want to just show you the results for ovarian cancer. This is the only study that we're aware of that is looked at this. You can see in this updated analysis was a significant increased trend with increasing quartiles of the average nitrate level in public water supplies. And again, that elevated risk for private well users. When we stratified our analyses by vitamin C consumption, this is just divided at the median intake for these women. We saw no association among women who had higher vitamin C intake for either the public supply levels or private well use. Whereas we saw a significant trend with increasing nitrate levels among those who had lower vitamin C intake and the risk for private well use was statistically significant. And this was a significant interaction for private well use. So in summary, the most consistent evidence is for colorectal cancer. There's still few studies of specific cancer sites, and the limitation I think most notable for these studies is that private well users who have the highest exposures are usually not considered due to the lack of measurement data. And some studies have not looked at factors affecting nitrosome compound formation. So my last health outcome just briefly that I'll talk about is thyroid disease. Nitrate directly inhibits iodide uptake by the thyroid, and this results in decreasing concentrations of plasma thyroid hormones and increasing levels of thyroid stimulating hormone, which chronic exposure to TSH can lead to thyroid hypertrophy and potentially as a mechanism for cancer. There's been one study in the Netherlands that found women with higher nitrate levels in their well water at an increased risk of hypertrophy. And that several studies have looked at hypothyroidism, which I'll show you now. There was a study in Slovakia looking at subclinical hypothyroidism in children that was associated with higher nitrate levels in the drinking water. In the Iowa Women's Health Study, women who had higher nitrate ingestion from both diet and drinking water had a higher prevalence of self-reported hypothyroidism at the time of enrollment in the study. And we did a analysis in a cohort of old order Amish in Pennsylvania, Southeastern Pennsylvania, who primarily use private wells. And we estimated nitrate levels in their drinking water. Those who, the women, but not the men who had levels greater than six milligrams per liter had higher serum levels of TSH and subclinical, higher prevalence of subclinical hypothyroidism. We are doing ongoing research in a really interesting cohort of the agricultural health study. It's a cohort of farmers and their spouses in Iowa and North Carolina. 60% of the cohort use private wells at the time of enrollment. And we estimated nitrate levels in those wells in collaboration with the U.S. Geologic Survey, a spatial statistician, and I'll show you a map in a moment with those levels. People on public supplies, we link to the historical measurement data for nitrate and disinfection byproducts. And we also estimated nitrate and nitrate intake using a frequency questionnaire. So this is the predictions for nitrate levels in private wells in the Iowa portion of the cohort. About 25% of the cohort had levels above five milligrams per liter. And 13% predicted to have levels of 10 or more milligrams per liter. And this map is separated by well depth. The top map is for shallower wells. You can see the high nitrate levels kind of in the dark red color are in the western part of the state. And then the deeper wells that high nitrate is located in the northeast area where there's a lot of carstiology. So to wrap up, I wanted to just point out some research needs. I think it's going to be important to clarify the relationship between nitrate ingestion and nitrosub compound formation. At levels below the maximum contaminant level, below 10 milligrams per liter, particularly in that range of five to 10, where sometimes we are seeing some increased risk for some outcomes. It's also important to evaluate additional factors that influence endogenous nitrosation. And I mentioned that we're a microbiome that we can now measure in our studies. And certainly incorporating biomarkers would be important studies that have biologic samples. It's important to consider other water contaminants that may co-occur with nitrate and certainly do more studies in populations, especially with a high range of exposures. So with that, I'd just like to thank my collaborators on some of our research that we published here at the National Cancer Institute. And also my collaborators at other institutions. And then finally, I covered a lot of literature. So you can find pretty much everything I talked about in two reviews that we did the first in 2005 and one more recently in 2018 and references are here. So I thank you for your attention and happy to take any questions. Thank you very much. Very excellent presentation. We have about two minutes for questions. And so panelists can ask a question by raising their hand or in chat and others can communicate via Slack. So the floor is open to questions. I've got a question. So I don't know where to begin, but I guess the most simplest way I could say is of the of the issues that you raise relative to the health effects of nitrate and drug work, what do you think is the most alarming in a developed world versus in a developing world? Oh, that's a good question. Certainly, you know, the very preventable acute effect of mathematical of anemia is still an issue in the in parts of the developing world in areas where people rely on private wells and there's a lot of agriculture. Some of that contamination is often due to animal manure, as opposed to chemical fertilizer nitrogen fertilizer. In the in the United States or other developing countries, you know, of course, my focus is at the National Cancer Institute has been mostly studies of cancer. We really are taking a look now at or trying to look at mixtures because people aren't exposed to one thing at a time. I think that's an important area for future research. Like in Iowa. It's, it's interesting in the nitrate levels are high in surface water surface water is used for a lot of public water supplies and there's also a lot of elevated levels of disinfection byproducts so those kind of scenarios where you have multiple contaminants I think it's important to try to tease that apart. Okay, I see that we had questions from three other people Chris Clark, Tom Hebert, and Jennifer part one but let's let's delay those until we have the discussion period in because we want to move on to the next speaker so very again thank you very much for your great presentation. Okay, so it's now my pleasure to introduce Craig Cox. He has started his working life to issues of conservation, since joining the Minnesota Department of Natural Resources in 1977 and the field biologists following degrees in wildlife ecology and agriculture implied economics from the University of Minnesota. Now Craig currently leaves the environmental working groups research and advocacy work agriculture, public health environment and climate. Today he's going to be talking to us about where is drinking water contaminated by nitrogen from agricultural sources. Craig over to you. Thank you. Well, happy to be here everyone glad to be interacting with you. We're sharing excerpts from several reports produced by a team of analysts and EWG's Midwest Office in Minneapolis. And before I begin I want to acknowledge two members of that team in particular, and we are second girl who has completed most of the drinking water data analysis. I'm going to be presenting and so on run quest who's done the spatial analysis you'll also be seeing in a series of maps. So if I could have the next slide please. So with two exceptions, the data I'm going to be presenting are from EWG's national tap water database. It's set a water testing data from about 50,000 community water systems since 2013. It's about 32 million tests and 284 chemicals detected in finished drinking water that is entering the distribution system. To build this database we requested test results from all 50 states in Washington DC and the nitrate data that I'll be presenting is a subset of that larger database. So at the outset, the team in Minneapolis started looking at two year average test results between 2016 and 2017 across all active community water systems in the United States. And you can see the results on the slide, about 5.5 million people were supplied drinking water with average nitrate that half the legal limit that's five milligrams per liter, a level that I think Dr. The presentation would suggest should be a bit of a red flag and about 116,000 people were supplied with drinking water at or above the legal limit. And very important for the agriculture connection, 94% of systems with elevated nitrate serve 25,000 or fewer people, mostly small rural communities. So, but as we've continued to work with these data. It's apparent that average can't contamination may not always be the mess metric for understanding health consequences and Mary's presentation touched on this. And I just wanted to show this example from California because it shows just how much estimates of exposure can change, depending on how you look at these data. And as you can see in California about 2.7 million people were supplied with drinking water with an average at or above five milligrams per liter. But 25 million people got drinking water at that level at least once between 2003 and 2017. And the point I'm trying to make is there's many different ways to look at these data, depending on what's relevant for health effects, or policy and your thinking about the consequences of this exposure, you know, really changes depending on how you're looking at these data. It's also important to remember that most small systems are testing or at least reporting testing only once every year. Next slide please. So we took a closer look at those smaller systems that I mentioned make up 98% of communities with average nitrate at or above five milligrams per liter. As you can see on the map, these systems are concentrated in rural counties surrounded by agricultural fields that are receiving lots of fertilizer and manure. Those are the gray tones on the base map. The pink dots are the system locations. And in addition, those systems are concentrated where nitrate is particularly likely to leach to groundwater, because the vast majority of the smaller systems depend on groundwater for their drinking water. Next slide please. And as you probably saw or noticed on the map. These systems are highly concentrated in major agricultural states. So 69% of the systems with elevated nitrate were in the just in just the 10 states listed in the chart that you see now, serving about 1.5 million people. Next slide please. So we did ask the next obvious question, which is what evidence is there or is there any evidence pointing to the extent to which nitrate contamination is increasing in these systems. So we decided to look at 10 states where nitrate contamination is widespread. And we looked at all systems, not just small systems. And we looked at all systems with at least one test at or above three milligrams per liter, which is sort of generally considered a marker of contamination above background levels. So in that set, we looked at just over 4,000 communities serving about 46 million people. And we found about half of those systems serving 21 million people showed an upward trend in contamination. Of those systems, 959 serving 13 million people that upward trend was statistically significant. And as you can see on the map, a lot of the systems testing at or above five milligrams per liter and at or above 10 milligrams per liter show an upward trend in contamination, which we find concerning. Next slide please. We also looked at the magnitude of the increases in systems that did have an upward trend. And we found that those increases range from 17% in Kansas to 46% in Wisconsin. And again, small systems were far more likely to be seeing increasing contamination. Next slide please. This is just a look a closer look at the two states that bookended the analysis that I mentioned before to give you a picture of what that pattern in individual states might look like. The most important takeaway here is that these nitrate levels can vary substantially from year to year. In both surface and groundwater systems and to that point, all of the systems on the Wisconsin chart that's at the top of your screen, all of those systems are groundwater based systems. So I think this variability also goes back to the point I