Contact Dr. Haiying Tao via email at firstname.lastname@example.org and contact Dr. Dave Huggins at email@example.com.
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Drew Lyon: Hello. Welcome to the WSU Wheat Beat podcast. I’m your host, Drew Lyon, and I want to thank you for joining me as we explore the world of small grains production and research at Washington State University. In each episode, I speak with researchers from WSU and the USDA-ARS to provide you with insights into the latest research on wheat and barley production. If you enjoy the WSU Wheat Beat podcast do us a favor and subscribe on iTunes or your favorite podcasting app and leave us a review while you’re there so others can find the show too.
[ Music ]
Drew Lyon: Welcome to the inaugural Ask An Expert episode of the WSU Wheat Beat Podcast. In December, we asked our listeners to submit questions for this special episode. And we invited two experts to answer those questions. Our two experts today are Dr. Haiying Tau and Dr. Dave Huggins. Haiying is an assistant professor of soil fertility and residue management in the Department of Crop and Soil Sciences. She received her Ph.D. in soil science from the University of Connecticut, MS in agronomy from China Agricultural University, and BS in agronomy and BS minor in agricultural economics from China Agricultural University. Her current research and extension focus on soil fertility and crop residue management, soil health, digital agriculture, land application of manure, nutrient management planning. Dr. Dave Huggins is a USDA-ARS soil scientist and research leader of the Northwest Sustainable Agroecosystems Research Unit in Pullman, Washington. He obtained his Ph.D. at WSU and has been working with conservation farming systems and precision agriculture for 39 years. His research specialties include soil carbon sequestration, nitrogen use efficiency, and soil health. Hello, Haiying.
Dr. Haiying Tao: Hi, Drew.
Drew Lyon: Hello, Dave.
Dr. Dave Huggins: Hi, Drew.
Drew Lyon: So, we asked our audience, our listeners to submit questions back in December. We got a total of about 10 questions, and 9 of those 10 were soil related. So, I thought we’d get our two soil experts in here today and focus in on soils. And there’s tangential things like cropping systems that’s attached to that, and actually one weed control question. So, so, I think we have a wider variety of things, but mostly related to soil. So, I’ll kick off this one, and this first question is a cropping systems question. And I’m going to turn this to you, Dave, to give us the first response, and then see if Haiying has anything she’d like to add. But the question is, and first it starts off with a bit of a statement:
“A popular cropping system in the Palouse is a three year continuous crop rotation. Many growers have practiced this; plant winter wheat the first year, spring wheat the second, followed by either a legume or barley the third year. The short rotation has exacerbated several issues that plague growers, including various soil-borne diseases and devastating weed resistance. A longer rotation would help to aid growers in managing these issues. In the long run, it would diminish the effects of these issues on their crops. If a longer rotation were to be implemented by farmers, what would you advise that rotation to be and why? And are there any problems you can foresee this new rotation having, and if so, what?”
Dr. Dave Huggins: That’s a great question, Drew, and one that is in the minds of many people, not just farmers, but researchers alike. And it’s not a new question, because this is something that we’ve been grappling with for, you know, since we started farming the Palouse in terms of what crops to grow. And I was just thinking about some of the history of our cropping systems. And they kind of go hand in hand with some of the changes that we’ve had in terms of reduced hill and direct seed systems too in order to try to accommodate the system and try to address some of the issues you just mentioned. I was recalling back in the 70s when a winter wheat spring pea was a dominant crop rotation. Of course that included some pretty intensive tillage. But as we started to move towards direct seed or no-till systems and reduced hill systems, then we recognized that we needed to spread the rotation out further in order to address some of the pathology issues, the disease issues, like Cephalosporium stripe, as well as some of the weed issues like Downy Brome, et cetera. And some of the first research that addressed this was actually conducted by Dr. Frank Young, now retired. But he had an IPM project where they actually looked at a three-year rotation of winter wheat, spring barley, spring peas, as compared to a winter wheat pea rotation. And that was one of the first ones that was analyzed by Dr. Doug Young, actually, an ag economist, and looked profitable from the perspective of a rotation that would work for us, and also kind of expand that rotation to address some of the wheat and disease issues. And so and you actually look at the crops that farmers grow, and now we have data that actually shows what gets grown every year if you look at the National Ag Statistical Service, they have what’s called a cropland beta layer, and it actually shows what crops were grown on a 30 meter, that’s about 100 foot, on a 100-foot basis, okay, throughout the region, actually throughout the United States. And so that comes every year. And when you start looking at the crops that are grown currently in the annual cropping region of the Palouse, you’ll see that it’s predominantly, well, it’s predominantly winter wheat. And, you know, you look at the percentages, and farmers are still probably 40% or more winter wheat. So, it kind of calls into the account that are we really practicing rotation and more crop sequence kinds of strategies here? And really farmers are looking at commodities that are going to, you know, be profitable for them. And so they tend to grow winter wheat as often as they can. [ laughs ] And sometimes until they start running into issues with things like some of the weed and disease issues. And then they’ll start to mix it up a bit in order to help manage those. So, to me, it really comes down to having tools in the toolbox, you know, different crops that we can have that are available, and hopefully