Conservation Outcomes Webinar: Research on Precision Ag for Cropland Phosphorus Management
Hello, thank you for being here, and welcome to the July edition of the NRCS Conservation Outcomes Webinar Series. My name is Elizabeth Creech, and I am a Natural Resources Communication Specialist with the USDA Natural Resources Conservation Service, NRCS, Resource Inventory and Assessment Division. We host this webinar series to provide key findings, data, and tools to support producers, other land managers, conservation partners, and members of academia and other researchers in pursuing voluntary conservation efforts across the nation. We will get started with today's presentation in just a moment. First, a few logistics. If you would like to receive email notifications with information on upcoming webinars, please subscribe to the NRCS Conservation Outcomes topic via govDelivery. You may do so by following
the instructions on the screen. A direct link to access the govDelivery subscription webpage will also be available in the meeting chat and is provided at the top of the NRCS Conservation Outcomes Webinar Series webpage. If you are having problems with audio, sometimes computer or mobile device headsets can help with both quality and volume. It may also help to leave and re-enter this webinar session. You may access live captions during this webinar by clicking the three dots with the word more on the meeting screen. This will enable you to select the turn on live captions function.
Again, please note that I will momentarily post additional links and resources in the meeting chat. One important resource is our Conservation Outcomes Webinar Series webpage. That URL nrcs.usda.gov/conservation-outcomes-webinar is currently displayed. This is where you can find resources from today's event, including a one-page additional resources guide and our presenter slides. The recording of this webinar will be available
via this webpage no later than next week. Finally, we encourage everyone to type questions or comments into the chat throughout today's presentation. We will address as many of your questions as we can during a Q&A session at the end of the event. If we do not get to your questions, or you have follow-up thoughts, please email me at Elizabeth.Creech@usda.gov. With that, it s time to get started.
It's a true honor and privilege to introduce our Natural Resources Conservation Service Deputy Chief of Science and Technology, Mr. Noller Herbert. Deputy Chief Herbert, thank you for joining us today. So, I thank you Elizabeth, and also thank you for putting this webinar together and the team that s been working on this series for some time now, and they are very informative sessions. So, I thank you Elizabeth.
So this afternoon, a good afternoon. And again, welcome to the July addition of our Conservation Outcomes Webinar Series. It's a pleasure to have you here for today's session. At NRCS, USDA s Natural Resources Conservation Service, one of our driving missions is working with farmers, ranchers, and other landowners and land managers to strengthen their operation and conserve natural resources through a voluntary effort. Simply put, helping people help the land. And, as USDA's primary private land conservation agency, we generate, manage, and share the data, technology, and standards that enable partners and policymakers to make decisions informed by objective and reliable science.
USDA's Conservation Effects Assessment Project, or CEAP, is a multi-agency effort led by NRCS to quantify the effects of conservation practices across the nations working lands. CEAP works closely with our science partners and other federal agencies and academia. Findings from these efforts inform improved conservation delivery for NRCS and support strengthening management decisions across the nation s farms, ranches, working forests, and other private lands. This Conservation Outcome Webinar Series enables us to directly communicate with you our conservation research partners and colleagues, agricultural producers, and other private landowners and land managers the documented outcomes associated with this work. Today's webinar will focus on a topic of great interest to many of us, precision agriculture, and the recent research of USDA s Agricultural Research Service, in collaboration with CEAP, on the use of precision ag technologies to improve cropland phosphate management.