made earlier about which metric, which metric are should we really be concerned about when thinking about exposures and health effects. Next slide please. We are now beginning to use census block data to look for disproportionate effects and exposures on particular communities. There's just two examples here in the San Joaquin Valley in California. We found that Latino communities are far, far, far more likely to be drinking water contaminated with nitrate. And as you can see in the larger table, that contamination is often at very high levels. Some very preliminary work in Minnesota, which you can see in the small table, is really showing the troubling intersection between income and race. And with more diverse communities in Minnesota that are affected by high nitrate tend to have higher rates of poverty as well. And we expect and worry, frankly, that these kind of results will be the rule rather than the exception as we continue to pursue this area of investigation. Next slide please. We also took a look at the potential cost of treatment in these systems if they should end up having to add a nitrate treatment system to their existing water treatment facilities. And this map shows the distribution, the geographic distribution of potential per person annual additional costs at the high end of cost estimates. If I could have the next slide please. So the estimates of potential costs very, very widely. And that's largely because of all the uncertainties that are involved in the unique circumstances of every, you know, of individual treatment systems. So, and of course, communities are going to try other options before they decide to build a treatment system, but some of those options like producing drilling new wells can also be quite expensive. What is clear and consistent in the data is that the per person annual additional costs will be higher, perhaps much higher in the smaller mostly rural systems that dominate the systems that are seeing elevated levels of nitrate in drinking water. If you add up all of the costs across all of those systems for, for iron exchange systems, the costs could range from 102 to 765 million dollars a year the additional costs. If reverse osmosis systems were needed that could cost as much as 1.5 billion dollars a year and additional treatment costs. Next slide please. So I want to touch on this. This slide touches on a really critical issue that was raised by both Kathy and Mary. And that is the exposure if people drinking water out of household wells. The issue as both people mentioned is that these folks are pretty much on their own. To test their own water and to take any action that they may want to take or might be needed to reduce nitrate contamination and that action can be very costly for an individual household. But the biggest issue and the troubling issue is that data are very limited, as Mary mentioned, in exposure through household wells. There was one study USGS did between 1991 and 2004. When they tested domestic wells, they found 7% or more of the wells in areas dominated by agriculture, tested above the legal limit. And 25% of shallow wells in intensively found areas tested above the legal limit. We did find and assembled data on household well tests from Iowa's grants to counties program that covers the cost of testing household wells if homeowners want to have their well tested. And you see the results of that of those tests on your screen and in the map. The map shows that wells with elevated nitrate are widespread across the straight state, excuse me. The gray counties on the map did not participate in the testing program. So this is nowhere close to a comprehensive assessment of household wells. In fact, there is no comprehensive database on even the number and location of household wells in Iowa. But you'll note that some of the contamination in these household wells was extremely high. Over a thousand wells tested at three times the legal limit, nearly 500 wells tested at five times the legal limit. And I think most concerning most of those very high test results are from the more recent tests between 2010 and 2017. Next slide, please. Now I'm going to change course a bit and be done with nitrate and drinking water and just raise in the two concluding slides the issue of toxic algae and cyanotoxins in drinking water. There is very little data available about cyanotoxins in drinking water because as of yet cyanotoxins are not a regulated contaminant under the Safe Drinking Water Act and therefore there are no testing requirements in utilities for cyanotoxins. Most of the attention in triggering these outbreaks has focused on phosphorus and temperature. But new research suggests that nitrogen may be playing a role in shaping some very important characteristics of the blooms once triggered. The best survey data we found to get a sense about how widespread the outbreaks are was from the National Lake Surveys in 2007 and 2012. But it's important to note that microsystem was not the target of these surveys. There was one chemical or contaminant tested for out of multiple, multiple contaminants that were used to give a sense of the health of lakes across the country. And many of the tests were taken at times of the year where there would be less chance of algal outbreaks. But those are the orange dots on the map that you're seeing are lake test locations. We tried to supplement the data as best we could by searching all state websites for any testing that had been done and reported. Those are the purple dots on the map. But it appears that microsystems are widespread in lakes and often exceed the health guidance for recreational water, which at least according to news reports seems to be the most dangerous route of exposure at the moment for human health with some pretty serious health consequences and including neurotoxins making people quite ill. So the cyanotests and microsystems specifically were detected in 39% of the lakes surveyed in 2012. 9% of the lake sample by states exceeded that recreational level. Next slide, please. So the data that we found, you know, there's no basis for evaluating trend and the number or severity of these outbreaks over time. We did have fun looking at news stories between 2010 and 2019. There were 71 news reports about toxic algae outbreaks in 2010, 508 in 2019. Obviously, news reports are not a good proxy for data on trend. I think what it's clear is these outbreaks are getting much, much more attention, especially after the incident in Lake Erie in 2014 when the drinking water supply was shut down for four days. The EPA has begun the process of determining if cyanotoxins should be regulated in drinking water. So my guess is we'll be hearing a lot more about this issue related to nitrogen and public health as time goes on. Last slide, please. So thank you so much. It's really a pleasure to be part of this presentation looking forward to all of the workshops to come on my slide set that you'll be able to get I have provided links to all of the studies that I've cited coming out of our Midwest office. Thanks again. Thank you, Craig. What a nice presentation. So we have about nine, eight, nine minutes for questions here. And so again, you can panellists can put something in the chat or raise your hand, and then people who are the webinar can ask questions via Slack. If people are queuing up. I've got I have a question for you, Craig. So, what about our neighbors to the north, Southern Canada have the same issues with nitrate and drinking water as we would. I don't know the answer to that because we haven't looked. Okay. Any other questions. There's a question in the chat box. Thank you. So I'll read it. So are there any states with trends of declining groundwater nitrate concentrations that if so anything we can learn from those trends. For example, differences across states in terms of regulations and enforcements. And this is from Sarah place. That's a really good question. There are I mean, as you sort of guessed when I was presenting the data on trend that there was close to half of the systems. Didn't indicate an upward trend, and they some of them did most of them did indicate a downward trend. Although the downward trends were less statistically significant than the upward trends. We didn't try to suss out why that might be the case. But that's a that's an interesting idea to to to see what we could find there there is one issue of trend that I think reflects action being taken in the states if you remember that crowded graph of all 10 states. Notice that Nebraska's has high contamination, but that contamination has seriously leveled off in the last few years and Nebraska is one of the states that has a fairly aggressive and strategic and smart program in place to reduce contamination of groundwater with nitrate so I found that association interesting but I we, I have not looked at the policies in place in the other states. Thank you very question from Ken Casper. Can you want to unmute yourself. Right, my question is, Greg, you mentioned that some of the data you report and show on some of your slides is simply one measurement in a year. Is that right. Because the variability must be huge so it seems to me there needs to be a better tracking method for this because I mean what portion of the observations you see are simply one measurement for example. He can good to see you. It's been a while. Yeah, I mean, the testing that's required under the Safe Drinking Water Act is minimal for most of the small systems that are showing elevated nitrate and it would be great to see far more testing than is required under the Safe Drinking Water Act but in terms of looking at drinking water that's the best we have. It seems to me that the cost might be prohibitive for small city, you know, small rural city water systems. So perhaps some program that provides funds for testing might be useful. That's a good idea. And also, you know, as I'm sure as you know, the testing protocols can be changed on a state by state basis and there are some states Minnesota, for example, that if nitrate levels rise to a certain level, at least recommend if not require additional testing in those systems. So that that could be another approach to take to try to get a better data set. And I do think your question about precipitation and weather probably drives some variability that I showed in those slides, which is concerning given predictions at least in the Midwest for substantial increases in extreme events. Let me introduce here a question from Slack. I'm wondering if these, these upward trends in the increase in nitrate concentration is primarily driven by agricultural practices, fertilizer inputs, irrigation, etc. Do we have an understanding of what the primary sources for these elevated nitrogen levels. Well, I think I'm relying on Matt Helmers to talk a lot about that specifically. We have in other studies, not not this one looked at the intensification of agriculture. In the states with high nitrate levels there's certainly a signal there of the intensification over time and in some areas, you know the concentration of animal feeding operations has gone up dramatically. And that's increased the nitrate load, nitrogen load at least so I think you could draw some conclusions from that and Matt may talk about this, but there has been a substantial increase in corn on corn rotations, which would increase the fertilizer applications, and particularly in areas that are producing a lot of ethanol. Great. Thank you. And we have a question from Tom Burke. Hey Craig, great presentation. I was struck by your map on the costs of treatment and the variability and I was first wondering if you'd comment on that variability and what drives it, but also a question of whether source reduction might reduce those treatment costs, ultimately. Thank you. Well, that you know he WG is both a research and an advocacy organization so the reason we did the cost study was to try to put much more emphasis on prevention. You know, rather than treatment as the way to solve this problem that this problem and I think highly targeted strategic prevention measures would go a long way to avoiding those kind of treatment costs and if you if we. If we look at the, if we had time to look at more detail on some of the, some of these issues you'd. You'd see that oftentimes with these small systems the area contributing nitrate to groundwater can be relatively small. So that it would not be a huge undertaking to us to target prevention measures to those well had protection areas and at least provide some short term reduction in. Costs, but your first part the costs. You know