 Okay, let's get started with our second talk for tonight. We're gonna talk about nitrogen, which is one of the most important nutrients in the soil. And here to discuss how nitrogen cycles in our soil is Carrie Knudsen. Carrie's the horticulture agent in Grand Forks County and she received her master's degree in horticulture from North Dakota State University. And she's currently working on pursuing another master's this time in natural resource management. So Carrie's been with NDSU Extension for 16 years. She is an expert in plants and gardening and soil are her passions. Okay, someone who please soil is a passion. That is a unique person. You're crazy, Carrie, I gotta tell you about that. But Carrie, I can't wait to hear your talk. Welcome to the forums. All right, thank you Tom for that introduction. And I will admit that soil is not as flashy as those pictures that Don showed us of the melon. But if we didn't have soil, we wouldn't have those melons, right? So true. All right, so tonight we're gonna go through talking about the different roles that nitrogen does for our plants and our gardens. We're gonna talk about the different processes. The nitrogen cycle is very process heavy. I think that can be intimidating for a lot of gardeners. But we're gonna take the time to go through some of that terminology. We're gonna briefly touch on the nitrogen and carbon cycles, how they're intertwined, a little bit on synthetic nitrogen, and then finally look at the nitrogen cycle as a whole. And then mention some environmental impacts from having excess nitrogen in our soils and then how we can more sustainably manage nitrogen in our gardens. So what does nitrogen do for our plants? Well, if you've been gardening for any amount of time, even I've experienced this, you have plants in your garden that are a little bit smaller, they're a little bit yellow, they're just not performing as well as some of the other plants in your gardening space. And those are usually clear indicators that your soil is lacking some nitrogen because nitrogen stimulates growth in our plants, the roots, leaves, and stems. It gives plants their deep green color because it's an important part of the chlorophyll molecule. And it's a building block. It helps plants build their organic tissues, which we eventually get to eat. So we're gonna start on talking about some of the nitrogen processes. And when we talk about the nitrogen cycle, I want you guys to close your eyes for a minute and imagine you've just been at a large convention center or a large arena at the concert of one of your favorite performers. There's 30,000 people all trying to leave at the same time, but they're not all trying to leave the same way. Some of them are walking backwards, some of them are running through, some of them are taking their time. The nitrogen cycle is like that. It's a little bit messy. There's lots of things going on. So we're gonna start talking about how we can gain nitrogen in our soils and in our gardens. The first one is through biological fixation. And most of us are familiar with this through our legume crops, our bees and peas. They form a symbiotic relationship with a rhizobium bacterium. There is a cost to the plant for that relationship, about 50% of what they produce goes to the bacteria so that it can fix nitrogen for the plant. There is also free living forms of fixed nitrogen fixtures out there like cyanobacteria and other bacteria that are just doing their own thing. That's how they live. Another way that we gain nitrogen in our soil and our garden soils that are plants can be used is through essentially it's called mineralization but I think of it as decomposition of those organic materials. That plant matter that's in their soil, the microbes are working on breaking it down, converting it to different forms so that plants can use it. And most of the time one of the forms is ammonium. And then nitrification is the conversion of that ammonium to the nitrate form. So nitrate with an A. And this is the most preferred form that plants like to take up and use. It does have a negative charge on it and it is a process. I should mention that these processes are governed by bacteria and microbes in the soil. They're also kind of ruled by the soil conditions. If it's too wet, if it's too dry, if it's windy out on the soil surface and what other nutrients are in the soil too. They all kind of affect how these processes go. And nitrification can be, is the conversion of that ammonium to nitrate and it can go backwards too. And one of the middle products of the nitrification process is nitrate with an I. Some of us have heard of that nutrient before. I don't know if it's a nutrient, but that chemical before. And then other ways that we get nitrogen into our soil profile is just adding synthetic nitrogen or adding organic nitrogen in the form of animal compost or manure compost. So how do we lose nitrogen? Nitrogen is lost in the soil through immobilization. It's a big word, but essentially means that the plants or microbes in the soil are using that nitrogen for their processes, for their growth. And it's not available for other plants to use. It's not necessarily a bad thing, but it can