profitable, which has also been a real issue with a lot of our alternative crops, having actual crops in the toolbox that are profitable that we can mix it up with to address the various issues that are often unique for every darn farm. You’ll want to go in and be able to have different options in terms of how to manage those scenarios, those different issues that you have. And also to respond to various, you know, prices, et cetera. So, to me, it becomes important to have a diversity of options that we might have that we can basically use in order to manage everything from a short-term economic perspective right on through to some of the weed and disease issues. And, you know, winter wheat’s not going to go away, [ laughter ] I don’t think, for us. That’s a really profitable, well, that’s our most profitable crop, for the most part, that’s why we see it grown so often. Some crops that do really well afterwards in direct seed systems, we’ve seen, and this is looking at a sequence perspective, garbs tend to do really well after high residue, so if we’re starting to look at some of the, you know, basically the yields we’re getting now, winning, you know, yield contests in the United States, you’re looking at yields, you know, in the highest producing areas of starting to approach 200 bushels. I mean, it’s incredible. And, of course, that produces all kinds of residue. And this is a challenge, of course, for subsequent crops, you know, and options from the standpoint of tillage, et cetera, direct seed systems. But a couple of crops that do really well that tend to like high residue loads, this is where we get into the sequence thing. And it’s, it’s kind of managing their, or thinking about the residue loads, et cetera, our crops like garbs and spring canola for us, they both do well under high residue situations and under direct seed situations, under high residue conditions. So, those are kind of sequences that are worth looking at. Also, if you’re looking at winter wheat, it’s by far the best in terms of a sequence following some of our pulse crops like winter, like, sorry, like lentils, peas, garbs, again, one of the reasons is because those pulse crops just use less water. There’s more stored water in the soil that’s carried over for that winter wheat crop. And so we tend to see, we tend to see some advantages there as compared to other crops like spring wheat or barley that use more water, and consequently, then you’re starting off with a little bit less of a profile in terms of stored cellular water going into that winter wheat sequence. And so, you know, I think coming up with a rotation, I don’t think there’s any magic here in terms of, in terms of what might be out there that you can take a look at. But what I’d like to see, though, in the future, and there’s some progress here from the standpoint of current research looking at, I’d like to see more winter options. Okay? So, winter peas is one. But there’s a lot of winter options from our, from our spring crop kind of parts for, from everything from oats to barley to peas to lentils, et cetera. And I’d like to see that expanded because quite frankly we can, we have, those have a higher yield potential for us in our Palouse region and gives us a competitive advantage, you know, in terms of other regions we can grow winter crops here. I’d like to see more winter crops in our portfolio. Otherwise, there’s exciting movement in terms of looking at intercropping systems as well. And that might be a future thing that we look at in terms of trying to diversity our systems. And that might be helpful from the standpoint of addressing some of the weed and disease issues as well. So, I’d like to see that from a research perspective move forward. And I’ll just mention to say too that from our unit’s perspective, we’re now in the process of advising for a cropping system to grow. So, one of their charges will be to pursue some of these kinds of alternative, alternatives, or developing more alternatives, basically for us in terms of cropping systems.
Drew Lyon: You mentioned, you know, the money maker is winter wheat, and you want, a lot of growers want to grow that as often as possible. I know from a weed control standpoint, being out of a certain crop for two years at least really has a rotational benefit, you know, longer might be better, but then the economics become, become an issue. Do we have those couple other crops that you could insert between winter wheat crops when you wanted to deal with a disease or weed issue?
Dr. Dave Huggins: Yeah, good question, Drew. And, again, you know, this has been a real issue for us historically because many of our alternate crops haven’t been in some cases profitable at all. There was kind of, you know, treading water in terms of the economics of those. And that is a question that comes up every year. And so, yeah, we do have spring crop options, you know, everything from if you want to start, you know, spooling together rotations, it’s kind of a hand waving exercise a little bit in terms of what that might look like. But things that we’ve been looking at is replacing some of our spring wheat with spring with spring canola. And this is really to address some of the Italian ryegrass issues. And that’s been one of the management tools that we’ve used effectively to try to put the sequences together. So, that was a winter wheat, spring canola, and then we went to garbs and then back to winter wheat in that scenario. We also have research that goes from winter wheat to garbs to winter wheat then back to canola again. So, it’s kind of a four-year rotation, but emphasizing the winter crop in there. You can probably poke holes in that too from the standpoint of various options or issues that you’re going to have to grapple with. Again, a lot of those issues tend to be unique for every farm, and, you know, your history is out there in terms of trying to look at what might work for you.
Drew Lyon: So, I know another part of this question was “how might this rotation be different in a conventional system versus a no-till system”, and I know when I was in Nebraska if you had tillage in the system, the rotation wasn’t quite as critical to weed control as it was if you were in a no-till system. So, do you see the same do you need to look at rotations differently in a no-till system than in a conventional till system in your opinion?