we relied on a. University of California Davis report that help suss out parameters to help us estimate those costs but there's so many variables one is how high is the contamination. You know what's the flow through of the system. It is, you just need so much more information about individual systems to be able to make. And of course what are the other options, can you drill any well, can you hook up to a rural water system. Can you blend water from a contaminated well with an uncontaminated well this just there's. It's hard. Thank you. That note. Again, we get again there's several questions in the chat and elsewhere that we can come back to in the question answer period at the end of the presentations. So, again, thank you very much. So, I'm very pleased to introduce our next speaker. I'm going to ask him you've seen his face just recently, because he asked a question. Ken is the emeritus professor of agronomy at the University of Nebraska, and as an agricultural consultant currently over a 40 year career by the way I've worked with him for half of that career. His research is focused on insert ensuring local to global food security, while conserving natural resources and the technical environment. He's worked on many of the world's world major coffee systems, and he currently works at the intersection of intensive agriculture environmental advocacy to improve yields profit soils and environmental performance. I think he's going to be talking to us about the role of nitrogen in the US agricultural systems and the need for robust metrics to qualify. Ken over you. You're muted Ken. Yeah, thanks Jim. It's been a long ride indeed. I'm going to. I'm going to share my screen because my. Oh, are you going to get it up for me, or am I going to share it. Either one. It was a slow connection earlier when we tried it, but let's try it. See if it works this time. There we go. So my job is to talk about the role of nitrogen in US agricultural systems and the metrics and the need for metrics to qualify it. Yeah, it's slow. I am sorry. So you're going to have to let me be a co host and and do this. If that's possible. Yeah. Sarah, can you make him co host. I'm working on it right now. I think I might need Eric Edkin to help out. Okay, I'm ready. Thanks Ken. All right, you should be a co host now if you want to try to share your screen. Thanks for waiting. Okay. Is it sharing now. Yes. Great. Okay. And yeah, okay. Well, let's go back here. Let's go to the top here. Okay. There we go. Okay. So, you know, at the helicopter level, the role of nitrogen is that it's one of 15 or so essential nutrients require required for growth of all life on earth. Including plants and animals. And of the 15 nitrogen is needed in the greatest amounts. Particularly to build proteins enzymes DNA RNA other nitrogen containing compounds, but a key fact is that 50% of the protein in leaves is the rubisco enzyme a protein, which catalyzes photosynthesis so essentially nitrogen drives the creation of biomass on earth. And the as a result as crop yields rise, so does the nitrogen uptake requirement to support the greater crop biomass. And I think that's a key point to remember here. We're going to be producing more food for a larger population it's going to require more nitrogen. Another role of nitrogen agriculture is that it's not only essential for the bacteria fungi and micro mesoflora in soils, but it. These micro organisms govern the degradation and turn over a soil organic matter which in turn releases nitrogen back into the soil system become available that becomes available for crop uptake or losses. And a third role is that if you're thinking of sequestering carbon in relation to climate change, organic matter contains about 5% nitrogen by weight, so that if you're going to store a ton of carbon. It's going to require 50 kilograms of nitrogen, in addition to whatever the crop requires. The nitrogen's got, you know, the good bad and the ugly, and I'm going to focus on the in terms of agriculture and I'm going to focus on the good that is the food production aspect with certainly with linkages to the to the health hazards and the environmental pollution. When to start though with this idea, well focus on bread baskets why because these are regions that produce a large surplus of one or more agricultural commodities typically cereals and oil seeds. Not only to meet regional demand but also to contribute to food supply at globally important scales and that's that's that's a key, because in the world as we know it there's only a few bread baskets. The maize and soybean bread baskets of the Central US Plains, the Brazilian Serato and Argentine pompous, the wheat or small grain systems of Northern Europe, Central Europe, and the Indo-Gangetic Plains of India and China, and of course the continuous rice systems of Asia. But these systems are the foundation of the human food supply and they also are responsible for most of the nitrogen use in agriculture. This is what it looks like in a one of these systems that are in bread baskets. This is a rice system in Asia, and if you withhold nitrogen, that plot that's embedded in that photo is one that didn't receive nitrogen but received everything else in the field at large. And the fact is, and this is the key point, it will yield about 50% or less of the yield with farmer practice using the standard nitrogen rate used in the area. And that means that if we're going to limit or eliminate nitrogen fertilizer, it means that only one in two of us could exist today. And in by 2050 with a prediction of 10 billion people at least, you're talking about a third, it would support a third or so of that population. And the problem though is that controlling the fate of N applied at levels to meet human demand in these bread baskets is extremely difficult. And then losses for agriculture you've heard are causing enormous environmental degradation and health consequences. But if you read, if you eliminate nitrogen, there are other consequences. Agriculture would have to expand massively to overcome the lower yields. This is what it looks like I took this picture in 1980 in the Amazon jungle. And this continues today at an alarming weight rate and these lands are converted to grazing and cropland. And it also forces people, poor people to farm lands that really should not be farmed simply because we need food. On the other hand, this is what it looks like when you produce crops near the yield potential ceiling. Here's a corn crop in southeast Nebraska that's going to yield 18.5 metric tons of grain about 300 bushels per acre. And another 18.5 tons of residue that could be returned to soil to maintain or increase soil organic matter. And the fact is, and this is probably one of the most widely hidden fact, is that the highest efficiencies for water, light, nutrients, energy, and the lowest greenhouse warming intensity per unit of production occurs in high yielding irrigated and favorable rain fed systems. So for instance, here are rain fed, these are all based on farmer reported data in Nebraska. And Nebraska has a harsh rain fed area compared to my colleagues like Matt Elmer and others in, in Iowa and Illinois. And so we have relatively low yields and uncertain rainfall, but you see that not only do you have larger inputs to irrigated system, there is more nitrogen applied. But it's used with much higher efficiency when you have more certain water supply and when you can control factors that limit crop growth. And it's the high yield systems that have greatest potential to have highest efficiency for things like nitrogen water and energy and lowest low warming potential. Which leads to this existential question at a time when we're dealing with some existential issues. Can we sustainably intensify our crop production systems on existing farmland while avoiding massive conversion of national habitat to crop production and do so without environmental degradation or health problems below exceptional thresholds. Corollary questions are, can we measure the end losses for agriculture that contribute to this degradation and do farmers have robust tools to estimate their losses. You need a target. Here's the point I want to get to. It's been so hard in my 50 years in this business working on nitrogen issues, because it's like boxing with a shadow, we can't really measure things. And it's because it's complicated. There's so many pathways nitrogen is such a transformable undergo so many transformations in the soil system. So you have inputs coming into the soil. You have crop uptake you have removal and harvest you have return with crop residue in a perennial crop like a tree crop a fruit crop or a vine. It increases biomass each year and there's a little bit of nitrogen that goes into increasing that standing biomass. But then you also have these insidious losses both gaseous with the greatest concern for nitrous oxides and climate change and and also nitrate to groundwater. But here's the clincher as I mentioned, we can reliably measure some of these components and I don't have time to go into why, but we can certainly talk about it. But and of these that we can reliably measure even fewer at reasonable cost and effort. So we're dealing with a complex system in which we can really only measure well and reliably and at reasonable cost and effort, a few. One of those I would say the soil nitrogen supply available available for crop uptake is the most important because, essentially, we apply fertilizer to supplement what the soil can provide. But if you can't estimate what the soils providing for the crop during the crop growth period. The tendency always is to apply a bit more than you need as an insurance policy. The most important thing we don't measure well is the inputs from biological nitrogen fixation from legume and gaseous losses, the leaching losses. And those are mostly a problem simply because we you can measure it at one point. It's so heterogeneous over a field that you need the cost to do it well to get an average for even one individual field is exorbitant. So this is like you're driving blind, trying to get somewhere, and that somewhere is improved nitrogen use efficiency and reduce losses. But yet, the response to nitrogen in a given field follows a very predictable pattern. You have here work done in 1977. Now this work was done in uniform plots where soils are very uniform so you don't have the heterogeneity issue in time and space. And with these incredible tools this was a double label nitrogen experiment where they use the isotopic nitrogen to trace the nitrogen applied over several years. What you see is a standard that this would occur in any field, it may be with different numbers, but the patterns would all be the same. You have a as nitrogen applied increases you get an increasing yield to some maximum, and then it might level off or decline. Meanwhile, the nitrogen that's leachable in soil or available for loss via gaseous pathways stays relatively low until the amount of nitrogen applied. Exceeds the amount of nitrogen required for optimal crop yields. So the key is how can we control nitrogen to keep it in the efficient part of this curve. But the problem is that individual fields, when looked at across lots of them, when we try to measure things, this happens to be nitrogen oxide emissions, it could be nitrate leaching. You get a cloud of points really with fancy statistics, we can come up with ways to get a statistical central tendency, but it's not robust. And it's certainly not good enough for farmers to make management decisions on. Now, there are a number of parameters that define quantitatively nitrogen use efficiency, I won't go into them, but much has been written about them. Only one is very simple. We call it partial factor productivity, which is the grain yield per unit of applied nitrogen. So a grower knows how much nitrogen they apply, they know how much yield they get, and so they know the ratio of yield to fertilizer nitrogen applied. And we can also estimate a rough nitrogen balance, which is the difference between an input supplied and fertilizer manure and compost and end removal and harvested grain seed fruit or other crop materials. So these are the things that right now we can monitor. Can they, could these be useful? Well, it depends on the scale of assessment. And at a single field or farm level, they're good for estimating the direction of change, assuming you hold all else constant and assuming you're also maintaining your soil organic matter level. But if you're getting a smaller and balance that is a less difference between the amount applied and the amount