get us gardeners into trouble and we'll talk about that a little bit later here. I also want to mention erosion. Ammonium has a positive charge and that means it is held on to our soil particles. And when we have erosion through wind, which we had a lot last year or through the soil particles moving with water, we're losing that nitrogen. It's not in our soil profile for our plants to use. We can also lose nitrogen through volatilization, that ammonia form, turning into a gas that's lost to the atmosphere. The intermediate product between ammonium and nitrate is nitrite and that can be lost to the atmosphere as well through denitrification. And then leaching, which is the loss of the nitrate with an A because it has a negative charge through a lot of water movement because it has a negative charge, it's not held on to our soil particles and it's easily lost through rains or irrigation. But this can also happen to organic nitrogen in the soil too as the microbes are breaking down those molecules they're gonna flow through the soil profile into the waterways and be lost to our gardens. So let's take a minute to talk about carbon and nitrogen. The cycles are connected and that is because the microbes need nitrogen to break down carbon so they can use it in their bodies and in their processes. And if you've ever composted, you know, the terminology of the seed and ratio. You have greens that are high in carbon, or excuse me, high in nitrogen like grass clippings or vegetable peelings. You have browns that are high in carbon like newspaper, cardboard, things like that, dried leaves that are higher in carbon. And those microbes need that nitrogen to break down that carbon. And if we have too much carbon, if you remember the word immobilization from our previous slide, previous slides, they're gonna use that extra nitrogen and it's not gonna be there in the soil for your plants to use. And then you might experience some of those symptoms of plants that don't have enough nitrogen. They might be yellow, a little bit stunted, not growing as well. An example for me is when this happens is I use wood chips in one of my nontraditional garden beds and I always need to apply a little bit of nitrogen to that area because those wood chips are slowly decomposing and using the excess nitrogen and it's not there for my plants to grow. So I thought it was really interesting and this is something I feel that I should have known as a person in the horticulture industry but I took advanced soil nutrient cycling class from Dr. Kaili Gash, she was a professor at NDSU. Well, I learned all this information from but I also learned how synthetic nitrogen is produced and it's produced through a process called the harbor brush process. And it takes that nitrogen gas from the atmosphere, uses high temperatures and pressures to break those bonds. And then that is used to make our synthetic nitrogen fertilizer. And all this process is very high, intensive and energy concerns are fossil fuels and it's estimated that it consumes about one to 2% of the world's energy but it also increases a production in our gardens as well as agriculture fields. So I just thought that was interesting. I think they developed that process in I think 1918. So it's been around for a while. All right, so we finally get, I'm sorry, this has been there the whole time, finally get to our nitrogen cycle here. So you might recognize some words that are familiar. And I do wanna note that this is to me appears to be a corn plant in the middle of this cycle. To my knowledge, corn does not fix nitrogen. So let's just imagine this is a nice green bean plant in our garden. So it is gonna take that nitrogen from the atmosphere. It's gonna fix it at a cost to the plant but it also provides nutrients for the plants. Now, when that plant dies or when we have waste from animals that organic matter is put into the soil profile and we have our organic nitrogen. The organic nitrogen can be broken down by microbes through the process of mineralization and it's released into the soil profile for plants to use. And one of those forms is ammonium. And ammonium can also be used, remember that word immobilization, it can be used by microbes in their processes as well. Ammonium can be converted to nitrates through the process of nitrification but it can also be lost in the nitrogen cycle. It can be lost through leaching. It can be done through a reversal of the process and also used by plants. And then we have a couple losses here. The ammonium can be volatilized into the atmosphere and the same as the nitrate, it can be lost into the atmosphere. So nitrogen, as you can see through the cycle, it's a messy cycle. There's lots of ways that it can leave and come into our soil for our plants to use where we're finding concerns is when we have too much nitrogen in the soil, it's not being used and it's being lost and through the soil profile and that can be into groundwater. When we talk about human concerns because we're drinking that water and this is most common in soils that are lighter in texture, they're more sandy or it even can happen on a little bit heavier soils if there's a heavy rain event, the nitrate can be leached through