University Place

Our first speaker of the day is Dr. Jerry Hatfield. He's the Laboratory Director of the USDA's National Laboratory for Agriculture and the Environment. And he'll be talking about why it is important for agriculture the science of soil health. Please help me welcome, Jerry Hatfield. (audience applauding) Thanks Matt and thank you for being here because we will talk about a lot of different things today, but we'll talk initially about what state our soil is in and why we need to think about this from a different perspective and here's my contact information, particularly that last piece in there because I find that they often have questions at the end of this. I do have two directorships. I direct the National Lab and I direct the Midwest Climate Hub as well. Which basically means that you as taxpayers get extreme value out of me (laughing) because I have two jobs for one salary. We'll talk with why soil health's important. We'll talk about soil degradation. We'll talk about soil enhancement. We'll talk about how agriculture or cover crops fit into that picture briefly. And we're gonna talk about the future demands of agriculture in all of this in a short period of time. And so we'll talk about why soil health's important and we'll just start off with this scenario right here. And this is a study that we did, this is yields from Kentucky, Iowa and Nebraska. This is soybean yields, it's plotted relative to the National Crop Commodity Productivity Index which NRCS has in their database. Each one of those points on there is the average of 40 years of data from that county. So what you see is that as we improve or the soils get better the higher the yields, except in Nebraska. And it's not because Nebraska knows how to grow soybeans better than Iowa it's because we cherry-picked the counties that were only irrigated in Nebraska. So if you can control the rainfall by irrigation soils don't really have an impact on average county yields. But if you're dependent upon that soil to store water throughout the whole growing season it is direct relationship between that average county yield and the quality of the soil that's there. It really comes down to how we manage our water. We see that with maize as well. We'd already made Nebraskans gloat enough so we didn't put in the Nebraska irrigated corn yields on this graph. But you see the same relationship in all of this. And in fact there are points in Kentucky that which there was zero yield in some years because of complete failure of that crop. And so if you look at the quality of the soil out there it puts an economic value on it as well. And if you look at the National Crop Commodity Productivity Index across the Midwestern states cause we've been looking at how this changes spatially, how the crop yields behave temporally in all of this and you see that the really good parts of that a little bit into Indiana, Illinois, Iowa into Minnesota. One of the things that we're looking at is if we extend the ranges of cropping systems because we're changing the temperature, we're changing the precipitation regime, we're not gonna move it into high-quality soils. We have a rapid expansion of corn and soybeans into the North Dakota and South Dakota and you can just look at those colors and they don't turn really dark brown. So we can't expect, unless we really do a good job of irrigation management to get 250, 280 bushels yields out of North Dakota and South Dakota because the soils are going to become the limiting factor in productivity. And so when you begin to look at all this piece of the puzzle and just to put it in an entirely different perspective for you this is another way of looking at this. This is a field that's just west of Ames, left side is a remote sensing image that was taken in early August. Same index three weeks later in the late of August, those numbers on there are the actual harvested yield at the end of the season. In that left-hand side that whole crop was fairly uniform, a few little spots there. Three weeks without rain cost us 40 bushels of productivity because the soils did not have the capacity to supply water to that crop when it needed it during the grain-filling period. 40 bushels at $8 a bushel, you can do the math in what we lost in terms of economic productivity in all this. We see this variation as well and you can look ad nauseam at yield maps in there you find that there are yield maps. You have low yielding parts of the field, you have high yielding parts of the field. Those low yielding parts of the field are generally across the Midwest water limited. That tends to be the number one reason that we have changes in crop productivity. It's not nitrogen, it's not nutrients, it's water. Water is the number one factor that influences crop productivity across the Midwest. And now the sad truth is that as we endure more climate variability that rainfall regime is going to become more variable as well. So expect increasing variability in productivity and so we've been looking at that using this type of analysis, it's a yield gap analysis. I'll explain this briefly to you. That upper-line on that is what we define as the attainable yield. That is the yield that doesn't really have a major weather impact. And it's statistically fit though that you see that there's about five years that that line goes through. The solid line below that is the actual county yields in Story County, the dashed line below that is the yield gap in