removed, we know, because again, we know because every field behaves this way, we know that you're moving down. If you reduce the excess here relative to the amount the crop needs, we know that you would be reducing the losses. But you can't tell how much or get a quantitative estimate. It's simply not a tool for that. But a farmer could know if they're moving in the right direction assuming all else equal. And balance becomes increasingly robust as the scale of assessment expands to include larger regions watersheds and nations, and especially is the ancillary farmer data reported increases about soil texture soil organic matter rainfall etc. And with more farmer data and balance is likely to become a more useful tool at the field level. And finally, I think in balance can be improved with a highly focused national R&D program but we can talk about that. But I want to mention here that improving field level nitrogen efficiency is only part of the answer because we also need know that we must use other tools as well that reducing and losses through applied fertilizer through improving efficiency in these high yield systems is not enough you also need landscape design, perhaps constructed wetlands that choke points, high risk cropland retirement cover crops, etc. So recognize that I'm talking about part of the answer not all of it here, but a significant part. I want to highlight this that in my entire career there's been very little effort on a co cohesive coordinated program to get better estimates of the things that we need to measure or estimate to provide farmers with more reliable tools about how well they're performing on losses on and losses which is essentially the end of the day what what we're trying to reduce. I have every confidence that with a modest relative to say what we spend on many other things, a modest national program over five years you could get the you and the key is to understand the system so well that you can simplify a metric on the far side of complexity. So I want to conclude sustainable intensification is the path forward to meet food demand without massive expansion of crop and livestock production area and negative environmental outcomes, because highest efficiencies for land water energy and nutrients are saved in well managed high yield systems on good soil major bread baskets is a metaphor for good soils, as well as an irrigated systems worldwide irrigated systems here meaning your fruit not vegetable system which are also high yielding and receive lots of inputs. An issue is it possible to control the fate of apply, apply in any systems critical need for robust metrics to help guide and inform growers as they strive to achieve cost effective solutions, and to provide a strong quantitative framework to unleash public and sector research investments to accelerate development of technological innovations, innovations and breakthroughs to address the challenge. And I can tell you, I have every confidence, we can achieve a nitrogen pollution free high yield agriculture, if we focused on it. But the focus has to be on increasing yields and reducing the the environmental and health negative effects, and you have to do that work together we seem to separate the two. We have the environmental scientists going and measuring nitrate and looking at how high nitrate affects the biology or the health. And we have the agronomist, trying to increase yields over here. We need to put the two together we have to, we have to increase yields, and at the same time, reduce negative effects. And if you had a program with that explicit goal, well funded across a wide range of disciplines, not just agriculture. Any discipline that can help. I have every confidence that we can do it. Great. Great. That's that's great Ken, because I'm the environmental scientist, you're the agronomist. And so now we're going to open it up for a couple questions and we have Mark Bell has a question so Mark if you want to highlight your video we can spotlight you and you can ask your question. Can you guys hear me. Alright, thanks for your presentation. So I work out in California and on the human behavior side of nitrogen management. We often hear the nitrogen is crop insurance idea. And I part of that idea is that the percentage of the budget that is spent on nitrogen is relatively small so it doesn't really have a payoff to be efficient in the use of it. And also that the cost of over applying nitrogen are born are not bought born by the farmer but they're born by you know the public or the environment can you comment on those two aspects of that. But first off, so that others know that for commodity crops, unlike the high value vegetable and fruit crops of California, the cost of nitrogen is significant, just simply because the value of the crops are smaller. But in California, I think that perhaps that the challenge you mentioned is is one of the past because the new regulations that are in place are going to require growers to comply with water quality standards. And so I think in going forward, the California agriculture has an incredibly is possibly now at the point of the spear in terms with dealing with the nitrogen problem and regardless of cost. Asking requiring farmers to demonstrate it's up. It's the growers responsibility, either individually or in coalitions to actually demonstrate to the California water authorities and environmental authorities that they are complying with regulation so I'm not sure that any questions still relevant anymore. Well let's pick that discussion up during the overall question and answer period at the end. We're going to also hear the questions from john Jones and Jennifer McPartland, but now I'd like to move on to our next speaker Matt Helmers. So can thank you very much for an enthusiastic presentation. Matt Helmers is the director of the Iowa Nutrient Research Center, the Dean's professor in the College of Agriculture and Life Sciences, a professor in a department of the long name at Iowa State University. This research area includes studies of the impact of nutrient management, cropping practices drainage design and management and strategic placement of buffer systems on nutrient export agricultural landscapes. Today he's going to be talking to us on the geographic scale of the nitrogen challenge in the United States. Matt, over to you. Okay, thanks a lot, Jim, and, and certainly humbled to be invited. As I look at the other speakers I kind of am reminded of the Sesame Street song one of these is not like the other and that's the way I feel and in being on this panel. Maybe not not qualified and so I work a lot on the solutions or ways we can reduce nitrate loss from our agricultural landscape so I'm very interested in some of the talks that are coming up the next couple weeks. But what I was tasked with and this was I think interesting for me to try to put together some of this is thinking about the geographical scale and I think some of the things that that Craig talked about and maybe some of the questions. That we didn't get to be there we can kind of will kind of see why we see some why we may see some of the problems we do in certain areas of the country. And so if we can go to the next slide. So, as we look at, and this is this just illustrates cropland acres by county from USDA NAS from the sense of agriculture in 2012. And so it's not normalized by the size of the county so you'll see some of those counties up in Montana that are very large in size and have a lot of acreage but I think we can see, you know, areas that show up are some of the areas of the Great Plains, the upper Midwest, up into North Dakota and then out into California and areas of Washington so a lot of areas, a lot of landscapes where we would have annual cropland production, you know, some of these areas we some of these areas of corn and soybeans, certainly in the upper Midwest, a lot of corn and soybeans. But but I think it's important to kind of see where where we have intensive agricultural production throughout throughout the US if we go to the next slide. And then I think it's also important to understand some of the changes that have happened over time and and this is just for Iowa, but I think a lot of other states are would would have similar relationships and so I think this also. So we kind of think about this as we think about some of the changes and trends over time that maybe Craig talked about as well and so this is Iowa and that top gold line there is the acreage of corn in the state of Iowa. So there are sometimes when when I've heard, you know, we see an exponential increase in corn acres in Iowa, but actually since the 1920s, we've grown about 10 million or more acres of corn in the state of Iowa. So in a state of 36 million acres, you know, we've grown above 10 million acres of corn really since the 1920s. But what what has changed is if we look at things like the gray line there, which is the estimated pasture acres. If we look at the the kind of burnt orange colored line that's the old acres, and even the hay acres so if we look at those acres of pasture, hay and oats, we see that decline, specifically happening a lot after World War two. And so along with that came an increase in in soybean acres so that the or or the the green curve you see there that the one that really increases is our soybean acres. So we went from a more diverse cropping system where we would have had living plants and roots on the land a greater percentage of the year, some in perennial some in small grains. We've converted to primarily a corn soybean cropping system, which would would use water and then corn specifically using nutrients similar times of the year. And so as we think about things like when our precipitation pattern comes we get a lot of draw a lot of the upper Midwest we get those spring precipitation excess precip. That's when we can lose that nitrate so as we think about this I think one of the things we have to recognize is this change in land use that's that's come over time and we'll talk a little bit about some of the nitrate losses maybe from some of those those perennial systems. Also think is we think about maybe some of these areas we're seeing increasing trends in in nitrate. We also have to recognize what the lag time might be between the land management practices we implement on the surface and how long that it takes for that water to get to, you know, our groundwater in some areas that maybe relatively quick at some some areas, maybe a lot longer time. Okay, next slide. I think Ken kind of talked about this from the nitrogen cycle, but that you know I think the big thing that I'll focus on are those inputs of fertilizer or manure, and then the outputs that we see in the blue down at the bottom, whether it be seepage or artificial subsurface drainage. Next slide. So now, let's look at where we're where we see commercial fertilizer inputs across the US and then the next will be the manure. But this is from some work databases from USGS there kind of a few different folks that have put together some of these county level estimations of a fertilizer and manure inputs but this USGS one was one that the kind of could kind of look at. Again, this is not normalized by the size of the county so I think what's what's interesting is we see some of these counties in Iowa, for example, Kassuth County that's that dark blue one up in North Central Iowa, you know, pretty dark blue, but a lot smaller size than say some of those counties in in California. This is just total pounds of estimated total pounds of commercial fertilizer that are going into that that county. And so, you know, we see a lot of these areas with high fertilizer inputs are also areas with high crop land. So those kind of those corresponding. Okay, now if we go to the next slide, a lot of these areas also have relatively high amounts of manure livestock and so this is the estimate of nitrogen and phosphorus from animal manure. One of the things that I think is is one has to think about in sometimes looking at this animal manure is that some of these areas if we look at up in North North Central Nebraska. That big county there where Valentine is that would have a lot of beef cattle and some of those may be on pasture but some of that may be included in animal manure estimate so so kind of important to recognize but we can again see, you know, and in California, and then through some parts of some of Iowa for those that that know Iowa give you a little quiz can you can you guess which county that is up in the Northwest corner. What's interesting is that that's a county that has pretty high commercial