 Welcome to the 2019 Alabama Crops webinar series. My name is Audrey Gamble. I'm an assistant professor in the Department of Crop, Soil and Environmental Sciences at Auburn. And I'm also the soil scientist for the Alabama Cooperative Extension System. Today I'm going to be talking about cover crops systems. So just to get us started, I want to talk about what a cover crop is and why we use them. So cover crops are crops which are specifically planted to provide protection of the soil and benefits to soil quality. So some of the different benefits that we can receive depending on what types of cover crops we're planting would be protection against erosion and nutrient loss, improved water infiltration, supplemental nitrogen if we're using legumes, scavenging of nutrients, which by nutrient scavenging, I mean, roots that explore, roots from cover crops which explore deep into the soil profile and bring up nutrients to the soil surface so that the next cash crop can use them. Breaking up of soil compaction, conservation of soil moisture, increased organic matter storage and suppression of weed growth. So really the ultimate goal of using cover crops is to improve soil quality so that soils will continue to be productive for cash crop production for longer periods of time. And so today I want to talk about several topics related to implementing cover crop systems, including cover crop selection, planting, management and termination as well as planting into cover crop residue. So I'm really just going to skim the surface of all these topics and then I'm going to point you in the direction of some resources that go deeper into these topics from the Alabama Cooperative Extension System as well as the Southern Cover Crop Council. So one of the first considerations for producers when thinking about implementing cover crop systems is what types of benefits they want to receive. So depending on the benefits that they want to receive, they may be looking at using different species of cover crops as well as different biomass levels. So we know that with different biomass levels, we can expect to receive different benefits from the cover crops. And so with lower biomass levels, we can expect to see protection against erosion and nutrient loss and improvements in water infiltration. And as we increase levels of biomass, we can start to see additional benefits such as conservation of soil moisture increases and organic matter storage and some early season weed suppression. So when we have high levels of biomass that also have a high carbon to nitrogen ratio, that provides a thick mat of residue on the soil next to the cash crop, which can help with some of that early season weed suppression. So another consideration for producers when deciding what cover crops they want to implement is the species of cover crop. So with different species of cover crops, we can expect to observe different benefits. So some of the small grains such as cereal rye, oats, wheat, those can provide, have the potential to provide some of that high biomass, which can assist with weed control and conservation of soil moisture, as well as increased organic matter. And we know that increased organic matter can help help improve the nutrient holding capacity and water holding capacity of soils. Small grains can also have fibrous root systems to scavenge for nutrients and bring those back up to the soil surface. And they have the biomass levels to help improve water infiltration and prevent erosion. So legumes species such as crimson clover, hairy vetch, other clovers, other vaches, can of course fix nitrogen and that nitrogen that is fixed from the atmosphere will degrade and hopefully provide some supplemental nitrogen for the subsequent cash crop. So legumes also provide enough biomass to help with erosion prevention and improve water infiltration. And then the last kind of class of species of cover crops would be brassicas such as tillage radish or canola. These species have deep tap roots, which can break up soil compaction and also scavenge for nutrients deeper within the soil profile and improve water infiltration. This is just going back to legumes and some of the benefits that they can provide. This is a graph showing nitrogen production and pounds per acre with some of the different cover crop species. So you can see crimson clover, which is our most common legume cover crop burn in Alabama can provide it can fix about 150 pounds of nitrogen per acre. With a good stand, not all of that nitrogen is going to be available for the subsequent cash crop, but we can typically depending on when that cash when that legume is terminated, see about 30 to 50 pounds of nitrogen to help supplement growth of the subsequent cash crop. I'd also like to point out that we have some on this, this next slide, we have some information sheets on some of these various cover crop species that helps to discuss some of the benefits that one can receive from various species of cover crops as well as various information on planting and managing those cover crops. So moving on to cover crop planting. This is a chart that was put together by the Southern cover crop council, which myself and many other researchers from land grant universities in the southeast and government researchers and farmers have been involved in developing some resources. So this is a planting guide for some of the various grasses, legumes and brassicas. We can see that most of our grasses that are grown in Alabama, the optimal planting time is going to be in October, November. The earlier that we can plant grasses such as rye and oats, the more growth we can tend, we tend to get on those and the more biomass that we can achieve. However, some of our cash crops may prevent us from playing early but you know just ensuring that we plant those as early as possible is going to help help to improve that those biomass levels that we receive. And of course later into the growing season in March and in April is when rye and oats and these other grasses can really put on some high biomass so terminating as late as possible is also going to help with increased biomass production. Legumes need to be planted by early November at the latest to get good growth