Dr. Dave Huggins: Yeah, Drew, that’s definitely the case. And, you know, that’s one of the reasons why, you know, we started looking at those three-year rotations, to begin with, and going from a two year to a three-year rotation was because we were reducing tillage and going to no-till systems, and we had to basically come up with other ways to manage those weeds besides, you know, having the tillage element in there. And we still see that today. And, you know, I think some of the barriers we still have indirect seed systems are what to do after winter wheat. And we mentioned the winter wheat, spring wheat rotation well. It’s tough to have spring wheat in there when you’ve got, you know, tons and tons of residue to fight in the spring, and those residues are keeping the soils cold and wet. [ laughter ] And you, and you want to get in there as early as possible, you know, in terms of planting spring wheat. And quite frankly, were going to be suboptimal with respect to temperatures that are favorable for spring wheat under those conditions. So, everything that we can there are all kinds of reasons to do tillage under that type of scenario in terms of tillage that allows us to get onto those fields a little bit earlier and then, and under long term no-till, I will say that there are circumstances as those soils improve, infiltration improves, et cetera, where we’re seeing that we’re able to get on those soils a little bit earlier than we thought we could, but we still have colder soils for the most part under those direct seed systems that is suboptimal for going in early and planting something like spring wheat. So, I see that as a real almost barrier from the standpoint of trying to do no-till or kinds of systems or direct seed systems under those circumstances. Easier, much easier to plant spring canola in a lot of ways or spring garbs.
Drew Lyon: Okay. Haiying, you, in addition to your soil fertility work, do a lot of work in residue management. Do you, how do you see this issue playing out? Do you have anything to add to what Dave said, or do you have something you take exception to what Dave said?
Dr. Haiying Tao: I just want to add some nutrient management component to the diversifying crop rotations. When you include legumes crops in crop rotation, it actually is beneficial for nutrient management, because legumes can fix nitrogen and require very little nitrogen applications that is not only beneficial to farmers caused in fertilizer applications but also is beneficial to soil health, because with a reduced fertilizer applications, especially nitrogen applications, you know, nitrogen application impact on soil health is reduced. So, with soil conservation point of view, including legume crops in the crop rotation is beneficial. As far as another aspect of soil conservation, for example, residue cover on the soil suffers to prevent soil loss, it really depends on where you are and the yield of yield potential of the crops in the locations where your cereal crops produce a heavy amount of residue, including legume crops that produce less of the crop residue, maybe it helps with the decomposition of heavy crop residue. But if you are in the locations where you don’t produce a lot of crop residue, including legumes in the rotation will even reduce further of your total amount of biomass that can be left on the soil surface, which is, could be including some negative impact to the soil conservation in terms of soil loss.
Drew Lyon: Okay, I think this is a topic we could probably spend the entire episode on, because there are so many components to crop rotation. But let’s move on to our next question, so we can get through, through these. Our next question I’m going to give to you, Haiying, because it’s dealing with big data. And as part of the Farmer’s Network, you have some experience dealing with big data. The question is:
“I would like to hear about whether and how big data, that is, analytics of rainfall patterns, water cycles, fertilizer requirements, satellite imagery, et cetera, is being used in the Palouse. Microsoft’s Farm Beets program or Bayer’s Digital Farming Subsidiary are two examples. But we’d like to hear how neighbors are actually collecting data from these sources and their equipment and implementing the results, resulting outputs.”
Dr. Haiying Tao: Many farmers have GPS and yield monitors that are mounted on the combine that allow them to collect yield data on the go. The yield monitor can produce very powerful yield maps that farmers can use in many aspects of decision-making. I know some farmers and their field agronomists have been using yield maps, historical yield maps to produce zone maps and those farmers have variable rate application equipment can then use the zone maps to guide their nutrient applications at different rates for different zones within a field. And some farmers have protein monitors that they can mount on the combine and collect green protein concentrations at, on the go when they harvest. The protein maps are also a very powerful piece of data that farmers can use to visualize green protein concentration on the go and to learn where they did or did not have a sufficient amount of nitrogen during the growing season to produce the protein concentration that they want. And when you add, when you have both field monitors and protein monitors, you have both information on yield and protein at any given location of the field and put those two pieces of the information together you can calculate the nitrogen removal from green harvest, as well as total nitrogen uptake at any given location of the field, which is a powerful piece of information that farmers can use to get feedback for their nitrogen management practices. And then they