the soil profile. And it can also happen if we're applying too much organic matter that's high in nitrogen, that's not being used by the processes in the soil. And this affects human health in a couple different ways. If you ever heard of Blue Baby Syndrome, it's because of excess nitrates in water. There's nitrate poisoning in livestock which happens more often in dry years. And then there are cancer risks associated with some of the nitrogen byproducts from this process. So there are some harmful effects to us by having too much nitrogen or applying too much nitrogen and not being used by our plants. But it also affects our environment. And I mentioned that we can have nitrate in drinking water. We can also get different forms of nitrogen in our water bodies that can either be through leaching or erosion of soil particles. And naturally these water bodies are low in nitrogen. The ecosystem keeps itself in check and everything's happy. When we get too much nitrogen, there is accelerated growth of plants in the river and water systems. And this can lead to a clouding of the water and reducing the amount of light that goes down into lower into the water column. So submerged plants are not able to photosynthesize as much as they used to. Another side effect is when all those plants die for one reason or another, that organic material needs to decompose and that uses a lot of oxygen in the water as well. So having too much nitrogen can decrease water quality and it can kill organisms just by reducing the amount of oxygen that's available in the water for animals and plants. So how can we manage nitrogen in our garden? Before we can talk about that, we're gonna take a step back and talk about nitrogen in the cycle or the nitrogen cycle in nature, excuse me. So think of that nitrogen cycle that we looked at. There's lots of things going on, lots of things moving. But in a natural system, there's not a lot of extra nitrogen. As soon as some nitrogen is released and converted in the soil profile it's used by microbes or taken up by plants, it's used right away. Our garden is not a natural system. We try to get it as close to nature as we can, but it's still a disturbed system. And these disturbed systems have larger amounts of nitrogen that can leave the system. So our goal as gardeners is to not to absolutely stop the amount of nitrogen that we lose in our soil and our garden, but we wanna minimize the amount that leaves. And there's a few ways we can do that. So the first one is I always recommend doing a soil test, at least every three to five years for gardeners. And that will give you a good base recommendation for how much nitrogen to apply. You should also do this for lawns too. Too much nitrogen can be a bad thing for lawns as well. If you have a sandier soil, you can split in that your nitrogen applications do one at planting and then one a couple of weeks later, there's lots of information on extension websites on how to split your nitrogen applications if you have a more sandier soil. And kind of the capstone way for us to help minimize the loss of nitrogen in our gardens is to build the soil health in our gardens. A good way to do that is to prevent soil erosion by keeping our soil covered, whether that's with mulch or using cover crops. You can also interplant your plants in your gardens, maybe mixing in some beans and legumes, giving some extra nitrogen to those plants. You can also do your crop rotations based on those legumes, doing your peas and beans in one area and then switching over. And that's spot next year to a crop that has a higher nitrogen need to use that nitrogen. And a good thing to do for gardens all around is to use compost. You can make your own, even if you're using someone else's, make sure you test it first so that there's no herbicides in it. But you're just returning that nitrogen instead of putting it in the landfill or somewhere where it's not gonna be used. You're returning that nitrogen to that cycle in your garden, along with other nutrients too, so that can be used again. All right, I think that's all I have for tonight. My email and phone number up there if anybody has any questions. Hopefully everyone is still awake. Yeah, we're definitely awake. And we got a few questions here for you, Carrie. This person asks, is there a best way to apply nitrogen to your garden soil, a best source or? A best source is up to you. There's lots of different sources. Common fertilizers are like ammonium sulfate. A lot of farmers use urea. I'm blanking on some of the more organic forms too. Or you can use animal manure, but I would be cautious because you wanna make sure that it's well composted so you don't have, you're not applying a lot of nitrogen. And then with animal manures, you can get a excess buildup of salts and phosphorus and even potassium as well. Would like to fish emulsion be a good organic source? Fish emulsion? I think it could work. I look, it's just because it's organic, doesn't mean you can just spray it everywhere. You have to look at the analysis and figure out how much you need, how much you can put down. What your soil type is too, you don't wanna be over applying it because it's just gonna leach