nutrient or nitrogen inputs, and then manure nitrogen as well that's Sue County in the Northwest Iowa. I think now if we go to the next slide and combine these two. Yep, John Jones got it right Sue County. If we combine these two. We really see some of these areas and in the Corn Belt of Iowa, some areas of Nebraska that we've talked to a fair bit about, and then in in California, and then even into the high areas of Texas, where we have combined high pounds of nitrogen combined from commercial and manure and. So, and then we have high annual or high row crop production or high annual crop production in these areas as well. Let's go to to the next slide. Okay, so why might some of this this be important and and as we think about how nitrate may move Mary made a comment about high nitrates in surface waters in in some areas of Iowa, and then Craig and others have talked about some of the high nitrate in shallow groundwater as well and so I think we it's important to understand how the water is moving in those landscapes and how that might impact where where that drinking water source or why some drinking water sources may be impacted differently. So in many areas of the US we might have what we would call naturally well drained soils, so that we get precipitation, we get to a movement or infiltration of that that rainfall that we get. And then excess precipitation that's in excess of what the plant may uptake or of what the soil can hold may move deeper in the soil profile through deep percolation or through natural lateral flow pathways. And in those naturally well drained soils that leachate of nitrate and in some cases, phosphorus, we would see that loss of below the plant root zone moving in those deep percolation pathways or lateral flow pathways and so that would be why you know in some of the areas, maybe in western Iowa places in Nebraska, we might see that shallow groundwater high and nitrate because of that deep percolation that's moving, you know below the plant root zone. There are many areas in specifically in the upper Midwest where those soils are what we'd call naturally poorly drained, such that if it were not for what's in there which is artificial subsurface drainage network, those soils would stay saturated a great percentage of the year. Early 1900s early settlers came into these landscapes started to drain this landscape with a series of, you know, drainage ditches stream straightening drainage ditches, and then this artificial subsurface drainage network. So in those landscapes that infiltrating water that that would move nitrate below the plant root zone is short circuited to the stream through these subsurface drainage networks and so there would be direct delivery of that that nitrate that's intercepted by the drainage system right to the stream so that in those landscapes so that's where the delivery of nitrate or big delivery mechanism for nitrate to the streams but I think it's important we lose nitrate from both of those systems. It may just be delivered to the downstream water body whether that be groundwater or surface water in a different fashion. So let's go to the next slide. This just illustrates the estimated extent of tile drainage and this is from the USDA Census of Agriculture in 2017 that illustrates we look at that upper Midwest landscape of Minnesota, Iowa, Illinois, Indiana, Ohio, very dark blue. So high amount of this artificial subsurface drainage in those counties. And if you think back those are many of those counties are also high in in annual crop production and high in nutrient inputs, such that now we see high nitrate coming out of those tile lines from from those systems. Let's go to the next slide. So I think this just build a little bit on on Ken's point and maybe illustrates some of the challenges that we have in certain landscapes maybe on in some of these areas with these these high productivity soils higher organic matter soils and so this data. Right here is all from from Iowa. Okay, from replicated drainage plots that we have in Iowa. Most of a lot of the data is from North Central right in the heart of that area and blue and tile drainage country. But this is so in Iowa. These are primarily a corn soybean cropping system corn soybean rotation. And this is looking at the nitrate concentration that's coming out of the drain line flow weighted annual nitrate concentration for for the corn soybean cropping system. And this is the concentration of the nitrogen that's applied for that corn crop. Okay, and what we see is that as we increase nitrogen application rate this is similar to what Ken showed as we increase that nitrogen application rate. We see higher nitrate coming out in what's lost below that plant root zone and then picked up by the drainage system. One of our challenges in many of these soils is even when we have put we put no nitrogen down in this annual cropping system. We still see nitrate concentrations in that tile drainage water of five to 12 parts per million so even you know in a year or two, even above the drinking water standard. Now, it is important to recognize. We have some restored prairie plots, similar to these. And we've monitored for those for about 10 years, and the nitrate concentration leaching below the prairie root zone intercepted by our tile lines is less than one part per million. So if we, you know, have those perennial systems out there living roots, living vegetation, a greater percentage of the year. We see much lower levels of nitrate in that tile water, and I would say those prairie treatments also got nitrogen fertilizer of 75 pounds of nitrogen per acre per year or right around that. Next slide. Okay. And, you know, just to kind of illustrate kind of this point about the impact of, you know, cropland and annual cropland. This is some work done a while ago now, but a colleague, Dr. Bill Crumpton, looked at relating flow-weighted nitrate concentration, the red dots there and red curve, related to land use in the Upper Miss and Ohio River basins. And we see a strong relationship between, you know, as we increase that annual cropland, we see increasing nitrate concentrations. Next slide. Okay. And this is, again, just illustrating one of the rivers in Iowa, the Raccoon River, that primary drinking water source for the city of Des Moines, illustrating that many times that the river water is above that drinking water standard of 10 parts per million. Next slide. Okay. And I found this interesting as well. This is a map from USGS that I think fits well with what Craig talked about, is the predicted nitrate and shallow groundwater in many of these areas. And we can see, you know, in those areas of, say, the high plains of Texas, areas of Nebraska, areas of California, those were areas with high row crop, high nutrient inputs, either manure or commercial fertilizer and estimated to have high nitrate in that shallow groundwater. You'll notice that if you look really closely in Iowa, there's not quite as much red as what we might think, and a lot of that think is because, especially as we look at some parts of Iowa, because of that tile drainage that we have that's taking that right to surface water. And because of those poorly drained soils that would prevent some of the movement below the plant root zone. Okay. I think my last, one more slide. Okay, so my summary, again, maybe not anything people don't know, but we have substantial areas of the US and annual crop production. The amount in annual crop production is grown over time if we, as we decrease maybe some of the pasture and hayland in areas, a lot of these areas also have extensive nitrogen inputs both from commercial fertilizer and manure. We can see nitrate leach below the plant root zone and that's susceptible to loss to downstream waters, both surface and groundwater. And, you know, that tile drainage drop much of the upper Midwest delivers nitrate that's lost from the crop root zone to streams. And as we look at it, you know, we combine that crop land with N inputs. And we, you know, it's no surprise that we see elevated levels of nitrate in our surface and groundwater resources. So with that, happy to answer some questions. I think we have a couple minutes left for questions. Oh, we do. Thank you very much, Matt. That was excellent. So we have some time for questions. So David to Jack, you have a question in the chat. Do you want to show us your video and ask the question. You bet. Thank you. Do any of the speakers today have any sense of how important failing suck septic systems are to the overall contribution of nitrogen to the ecosystem. There are over 20 million households that use septic systems in the US. And there are reports that a sizable percentage are failing over. Yes, I don't have, you know, any, any data in particular on that, you know, I do think as we look at some of these areas. You know, we still need to recognize that the big footprint that agriculture is having in those areas too but but we should certainly shouldn't diminish those those other potential sources and so. Yeah, those septic systems are something that we need to continue to look at and I don't know if anybody else has any specific information. Other questions. Looking for any questions in the slack. I have a question for you. Let's take us out 20 years. What do you predict. Well, that's a great question. And so that's where I think the next the next thing on on thinking about solutions in the next few weeks are important. You know, I think that we can look at look back in time. You know, there's a big movement on trying to get, you know, cover crops on the landscape. Crop diversification can help us, you know those living roots we have we have a lot of data that cover crops, diverse crop rotations can really help us so you know I think history, kind of a history buff you know history can be a good guide and we can think about what our landscape look like, you know, 6080 years ago, with a more diversity on the landscape, and in some areas that may be diversity and crops. In some areas that may maybe diversity and in wetland strategic wetland placement, prairie strips, you know, a number of practices so I think we have a lot of those those tools out there. But I think, you know, one of the guiding principles is having something growing on the land, a greater percentage of the year to take up water and to take up nitrate that may be in the soil profile. Now having received any questions. There's a question. How do you think about incentivizing that that diversity I mean I think that's, that's one way to do it I think that, you know, one of the things is, you know, can we can we build markets for those, you know, so that they're a bit self sustaining. I think I've been back in Iowa for almost 18 years and people we need a third crop in Iowa and people have been saying that for a long time. I think we do, you know, we need other other crops that are other systems that can be economically viable to There's a question there about something about the changing climate on end losses and I think that is that is, that is a big issue and and somebody asked that kind of a craigs as well. And so, you know, at least throughout some of the upper Midwest we see projections for wetter springs and drier summers. And if we see some of those wetter springs. And that's the period that we don't have anything growing and so we'd be more susceptible to leaching losses in the spring of the year so and I think that if we get more preset. We are likely to get more water movement through the soil profile and more nitrate that's going to be lost from that soil profile. That was my trying to answer can you say something about changing climate on end losses. So increasing preset. Okay. Don't see any hands. Let me. There's one last one has there been any work looking at declining hay and pasture acres in Iowa and increasing in in loading. There was some work that Jerry Hatfield is on Jerry Hatfield and Chris Jones looked at some of the raccoon river data if I'm not mistaken, and looking at, you know, kind of a long term history and and changes in some of the land use that we've seen and the increases in in nitrate that that we're seeing in the raccoon river and so I think that kind of illustrated how that reduction in the diversification of the of the operations led to some increased nitrate loading in the river. We have a question from Kathy clean. Great talk. Hey, this is actually a question that that Craig threw in in slack or in the chat but I wanted to answer and ask what, um, what, how successful do you think cover crops can be, if there is extensive adoption. I think that is a platform forget