can also use this information to produce zone maps for green removal, nitrogen removal from green harvest, and nitrogen uptake during the growing season. And then you use this information to fine-tune nitrogen management for the future at any given location of your field. But as far as I know, there are not many farmers who have protein monitors. I think we need to provide farmers with more information, the benefit in agronomics, in economics, of purchasing this equipment, and the benefit that they can get from using this equipment for decision making. And with that information, maybe it’s more encouraging for farmers to adapt to this kind of technology. As far as remote sensing imagery, remote sensing imageries are now more available than ever before. And you can get remote sensing imagery using cameras mounted on UAVs, mounted on airplanes, and you can get high resolution, high revisiting frequency of satellite imagery at a lower cost now than before. And with these remote sensing imageries, you can calculate many different vegetation indices. For example, NDVI and NDRE, which most farmers and consultants are very much familiar with. And using these indices, you can incorporate this data into your decision-making. So, the NDVI and NDRE are very well correlated with crop yield and chlorophyll content in the biomass with this good relationship, even though that you can use remote sensing imagery to predict how much nitrogen is taken up by your crop. And you can predict a yield. And then you can use this information in the decision-making. I know a few farmers have been working with their consultants using the remote sensing imagery to produce zone maps. But I think using those zone maps for guiding variable rate of applications, there’s still some way to go. I know there is some research that was done in the Palouse area and found a very good relationship between remote sensing imagery and yield and nitrogen uptake. But this relationship consistent, are they consistent across different, different corridors? Are they consistent across different soils and ecological zones? And how to translate the remote sensing maps into the maps for guiding variable rate applications, I think we need a little more research, and especially we need tools that are convenient for farmers to use this information and translate this information into manageable decision makings, you know, that farmers and consultants can actually easily use. But there are many scientists that are working on this. And hopefully, in the near future, we will have those tools. As far as the tools that farmers use for creating zone maps, there are service providers that have those tools that can create simple zone maps. But as far as guiding, you know, variable rate applications I think we still have some way to go. So, now I think there are some reasons that these maps are not widely used. Actually, many, many reasons. But I just want to mention a little bit on the agronomic side of it. So, with algorithms that we use for now is to zone, create zones, and the read for the zone is still based on a lot of time-based on yield grow method, which is one unit nitrogen requirement for the whole state that brings a lot of uncertainties in your variable map, prescription maps, and that reduces the value of variable rate applications. And there are prediction models that you can use, for example, Cropsis in Washington state, I think Dr. Dave Huggins has a lot of research on that, I may need to invite Dr. Huggins to talk about Cropsis system in Washington state.
Drew Lyon: So, I guess one of the things I think of big data as just all of this data that’s, that people can collect. How do they manage that? [ Dave laughs ] There’s one thing to figure out what it means, but how do you, I mean, I sit down with a spreadsheet from a couple of years of a small plot and I’m already overwhelmed. And now you’re getting this data on little segments. How is all that managed?
Dr. Haiying Tao: Absolutely. That’s one of the main reasons that the big data is not widely used. Big data, you cannot manage back big data using spreadsheets. Big data is not meant to be able to be handled by regular softwares and analyzed statistics. It requires more sophisticated servers, more sophisticated databases, more sophisticated analytical methods. And you need really put all those pieces of information collected using different sensors and tools. You need to put them together and do some sophisticated mathematical and statistical and economical, all those kind of analyticals together, and produce knowledge that you can use. Not only that but also you need tools, to be able to translate the knowledge into the usable tools that farmers and consultants can use and can understand. So, but we don’t have that. But I know in recent years, especially within a few years, there are many, many researchers who realized this is a bottleneck of using those big data that we have the technology to collect so that there are many researchers are working toward this. And I recently, I am working with 15 universities, which we just got a four million dollar grant to get this work started. And, yeah, I mean, it’s, we are, I mean, it’s not enough, of course. It’s super expensive to do this. But at least this, the grant can get us started. And I know there are many other groups that have grants and started working on this as well. So, hopefully, in the near future, we’ll work together, and, you know, move this forward as quickly as we can.
Drew Lyon: Okay, Dave, Haiying gave you a little nod to talk about Cropsis, but I also wonder, you do have used a lot of these zone mapping things on the Cook Farm. If you could just briefly talk about Cropsis and your experience on the Cook Farm.