NRCS supports conservation precision ag technology for all types of agricultural operations. Through SMART nutrient management, NRCS emphasizes specific precision ag driven activities and technology to reduce nutrient loss by assessment of comprehensive, site-specific conditions to maximize their economic benefit while minimizing environmental impact. For example, in-field conservation practices, Conservation Practice 590, utilizes the four Rs that are right fertilizer, at the right rate, at the right time, at the right place, with the attention on soil test phosphate, P level, when to use P, when to use postulate-based fertilizer application rate, phosphate draw down strategies, method placement technology, intuitive variable rate, nutrient application, and innovative manure injection technology. So that's one practice that we do. Conservation Practice Standard 327, conservation cover, to reduce surface transfer of phosphate. Conservation Practice Standard 328, conservation cover rotation, considering the crop phosphate removal. Again, conservation practices, with proper planning, work together for the reduction
of phosphate losses. And again, all this to say that to carry out the mission of NRCS to help people help the land, and to help people put conservation on their land. Again, I appreciate you all joining us. Now I would like to turn it over to Chris Lester, Acting CEAP Cropland Assessment and Modeling Team Leader, to provide details on this webinar and introduce our guest speaker. Thank you. Thank you, Deputy Chief Herbert. It is an honor for you to join us today. And I'd also like to thank Elizabeth Creech, and all her efforts in organizing this today. And we certainly
thank Dr. Doug Smith for taking the time to join us and presenting his research today. Dr. Smith s research is very relevant to NRCS s SMART nutrient management and climate-smart agriculture conservation efforts, and USDA's Conservation Effects Assessment Project Cropland Assessments quantify the effects of voluntary conservation efforts across the nation's cropland using confidential farmer surveys coupled with modeling. When we were comparing national CEAP 2 to CEAP I findings, our biggest lesson learned was related to nutrient management. And with the push to increase our conservation tillage acres, we overlooked the importance of incorporating nutrients as well as the proper application timing.
We ve also seen by CEAP 2 that we had an increase in variable rate technology and enhanced efficiency fertilizer. Dr. Smith's expertise and research in phosphorus fate provide an excellent resource that can help us address our concerns with phosphorus nutrient management and climate-smart conservation efforts. And at this time, I'd like to turn it to Dr. Douglas Smith. Thank you, Chris, and thank you everyone. I assume if you can't hear me, someone will let me know. But it's a pleasure to visit with you today about some of the lessons that
we've learned from work with CEAP over the years and how we're using that to move toward using precision ag technologies for phosphorus management in croplands. I'm a part of the USDA Ag Research Service, which is the in-house research agency for USDA, and I would be amiss if I didn't acknowledge my co-authors on this, which are also USDA, as well as several contributors from University of Kentucky and University of Wisconsin. So, I have worked with the Conservation Effects Assessment Project for pretty much my entire career. The work with CEAP, umm, we began that I think around 2002 or 2003. At the beginning of my career I worked in Indiana, and we had at the time the only Conservation Effects Assessment Project Watershed Assessment study in the Lake Erie region. And I've learned
many lessons which have driven me to the research paths that I'm following now. And I'm going to, to start out with some of those lessons. This is a satellite image of Lake Erie. Those of you unfamiliar, maybe you can see my arrow.
This is Detroit, Michigan. Here is Toledo, Ohio, and Cleveland, Ohio. As you can see, this large algal bloom in 2011 covered pretty much the entire coast of Ohio. Tourism, especially around the Lake Erie coast, is about a billion dollar a year business, or was at the time. Many people come to the region for fishing in Lake Erie. It's one of the world's greatest sport fisheries. The Charter boat captains report that, in order to get to the fish, they must drive through these algal blooms, and the algal blooms will actually slow the boats down one or two knots to get to the fish.
Doesn't take much phosphorus entering Lake Erie to cause these algal blooms. In terms of total phosphorus, it's only about 1 to 1 1/4 pounds of phosphorus per acre per year entering that is causing these large algal blooms. Back in the 80s when no-till was in its infancy, we assumed that if we stopped the sediment through reducing erosion, we would stop the phosphorus. To a large degree, that s true. We've done a tremendous job at reducing erosion and total phosphorus entering the lake.
However, what we didn't realize was this soluble phosphorus, which seemed such a small component of the phosphorus, is very bio-reactive, and small amounts of soluble phosphorus or dissolved phosphorus can drive algal blooms to a much greater extent than the total phosphorus. Algal blooms, every time they happen, it's the farmers that get the bad press. It's the farmers that get the news headlines that they're causing the algae blooms. Umm, so while I was working in the Western Lake Erie Basin, on the left, you can see an Indiana survey where we compared a surveys from farmers, what they were actually applying to what the recommendations were, based on their actual yields for both corn and soybeans. And you can see that, 73% of these fields, phosphorus applied at or below the phosphorus recommendations.