about the problems of incentivizing for the moment just can that work and and what needs to get to be done in terms of development of seed or other variations to do that. So yeah, I think I think cover crops can be can be quite effective. We have a lot of data from North Central Iowa so you know I think they're going to be areas of the country where we can get more consistent growth of the cover crop but even in North Central Iowa which you know Kathy is, you know, it's pretty can be a pretty cold area in a challenging area to get cover crop. We, we've still been able to see you know 30 to 40% nitrate reduction when we've implemented that winter cereal right cover crop so you know I think now if we go into Minnesota that you know it might be a little more challenging there but I look at you know if we can do it in North Central Iowa. You know I think we can do it a lot of areas. I think that could be remiss I should have talked, but I think cover crops could be especially effective in areas where we have integrated crop livestock systems where they can raise those cover crops and really see you know some short term from that. So as we think about that diversification of the system is now how do we get back some of those integrated crop livestock systems where there's a greater need for forage within the operation. Awesome just a quick shout out we're going to hear more about cover crops and the next and the next work next week so but thank you that's super helpful. Okay, we have a question from the slack that I think you can see that. I don't have slack. It's in the chat but I'll read it. Is the sunk cost of our current production system going to allow the kind of changes necessary for environmental improvements. A previous presentation so that should suit Kelly didn't person participate in a study, which tells me there is stiff political resistance to some of these issues. I think there, there are certainly challenges with this, without a doubt. Yeah, I, you know, they. Yeah, certainly there there are there are challenges you know we have it. And I think we should recognize has taken us, you know, it. This is not something that's going to shift overnight. It's going to change as well you know I mean this is it's taken us quite a while to get into this type of system it's going to take us a while to change that but I think they're, you know, their opportunities as we think about, you know, society and thinking more about where their food systems come from. I think they're going to be more and more opportunities for, you know, for thinking differently about how our landscapes are used into the future. Thank you very much. It's a pleasure to have heard your talk and see you interact with people and now we're going to move on to Eric Davidson. So, Eric Davidson is the Professor and Director of the Appalachian Laboratory at the University of Maryland Center for Environmental Science. His research includes terrestrial nutrient cycling, greenhouse gas emissions from soils. He's the global biogeocompatical cycle and sustainable agriculture. He's the past president of the American Geophysical Union has served as editor of a number of biogeocompatical journals listed too long for me. Today Eric is going to be talking to us about the leaking the nitrogen cycle, the leaking nitrogen cycle across scales from far to food services to ecosystem, very broad scale. Eric, good luck. Thanks, Jim. Pleasure to be here. Thank you for the invitation to participate. I want to recognize my co author, Xin Zhang, who is a professor at the Appalachian Laboratory as well and his contributions is very significantly to the content of this presentation. The concept of a leaky cycle is something that Mary Fyerson and I came up with a metaphor a while ago about when we were trying to figure out what controls trace gas emissions. And of course that's not the topic of what we're doing here, but I wanted to bring that up in terms of showing that this notion of nitrogen flowing through a pipe and holes in a pipe is where the pollutants that we're worried about are coming out. This is a useful metaphor that's since been adapted to think about the crop production system and animal production systems with leaks in both of those pipes, both in terms of gaseous products going up to the atmosphere and soluble forms, particularly nitrate is what we're concerned about here. Other soluble forms could also be converted to nitrate once they get into groundwater or into streams. And the metaphor has us, you know, is that we put nitrogen into that crop production pipe in the form of synthetic fertilizers and manures and nitrogen, biological nitrogen fixation. Out the other end of the pipe we get some crops that we consume directly, but it's surprisingly the vast majority in terms of the amount of nitrogen gets fed to animals to livestock, and that in turn is yet another pipe with a whole bunch more leaks in it that can result in nitrogen going into the environment. And at the end of the amount that we actually consume is really a very small fraction of the inputs. And so that's why it is sort of an inherently leaky pipe. There are some things that we have control here we have control of the types of inputs. We have some control of the efficiencies and we've already heard some about some discussion of that in terms of the cultivars in terms of cover crops in terms of other best management practices like stratification inhibitors and things like that I'm not going to go into those the subsequent talks in subsequent weeks I imagine are going to go into those and more into more detail. In some cases we can some of those things that we can use best management practices can help us plug up or make these these holes in the pipe a little bit smaller. And so that we have less of that surplus nitrogen leaking out. And then I'll just mention in passing very briefly that there are also some possibilities of you know engineering treatments that would all say it at the edge of field. And I think that's another topic that's going to come up in a couple of weeks that will be delving into more deeply. So this diagram is sort of like a leaky pipe here we have the plant growing in the soil and we have the different nitrogen inputs and by the way the size of those blue arrows are roughly proportional to the global average the global sums of those different inputs into systems. There is some cycling within the system. There is a crop product that's taken off and we often think of it in terms of the grain but it could also be if there's straw or or Stover that's actually removed and used for some other purposes. And then we have these leaks in the pipe that are in terms of the volatilization the gaseous losses and the leaching and runoff including nitrate which is our focus here. And what Jin Zhang my co-author here and I have worked on is is defining how this system works and how we can look at trends over time and I'm going to introduce a few concepts that actually can is already introduced. He talked about nitrogen use efficiency. He talked about one that's a little bit different than the one I'm defining here. He talked about partial factor productivity. I'm talking about simply the ratio of the nitrogen that's removed from the system over the inputs. And then what I'm calling and surplus and can called and balance and that's simply the difference between the inputs and the outputs. And then we can rearrange those equations in this particular way here that allows me to show the next diagram. Which is a little complicated but let me let you walk through it and so in that in on the X axis we have the yield. Of course we want higher yields when we can on the Y axis we have nitrogen use efficiency that goes from zero to one. So if we were perfectly efficient it would be a value of one if we're soil mining taking more out of the soil than putting back in then you get values greater than one. And what these this example shows on the shading that the different shading here is the end surplus or and the further you go down into that dark deep dark chasm of black the more and surplus you have in the more end pollution. And we've already seen diagrams from previous speakers showing that there is a scatter but there is a correlation between and surplus and and balance and nitrate leaching or gaseous losses. And here are some examples of various countries that fit in in this space. The United States is this light blue one going from 1961 with five year intervals here and during that time after in the 1960s and 70s yield was increasing in the United States and efficiency was going down. But then with a whole bunch of changes probably including different cultivars and different management practices increased irrigation a lot of other factors. Yield started to increase without further declines in nitrogen use efficiency. And in fact recently yield has continued to increase and we're starting to increase efficiencies. France is another example that has increased its efficiencies and this is largely due to the nitrates directive in in Europe and also reduce subsidies. China on the other hand has followed this path of of subsidizing nitrogen fertilizers for a long time and emphasizing food security over everything else. And so they've increased nitrogen use very high rates of end fertilization and as a result they've increased yield but also greatly increased nitrogen pollution. What we would like to have of course is that all countries would move over here to the right. And if we do some projections of the food needs in 2050. Take that from an FAO report and just take an average of what we would need in every country in order to meet those demands. We would have to have a yield that was in in the order of a little over 100 kilograms of nitrogen per actor per year taken off of the field in the harvested crops. But if we also look at the the literature on planetary boundaries and what is sort of the limits of safe operating space including leaching of nitrogen. We want we would prefer to try to keep our end surplus that difference between crop yield and what's taken off the crop and the inputs to 40 or below 40 kilograms per hectare below. And so what we really like to do is move countries of the world to this upper right quadrant where there's sufficient food production with low pollution. And you can see that nobody no country has has has gotten there and none that I've shown here but many of them are starting in the least in the developed world starting to move in that direction. And there's even some data recently that China has started to turn the corner a little bit here as well. But I want to talk about more than just crop production. I want to put it in a broader scale of of it's it's not just producing the crops but also we need to think about how it's integrated with the animal production system. We just heard about that in the last Q&A system Q&A session how that is integrated with the agro food system how we transport to market and actually consume it and then how that fits into the landscape. And so I want to present that in terms of how efficiency changes as we move from one part of this continuum to another. And remember that slide that I showed you before with all these different countries showing yield and and nitrogen use efficiency. The global average for NUE was about 43%. So let's start with a point right here at 43% for the cropping system. As we move from the cropping system to the crop animal system we add this second pipe remember so we now have more another pipe with more leaks in it. And as a result our nitrogen use efficiency on a global average drops to about half. And then finally if we consider the food system which includes food waste both waste that happens on the farm especially in developing countries. And in the in the production of food and at the at the dinner table especially in developed countries that efficiency drops even further. I think in the next few weeks we're going to hear about a lot of the ways that we can deal with each of these technologies for improved management practices. Maybe some market and policy incentives some shifts in crop mixes that we just heard about including improved livestock management of managing their feed. More integration reintegration of animal production with crop production and this hence more efficient recycling of manure. And also some things that can be done to reduce food waste and to affect dietary choices. So we think of these different systems as being a hierarchical system where the cropping system is nested within the animal crop system which is nested within the food system which is nested within