Dr. Dave Huggins: Yeah. And just kind of reiterating what Haiying just mentioned, you know, we’re kind of in the fourth revolution of agriculture now, digital agriculture. And I was just reading an article where, you know, farmers are really grappling with how to manage the kinds of data that are available. [ laughter ] And us researchers are also, you know, trying to grapple with that issue as well. So, I’ve hired an ecoinformaticist, basically. This is a person that’s able, that has the expertise to actually work with data in the cloud and elsewhere, you know, in terms of getting beyond the spreadsheets that we all grew up with from the standpoint of our research and going to the next generation here in terms of how to manage data and the computing power, et cetera, that’s needed to do that. And Haiying mentioned Cropsis. Cropsis is a model that was developed at Washington State University by Claudia Stockhol. And this is what’s called a process-oriented model. And basically, this is going to take data information about your soils and about your other environmental characteristics. It’s going to combine that with weather data at a daily time step, that’s what’s called to drive the model, and actually can then be used to predict different outcomes that you might get across the field, or across a region. And the actual application that we used it for most recently is looking at flex crop options. And this is where we just wanted to predict what might be the potential yield of spring canola versus spring pea in the case versus spring wheat in February before you actually planted them across the region. And so this was, we use Cropsis basically to take historic weather data and to apply it to the model, and then to grow the crop in the middle itself, and then to map it regionally to see, okay, what would be the expected forecasted yields across this region for those three crops? And we would have that available for February. And it was interesting, February was kind of a good mark for us. We did this also starting with the fall before right on through, and month by month we went through and reran the model to see what kinds of results we would get. And to see that we knew that as we accumulated more precipitation, et cetera, that would be unique for that year, that our model forecast should become better. Right? And so we have actually found that by February 1st, we could actually do pretty well in predicting the future crop yields by about, we could explain about 70% of the yield variability by February 1st. And this just comes back to the fact that we rely so much on stored soil water, et cetera. And so, so we produced maps like that that we think could be used as a forecast for farmers to actually look and see, well, what’s the expectation? And you could also append to that data from February 1st, you can look at the historic data again to look at scenarios through the, for the rest of the season, right, to grow the crop. And you can actually look at the past 30 years of data, basically weather data, and apply that to the model, and get a range then of yield expectations for each one of those yields across the region, again, and that can give you an idea of what the range is and how much variability you might expect in terms of that particular yield. So, that’s just one application of a process-oriented model Cropsis, Cropsis predicts all kinds of other things besides yield, everything from carbon sequestration to water use and other kinds of factors. So, I think, so, in the future, I think some of the secrets in terms of the use of those big data are being able to couple that with process-oriented models like this. And then also to check them, you know, from the standpoint of through the season. And this is where some of the remote sensing data, et cetera, are currently used to be able to actually combine with the model to kind of true up the model in terms of, well, what’s the current state of affairs, well, you could use remote sensing as a strategy to do that, and to basically correct the model as you go along in terms of what’s actually going on regionally throughout, well, throughout the region. So, that’s just one application. There are many others that could be explored at all kinds of scales from regional right on through to, you know, foot by foot on your farm.
Drew Lyon: And I spent a little time in Australia with working with a model called APSIM, which is a similar process.
Dr. Dave Huggins: Yep.
Drew Lyon: And for my use, I’ve made a lot of assumptions, [ laughter ] because you could put all sorts of data in there, but I just didn’t have it. So, that’s where big data could really help, I suppose, make these models more accurate.
Dr. Dave Huggins: Yeah, you know, model validation or corroboration sometimes we say is extremely important. You have to and, you know, our models are only as good as the kinds of data that we have to check them, et cetera, and to basically formulate the model and to make improvements on them. So, there’s this back and forth that goes on in terms of, yeah, we model, but what was the outcome? And how well did the model do? And we have a ways to go there, even with Cropsis, that we’ve worked with for decades now in terms of those models being extremely, extremely accurate, as accurate as we’d like them to be. And so I think that’s always something to take into consideration in terms of the use of any data or any model that’s a forecasting model in terms of what is the certainty around it? And this is something that we pressed modelers to give us more, you know, information on, is, okay, we see what you’re predicting, but what’s the uncertainty around that number? And it’s always good to really place that number than in this context of the uncertainty around it. Okay, that’s the number, but what is the plus and minus of that that you might be trying to predict that uncertainty around it is extremely important to recognize in any model.
Drew Lyon: Okay, time to move on to our next questions, which comes to you, Dave. And this one is on kind of soil health, soil nutrients. The question is:
“On hillsides and nobs that have lighter colored and less productive soil, what elements have been stripped away? And is there any way to repair damaged soil in our lifetimes?”
Drew Lyon: Yeah, great question. Of course, as we look across our Palouse hills, we see lots of different kinds of situations with respect to soil. And that shows up, of course, in our crops. You can see it, you can visualize it. And, of course, a lot of that comes back to just the history of soil erosion over time. And also what those soils started with, with respect to the native condition. There was quite a bit of variability even then. And so, you know, our farming, of course, has also impacted our soils over time. And, you know, I still remember at a field day asking the question, well, what’s the most important soil health variable? And a farmer saying, well, about six feet of it. [ laughter ] And there’s nothing that beats depth when you come to a cropping system that really relies on stored soil moisture, right, to drive crop yield. And so depth is critical to us in terms of, well, I would say number one soil property. And, of course, erosion has robbed us of some of that depth, particularly in those upland positions where everything is departing that landscape [inaudible] everything is moving away from that and down the slope. Right? So, that doesn’t get replenished. And so those areas you can see where we’ve lost depth. That’s where our yield potentials have gone down. And that’s where we struggle. And as we get below about two feet or so of soil depth, of rooting depth, actual rooting depth that we can have, then our yields start to really plummet. And it’s difficult to regain soil depth. I mean, you can look at soil formation, and it’s pretty slow, so it’s not going to happen in your lifetime. It’s going to be generations, you know, to build it back, unless you are more proactive about it. And I’ve seen farmers, you know, haul dirt back up on top of the hillside and up on those summit positions to increase the yields in those locations. That’s quite an effort in order to try to do that. But that soil depth is something that’s very difficult to replace. The other thing, of course, is the decline of soil organic matter. And, of course, as we lose productive capacity on those summit positions, we lose the capacity to return residues and roots to those systems. And so it becomes harder to rebuild organic matter overtime to replenish those. And we try to target about 3% organic matter. It’s a good target, soil organic matter, to try to look at, you know, having the benefits of organic matter that are there. And, of course, organic matter is a storehouse for nutrients, like you mentioned before. And everything from, you know, the nitrogen and phosphorous to some of the micronutrients as well. And but we do see those locations depleted in organic matter. They’re not going to have the same nutrient supplying power as other locations in the field should be watching them in terms of some of the micronutrients, et cetera. Should also be looking at them from the perspective of potassium, which also tends to be showing up in some of our soil tests as being, as being something that we should be thinking about in terms of fertilization in those locations. That has to be balanced by their productive capacity, again, and some of the economic returns, at least short term, may not actually support some of the inputs that we’re talking about in terms of those locations.