I worked with some colleagues at Ohio State University, and they did a survey of farmers in their region of Lake Erie. Theirs was a much more extensive survey and 90% of the fields from their survey resulted in phosphorus applications that were at or below the phosphorus recommendations. So, all that to say, it's the farmers that are getting the bad press, but if the majority of farmers are following the recommendations, maybe we need to re-examine the recommendations that the farmers are getting. There's some breaking news: Not all fields are homogeneous across the field. You can see from this photo that not growing consistently across the field.
And precision ag technologies, when they were first coming online, the things that I was hearing about them was that the high yield in an individual field marked that field s potential, and that we needed to be placing more inputs into the low yielding areas in order to bring the entire field up to that yield potential for the field. Whenever I was first learning about some of these technologies and I saw some of the yield maps from some of the fields that I had worked with, with producers, I had some concerns about some of the yield maps that I saw where there was poor yielding areas, or areas that I knew were areas that needed, say, grassed waterways because they were very hydrologically active, there was rill or gully erosion happening there, so why would we want to add resources such as fertilizer to these areas that are hydrologically connected to streams? So, we've gone into precision ag with an interest in optimizing production as well as economics and resource concerns. Taking some information from Purdue University, where they've done a survey of crop input dealers, they surveyed these dealers nationally, but there is a very strong representation in their survey from the Corn Belt. The circle at the top highlights variable rate fertilizer applications. As of last year, about 88% of the dealers reported that they were currently offering variable rate fertilizer technologies.
You look down, below, in the circle there, there are greenness sensors for nitrogen application, and only about 18% of the dealers. There is some potential growth in this portion of the market. And if we look at how this tracks overtime, so this particular graph shows how those dealers estimate the adoption of the technologies in their region on a, on a land area basis. So, you can see this gray bar here represents the grid or zone sampling, and much of the variable rate fertilizer applications are based on zone or grid soil map sampling strategies.
This green line at the bottom, that ends at about 8% coverage in their regions, is the chlorophyll or greenness sensors. If you're familiar with the product called Green Seeker, these are for nitrogen applications. And we know that, as you move through the field with a Green Seeker, and you identify areas that are hungry for nitrogen and you apply that nitrogen, you're going to get a good yield response from that application. So, there's very strong science behind these nitrogen application technologies. Umm, but so far, poor uptake in the industry. There is strong uptake of site-specific management
of phosphorus through grid or zone variable rate technologies. So good uptake, but the science is much weaker, and I'll demonstrate that later in the presentation. Here's an example from a farmer in Indiana that I worked quite closely with. This map shows his soil test phosphorus map. Many lessons that I learned just from this
one field right here. You can see there's a wide range in phosphorus levels, so the red area there is about 5 parts per million. The green area is about 70 parts per million of phosphorus in their soil test. This field is about 1/4 section. The farmer had been no-tilling at the time for about 17 years. Have not applied large amounts of phosphorus to this field for quite some time.
He was saving up to buy his own variable rate fertilizer applicator. Umm, so he d had pretty low amounts of phosphorus that he was applying, only about 2 gallons of poly ammonium phosphate per acre, which is roughly around 7 pounds of phosphorus per acre. Applying this in a manner that he did, thinking of this through a lens of soil health, I was, well, I wasn't thinking about soil health, but I was asking him about how he's able to grow a crop with such critically low levels of soil test phosphorus. And he said actually, this is some of his best yielding area, and indeed the high yielding area, or high soil test phosphorus area, was upon occasion a problem area for him. We look at this in terms of the fertility guidance. On the left column, here is the
results you get back from the lab. So, some of them report in parts per million. Other labs report in pounds per acre. Here, his results were in parts per million, so five parts per million. His yield goal, which you look at on the top, realistic yield goal was around 200, 220 bushels per acre. So, he should be applying about 115 pounds of P2O5 per acre. In fact, he was only applying about 7 pounds of P2O5.