through the soil profile before it does any good. And a lot of the fertilizer that we put down, the synthetic fertilizers, there's only a 50 to 60% use rate because of all those different processes that are going on in the cycle. So when we do apply fertilizer, how do we know, how can we tell for applying enough? Well, I would start off with the soil test. If you're questioning it at all, that's the best way to do it. NDSU has a soil testing lab. Tell them that you are looking for information on your garden and they'll give you a rate of what to apply. A very general recommendation is one to two pounds of nitrogen per thousand square feet of your garden. That's good. And since there's so much going on all the time, if we take a soil test at a certain time, is that gonna be a representative of what it's gonna be like in a month from now or nitrogen amount? That is a great question. And the answer is no, it will change because just even from the process of doing a soil test, because of the changes in the soil and the microbes, it's not gonna be an exact number, but it will give you a range. And then I believe the NDSU soil testing lab uses organic matter because as that decomposes, a certain amount of nitrogen will be released into the soil for your plants to use. So that's used in there as well. Okay, do you have a cover crop that you recommend for fixing nitrogen in the soil? Oh, cover crops are, they're interesting. So for any legume that you, you know, beans, field peas, any legume will fix nitrogen and put it into the soil. If you're looking at using it in the rows or different things like that, there's whole other issues with competition, but any legume will fix nitrogen, put it in there, and you can leave the material on top too because that's generally higher in nitrogen and let your garden do its thing. Speaking of legumes, do you recommend using soil inoculants on like our bean or pea seeds? So I'm in the middle on that one. I think there you can, but it's generally in our soils. And it's very specific to plants. So I'd make sure if you do buy an inoculate, that is to, oh, if I could talk that it is specifically labeled for the plants you want to inoculate to. Okay, so I may or may not help depending on the situation. Yep. There you go. Okay, how do you, can you explain again how wood chips and sawdust take away from the plant? Can you explain again how wood chips and sawdust take away nitrogen from a soil? All right, so those are two things that have a lot of carbon in them. And the little hungry microbes, as they are working down eating that carbon, they need nitrogen to fuel their bodies and they're gonna pull that extra nitrogen from the soil to break down the carbon and that nitrogen is not there for your plants to use. So that's why you recommend using it sparingly or you can compost it and get it broken down real well and then it shouldn't be an issue. And do you recommend a certain home soil test for people to use? Or just the NDSU laboratory? Yeah, there's so many nuances with it that I would recommend what's a soil test, 20 bucks plus shipping, maybe it's 25, 30. I would recommend going with a reputable lab. Okay, and in our flower gardens, do perennial gardens have a different nitrogen demand than annual flowers? So I would think of that in terms of how disturbed the system is. Your perennial system, if you're in there tilling up the soil all the time, there might be more opportunity for the nitrogen to leave but if you have a perennial garden where you have mulch covering it, that ecosystem is gonna function on its own and supply what it needs to the plants. But at the same time, like I said, you have to watch it because there might be a lot of breakdown of those wood chips initially tying up that nitrogen. You know, as far as that goes, like if I'm a little bit worried that those wood chips are tying up the nitrogen, like what are the signs of a hungry plant, a plant that's starving for nitrogen? Signs of a hungry plant, you'll know one when you'll see it, when you compare it to other plants, they're generally shorter, they're a little bit more yellow, they're just not as vigorously growing as your other plants. Okay, that's helpful. How about, can I use your Rhea when I fertilize my lawn? Your Rhea is a very, I think it's 46% nitrogen. It's really high in nitrogen so I would be concerned about burning lawns. It's used in agricultural productions and applied at very specific rates. So I don't, you would have to figure out how to do it safely, I guess is my answer on that. Very carefully, it's like a bomb. You gotta handle it carefully. It's very powerful. So maybe cut it in half or something, mix it with some sand or something if you want to. Or just buy a lawn fertilizer instead and make your life easier. How about, Doug, malorganite? Do you have any thoughts about malorganite? I've heard of malorganite, but I have not had the opportunity to study it so I can't answer that one. That's Milwaukee sewage sludge. Oh, okay. 620, 620, it's a good organic and safe fertilizer. There you go. What else we got here? Does the cocoa shell mulch affect nitrogen levels? I don't, I think they would because it's your decomposing. Anytime you're