Drew Lyon: Okay. Haiying, do you have anything you’d like to add to that or dispute about that?
Dr. Haiying Tao: [ laughter ] I just want to add to, you know, the impact of losing topsoil to a little bit. So, when you lose topsoil, you are punished by many different ways. Not only you lose nutrients from the topsoil, but also you are losing the depth of soil. So, for example, if you lose soil, you know, it meant your soil got reduced from four feet to three feet or from five feet to four feet. And the power of the soil can store water is reduced big time. And these, the water storage in the Palouse is very important for yield. So, I just wanted to add that.
Drew Lyon: Okay, very good. Our next question for you, Haiying, is:
“Could you have a brief update on the role of boron, zinc, phosphorous, and chloride in inland Pacific Northwest dryland wheat production, the role of each, and best time and form to apply, sharing any knowledge of return on investment according to soil test and rate applied?”
Dr. Haiying Tao: Let me start with phosphorous. So, as far as the function of phosphorous, phosphorous is a, is a structural component for ADP, NAP, TP, which are the, which are the components that provide energy sources for plant physiological activity. Phosphorous is also a structural component for nucleic acid, coenzymes. Phosphorous is important for feed formation. As far as fertilizer applications, we recommend phosphorous, soil test for phosphorus for making decisions on phosphorous applications, because the variability of soil test phosphorous does not vary a lot from year to year, so we recommend every you test soil, phosphorous every three years is good enough. And as far as soil loss of phosphorous from soils, so phosphorous did not get lost through leaching unless you have soils that are saturated with phosphorous or you have sandier soils. So, the main loss of phosphorous is through exhaustion. So, that’s, you know, another thing that you want to try to minimize the soil loss. And also in the Palouse soil test phosphorous varies a lot in different slope locations. And maybe you can save some money from the variable rate of phosphorous applications. As far as testing my theories, we are also thinking maybe it’s time for us to look at different soil test methods, because over the years, soil chemical properties, for example, soil pH and soil organic matter have changed a lot. And the current soil testing methods for phosphorous that we’re using may be not a property anymore, but we are not for we need more research on that. And we also need to revisit the read for phosphorous recommendations and add any given level of soil that has phosphorous. Again, that’s because we don’t know, you know, the soil chemical properties changed and the phosphorous fixation capabilities have also changed. So, we need to revisit those. As far as micronutrients, we, the soil tests for micronutrients are not as reliable as soil test methods for macronutrients like nitrogen, phosphorous, and potassium. We normally recommend farmers to take samples from both soils and plant tissue to, from both bad areas and good areas, and by comparing soil and tissue tests in both good areas and bad areas, and then farmers can have a good idea of if they indeed had macronutrients deficiency. So, as far as functionality, boron is important in feed formation. Boron is involved in enzyme activity, enzyme activities. Boron is important in cell wall formation, integrity. And zinc is also important in cell wall integrity. And zinc and phosphorous kind of help each other with their functionality. As far as fertilizer applications for zinc, you know, applying zinc at planting, then the application is okay. I got some questions from farmers, hey, can I apply zinc with my phosphorous, do they react to each other and reduce their availability? With the rate that farmers apply for zinc, it doesn’t really matter. You can do that. With boron applications, plants don’t require a lot of boron. Too much of boron, actually, can be toxic to plants. That’s why we don’t recommend farmers to apply boron at sitting with bend. So, we normally recommend farmer’s plot cast or foliar application is also a common practice. But as far as the agronomic benefit from boron and zinc applications, we don’t have enough local data to support the answers. Are they necessary or are they not? We need more research in Washington state. We also need more research to establish critical levels for soil tests and tissue tests. And you also asked chloride. So, with chloride, the function of chloride in the plant mainly is in the plant osmatic balance or charge balance. With chloride deficiency, plants can have this physiological leaf spots, which can reduce yield if the symptom is pronounced. And as far as fertilization, we recommend farmers to take soil test for chloride at two-fluid in depth. If they find the soil test chloride more than 30 pounds per acre, they are good, they don’t need to apply chloride. But if they, the soil test is between 10 to 20 pounds per acre, farmers may need to apply 10 to 20 pounds of chloride. But if the chloride test is less than 10 pounds per acre in the soil, we recommend farmers to apply 30 pounds acre of chloride. As far as when they should apply, we found that fall application is better than spring application and better than a full year application.
