 I'm Dennis Delaney, an Extension Specialist in the Department of Crops on Environmental Sciences at Auburn University, and I'm going to talk a little today about fertilizing cover crops to increase residue and the benefits from it. I want to give a lot of credit to Dr. Kip Balcom at the USDA National Solar Dynamics Lab here in Auburn for a lot of this research and a lot of the slides that will be presented today are coming from him, so I appreciate you Kip's input. What is a cover crop? A lot of people have different definitions. My definition is the crop whose main purpose is to benefit the soil or the next crop in one or more ways, but it's not really intended to be harvested for feed or for sale of making a cash crop. Some folks like to graze what they call cover crops, but again they'll kind of fall outside of the definition and become a forage or grazing crop. It's also used as a cover crop, so kind of a hybrid there. So again, there's all kinds of definitions from all kinds of different people. We use all kinds of grasses, legumes, forbs, just a whole lot of different things that we can use as cover crops to help improve the soil or benefit the next crop. Some potential benefits from cover crops, which you've all heard about those, I'm sure, erosion control, improving the soil and water quality, increased water infiltration, which can be real important at certain times of the year, actually getting this heavy rainfall into the soil, particularly in the summertime, minimizing nutrient loss, the runoff, the taking of soil and curious nutrients with it. Nitrogen, if you have legumes out there, can supply free nitrogen to the next crop. But that said, in order to really get advantage of these cover crops, we need to optimize the conditions and maximize the growth of them. You start out with optimum soil fertility and pH, just like you would any real crop, quality seed, inoculating any legumes with the right inoculant fresh, make sure it's alive, plant as early as possible to take advantage of any warm fall weather before it gets cold. I need good stand establishment, just like the cash crop, and then terminate as late as possible and still be able to establish your cash crop on time. Take advantage of all that money you already spent and in time in establishing the cover crop to get the maximum benefits from it. Cover crops do need fertility also, just like a cash crop. There's some differences between legumes and small grains. Usually we can assume that there's adequate PK and soil pH already there for a well-managed cash crop, unless a lot of biomass has been removed, in which case you may be removing a lot of potassium in particular, also phosphorus, sometimes in a cash crop, like a corn silage crop. So if you think it might be a question, it's a good idea to take a soil test. But on low fertility sites, sites that may be being brought into production, it can be important, particularly phosphorus for legumes, looking back the old rotation here in Auburn University campus, in 1896, those sites were relatively low fertility, and one set of treatments out there was splitting the PNK between the winter legumes and the cop half on those crops because phosphorus in particular was so critical to getting good growth out of legumes. So it can be important, most of the time is adequate PNK out there though. With the legumes, there's a wide variation in the type of legumes that you can plant, a lot of differences in production, but some of them might carry a batch, estimates for the nitrogen that you can provide to the next cash crop can be anywhere from 40 to 200 pounds of nitrogen per acre, and that depends just how much growth you have out there, how early you got planted, how good the weather was, how late you would wait to kill it, and all those kind of variables in here into it, and that's why there's such a wide range out there of how much nitrogen you can supply. But if there's no need to apply nitrogen in legumes, what about all the others? The grasses, the forbs, the brassicas, things like that. As you can see, there's a huge difference in this slide between a serobrain that's had 90 pounds per acre of nitrogen applied to it versus no nitrogen, and you can see with zero nitrogen, very little growth out there as compared to the fertilizer. And in a lot of cases, it may be really hard to recover the money that you've already spent on seed if you don't put some fertilizer out to kind of boost it on the lawn. It just makes a huge difference in how much mulch you can get, how much soil erosion you would prevent, and how much water infiltration you'll get later in the summer season. My rule of thumb is most of the time you want to have at least two tons per acre of cover crop biomass out there and really make it worthwhile. You can see this is a slide of some fertilization of cereal rye, and with zero nitrogen one year, I was able to barely make it over two tons per acre. Adding just 30 pounds of nitrogen per acre tremendously boosted the amount of biomass that was produced, and as you kept increasing more nitrogen out there, you got more biomass produced. And the biggest bang for the buck is that first 30 pounds of nitrogen really get it going. After that, you could just keep on increasing the biomass enough to really make a difference and add some mulch and organic matter back to the soil. There are some alternative sources that may be a little cheaper than commercial fertilizer, such as poultry litter. This is a test document conducted several years ago, looking at timing of applying the nitrogen poultry litter fall versus spring, compared to the commercial nitrogen, and it rates zero, 30, 60, and 90 pounds per acre, or one, two, and three tons of litter per acre. You can see again this is cereal rye, and you can see the amount of rye biomass tend to increase the higher the fertility rates, particularly with the commercial fertilizer, but also with the litter kept climbing. But again, the big bang for the buck right there is at 30 pounds of nitrogen per acre, or the first one ton per acre of litter. Again, after that, you keep increasing it, but you really want to make sure that rye cover crop is not stressed for nitrogen to get to your biggest return from it. As far as timing, between fall applied and spring applied, you know, a lot of times with our wheat crops, we put most of our nitrogen out in the spring, but with something like rye, where you're just trying to get the biomass early, get the good growth early, and then be able to terminate it in time to plant your summer crop, cash crop, fall applied is the best way to go. Again, just get as much biomass as you can, take advantage of that warmer winter weather that we tend to have here in the South. Of course, the big question is, do you get that money back? It's all nice and good to have more cover crop improve the soil quality, but does it actually increase yield? And this is a set of graphs of the cotton lint yield after the zero, 30, 60, 90 pounds of commercial nitrogen versus the chicken litter rates. And you can see with no nitrogen side dressed to the cotton that the cover crop does start releasing some of that nitrogen back to the cotton crop and will slightly increase yield, especially at higher rates, but it still takes some nitrogen on the cotton. The top set of lines is 90 pounds per acre of nitrogen in addition to what you put on the rye cover crop. So it does tend to boost yield. And again, that first 30 pounds per acre, one ton per acre of litter is what really gets you that that boost in yield after boosting about a cover crop is out there. One thing I was, you know, talking to farmers, I know there's a lot of cost involved between getting the equipment and the crew out there to plant these cover crops, buying the seed, buying the fertilizer, managing it. There's a lot of that goes into it, a lot of cost. So you always want to try to manage that to get the maximum amount of benefits from it. Sometimes it's hard to do. But again, I think in the long run, having the maximum amount of biomass out there will really be to the producers benefit. This is a quote from Dr. Wayne Reeves who was here a few years ago, that soil carbon and crop residues are really the key to making conservation utilities work. It's not really the lack of tillage or no tillage, but the production and conservation of crop residues that offers the most benefit to productivity. So again, if we're planting into a real sparse or real thin, unfertilized cover crop, or even just the stalks from the previous year, we may not do a lot to really help build that soil. But if we can make the most biomass, the best cover crop that we can and leave it out there without destroying it, destroying that or gaining that, that'll give us the most benefit to our next cash crop. And a lot of times it's difficult here in the South, but I think in the long run, it'll be worthwhile. Again, I'd like to thank you for your time and that's all I've got. Thank you.