decomposing something, you're gonna use nitrogen, but I'm not sure of the analysis on it of how much, what the seed and reissue is on that. Okay. This person had took a soil test. It was low in nitrogen, but high in phosphorus and potassium. And they use leaves to mulch. Is that why they have a lot of phosphorus and potassium? Generally the soil, our soils in North Dakota are just inherently high in phosphorus and potassium because of our parent material. I would say you're probably low in nitrogen because the microbes are breaking down the leaves if you've worked them into your soil. How about the snow cover that we had this year? It's so much snow. Is that gonna affect our nitrogen in the soil this spring? You know, that is a really good question. I think it all depends on your soil conditions. If you ended up dry, if you have a wet soil that froze, it's definitely gonna affect some of those micro processes and how we lose nitrogen into the atmosphere, but I can't say 100% on the exact details of that. Definitely the melting and the leaching, the runoff is gonna take nitrogen with it and soil particles as well. This person has an old El Salsa bromegrass field. So when they dig this up, is it gonna have a funky, like carbon to nitrogen ratio or? My instinct is to say yes because there's gonna be a lot of carbon in that material as it's breaking down. So you're gonna have nitrogen being tied up, but I can't tell you what exactly that is. You can do some soil testing on it or analysis of the tissues too to find out what that is. That's right. Don't guess, take a soil test. Got it? There you go. This is one of the better. Get out there shovel the snow and take a soil test. There you go. What do you think? How about this person wants, as I guess their soil test detects, they've got really high potassium. So they're really worried that they wanna fertilize their garden, but they don't wanna add more potassium to it. Is that a real worry or what do you think? Yeah, it's a conundrum because you have to use a fertilizer that doesn't have phosphorus. Was it phosphorus or potassium in it? Potassium in this case. So maybe use ammonium sulfate, especially if you have a higher pH, that's not gonna hurt. I don't know that there's any toxicity to plants if there's too much phosphorus or potassium, but there's definitely environmental impacts the same way that nitrogen can cause problems, they can too as well. Right, does anybody have you, I know you'd like to do a lot of house calls. Did you ever do a house call and say, this plant died of too much phosphorus? No, no, overdose of phosphorus or potassium. No, don't worry about it. Let's see, if you do use wood chips, should you just throw some extra nitrogen on top, top and safe for those hungry microbes? You can, you can do a spot treatment just around where the plants are, so you're not just throwing nitrogen out, that's not being used, you can water it into the soil or work it in, just make sure you calculate the rates correctly, you don't need to be applying a lot, you burn your plants and it would run off as well. How about, can you, this question on malorganite, again, there's a run on malorganite questions, can you use it on edibles? And my answer is yes, read the label though carefully, in the beginning when malorganite came out, it could not be used for vegetables, but the recent formulations have been, it's safe for vegetables, but read the label carefully before you use any product. How about, have you ever worked with nitrogen-fixing trees, like buffalo berry or Russian olive? Does that affect fertilization of the needs of the plant or the nearby landscape plants to those trees? There are trees that fix nitrogen, I just, I haven't worked with them and I don't know if they, you would think that in the soil environment, there is some benefit to the surrounding soil, but a lot of it probably goes right back to the tree as well. This person has a no-till garden and they like to rotate their crops, so do they really need to add nitrogen or just forget about it? I'm gonna go back to my old standby, I do a soil test. Don't soil test again? Okay. How else are you gonna know? I mean, it's not like a melon that you can, you know, a melon, look at it. You have to see what's actually in the soil and then that'll give you a good baseline to judge how things are growing. That's right. It's just like your kid's got it cold. Do you use a thermometer or you just guess? No, you use a thermometer, you gotta use a tool. Same with the soil test. Gotta use a tool, gotta use a tool, it's a simple test. Just do it. How about biochar in a garden? Any comments on that? Biochar, I think it's used in a lot of different places. It's wood that's burnt in a specific way that allows the pore space in it to expand so that it can hold on to nutrients in the soil. It kind of acts like organic matter. For North Dakota, it's good. I just, I don't know on what amounts because generally biochar has a higher pH. We already have generally higher pH soils. So I would caution you on how much you apply and to kind of experiment in a smaller area if you're gonna use it. Okay. So when I grow my garden this year and I want it to look as good as