 Well, hi, I'm Larry Chahachik, I'm a professor of soil science at NDSU in Fargo, and I'm going to talk a little bit about the effects of removing corn residue from fields. This is a topic that's been around for a little while, there's been interest in removing the residue as a source of biofuel feedstock. But in recent years, there's been a lot of residue removed also for livestock feeding purposes, a lot of times it's used along with feeding distillers grains to create some bulk and roughage with feeders grains to reduce the energy in livestock feeds. But the concern here has been that if we start removing the residue, we're removing some of the fertility and reducing the potential for yield. In this study here at Oaks, this has been going on since 2009. The interesting thing about the Oaks site is that it's a sandy site. There are a number of studies that have been carried on around the country, probably the two closest have been in South Dakota and Western Minnesota. Those are on loamy or clay sites. Sandy sites have a problem, a greater problem with wind erosion than the other sites do. So it is sort of a fragile site and that's what makes it interesting. It also has some interesting things to do with retaining water. Sands do not retain as much water as some of the clay yourselves do. So water has to be sort of applied throughout the season. This is an irrigated site. Water has to be applied throughout the season to maintain enough water for the corn to grow. The first pictures I've got here, a couple of pictures showing what it looks like to remove no residue, that'd be a 0% residue removal. You can see that sort of in the center of that photo and then on the right hand side is a 100% removal. Again, you can see an area in the center of the photo. There are some other treatments in there. This study's got 4 treatments, 0%, 33%, 67% and 100% removal. So all the residue is left on the 0% and all the residue is removed except what the stumps in the root systems are left in the soil from season to season. There's two different management systems. There's a continuous corn system and there is a corn soybean rotation system. Now within the corn soybean rotation, there's two parts of that. There's corn one year soybean the next year or soybean the first year and corn the next year. So both parts of that rotation are present. If we look at yields corn after corn, there really are not any significant differences either looking at the latest that we've got published and that's 2017 or the long term, the 2009 to 2017. Sometimes we see a little bit higher yield for the 100% removal but they vary from treatment to treatment and perhaps this tendency to the higher yield is an effect of warmer soil temperatures in the spring as the crop is planted. These are all no-tail so there would be no residue cooling in the surface and just a little bit of an edge in growth may help give us a little bit more yield in both the continuous corn yields and in the corn, in the corn and soybean rotation yields. There are differences. The corn and soybean rotation yields have a little bit higher overall yield but essentially the fertility has been the same about 226 pounds of nitrogen applied to each of these at least in the recent years. So there doesn't seem to be much difference between whether we leave the residue on or remove it all or leave part of it there, remove part of it. In 2013, we did some work on the physical properties that's something that's not been looked at but in the unique soils that we have. The sandy soils we know they don't retain a lot of water. They also, because the sand do not aggregate very well because of the like of clay particles and if you remove organic matter you might also be removing the glue, the binds, the soil particles together. So we did a number of different things. One we looked at the infiltration rate, the single ring infiltrometers and measured the differences in rates of water infiltration over a period of time and in the corn after corn the zero percent rate had about two and a half times greater infiltration rate about 22 millimeters per minute versus the 100 percent rate at 9 millimeters per minute. So it was essentially about an inch per minute versus about a third of an inch per minute. So there's about a two-thirds reduction because we took off the residue and part of this was due interestingly to the fact that we found as we were putting our rings in and then taking them out there were many, many more earthworms in the zero percent removal and there were very few in the 100 percent removal. Part of this is that earthworms feed on the surface of the soil on any organic matters up there. So zero percent actually had a lot of macropores which allowed the water to move through much, much quicker and much more faster than the 100 percent removal. So that was an interesting observation we made. In the box plots here sort of show the differences between treatments. Again in continuous corn the infiltration was the highest in no-resid removal. We also looked at a couple other things. One of them was look at the windy erodible fraction. Again if you don't have a cover protecting the surface as well as leaving organic matter to help bind the soil particles together you can have wind erosion on these soils even under no-till. What we found was that the 100 percent wind erodible fraction was the 100 percent removal had about 40 percent of the aggregates were of the size that can be eroded by inches which is by wind. It's about 0.84 millimeters which is about the size of the sand grain or the square of a in a regular window screen about the opening in a window screen is about the size of the particle that can move. Anything that size or smaller can move if it's not cemented together. The lowest wind erodible fraction was found in the zero percent removal or where all the residue was left on the surface and that was 35 percent of the aggregates there were able to blow away. We also looked at the aggregate stability. Again this is sort of a measure of the glue, how well the soil particle are glued together which is also related to organic matter and we found that the water stable aggregates were about 58 percent they would not disperse in water in the no-residue removal and about 48 percent about 10 percent less in the water stable aggregates in the 100 percent removal. So again there's this effect of removing the organic the biomass can affect the organic matter. Now remember this was nearly over five years ago so it may be greater now but we haven't had a chance to look at that again. Now in the corn soybean rotations we've got corn wind year soybean the next so we looked at both phases and the only things we saw in the physical properties was the infiltration rate on the zero percent removals was 17 millimeters per second a little bit slower than for continuous corn and the 100 percent removal is about 11 millimeters per second a little bit faster. Now remember there is some residue that's left after the soybean crop the soybean crop is not removed so you have some residue there that helps protect the surface and also provide some organic matter to help bind soil particles together. The other thing we found that the winder rotable fraction again was higher in the 100 percent removal the winder rotable about 47 percent of the aggregates were in the winder rotable size for the 100 percent removal and about 35 percent in the zero percent removal. We also looked at the plots that were in soybean and the only thing we found was there was a little bit of difference in the dry aggregate stability there's two ways you can look at aggregates you can take aggregates keep them in a moist stage just as they come out of the field and using a sieving method determine how stable the aggregates are or you can dry them air dry them that you might find after a you know after the soil has dried out the we usually know that the wet stable aggregates are not going to be affected by rainfall as much by being broken up but the dry aggregates a lot of times do have a little bit of a problem because a raindrop hitting it will cause them to blow apart and and the water stable aggregates for the zero or the air dry water stable aggregates for the zero percent removal on the under the soybean crop was about 87 percent of them are stable and with the 100 percent removal was 80 percent so this is a very small different but slightly more or slightly less water stable aggregate so we there's a lot of interesting things in this this site here overall if we would look at you know does removal affect our yields a lot of the studies have not shown that but remember that when we take the residue off the surface we still have probably close to half the corn plant underground and so there is some organic matter that's being returned I think most of the studies that are out there in this part of the world in the plain Great Plains or the Eastern Plains Western Corn Belt is that we need to leave about three and a half tons of residue on the surface to maintain organic carbon we've looked at organic carbon but in 2013 but this area has been disturbed there were some drip lines that had been installed so there's a lot of variability organic carbon and we couldn't really separate any components out of there that that would look like one treatment or other had better organic matter in it as far as nutrient offtake killing the crew been doing some estimations on it there is some phosphorus and potassium taken off but a lot of times in the corn residue there's not a lot of nutrients left it's just a lot of the more lignified material mostly organic material not a lot of nitrogen most of the corn runs around a CN ratio of 60 to 70 to 1 so there's not a lot of nitrogen in there so there's not a lot of nutrients there's a lot of carbon being taken off still we still a lot we need to learn about this but but I think particularly the physical properties are something that been really interesting looking at this particular study so I guess this is still a to be continued story