between. That's not the important part of this. The important part is this graph on the lower, right side. Because what we've been looking at is the fraction of obtainable yield. If you look at that difference between attainable and actual yield out there and what we're finding is that 80% of the time we're losing 20% of that crop and it's due to short-term stresses. That big part, that 20% or that full loss of all the yield and everything else is due to the droughts of 88, the droughts of 2012, floods of 1993 and a number of different things. But that 20% yield loss is due to short-term stresses in which we calculate that we may have needed two inches of rain over a 10 day period and we only got one inch. And so our soil reservoir was limited in all of this. So you get to see the soil impact in this particular piece. And so that 20% in terms of that yield loss is within our capabilities to manage that soil to improve the capacity of that. We can shrink that or by soil degradation you can expand it. And so this type of analysis and we've actually conducted this for all 677 counties of the Midwest so we can give you a whole library of how different counties are responding, all these different things. But here comes the other piece of this puzzle and show you why soil is important. This is just an example of the crop insurance claims, by year across the Midwest for soybeans, we got it done for corn as well. The top two insurance claims for both corn and soybeans across the Midwest are excessive moisture and drought. And sometimes that gets claimed in the same field but we actually have it down to the field level but I can't share that data with you. And again you think about those two claims, excessive moisture and drought, you think about what that really is, it basically is because we have increasing rainfall in the spring, we have drowned-out spots, we have lower productivity because of that. Drought on the other hand is because we have limited water available during the grain-filling period. That accounts for 55% of the crop insurance claims across the Midwest both in corn and soybeans. The third one, in terms of there, is frost and you can see it's a very distant third in all of this. So soil, we see reflected in how we manage our soil even in terms of our crop insurance claims that are out there. So over time what I've built is what I call the soil degradation spiral and you can put whatever definition you want to poor land management at the top and that poor land management can be anything from residue removal to tillage in all of this. If you look at degradation and you look across all the literature, is that tillage and residue removal are the top two things that lead to soil degradation and the first factor that's effected in that is the aggregate stability. The aggregates no longer have organic material coming from biological activity and they begin to degrade back into sand, silt and clay. That's where we see the compaction and the crusting come in in soils. We see water and wind erosion, we erode that soil, we see reduced plant growth. We don't have the plant growth, we don't have the soil biology. If we don't have the soil biology we tend to reduce our yields and we wonder where soil productivity went. That upper part is that we're now more susceptible to the extremes of weather that are there. And in that lower part we have a negative response as to weather variation. Anything that varies outside of the normal is going to become much more magnified in the overall system of what goes on. So you just think about how this begins to work in the overall process. And you go back and you look and these are common scenes out of Iowa, these are 2013. You see there's a lot of erosion in there and if you look at the daily soil, I would say daily soil erosion project you see that in 2015 there were estimates in excess of 100 tons per acre across some of the counties. And so you have to ask yourself relative to the soil resources of the Midwest is how much is tolerable in terms of loss? And if you look at it from a different perspective everybody says, well if we're only at four tons and acre you know it's only 0.25 inches per year across that acre and that little mound of soil is pretty small on a four ton. But take and farm 40 years at four tons and that's a pretty big pile of soil. That's 160 tons of loss over that four year period and one inch and that one inch is coming off the upper surface out there. The most critical soil layer that we have is the upper 1/4 inch of soil. People always ask me what soil health test should I use out there and I've been telling producers that you're best soil health test, go out and look at your field after a two inch heavy rain and tell me what it looks like. Because if it's ponded and it's slaked you don't have any soil health because those aggregates are not able to withstand that. I see run-off out of fields that have less than one inch of rainfall in a 24 hour period. Ladies and gentlemen that is unacceptable. That is unacceptable because the other part is that we rarely get one-inch rains in a 24 hour period, most of the time we're getting five inch, eight inch rains in a 24 hour period. So it really becomes a different dynamic. The other part of this is we have to admit in the Midwest is that we do have wind erosion as well. This is a field just south of Ames, 2014. That's a stump on the edge of that field, there's two inches of soil on top of that and if you