So, if we translate that to what he should have been applying in terms of the type of fertilizer, he was only applying about 2 gallons. He should have been applying about 30 gallons per acre of that product. Here are the yield maps that he provided, and this is for corn and for soybean. And you can see, indeed, some of his highest yielding areas are in this critical zone down here. So, there are a lot of lessons to learn. I think one of the things that we need to think about is how we have not updated our fertility guidance since the advent of no-tillage. So, we look at the fertility guidance in terms of a soil chemistry set when we used to plow the heck out of, out of it. Umm, now, it's
needs to be viewed more as a soil biochemical set. In Canada, they've seen some similar things. Real briefly, they have some plots that, uh, where they apply phosphorus and nitrogen to these plots, and this is the soil test phosphorus, and plots where they have withheld phosphorus since 1995. Much lower levels of soil test phosphorus here, and not applying phosphorus to actually get higher yield than the plots where they do apply phosphorus. Through my time working with CEAP and some other programs, I did have opportunity to visit with farmers that manage more than about 85,000 acres in the Western Lake Erie Basin and nearby areas. Interested from that one map that I showed about what their phosphorus
lessons could be learned from them. So, I asked them all about their nitrogen potassium deficiencies. They were common. They could all point to what the symptoms looked like in the field, when they occurred, and when these deficiencies would result in a yield drag. Phosphorus deficiencies were only reported in certain circumstances. One is where you plant while it's wet, so the seed is put into a trench where there is sidewall compaction, and the root cannot penetrate through that side wall to go explore the soil to bring phosphorus back to the upper part of the plant. A second is when you plant, the crop emerges,
it gets to be about 6 inches to a foot tall, and then you get a cool, wet period after it emerges and that slows the root growth, and then after maybe 5 or 10 days, you're going to see some phosphorus deficiency symptoms. And then a third was about 35 years ago, I don't remember the name of the herbicide, but it was known to inhibit root development of corn. So, most of the producers could not pinpoint that these phosphorus deficiencies were resulting in a yield drag though. So, one thing we do know is that phosphorus supply to the plant
early in the season is very critical to determining crop yield. We know that this happens by V4. When we talk about crop growth stages, we talk about V as being the vegetative stages of corn growth and R being the reproductive stages of corn growth. Uh, so V4 is where we know that it's critical to have phosphorus supply to the plant, and that's where we have four true leaves. So, what's wrong with our current fertility system? We developed our current fertility system based on broadcasting fertilizers. In the old days, we would till this fertilizer in. Those fertilizer applications were designed to supply some level of critical soil test
phosphorus to the soil. Since we moved to no-till we no longer till that fertilizer in. So, we do have some opportunities to enhance phosphorus runoff by those activities or over supplying phosphorus to the soil and building the soil test phosphorus levels too high can also result in phosphorus runoff. So basically, we've designed a system that's very quick and easy, but there are some tremendous inefficiencies in the system, because we're basically feeding the soil in order to feed the crop. And one of the areas we want to move into is, can we be more precise in feeding
the crop? A quick item about placing those fertilizer on the surface without incorporating it. We did some studies here where we surface applied three different fertilizers. So, we have a dry monoammonium phosphate, polyammonium phosphate is a liquid, and then poultry, obviously a dry material. So, we would spread that on the surface and then rain on it, and we would get pretty high levels of phosphorus loss.
Alternatively, we would inject that fertilizer. We would do that by digging a trench, placing the fertilizer in that trench, and then covering it up. And it would only have to be about half of an inch to an inch deep. So, not a tremendous amount, but that more intimate contact between the fertilizer and soil greatly reduced the amount of phosphorus loss.
Moving on to the precision ag technologies, umm, most producers that do not use precision ag technologies on their planters so-called dumb planters you have to go through the field a little bit to see what your seed placement is, make sure that it's correct. You do that by getting out, digging, making sure that you have the correct depth, the correct lateral spacing. Here, we want our seed to be about 7 inches apart. So, if there are troubles recognized at this point, then you adjust the planner until you get it right. Once you get it right, you keep on trucking through that field, and you never
look back. Where we, I know precision planting technologies have been adopted, almost every producer that I know that has done this, they get maps such as this. So, the green line you can see there is where you have good singulation. There are some blue dots you can see interrupting those green lines, which is where you get doubles. So, either you're dropping two seeds at once, or instead of every seven inches you drop a seed about every three inches.
There are also some yellow dots in that monitor that show where you're getting skips. So, instead of every seven inches, it might be every 14 or 21 inches between the seeds. Last year we bought corn seed for about $450 a bag. The people behind these screens know how much that costs. So immediately, whenever they see poor singulation, this is what they
do. It doesn't matter where they are in the field, they stop. They try to figure out what's going on. They can identify which row unit on the planter is the problem. So, this technology gives producers a very solid data set to check their resource management and whether it's seed, some other technologies can look at fertilizer placement, and some different things.