Don's garden. So should I put the fertilizer up? Maybe it actually has Don this. I don't know. I don't think anybody has a garden as good as Don. Mine, isn't that for sure? But should I put the fertilizer down one week before I plant or two weeks before I plant? Three weeks before I plant? I would put it down right before you plant and then it's in there. And you can do a split applications throughout the year too. That's just what I recommend. I think there's lots of different ways to do it but the longer you leave it in there, the more chance it has, especially if you have bare ground it's not being used. So you might lose it. You might lower the efficacy rate of your fertilizer. Yeah, there's no advantage for putting it on three weeks earlier. It's just, you're gonna lose some of it. How about where do those soil microbes hang out? Are they near the surface or do they like to go deep? So the soil microbes hang out on those soil particles. I like to think of soil particles as like a book that you've opened and the pages kind of stuck and those microbes are in those pages where there's water films. Soil aggregates, if you've ever dug a lawn up and you've seen the granular soil around those soil roots, that's kind of a soil structure. That's an aggregate where those microbes live. They need the water film and they kind of need that protection of the soil aggregates. So if I wanted to have a great compost pile, do you have a resource that you would draw me to? There are lots of great resources. I would go to search extension.org and search compost and you will come up with a lot more information than you can probably look through one, how to create a good compost pile. Okay, so I start by searching extension.org. Yep. And then from there I'll look for compost information. Yeah, I don't think NDSU has, there might be one, but I don't know if it's updated on composting. Well, a great compost pile in Minnesota is the same way as a great compost pile in Minnesota. There you go, there you go. Yeah, ours will be better though, it's North Dakota. How about a general question? I got clay soil, how can I improve it? Add compost, add organic matter. Black gold. Yep. Okay, let's see here. Is it easy to test your garden soil? It is, if you know the steps. So most extension offices have the extension or excuse me, the NDSU soil lab information sheets. It tells you how to take a soil sample. You want a representative sample of your garden area, so you maybe think of your garden and do a W pattern or a Z pattern across it. Sampling along, you want at least depending on how big it is, six to eight different samples. Gardens, you can use a trawl. Go down four to six inches, put that in an ice cream bucket, mix it all together. You're just getting a composite sample and then you mail off about two cups to the soil lab to test. Okay, you mentioned ammonium sulfate before. Where the heck do you buy ammonium sulfate? I think you can get it at a lot of garden centers, our box stores and a lot of people use it because it has sulfate in it, which can lower soil pH. Which is good for most of us, huh? Yep. Here's a question, I don't quite understand it, but you will, I'm sure. Have you ever heard of plowing snow under for nitrogen? Have you ever heard of plowing snow under for nitrogen? Oh, plowing snow under. I have not, but I'm thinking the logic with that is sometimes nitrogen gas can become dissolved in rainwater. So I'm wondering if that's the train of thought that they're going with snow, that the nitrogen is captured in those snow crystals and by turning it over, keeping it in the soil that the microbes can use it. I don't know, that's just my best guesstimate there. Sounds like a lot of work to me. Especially at the ground's rows. I heard of moving snow. Don't ask that question in late March, especially when you get snow tomorrow again. Okay, I think we got it. How about one last question about, have a young tree, is there a way that I can monitor it for signs of nitrogen issues, like too much nitrogen or not enough nitrogen? I mean, visually, again, you'll see that it's maybe not growing as fast as some of your other trees. It might be a little bit more yellow, but again, I'm a broken record. If you have concerns, I would go back to the soil test. You're going to want to sample a little bit deeper. There's different zones, zero to six, six to 12, and I think 12 to 24 that you can do for trees, too, to see what nutrients are in that soil for your tree. Yeah, if you're overdoing it, my guess is you're gonna be burning the edges of the leaves. That's what, because you know, that's why people already say, my God, I just spent $200 for this tree. You're gonna live and you're gonna be, I'm gonna take care of you so well. I'm gonna fertilize you every week. I'm gonna water you constantly. You're gonna live, and so they overdo it. So if you got burning on the edges of the leaves, you could be overloving that plant. And if it's pale, though, that's a sign you're neglecting it, huh? Yeah. Okay, that's great. Okay, thanks. Thanks, Carrie. It's really good. We appreciate it. Thank you. Those are good questions, everybody. I'm glad you were paying attention. Thank you. Thank you.