back-calculate off the soil that's deposited on the side that's roughly four tons of soil lost from wind erosion in a state that really it's not supposed to have wind erosion. So we see that more and more and again you see the bare soil that's out there. And that is those nice aggregates and the fertility that goes off that field. The ditch will really go quite well but the field will suffer over time. So what I built in all of this is what I call the soil aggradation climb. Remember that the spiral is the thing that's a slippery slope that's going down. The aggradation climb is something that goes back up but the base-layer in all of this is soil biological activity. Soil biological activity is really how it all begins because it's the biology that cycles the organic matter, it's the biology that improves the nutrient cycling within that soil profile. Those are what we refer to as the invisible and dynamic processes in all of this. And then as you begin to improve that soil you see improved soil structure, you see improved water availability and ultimately you end up with improved efficiency, improved yield, improved profit. But we build soil through biological activity, not by physical or chemical manipulation. You cannot till the soil into good soil health. Really think about the impacts of all of this because when we think about managing the biological component in our soils out there is what do those soil microbes, what's that biological component want? It wants food, it wants water it wants air and it wants shelter. What do you want? Food, water, shelter, air, right? So whatever you want is what those soil microbes want and what the soil biology wants in order to function properly in all of this. And so when you think about these dynamics and residue on the surface, the piece is really about how do we stabilize that micro-climate at the soil surface to allow the biology to express itself. Because if we look at a bare soil out there, we look at that bare soil even in Ames is that soil surface temperatures will get to 120, 130 degrees Fahrenheit at a one-inch depth it will be well above 104 and at 104 degrees we denature proteins. We basically, because of our tillage practices and because of the bare soil we have out there we cook the biology out of the soil. We basically put it into a system that it's no longer capable of surviving because it's just too hot, not to mention that it's too dry, doesn't have a lot of the food source and all of this. But immediately we just start with the temperature and so we just look at how that residue layer begins to change the overall dynamics because we reduced the temperature extremes, we reduce the moisture extremes and we'll continue supplying food source back to it. And so we divided this in two ways, one is that passive blanket out there, if you think about corn residue as being that passive blanket and then cover crops is an active protective blanket. From the physical point of view of what it does in absorbing rain-drop energy, of what it does in terms of changing the temperature regime, changing the moisture regime. Passive and active blankets behave very much the same way. The advantage of that active protective blanket is the continuous supply of a food source to that biological material throughout the season. So basically you extend the length of the time in which you allow the microbes to eat. Think about it in this way,

you're all gonna have lunch today at 12

30, what if that is your last lunch for the next three months? That's the way we feed our microbes. And we expect them to do all these different things in the soil is that they have to be constantly fed as well. And so when you look at this it really becomes a different dynamic. So there's this big, complex soil biological system that's out there that goes all the way from mammals, gophers, moles, mice, groundhogs, prairie dogs, depending on what audience I'm talking to, all the way down to algae, fungi, all of this. Those basically become nature's plow, there's a lot of movement of material that goes on back-and-forth. The microorganisms are cycling water, they're cycling air and they're cycling nutrients as part of this. And the factor that is most neglected is the air exchange between the soil and the atmosphere. That excessive moisture claim that's there is oxygen. Because when we get a ponded soul we see a reduction in the capacity of that soil to exchange oxygen back-and-forth and you see corn becomes yellow, beans become stunted. Everybody says well, that's because they don't have any nutrients, all the nitrogen's leached through, no. It's oxygen, oxygen is really the major, important part of this overall process and it is the most neglected parameter that we've measured. We measure a lot of CO2, we measure a lot of nitrous oxide, we really want to look at soil health we need to be looking at how this soil exchanges oxygen between the soil and the atmosphere. So we really need to rethink how we begin to look at this overall piece of the puzzle. If you look at this, and the reason the two elephants are there, is that underneath that soil surface on a really, really healthy soil you have the equivalent of two African elephants. They're just not packaged as elephants but they have the same equivalent weight in all of this. So if you think about residue and cover crops, the first and most important part of what they're doing is stabilizing that micro-climate of the upper soil surface. And they're providing the food source for the microbes and they're providing a source of nutrients to be recycled. A divert just a little bit, yield contest winner in corn last year was 532 bushels out of the state of Virginia. -