Here, a case study looking at, on the left we have yield monitoring of wheat in 2017, and in this portion of the field is an area where we where not able to harvest because it was too wet. Turn around in 2018 when we planted corn. Again, it was too wet to plant this portion of the field. So, we have a zone here that we know we have resource concerns with. Second field, and I will talk about this field quite a bit in upcoming slides. In 2017, the wheat, it was too wet to harvest a sizable portion of this field. Contrary to the other
field, this field in 2018, we were able to plant it, but I'll show we did have some yield problems in this portion of the field. So, some of the immediate impacts of adopting precision ag technologies, the producers get immediate visualization and feedback from the operations that they're doing. It makes these producers more prone to pay special attention to these new-found problems with their equipment. I would say it gives hard
data for a people that are focusing on resource concerns, such as NRCS personnel, to visit with farmers to talk about, take some of these yield maps and identify where some of their resource concerns are. Some, maybe some of these areas could use a grassed waterway or other practice to improve. We'll move into some work on how we were developing some, some ways to manage fields differently. So, this happened at Riesel, Texas, where we have an experimental farm.
We planted corn in 2018, 19, and 20. We took data from the combine, cleaned it using some publicly-available software, brought it back into GIS, put the data on a 16- foot by 16-foot grid, looked at uncertainty. We mapped for each year and then for the mean for all three years the average and also the coefficient of variation which is a measure of variability. And then we translated those variables in yield stability zones. And then from that
we brought in some gross margins and some other items. So, this is what the data looks like right off of the machine. This is three fields for 2018, 19, and 20. And just scatter plots of what those look like for the nine different
fields. Each one of these is a single field. Each bar is one year and what the scatter in each field looks like. As you can see, 2018 was an extreme drought. I think we got about one or two inches of rain after we planted. So, yields are very, very low, and you'll see our variability in almost all of these fields is very high because we have such low yields from this drought here.
So, here we're mapping, taking the clean data and putting it back on the maps. We've done that, so this shows the average yield for all three years for each of the nine fields. This is the field that I said we talk about later, and you can see in this region where we couldn't harvest the wheat in 2017, we had very low yields on average across this portion of the study. Looking at the variability, we also have very low variability in this
portion of the field, so it's stable at being unproductive. What we d really like to have is stable at being very productive, but we know that's not the case in this part of the field. I'll also talk about some work in this field. SW-16, W-13, and then Y-13 in a little bit.
So, the yield stability zones, we cut the fields up in the zones where there is zone A is high yield, low variability. So, it's stable at being high yield. Zone B it's high yield, but there's a lot of variability in that, which is the case for most of our fields given the extreme drought and the flood years that we had. Zone C is, it s low yield, but there s a lot of variability in there. And then Zone D is its low yield, and low variability, so it's stable at being low yielding.
This is what this looks like on the map, and there in the circle you can see the large contiguous pink zone that is zoned D. So, it's stable at being low yielding. And then here we put in the gross margins. For any ag economists on the call, you can see the formula there that we used to make these calculations. We put in numbers for all three years, and you can see in, in portions of this field, we're losing up to $610 an acre. Now that's a bit of a misnomer, because that's a 16 foot by 16 foot zone. But if you extrapolate that zone out to an entire acre, that's how much it would be. So, based on these yield stability zones and the economics, two of the fields so, I mentioned we'll talk about a few extra fields. So, this one, we took Zone C, so high, or, low yield,
but high variability. We reduced the input, so, the seed and the fertilizer to 80%. And then the low yield, low variability so stable being low yielding it's at 60% of the crop inputs. We did that, the same thing for this field here, W-13. Two fields, that Zone D, we completely eliminated crop production in that Zone D. So, this is what the 2022 yield and gross margins look like from these fields. And then the, on the left, we have the average gross margin from all three years, and you can see there's quite a bit of variability both within a field, across the yield or the stability zones, umm, but also among the fields. And
in regions like this, the Zones C and D had quite a bit of loss. Last year, 2022, which is the first year where we adopted this new management strategy, so this SW-16, W-13 are fields where we reduced the inputs. And you can see that the Zones C and D are competitive, gross margin wise, with the Zones A and B. And then in Zone,
field Y-8, we completely eliminated farming in zone D, so there is no data from that portion of the field. We do, last year was also a drought year. We got enough to produce a crop, but not enough to produce runoff. So, here we're comparing runoff data, umm, from this current year where we kept the same management. We're also in corn. Umm, so we got runoff samples in April and May this year. So that's what I'm calling the after period. The before period, rainfall during April and May was similar in 2019, so that's what I'm, I'm using as comparison is April and May of 2019 to April and May of 2023, here.