Drew Lyon: Okay, Dave, do you have anything to add to that?
Dr. Dave Huggins: Yeah, I’ll add a little bit, just about potassium. I think this is an element where, you know, increasingly looking at more so from the standpoint of potential deficiencies, this is more for the high rainfall areas, not so much for the dry, real dryland areas. But, but, you know, potassium is just essential from the standpoint of, oh, water use efficiency. And it basically helps to control the openings, the somites in the plants themselves, so these are the openings that allow carbon dioxide in. But at the same time, they let water out. And so potassium helps to regulate that opening in terms of how open or closed it is. And so it’s essential then from the standpoint of water use efficiency. And I think this is an element that we’re looking a little bit more closely at in terms of some of the blend areas where we think we’re looking at more and more deficiency issues. And just to add to what Haiying said as well, you know, in terms of looking at critical nutrient concentrations and tissue, much of this research hasn’t taken place on the Palouse. It’s, we’re borrowing data from other locations in the world basically to try to come up with numbers here. But as everyone knows, in agriculture, everything is unique, and there’s a little bit of danger in terms of borrowing data from other locations to apply them directly. And so we’d like to have our own information from the standpoint of, well, what are the critical nutrient levels in plants for plant tissue testing? And how does that relate to our soil tests, you know, in terms of what we’re seeing now? And that’s a little bit of the research we’re now conducting. At the Cook Agronomy Farm, we have a lot of variability in micronutrients there. And we’re trying to then make the link between some of the tissue tests that we have to the soil test and seeing if there’s, you know, building the database, basically, to try to assess deficiencies or sufficiencies of those nutrients.
Drew Lyon: Okay, so I guess the message from both of you is there’s still a lot of work to be done in this area of micronutrients, and that work is continuing. Let’s go onto the next question. This one for Dave:
“Could someone discuss enhanced nitrogen and rainfall efficiency from continued direct-seed with very limited tillage only to break up heavy straw? We feel that our old formulas are not correct, but they do give fine results far above what the formula predicts. And the update would be appreciated.”
Dr. Dave Huggins: That’s a good question too. And Haiying touched a little bit on this already. But, you know, it’s important, I think, you know, from my perspective to recognize that a lot of these equations and formulas that we use are guidelines. This is where you start in terms of trying to assess, you know, your nutrient management program. You don’t end with those. You’ve got to, you modify from there on out and you recognize that there’s a lot of different scenarios out there that that formula isn’t going to be able to address and do so in a systematic, you know, and predictable way across every thesis. And some of the elements of that that we have tried to address is when we want to more direct seed systems, we started to look at how nitrogen might be released from organic matter through mineralization. So, what is the supplying power then under no-till as compared to our conventional tillage system? And this is where we started to use the number 17 times, so organic matter percentage, in order to come up with an estimate again, a guide towards, well, what would the expectations be in terms of your organic matter being able to supply more nitrogen. Of course, and then that compared to 20, you know, for conventional tillage, recognizing that tillage basically helps to cycle some of the nitrogen and organic matter more quickly and more rapidly. But over time, your no-till systems will build organic matter. And also you’re going to be building up what we call more active organic matter, organic matter that turns over more quickly over time and is able to release all kinds of nutrients in addition to nitrogen. So, so, this is not a stable situation in terms of, okay, we can just apply one number, two and be correct, there’s other factors too, like salt pH that impact how much mineralization happens. And as pH goes down, the mineralization from soil organic matter of nitrogen tends to be slowed up. And so that also impacts then how much nitrogen we might be getting from soil organic matter. And the other big factor to me is just our unit nitrogen requirement. And everyone probably knows, okay, and this gets back to the efficiency issues you were talking about, the 2.7 pounds of nitrogen per bushel of soft light winter wheat as derived from assumptions and tests of efficiencies. And actually assumed an uptake efficiency of nitrogen to 50%. Well, what if you’re better than that or less than that? Then that changes what that actual number is in the field. And so, again, this is a guide that gets you started. It’s an assumption that’s made in terms of efficiencies made. But if you’re increasing efficiencies through the use of precision ag, et cetera, then I would expect that your efficiencies are actually going up, and that that number may not be you might be much less than that. And then other locations where you might be over that in your field. And so, and so there’s definitely differences across the field itself in terms of what that actual number is that unit nitrogen requirement in terms of, and any given year for that matter. But we can impact that through our nitrogen management. And now, you know, with the addition of stabilized nitrogen options and other kinds of, and timings and precision ag, we have tools in the toolbox to try to increase those efficiencies and change those numbers. Again, the numbers are guides. The equations are guides. You go from there to basically fine-tune over time. And this comes back to what Haiying was talking about. We need ways to evaluate how well did we do. And that’s where some of the yield monitoring, the protein sensors, et cetera, and the combined, the remote sense data in terms of normalized red edge data can be used to basically calculate how much nitrogen was exported from the field. Compare that to nitrogen inputs that you may have for fertilizer. And to use those ratios to assess how well did we do in any given portion of the field. So, I really do want to emphasize that the evaluation piece is critical towards beginning to fine-tune your nitrogen management within the field itself. And we do have the tools, the technology to do that now.