Voiceover

you're all gonna have lunch today at 12

Yeah! Anybody tell me what that tillage practice was in that system? No-till. A 20 year no-till field, in fact all, if you go back and look at the yield contest winners and anybody that got above 400 bushels in all the different categories in the National Corn Grower's contest, was all under some form of conservation tillage. We have yet to win the national corn yield contest with conventional tillage. What should that be telling us? That we can't supply enough inputs without the soil being there to begin to allow the genetics to express themselves. All of this I have to remind you is a very complex set of interactions. That we have a carbon cycle, we have a water cycle, we have a nitrogen cycle that's going on, they are going on above the ground, they're going on below the ground and crops are really about capturing solar radiation, driving that carbon process, driving the water process and in some form driving the nitrogen process. What cover crops do is basically extend the length of time in which we effectively capture solar radiation by a crop and convert that CO2 into some sort of carbon source. And if you look at the months in which we extend that both in the spring and in the fall that's were carbon accrual and that's where soil begins to change. If we look at corn, soybean systems it's a fairly narrow period across that but there's a lot of sunlight that's lost in terms of why we drive this overall process. One of the things that fascinates me is really what changes under a no-till system because it goes back to this aggradation climb that I talk about. One of the first things that you see change in no-till and we see it change right near the surface is that we begin to restabilize the aggregates. That aggregate stability is extremely fragile, it takes only a year to begin to degrade those aggregates. It takes only a year to begin to build those aggregates back up. The unfortunate part in soil science is that we're so fascinated with a zero to six depth that we don't measure zero to 1/2 inch. Because it's the zero to 1/2 inch that really is the gateway and we go, well we didn't accrue any carbon. We accrued a lot of carbon it's just a matter of how we stratified it because in the zero to six inch that gets diluted out fairly quickly. But if we get really near the surface and look at it and you get down on your knees and look within that canopy, underneath of those crops and change that you begin to see the aggregates change very quickly. And so that becomes the gateway of all of this and you look at that initial phase that's out there. We change our systems, we reduce this we stabilize that micro-climate for the biology to work we see the rebuilding of the aggregates. And I'll flip clear to the maintenance side of this because now this gets into the real aspects of what soil health becomes in terms of it's worth. Is that we do see a continuous nitrogen and carbon flux so cycles are entirely different dynamics when we have long-term no-till. We have continued to increase our carbon content, we improve water storage capacity, both from the capability of that soil to infiltrate water, but also to increase the water holding capacity. We do see increased nutrient cycling in all of this. In fact in high no-till systems you see a lot of nitrogen coming out through the overall system. There's one other piece of this puzzle that we've also overlooked. Everybody complains about how cool or how cold no-till systems are in the Midwest. I can't do no-till because it's cold and wet. I need to have that soil warm up. I need to have warm-up for this. But I'm gonna tell you and I'm gonna go on record, on public television, that you got it all wrong. And that's the fact that maybe we warm our soils up to quickly and we mineralize too much nitrogen early in the season and if we let it warm up slowly we change the whole nitrogen dynamics and we feed that crop differently throughout the whole season. Because one of the things that you see in no-till systems that the leaf chlorophyll, the leaf nitrogen dynamics behave entirely different And maybe we need to be thinking about how that whole soil temperature, soil nitrogen plant growth response begins to change. It's something for you young scientists to go figure out and how to really bring that into practice as well. And ultimately what we see is reduction in nitrogen and phosphorous use in a lot of these crops. In a webinar that I gave to NRCS three weeks ago now, I always talk about the value of improving you soils is somewhere between 75 to $80 an acre improved profitability. There was a producer on there from Indiana and says, "No, you have it all wrong." He said, "My profitability "because I've improved my soils is 90 to $100 per acre." And he farms 6,000 acres. That's not a bad return, (laughing) if you think about that. And then there's an individual in Minnesota that I just talked to that said, "Yes, I've been in no-till for 20 years, "Southern Minnesota, and over-time "I've seen my nitrogen rates go down, "I only need 120 to 130 pounds "to grow 220 to 240 bushel corn." All these different dynamics are going on. Now I'm gonna give you some sad truth of what you're gonna face. And that is that