So here we have two fields that are control fields were management was not changed between these two periods. Looking at the phosphorus loss, umm, from these fields, there's a huge range in the amount of phosphorus loss. So, this first field, the phosphorus loss increased by 60%, once we got into the transition of where the new management is on the other fields. But in this control field, we increased phosphorus loss and the other control field, there's an improvement of about an order of magnitude in the amount of phosphorus loss. So, a huge range, so this is not stable.
Where we reduced inputs, we did have two fields, but only one of those fields had water quality monitoring on the field. So, in that field we reduced the amount of phosphorus loss by about 98%. In the two fields where we eliminated inputs from Zone D, we reduced phosphorus loss by about 85 to 97% in this transition. So, we can't say anything definitive yet, but it is interesting to at least note that the amount of variability in the phosphorus loss where we've reduced or eliminated inputs, it's much more stable than the control fields.
So, some kind of intermediate benefits to this, it does take several years to understand the system, but we think that, ah, when looking at annual yield, the variability in the yield and economics really does provide some power in adjusting the management within the field. I think we're very lucky to have an ag economist on our team, in bringing this information in and helping us adjust fire on these low yielding areas is going to be a benefit. Preliminary work shows that there could be some benefit to water quality. Crossing our fingers. We need more years of data to produce a more robust data set to confirm this.
Bringing into some work with colleagues, particularly at University of Kentucky, where we're starting to work together on precision fertility. So, what do we really know about fertility? Are our fertility recommendations correct? And then some work, they and we are doing here on precision fertility. So, take a step back and looking at how these zones or grids are made in order to drive the variable rate technology, application of fertilizers. Here they have one field and
they've adjusted kind of the start point of sampling their grid on each field. So, they're all on 2 1/2 acre grids on the left or on the right. You can see stacked together what these grids look like. They have also sampled it on a 1 acre grid as well as a .1 acre grid. Looking at all the data across all of these five sampling schemes,
the data tend to skew to the left, towards lower levels of phosphorus than the whole, but each one tends to have a long tail where they pick up hot spots within the field. Looking at the summary statistics of this umm, with the exception of 1 treatment here, the 2 1/2 acre #2 here, umm, the, this one might give, depending on which fertility recommendations you're looking, at might give a little bit different information on how much you should fertilize the field or portions of the field. Then all except for this one case, there's a tremendous amount of variability as measured by this coefficient of variation. There's a tremendous amount of variability across these fields.
It's not only the soil samples that are used to determine these zones. Many people will bring in information from some of the NRCS soils databases to look at topography and soil texture, slope or elevation, or different things to develop zones. So, we also know that these are important in many aspects of fertility management. Even if we can develop the best possible maps, do we have precise recommendations? I don't want to bore you too much with how some of these recommendations are made. There are at least three different philosophies in how to guide fertility management. So in this graph, representative values for Mehlich 3 phosphorus levels, and then how much phosphorus you should be applying.
Umm, some people say that you should only supply enough to make sure the soil has enough buffering. So, if you're extremely low, you need to add a little bit of fertilizer, and taper that off continuously until you reach some critical threshold on the field. Other people say, at very low levels of soil test phosphorus, you've really got to, first, to overcome some of the buffering capacities there and also to bank some phosphorus in case we get into another situation of $1000 a ton for fertilizer. Looking at how these recommendations were developed, you would get a series of tests that may give different critical soil test phosphorus values. So, it may range, it may be 30 on this particular test, 35 on this next one, and then 40 on the next one. And then they would find these zones with different levels of soil test phosphorus and do fertility curves where they apply different rates of fertilizer. And even in that, there's
some pretty big variability that can be built in. So, from these fertility recommendations, we've actually built in a lot of extra cushion, or insurance, to try to make sure that producers don't lose yield based on our fertility recommendations. We think that, using precision ag, we can come up with a hybrid approach. Once we learn more about how some of these zones interact and what some of the real players are in determining whether or not you're going to get a fertilizer response, we'll determine a lot in how we should guide phosphorus management for sustainability.