on those. Crimson clover again is going to be our most common legume planted in the southeast. We can expect good growth throughout the state of Alabama with crimson clover and good stands. And those again are going to put on most of their growth in around March and April. Brassicas like daikon radishes really need to be planted early. If they're planted late October, early November, we really don't get very good growth on those at all in Alabama. So the earlier the better to receive growth of these brassica cover crops. There's several different methods for planting these various cover crops. The most common is going to be planting with a no till drill. This is going to provide the most uniform stand, but other other methods such as broadcasting with a spreader and aerial broadcasting can be beneficial in certain scenarios as well. So with broadcasting, we typically have to increase recommended seating rate by 20 to 50%. These information sheets that we have on the Southern cover crops council website will discuss some of the different seating rates for planting with a no till drill versus broadcasting and aerial broadcasting for all the major road crop species. We also have some resource guides for setting up and calibrating drills and spreaders on this website, the southern cover crops.org website to provide some more information on setting up and calibrating drills or broadcasters to plant cover crops. When it comes to managing our cover crops and fertilizing, it really depends on how much biomass you want to produce. Of course, maintaining pH phosphorus and potassium according to soil test is going to be important to ensure we have growth of the covers and that's going to be important for your cash crop as well. So maintaining soil test levels of pH or of P and K and maintaining soil pH is going to be important for cover crops as well. And nitrogen again, a lot of that has to do with how much biomass you're trying to achieve and how much input you're willing to put into this. So nitrogen, if your cover crops are planted behind a legume crop such as peanut or soybean or if you're in a high organic matter soil, if you're not trying to achieve those very high levels of biomass for weed suppression and organic matter build up, you may not even need to supplement any nitrogen. We can get a good stand of various brassica and small grain cover crops without any nitrogen in this type of scenario. Now, but for high biomass, there is going to be more inputs to provide enough biomass for weed control and other such benefits so supplementing 30 to 50 pounds per nitrogen per acre will be necessary. And again, planting early is going to help put on as much biomass as later planted cover crops with more nitrogen. So this graph that I have on the right shows some research that's been done by Kit Balkam of the soil dynamics lab in Alabama showing rye biomass according to planting date. So we have mid to late October planted rye here in the blue line early to mid November in yellow, mid to late November in green and then early to mid December in red. And so you can see that if cover crops are planted early, specifically rye in this case, we're getting the same amount of biomass. When we're planning mid to late October as we would planted, you know, maybe mid November to late November with 90 pounds of nitrogen added and so getting those crops in early is going to be key to to maintaining those biomass levels. And then of course, if we're planning legume cover crops, we still want to inoculate those to promote nitrogen fixation so they can fix their own nitrogen they're not going to if you have a pure sand, don't need to supplement any nitrogen. But we do need to make sure that legume seed is inoculated with the proper inoculant cover crop termination timing is going to be critical, because we want to be able to optimize, optimize by. Mass production, but still terminate early enough that we're not going to have negative effects on our cash crop. So we recommend terminating on typically two to four weeks prior to planning of the cash crop. This helps ensure that we have good soil moisture since actively growing cover crops can deplete soil moisture. And this also is going to allow in recharge of sub soil moisture. If we get a good rain in there. Terminating two to four weeks prior to planning is also going to help prevent nitrogen and mobilization. This is particularly important with small grains. Because small grains have such a high carbon and nitrogen ratio. They can actually tie up some of the nitrogen that that your cash crop is going to need in order to grow and so if we terminate early enough we can can avoid that scenario. Terminating two to four weeks prior to planning can also reduce the risk of some seedling born diseases and certain insects like cutworms, which can survive in covers until that cash crop is coming up out of the ground. And so we want to terminate late enough that we optimize biomass production but early enough that we can ensure adequate soil moisture and prevent nitrogen mobilization. So this is just kind of a balancing act and figuring out what works best with your particular system. There are several methods of termination, but in row crop systems we're going to typically be talking about chemical termination and this may be with or without rolling. We have producers in Alabama who do both. So there's a we have a lot of information on herbicides for terminating cover crops again on the southern cover crops.org website. Small grains can be easily terminated with glyphosate. Typically, one exception would be annual ryegrass since we see some resistance of glyphosate with ryegrass. Legumes, tank mixtures of glyphosate with glyphosate, dicamba or 2-4-D are typically effective. That's what we've seen in research trials as well as word from producers. And then brassicas, glyphosate plus 2-4-D can typically be effective and timing of termination relative to cash crop planning will influence whether residual herbicide should be mixed with the herbicides that you're applying to burn down. Cover whether those are going to help provide effective control. So for more information on terminating and also residual herbicides for weed control in