we're gonna face all of this in extremely variable climate. If you look at all this is that two things are going to occur. and they've already happened. One is that our annual precipitation's going up and that occurs across the whole Midwest. But there's been a shift in our seasonality, that red line at the top is the spring rainfall, the green line below that is the summer rainfall. What we're seeing is a widening of the gap between spring and summer and we've computed that for all the eight Midwestern states and so what we're finding is a shift in seasonality. So what you're gonna see is that you're gonna see an increasing amount of claims on excessive moisture because we're gonna have more spring precipitation, in fact it's so dramatic that in the April through mid-May period in Iowa we reduced the number of workable field days from April through mid-May in the last 15 years compared to the previous 15 by four days. We have four less days to get our fieldwork done in that six week period. That is dramatic, but it's also leading producers to make decisions that are not really conducive to soil health. We see a lot of compaction, we see a lot of things that are done in soil that are just a little too wet at times. So we see that piece of the puzzle. This is Wisconsin precipitation and those are just 30-year averages we've been computing. Wisconsin on a state-wide average, they don't have the extremes that we get if you go down into Missouri and all of this, but that precipitation continues to increase. Here's your seasonal total. Summer is actually going down just a little bit for you guys. Spring is trending just about the same so that makes the proportion slightly different but the real important part of this in all the signals across the Midwest is our summer rainfall is becoming more variable. Springs are getting a little wetter, shifting that, but the summer's going to become more variable. And think about the implications of that because we've built our agricultural system in the Midwest on reliable summer rainfall and I'm telling you that it's gonna become less reliable. So that means that our yields are gonna vary a lot among years and they're gonna vary more in soils that don't have the water holding capacity that allows us to take care of the short-term water stresses that are there. We did another little analysis looking at variability because this is just the trending between dry springs, dry summers, wet springs, dry summers in the different quadrants, just plotting May, June precipitation versus July, August precipitation. This is all the data from 1895 through 2014 in this. Minnesota is a little bit more stable than everything else but there are years that, the past five years, have basically been on the fringes of that period, the last 120 years in all of this. So the last five years have been among our most variable of anything that we've experienced over 120 year period. And you can see this is Wisconsin, 2011 you were in good shape. 2010 and 13, you're clear out on the fringe of anything you've seen. And you can expect those fringes to become more prevalent in all of this. So you look at this long-term projection and the long-term projection rainfall, this is the climate models that are out there, by 2080. Increasing winter precipitation, increasing spring precipitation and extremely dry in all of this and this is the suite of climate models. And we're already seeing that trend through the climate record as well. Just think about the implications of this, if our soil is not setup in a condition to handle that summer rainfall and to store what rainfall we get, because the other little piece of this, not only with trending in terms of changing seasonality, but we're also trending to more extreme events. We don't get those nice gentle rains anymore. Two inches, four inches, and in fact just a simple analysis of heavy precipitation, more than an inch-and-a-quarter per day is increasing very dramatically. So what rain we do get is gonna becoming in very intense storms in all of this. So think about what impact this makes for the Midwest if now we have excessive spring, reduced summer and less reliable summer and more variable summer. What's our whole production system going to look like? In looking at soil health we assume that we can change soil health without considering that we first need to change soil biology. And biology is linked to all those different attributes that we consider in soil health, infiltration rates, nutrient cycling, all of these different pieces. I'll get into this whole thing of just how the cover crops fit into this as well. Just a nice little rye cover crop. If you look at this and I'll point out the fact that why cover crops have become so important in the discussions of the Midwest. This is an analysis that we did in the Raccoon River, that nitrate, nitrogen concentration changes in the Raccoon River where related directly to the removal of small grains and hay from that watershed. It has nothing to do with nitrogen application, nitrogen rates. It is due to the fact that we took a cropping system out of there that removed water and removed nitrogen in the spring and into the fall a little bit and we expected to change by changing nitrogen. But in reality we're gonna have to change it by changing how water moves and how water is utilized in that whole cropping system. On a larger scale the principles of effective cover crops do affect water quality, because they