Working with the crew at University of Kentucky, they've taken pretty large fields and cut them up into small plots that measure 40 by 40. They rotate the plots so that they don't have, uh, so that they can use these fields for several years. They don't come back to a plot once they've used it. And then each plot has sub plots. So, this will be 2 rows of corn for 40 foot here, this will be 2 rows of corn for 40 foot, here and so on. They will apply, so APP is ammonium polyphosphate, they'll apply that
in this plot, and then right next to it they will not apply phosphorus. So, they minimize the amount of variability, spatial variability, within the field. On average, these studies show that there is a response to the fertilizer, anywhere between 9 and 18 pounds, or bushels per acre, in these fields. However, half of the time, there was no response to the fertilizer in these side-by-side comparisons, which is very important. So, we're looking at accuracy versus precision. Across the entire field, we know that the
average of all the soils is going to give us about the right fertility level, so it's accurate, but it's not precise. What we want to be able to do is be both accurate and precise. This is a measure of variability for all the parts. As you increase the amount of soil test phosphorus, so very high soil test phosphorus here, you look at these studies, there's very little variance. So, top to bottom, there's, there s no discrepancy there. Over here at very low soil test phosphorus, sometimes you get a huge response, sometimes you get no response to the phosphorus fertilizer. So, that's the key. Where are we going to find these responses? And this is a graph of the normalized yield as a function of the control yield. So, if
we look at the yield in that control subplot, as the yield in that controlled subplot increases in every instance, the impact of your fertilizer decreases. And then, this is another way, very strong statistician working on this study, and these two years, 2016 and 20, when there was a response to the phosphorus fertilizer, the thing that popped out was the soil test phosphorus level, this Mehlich 3P. In years where there wasn't as great a response from the fertilizer application, you did not see a response, a response in the yield coming out in these regressions from the soil test.
So, we've kind of developed this concept, the two cartoons here on the left, here you can see there's no phosphorus applied, and you get 180 bushels of yield. You have phosphorus, you get 260 bushels yield. Those roots are not able to fully extrapolate the phosphorus in the soil, because there's some limiting barrier. So, there's some root issue that makes the plant more responsive to the fertilizer. In the half of the time where there is no
response to the phosphorus fertilizer, we think it's because of this type of circumstance, where the plant is fully able to extrapolate the portion of the soil that it needs and get that phosphorus, so there is no response to the fertilizer in those cases. So, for the second time, I'm going to skip over some of this real quick and move into some of the precision fertility based off those cartoons, and what we mentioned very early on about the inefficiencies in the system and how we're currently feeding the soil in order to feed the plant. Can we move that closer to feeding the plant? So, we've moved into, umm, trying to see if we can't fertilize individual plants. So,
we, through this here we call it the individual plant treatment studies. It's incredibly inefficient. We realize that because we're doing this by hand, but we would just want to see if it's worthwhile. Here's a first year of study and we did get a response to our different fertilizer rates using this technique. And I'm going to fly through some slides real quick. Here is the yield. I'm looking at three different fields. Two of the fields we got good yield response, and one field, there was no yield response. This is considered a significant
yield response here, but you can see that there's a tremendous amount of variability across these different rates of fertilizer. An instance of getting yield response, here we're starting to look at landscape positions or foot slope versus shoulder slope. And then starting into the 4R's. So, the right place, the right time, the right fertilizers let s see, placement, source, fertilizer and timing. I know I messed that up, but, in this particular instance, in the foot slope, the only time we got a response was from this liquid fertilizer. The dry fertilizer didn't work so well this time. Here we're injecting the fertilizer 2 inches below the surface versus applying on the surface.