the cash crop, we have a lot of information on the southern cover crop website that has been provided by various weed scientists throughout the southeast. Some other methods for cover crop termination include rolling and crimping, mowing and incorporation. And these two methods for termination are more likely used by smaller production systems such as vegetable or fruit production and organic systems. But there are implements available as you can see in this picture. When crops are rolled and then crimped well, that can terminate the cover. But for some of our species like vetch, it can take several times of going over with a roller crimper in order to kill. So again, there's some more information on these various terminations at the southern cover crops website. At following termination, planning into cover crop residue can be intimidating for a lot of producers because with high biomass, it can be difficult if without practice to achieve seed-to-soil contact. And so there's going to be some modifications to equipment that are likely necessary to ensure that we still get good seed-to-soil contact when planning into high residue cover crops. And so in many of our soils in Alabama, we're going to need some type of non-inversion tillage prior to planting. Because we have hardpins that form in a lot of our soils. And so although cover crops can help with breaking up some of that compaction, research in Alabama has shown that cash crop yield is typically better when we have some kind of conservation tillage, non-inversion tillage used in the planting row. So in this picture here, you can see we've got a subsoiler that's where we've got a shank that's going deep into the soil to break up that compaction layer and a colter in front of that to ensure that the residue is cut and doesn't wrap around that shank. And so making sure that we have a good sharp colter that's far enough in front of that shank so that it can cut through firm ground is going to be important if you're using a subsoiler or a subsoil roller prior to planting. And then when planning into cover crop residues, wheel cleaners can be used to help ensure good seed-to-soil contact. These road cleaners should barely touch the soil surface so that they sweep residue out of the way, but it doesn't get caused hairpinning and minimize the soil disturbance. And so of course maintaining correct down pressure and using closing wheels that are correct for your soil type is important when planting into cover crop residue. And our friends at University of Georgia have made an excellent video on setting up your planner for planting into cover crop residues, and I've provided a link for that here that goes step-by-step into planting into high-residue cover crops. Just to finish off this webinar, I'd like to talk about some of the research that's being done in Alabama and cover crop systems. One of the topics that we don't have a lot of research on right now is cover crop mixtures, particularly including brassicas and cover crop mixtures within Alabama. And so we've got some studies set up at three different locations in different climates and soil types in Alabama to look at single species and mixtures of rye, clover, and tillage radish. And we've got any combination of these cover crops, whether it's two-way or three-way mixtures of these covers. And we're examining how those affect various soil properties such as organic matter storage, nutrient content and compaction, as well as some of the production aspects such as insect populations in cash crops following these various covers and of course cash crop yield. So we're looking at this in some cotton soybean rotations and cotton peanut rotations throughout the state of Alabama. We're also, again, because we don't have a lot of research on these tillage radish, doing some research on these. So we've got studies at a couple of locations in Alabama to look at various radish cultivars and planting dates of radishes to see if they're able to break through compaction layers. And we're also, you know, taking measurements on biomass that's produced with these and length and diameter of roots. So typically we see this large fleshy portion of the radish, which some people think is what's supposed to break through compaction. But radishes actually have this smaller taproot that goes deeper into the soil profile. This is a picture that one of my graduate students took that's going to about, I believe, a foot and a half into the soil. You can still see that radish root growing. He traced it that far. So we've got some research to look at that. And then also ensuring that we're using the right varieties of cover crops and seeding rates is important. Some basic research on this, just like our cash crops are going to have some very distinct properties, our cover crops. We need to be thinking about what varieties are going to work best in our system. And so, you know, we've got some studies throughout the Southeast. Auburn is a participant in these studies to look at some varieties of rye oats and triticali at different seeding rates with and without clover to see how much biomass is being produced. And so some of our, we have one year of data on this and some of our early results suggest that maybe we can cut back on our seeding rates for some of these small grains and still maintain the same levels of biomass. So putting back to about 50 pounds per acre, if we've got a single species stand of rye or oats can achieve the same, can potentially achieve the same levels of biomass. So we're continuing to evaluate basic information like this. So just to end this webinar, I'll again point you in the direction of some resources that can provide some more information. The southerncovercrops.org contains a lot of information on management of cover crops, terminating of cover crops, and planning of cover crops. And then the AlabamaSwellHealth.org website on the extension, Alabama Extension webpage provides a lot of information on benefits of soil of cover crops and improvements in soil health, as well as some of the research that's been going in Alabama related to soil to cover crops. So to end, I'd just like to thank you and provide you with my information if you have any questions.