the ecosystem. And if you put together that that acronym of CAFE it comes out as CAFE. This diagram is a little complicated but I'm showing it to show that we can actually put numbers to these boxes and arrows. I'm leaving out the losses because that would make the the diagram even more complex. But I just wanted to show that that's the way we can do those sorts of calculations and we end up with something like this and comparing different countries. Starting out with China. Notice that China has a very inefficient cropping system and it has a very high end surplus in other words low efficiency high surplus. And we've already talked about how they have very high rates of nitrogen fertilization there. Denmark on the other hand has a somewhat more efficient cropping system. But when you add their animal production system it because that's the biggest source of their end surplus. And that's because they import a lot of feed for an agronomic system that depends very largely on output of animal production. In the U.S. we have relatively high efficiencies that's because because of the crop mix largely we have a lot of soybeans for example. But notice that of the overall total end surplus this step going from animal crop system up to food system is is a pretty significant part of our total end surplus. So there's a lot of consumer wastage a lot of food wastage that perhaps could be ameliorated in in the U.S. And then we get to a developing country like Malawi there's so little nitrogen fertilizer used there it has a very low end surplus. In fact some areas it's probably they're probably still mining the soil. And so the problem there is not so much surplus but food security. Now I presented that in terms of countries but it could also be we can think of this in terms of a catchment or a watershed. And this is the upper Potomac watershed this is work done by a student who recently graduated Robert Sabo and is now working with EPA. And he's done this analysis of the upper Potomac to give you perspective here of Washington D.C. is just a little bit off to the lower right here. And there's gauging stations here and also gauging stations in a couple of the sub watersheds of the Shenandoah River north and south folks forks. And what we show over on the right is the historical trends of changes in loads from 1986 to 2012 of the load to to to the rivers. And what we see is that point source loads have decreased in all of these watersheds mostly due to improve sewage treatment over that period. However expansion of Turkey production and other poultry in the Shenandoah sub catchments has greatly increased and load from agricultural systems. Although not so much from the overall upper Potomac in fact there's actually been a decrease in load due to some improved efficiencies. There's been decreased nitrogen deposition. So there's a lot of forested area in there and because it's receiving less nitrogen deposition there's less load from the forest area into the rivers. And overall this expansion of Turkey production has canceled out the improvements in the Shenandoah watersheds. In fact in some cases canceled it out completely so there's an increase in load. But overall for the whole Potomac there's an overall decrease in load because there's been modest improvements in each of those sectors. Finally I just want to mention that as I said at the landscape scale when we start talking about moving up that hierarchy all the way to the ecosystem. We think of not only losses of nitrogen from grazing lands from agricultural lands from industrial waste. Someone talked about septic systems failing septic systems and whether we have denitrifying septic systems sewage treatment plants. There are additional opportunities in engineering of putting in bioreactors riparian zones constructed wetlands natural wetlands to try to intercept when we can't reduce those leaks to intercept what's leaking out and try to reduce it before it becomes a human health hazard. So my take home messages are that there are inputs and efficiencies and leaks of nitrogen into the environment that can be managed and we're going to hear a lot about that over the next few weeks. Efficiencies generally decline and surpluses increase as we move along that crop animal food ecosystem cafe continuum. And that cafe framework helps us identify the scales where policies may be most effective in mitigating and losses. So the answer for China might be different than for for Denmark or the US and it might be different for the Shenandoah watershed as opposed to the entire Potomac and so on. So with that thank you very much for your intention. Okay well Eric thank you very much a great presentation. I like the dark pit of nitrogen pollution. Nice little image. And now we open up for one or two questions for Eric and then we will go broader for all the panelists. So, Eric, I'll ask you a quick question, which is about that dark pit of nitrogen pollution you had on one of your slides. I noted the data stopped in 2011. Are the lines can you mention that China was getting perhaps better. How do the other countries look. We've updated some of those to 20 2014 or 2015. But there is a lag between the time that we have data available and the time that we can put it together there and so I can't really speak to that very well I'm afraid. Okay, thank you. Any other questions for Eric. Okay, well this concludes the individual presentation and questions to the individual speakers. Now we go into a 25 minute session for questions for the panel and the floor is open. And so I know that for most people there were questions that didn't get to be presented. And so this would be your opportunity to present those questions at this time. So I'm looking for hands up. I'm looking for something in the chat and I will try to be the ringmaster here. Okay, John Jones. Thank you. Thank you James and thank you to all the panelists this is really just excellent content and really a lot of fun to listen to. I noticed a nitrogen use efficiency is a great metric for either an agronomic or environmental performance of the system, but it doesn't always capture the high flow time the high concentrations or the high flows that occur that Dr. Homer's alluded to that happens different at different seasons at different times. How do we take a large approach and large geographies but still capture those periods of fairly high concentrations or loads that could deliver nitrogen and other other nutrients to to water bodies. Who wants to take a crack at that. So, John, I think the, the high flow problem, the peak, the short term episodic high capacity times. I think are going to have to be dealt with by landscape engineering. So in other words, on farm on field efficiencies are important. But they're not enough. You're going to have to have, you know, I've seen study and talk about a good researchable topic. There has been some good work on it, but I think it could be much better now with the new tools and the remote sensing and such. But the question is, what portion of existing farmland would need to be retired to catch 80% of these episodic event flows, because they do funnel through certain parts of the field. So you don't have to take out large parts of a field to catch most of the flow. So sometimes we're going to have to look at outside the field management per se to other options to catch these episodic events that are, yeah, probably beyond control at the field level. So I guess I would just add maybe a couple of things there is that I think that one challenge is that how nitrate moves. It's not quite, you know, especially with surface runoff, I think we can do some of that that is the smaller portion is smaller portion of the land is disproportionately contributing that may not be quite as much on on the nitrate. I do think in some of the tile drained areas somebody asked the question, I think there are things we could do with water management in these landscapes to try to capture some of that water and and reuse it as well. Again, that works where we know where the water and nitrate is coming out, you know, in the from those drains, you know, I really think in, you know, as we think about some of those landscapes where we don't have the drainage, you know, really trying to think about how we can have you know something living out there greater percentage of the year to reduce that residual nitrate in the profile. And so, you know, one of the things that we see in a lot of our drainage is that we see a little bit of an episodic kind of bump temporal bump and nitrate concentration, but not as much as you think if there's drainage that night, we see nitrate in that you know sometimes late in the summer it'll go down a little bit. And certainly we would expect I just say this right now throughout a lot of the upper Midwest I would expect if we get spring rains we're going to have high nitrate in our surface water because of the drought that we had. But, you know, a lot of times, it's remarkably stable throughout the year so it's, it does kind of come back to, you know, how can we limit some of that water flow and reduce the overall residual nitrate concentration in the profile. Anyone else would like to contribute an answer. Okay, Mary we have a question for you. Do you know the average background concentrations of nitrate in our saliva in the absence of any added ingested saliva. Yeah, I do not. But I would, I will hazard a guess that it would be low, although there is, depending on inflammation and other sources of nitrogen oxides in our body you could potentially have higher levels. I think again there's probably this inherent variation based on people's oral microbiome. A number of different species reduce nitrate to nitrite and we're actually doing some interesting work in collaboration with colleagues at University of Maastricht in the Netherlands who are in feeding study where they gave people controlled amounts of nitrate in drinking water at fairly high levels, but below the right at the acceptable dietary intake level in them in the EU. And it was actually the nitrate they looked at other things like different types of meat process me. It was actually the nitrate dose that changed the oral microbiome so we're just submitting that paper for her publication on the different types of meat didn't seem to make any difference and this is a fairly short term feeding study. But in terms of what that baseline was I could go back and look at our data bank for that particular study but I don't know that there's been a real systematic look at that. So Craig, you got your hand raised. Yeah, I have a question for Mary. I'm still stuck on the episodic nature of nitrate contamination and I was just curious. Your presentation suggested that maybe the adverse birth outcomes or other. I'm not being very articulate. Are there adverse outcomes that are more closely related to short term episodic exposure to nitrate versus, you know, the more chronic exposure that we tend to focus on more. Definitely for the game the most well studied are these abnormal congenital abnormalities or congenital malformations of the central nervous system sometimes called neural tube defects so it's in that first trimester of pregnancy when the neural tube is closing that the malformations are occur. And it's very critical what the exposure is during that, you know, roughly three month period. And, you know, different studies have done varying degrees of really trying to get at that level accurately because as you pointed out there isn't always data for, you know, quarterly measurements of nitrate for example, in public water supplies and certainly for private wells it's, you know, in the data I presented for Brenda, I didn't have time to go into the study design but they did try to estimate levels in private wells through modeling but that was, you know, sort of a everybody kind of got one level. So, there's a lot of uncertainty in the exposure characterization but certainly for congenital malformations the critical time is pregnancy and for neural tube defects it's that first trimester. For spontaneous abortions I don't know if it's really known but certainly again you're looking at pregnancy not a really long period of time. Thank you, Eric, can you have your head up. Yeah, I wanted to ask Matt about the historical record of different crops in Iowa since World War two. Since you showed that dramatic decline in in pasture land, can is it correct to infer from that that there was a lot more grazing on and that the grazing may have been interspersed with cropland and therefore there was probably more integration of crop and animal systems