A little bit of bump at the foot slope position from both of those. And we're also looking at horizontal placement. So, if we're placing our seed every 7 inches, do we need to be right beside that seed, or is there some kind of slack there? What happens if we accidentally hit right in between two seeds? And actually, in this instance, that seems to provide more benefit, when we're some distance away from the seed. Looking at, so this is this year's data. We're currently harvesting these plants, so I don't have data to show, but we did measure plant height at the third true leaf stage. So, liquid
and dry, we saw some benefit in plant height. Three different rates, saw some benefit there. Injecting and surface application both showed increased plant height. And then, all of the horizontal placements within the field within the row showed some benefit in plant height. So, looking at these studies, we know that we can get a yield response using this type of fertilizer applications sometimes. The results seem promising, but there's definitely more work to do, and we are working through all of these 4Rs of the 4R fertilizer strategy.
Overall conclusion, precision ag helps to producers to visualize their data and gives them hard data that conservation-minded folks like yourself can visit with them about resource concerns. We ve got to know how the system works, but it appears that there may be some economic benefit to the producer by adopting precision ag technologies and basing management off of these technologies, as well as some benefit to society through potentially improved water quality. Recommendations are right, except for where they're not, and we've got a big, pretty big team working on that now. The next step for us is, we've actually just had an unmanned ground vehicle like this delivered last week, and the next few years we're going to be using this to not only take measurements for us, but also to hopefully apply some of the fertilizers for us. So, really looking forward to the results, we have to share in the coming year. Well, thank you.
Thank you, Doug. I just wanted to kind of emphasize the importance of this research to NRCS and our conservation efforts. A systems approach to conservation recognizes that in-field variability, the productivity, and the impacts to our surrounding natural resources. And the goal of precision ag shouldn't necessarily be to increase the yield in all areas of the field, but rather to maximize the overall profit of the field while considering the impacts to the surrounding environment. Use of yield mapping, soil testing, and knowledge of individual field characteristics better enable the NRCS conservation planner, and producer, to apply precision conservation, resulting in overall economic gains for the producer as well as environmental benefits.
Proper phosphorus nutrient management is critical for enhanced plant growth as well as improved water quality and the surrounding ecosystems. The source of phosphorus and the method of application impact the amount of soluble phosphorus and runoff, and injection or incorporation of phosphorus greatly reduces runoff losses. Proper timing, the plant is able to utilize the phosphorus more readily, leading to an enhanced yield. Again, I want to thank you, Dr. Smith, for this, and I will turn it back to you, Elizabeth Creech. Alright. Well, thank you so much, Dr. Smith, for sharing your findings with us today. And
we've got 3 minutes left. If you all could hang on, we're going to go through just a few resources. But before I jump in there, I also want to give a huge thank you to our Deputy Chief for the opening remarks, and to you, Chris, also, and others with the Conservation Effects Assessment Project for the collaboration on this research.
So, once again, please visit the Conservation Outcomes Webinar Series webpage to access the additional resources one-pager and today's presentation slides. And then, if you do want to watch the recording of this, that will be available by next Friday, so, by July 28th. There's also a signup link there to receive Conservation Outcomes govDelivery email messages.
You'll see that at the top of the page. I'd greatly encourage you to sign up. You'll get information on webinars like this, [and] other resources from our team. And, if you're curious about additional NRCS work to quantify conservation outcomes across the nation's cropland, please visit the Conservation Effects Assessment Project Cropland Assessments webpage. You can access that page at nrcs.usda.gov/ceap. That's on the screen and I'll also drop that
in the chat. And then also, I'm going to put a link to our CEAP Watershed Assessments webpage in the chat. I know we were tight on time today. We didn't have time for questions, but please, you've
got our email addresses here, and I'll drop those in the chat as well. Email me and Chris directly with any questions you may have, or follow-up, and we can collaborate on that with Doug. And then, one final thing before you go, we really want to preview our next Conservation Outcomes Webinar. That's going to be scheduled for August 24th. So, we're jumping kind of
a different topic, one that I think folks will be excited about too. This webinar will feature research focused on multi-decade movement patterns and the effects of land use on at-risk turtle species in the Northeast, and Dr. Patrick Roberts of the University of Massachusetts will be our feature presenter there. So additional details will be posted to our Conservation Outcomes Webinar Series webpage shortly. We hope you'll be able to join us. Have a great afternoon, everyone. Thank you so much and I'll drop those resources in the
chat now.
2023-07-31 12:50