absorb and take nitrogen back into the root system. If we strategically place those in the watershed we can have extremely positive results on water quality. And hopefully Tom will back that up when he gives his talk. But we really need to understand how this all fits together as a piece of this. We did another little work, everybody says, "Well how much water they use." So we actually looked at rye versus oats cover crops, after soybeans in protection of this. We really don't understand much about the water use rates. You know how much water does this take up. I can tell you that spring small grains and hay, when we do the calculations are roughly about 160 millimeters of water from the time they green-up until the time we turn them in. Interestingly enough, USGS did a back-calculation for the Raccoon River on increased base-flows since the 70s. Their increased base-flow was about 164 millimeters, almost the same amount of water that was increased in base-flow as that cover crop took up, or that wheat and hay took up. I don't think there's a coincidence in that as well. So we actually have measured water use from this, we've looked at daily rate of soil-water evaporation rates. We don't really find much differences among systems. Bare soil had the highest cumulative water use because the types of things that we do in terms of tillage with bare soil and things like that. Tillage does cost you water, every time we till in the spring it's a half-inch of water evaporated. So you can begin to look at that system as well. So if you think about this whole benefits, relative to this climate variability that we're gonna have is this first part is just the reduced erosion that's in there is that it's gonna protect that soil surface even if you have a mat of winter killed oats, that's still a mat that protects it against the high rainfall intensities that are out there and allows that infiltration rate to continue within that soil. You have a living cover crop you have the advantage of not only that protective layer relative to the infiltration rates but you also continue to put attention on that system as well. The other part of that and I'll skip down in this whole piece is that supporting and maintaining the soil organisms. Cover crops are food for microorganisms. They basically extend the period of which we provide a full set of food for the organisms to work on. So they get to eat everyday instead of just once every three months. And so you look at all of this and they do recycle nutrients in all of this. So you look at all this structure in this. Here's the future demands of agriculture. Is that we talk a lot about climate smart agriculture, how do we really begin to build climate-smart agriculture? Climate that is resilient to all these extremes that we're gonna go through in terms of the dynamics of the weather that's out there and the first piece that we come with relative to climate smart agriculture is how do we build soil organic matter? And how do we do that by minimum tillage, conservation tillage? Soil organic matter is the third largest carbon pool on earth, so think about it from the standpoint of what does it mean for the cropping systems that's out there. Climate smart agriculture, the other piece is how do we integrate nutrient management practices such as green manures, legumes, cover crops, livestock manure into that system? And then how to really look at increasing water and nutrient use efficiency in all of this. One of the things that we see in really healthy soils and really high biological systems out there is that we actually see an increase in that leaf greenness in corn during the grain-filling period. And we pick up 20 to 30 bushels of increased yield because we have larger kernels. We haven't changed kernel number, we haven't changed the number of rows but we do plump out those kernels because that plant continues to work through the whole system in terms of this. And that's the piece that we underestimate. The bottom line in climate smart agriculture is about soil and water management. It's the piece that we fought hard to get into the whole context. It wasn't about plant breeding, it wasn't about building a different genetic, it wasn't a lot about how do we do different nutrient management practices, soil and water management are gonna be the keys to climate smart agriculture. So here's the challenges that you face. Is that we have to enhance our soil resource through soil health to increase the water availability to the crop. It's gonna pay us dividends all the way through. We do have to increase the biological activity of the soil to increase that organic matter cycling, nutrient cycling but we can't do that without creating first that stable micro-climate at the surface. The microbes have to have a stable place to work. If I changed your office everyday how productive would you be? Some of you go, "Oh, it'd be kinda nice, you know, (laughing) "nobody could find me." You know, but that's what we want our microbes to do, we changing them all over and then we expect them to really be highly productive in all of this. And we've got to protect our soil against the extremes of climate, extreme temperature regimes, more importantly the extremes in terms of rainfall that's coming out there. So there's your challenges gives you something to work on for the next 15 or 20 years but we'd really like to have this done by next year. (audience laughing) So with that, thank you Matt. (applause)