then and better recycling of manure at that time. So I think, yeah, certainly I think the farms would have been a lot more integrated than, I mean, you know, speaking from my own family's experience, you know, they would have had livestock on the farm and grazing on the farm and utilizing most of the grain that would be fed to the animal. So I think the manure would have been more distributed. I think that, you know, if we look at it, it probably was that that was deposited in the field would have been very close to the buildings, you know, so I think there would have been more, there would have been the animals would be more distributed on the landscape and we've had a lot of, you know, around the building sites probably the, you know, a lot of that manure would have been deposited right there but you wouldn't, you wouldn't see, you know, 4,000, you know, hog units, like, like we see now. So what do you see as the major impediments for farmers to be have an incentive to try to reintegrate animal crop systems. I think economies of scale are one big one. Eric, for yours, I'm speaking, we have a question for you from Slack. How do wetlands, how wetlands could intercept the nitrogen leaking that we cannot manage. Okay, well, from an engineering point of view, you know, Matt already mentioned that, you know, and I think Ken did as well about the, that there are possibilities of managing where the water goes and if you can manage where the water is going to divert it towards a wetland whether it's a natural one or or a constructed wetland, then it can go into a place where there's native, there's vegetation that can take it up and also so probably some anaerobic conditions where the nitrate can be denitrified, hopefully all the way to end to and not to end to oh which would then create a different environmental problem which is a greenhouse gas emission. So that last slide that I showed you was from a workshop we did 10 years ago on that was focused really on those types of engineering solutions, it's probably time for us to do another one. Although I think that might be one of the, the, the topics of of the seminar two weeks from now or later in this series. But even back then 10 years ago, there was a lot of work being done on constructed wetlands and how effective they were at reducing the nitrate coming through the system. There is one caveat, however, is that it can actually increase phosphorus leaching. So developing environments can actually liberate phosphorus so we have to be careful about those sorts of tradeoffs as well. Great thank you Mary we have another question for you several the folks would like to know potential health effects of nitrate and drinking water below 10 milligrams per liter. Okay. Well, I covered some of that in my talk. The way that we've seen increased risk of colorectal cancer and four out of five studies and those were with the exception of one study that did have some of the population living in private wells with elevated levels above the MCL. Those were largely below the regulatory limit and I mentioned in one study that was a case control study in Iowa actually it was in the subgroup that had lower vitamin C intake. Below the median it wasn't extremely low but the population that had lower intake of vitamin C and higher intake of red meat. So for cancer. And that's kind of where we are I don't, you know that's not really a lot of epidemiology studies. When you look at the I arc reviews that are done to identify carcinogenic hazards. We're looking at a lot more studies to, you know, draw firm conclusions from the epidemiology data the reason nitrate ingestion was considered to a though which is a probable carcinogen same as glyphosate which you might have heard about is because of the very strong animal data and human mechanistic data. So other health effects again there's just a handful of studies of thyroid disease but they're kind of showing that there may be something going on at levels, perhaps below 10 milligrams per liter. And then certainly I think that studies of neural tube defects. Again it's sometimes for different specific defects and this isn't my area of expertise. I would say that those studies look fairly strong. We covered that in our review with Jean Brenda reviewing that literature and she came to the conclusion that you know there was fairly consistent results for neural tube defects and again most of the studies had at some people exposed below 10 milligrams per liter. So that's kind of where we are and we're hopeful we'll be able to at least look at on additional cancers and thyroid disease in agricultural healthy population we have quite a range of exposure levels. Okay, thank you so we have a question for anyone. Can you speak to the impact of nitrogen in agriculture in the ever blades areas of Florida, especially for sugarcane farming regions. Now note that Wendy Graham is speaking next week she's from Florida. So maybe just a general answer if anyone has any expertise in that area. Okay, we'll just have to wait for Wendy's talk. So what do we have next we have no hands raised. I have a question for the panel. These are because of the focus these talks are mostly focused on the United States. What country of the world would we look to as being the best with respect to managing nitrogen and agricultural systems. Based on our data. I would say you the United States is one of the best. You know, obviously that doesn't apply to the entire. That doesn't mean that there aren't regional problems of course there are huge regional problems but in terms of national statistics. I would say that we, the United States has among the highest efficiencies and and probably I think someone maybe it was key can looked at in pollution as an intensity factor, so that it's a pollution divided by your production, and I think we would come out pretty well in that regard. Um, we have a question from Peter burner how effective are enhanced efficiency fertilizers. Are there any downsides to enhanced efficiency fertilizers. So I can, I can, I guess answer a little bit about what we've, we've seen or some others in the upper Midwest. You know, we've, we've seen and there's been some work specifically in Minnesota that gals Randall is done looking at at an inhibitor nitro pyrin. We've seen some reduction in nitrate leaching with the use of that especially if it's fall fertilizer but less effective it's if it's used in the in the spring so not seeing as much difference when we use it in the spring, compared to not using it in in the spring, just traditional I think it has some impact but you know we're again we're kind of looking at maybe five to 10% reductions so you know some incremental gains but I did see there was one how effective our riparian vegetative buffer zones and crop systems to capture the excess nitrate. From, from my perspective they can be very effective if that nitrate interacts with the root zone, or that zone underneath that that buffer. And so you know in some areas, it's short circuited through a tile line and that's why there's a practice saturated in the rivers that somebody else maybe Jane Frankenberger will be talking about, you know, in some of those areas with deeper groundwater flow there may not be an interaction to see some of that nitrate removal. You know where they're, you know where we have that interaction with that carbon rich zone below that that buffer strip prairie strip, you know we can see pretty substantial nitrate reduction. It's kind of the water and nitrate has to see that zone. And I think we have time for one more question. Getting back to the inefficiency fertilizers of their math right. It's a relatively small contribution but we need all hands on deck. The key is that we can't predict really very well where they work and when they work. They're very erratic and it gets back to that. The question I was raising that that that's the kind of focus that a good national program could answer in a fairly short time. If we put our minds to it at relatively reasonable cost. Thank you, Ken. So this is from body keeler to all the panelists and especially Mary curious what Mary thinks about how scholars have extended her research to make estimates of damage costs. For example reference reference link earlier, and then Grisham Sutton estimates from the EU. Do we know enough to estimate the damage costs of nitrogen in drinking water. That's a tough question. Again, I guess you have to way. I know the environmental working group did an analysis. You know, I think some of the cancers that were included in that analysis I guess I would not agree that there's really strong evidence yet. But I mean I think it's a worthwhile exercise to do that because you know that's kind of the external costs of our food production and I actually had a question myself because it looks like in upcoming weeks there's really not much about economics and I wondered kind of two things I mean a lot of the soybeans and corn in this country are fed to animals which is very inefficient way to get your protein. And indeed, you know, there was some of the cost of nitrate pollution, either direct impacts for human health or for environmental health were incorporated into the economic system that would certainly make things more expensive, especially me, but would potentially, you know be a mechanism for reducing nitrogen inputs. That's probably not even in with a new administration likely that that will happen but I just thought I'd mentioned that in Craig, Craig pointed out that there's someone pointed out early that you know, non point source pollution is not regulated. So the CAFOS have to regulate are regulated but the farmers applying nitrogen to the fields that's not regulated. Ending the question and answer period with the question about meat was near the dinner hour, we'll make this give us all food to potter food to think about. Now now going to turn over to Kathy who's going to preview the next session. Thank you speakers very much. You collectively did a fantastic job. Awesome. Thank you. Thank you, Jim, and all the speakers everybody that's still hanging in there at 530, give a virtual round of applause. That was really remarkable and really laid the foundation, as we hoped it would. As an economist I can't help but jumping in a tiny bit with Mary's last comments, their spot on Mary and others it is our hope that the economics of all of these issues run through the discussion and conversations so it is not meant to be off the table. At all it is definitely part of the charge. And in fact we do have an economist on the panel next week and and others so all I want to do now is say a giant thank you for everybody and tea up next week. At the same time, same place. Seven days from now, we will be looking more at decision making and options for control of nitrate losses at the farm level at the farm gate, so to speak. We will definitely get into incentives on behavior and economics. Linda Prokope from Purdue University is going to kick us off talking exactly what it is that we know about the decision making that stakeholders, particularly farmers, engage in how do they decide what to plant, how do they decide how much fertilizer, what plant, what crops to grow, etc. And so that will also certainly touch on economics but also behavioral aspects of social sciences. Bruno Basso will talk about the role of digital agriculture which came up a bit today. Cover crops, we're going to get a nice dive in including some really interesting economics information that Alejandro Plastina has collected. Lisa Schulte Moore is going to talk about integrated prairie systems as we heard today it's very important to think about getting roots back in our annual systems and they've got some amazing field trials to share with us. Then we'll be talking about the whole role of water movement, infield water management, irrigation issues in Nebraska, tile drain systems we're going to learn more about from Jane Frankenberger and what can be done with those systems. And then we're going to look directly at nutrient management, the kind of efficiency that we heard some about today with fertilizer application from Kerry Bulmer Sanders. David Lee is going to catapult us into some future technologies to monitor and loss and farm fields. And we're going to get a good snippet of information about issues in Florida and activities that research and what has been learned there about end management. So thank you all very much. We are delighted to have you. I'll sign off now and I really hope that you can join us next week. Keep bringing those questions, keep giving us reactions. Take care everybody.