Drew Lyon: I do get kind of the sense that part of this question also is, is nitrogen efficiency and water efficiency improved in direct seed systems? And my sense is it is, but it depends on where you are, you know, early on, it actually maybe ties up a little nitrogen. And then later so, how many years has it been, have you been in the system? Is that, is that true? And one is, will direct seed systems, in the long run, be more nitrogen and water use efficient? And how do you decide how to change that management as you go from a conventional to a direct seed system?
Dr. Dave Huggins: Yeah, you know, Drew, it’s a, it’s a complicated question. And, you know, in terms of water use efficiency, as well as nitrogen use efficiency, some of the factors that are contributing to that, one is just the increase in the atmospheric carbon dioxide levels. So, as the world, and us included, increase carbon dioxide in the atmosphere, that’s called a CO2 fertilization effect, and that, in turn, results in increases in yield and yield potential and water use efficiency. Predictions are upwards of 10 to 15% increases in yield just due to carbon dioxide increases in the atmosphere itself. So, there’s one huge factor from the standpoint of just water use efficiency. And in terms of soil, certainly as you’re longer in the system and no-till and you build up organic matter levels, I like to put it more in terms of this is building up your buffering capacity to meet variations in weather that might occur. You get the June rainfall, for instance, and now you have enough organic matter there with the waters and the temperatures to release more nitrogen in a, at the same time that your crops are actually needing it, because they just got more rain. So, from my perspective, it’s more of a buffering capacity in the system that you’re building and that can help you manage from a soils perspective by having that organic matter there to manage some of those variations and weather that we’re experiencing more of, quite frankly, in terms of our spring conditions.
Drew Lyon: Okay. Haiying, do you have anything to add to that?
Dr. Haiying Tao: I just want to add that with big data, then use of big data, we can actually predict the release of nitrogen from soil mineralization much better in using, you know, for any given nitrogen management practice, it’s any given soil, any given weather conditions, you know, we can predict better in terms of how much nitrogen is available in the soil.
Drew Lyon: Okay. One more question for today’s episode. And start off with you, Haiying:
“Is there such a thing as an appropriate amount of nitrogen per foot to be leftover after harvest of dry hand, soft wheat, soft white wheat, winter wheat, and then intermediate rainfall zone? We do not want to leave too much, and we wonder if there’s such a thing as leaving too little.”
Dr. Haiying Tao: So, with soft white winter wheat, you’ll want to use, provide enough nitrogen to reach the yield potential. If you have enough nitrogen to reach your potential is very likely you also reach your protein potential at 10.5%. So, if you see 10.5% of green protein concentration, you it’s very likely that your nitrogen management was good enough. Right? So, if you have the protein concentration higher than that, you may just have too much nitrogen. So, as far as how much nitrogen you should leave in the soil after harvest, it’s hard to say. For example, if you look at soil nitrogen tests in the first foot, at harvest, you may see a lot of nitrogen in the first foot. That’s because nitrogen mineralization happens throughout the growing season. And not all this nitrogen that’s mineralized from soil organic matter is used by current crop, especially the nitrogen that’s mineralized in later of the growing season. They’re not used by the crop. And that nitrogen that accumulated in the soil. And how much accumulated in the soil really depends on manufacturers, you know, how, how, what is the percentage of your soil organic matter, what type of soil organic matter you have, what kind of weather conditions, you know, what kind of soil moisture and soil chemical properties? And all this impacts how much nitrogen could be accumulated in that layer, right? So, as far as how much nitrogen should be left in deeper soil depth, then, you know, deeper than three feet, we, unfortunately, if you grow hard white wheat, you do need some nitrogen left over there. So, we found a very good relationship between how much nitrogen is left deeper than three feet with protein concentration. Because with hard red, you’ll want a high protein concentration in the green. So, you do need some nitrogen left in the deeper soil depth. So, but if you have too much of nitrogen left, that’s not economical for farmers, right? And if you have too much nitrogen left in the soil, you may think of considering using deep-rooted crops in the next year so that that crop can take up the nutrients in deeper soil death as leftover by the wheat. And we also found that if you have more than 100 pounds per acre left in the soil, by the time you plant next crop, it’s very likely that you don’t need fertilizer applications for the next crop anymore because it’s likely that you don’t have yield response to nitrogen anymore.
Drew Lyon: Okay. So, for a soft white, do you want as little nitrogen left over as possible after your wheat crop, is that so, maybe there isn’t anything that’s too little?
Dr. Haiying Tao: It’s very interesting. So, we did look at the relationship between how much nitrogen left in the deeper soil depth, or with green protein concentration, with soft white. We did not find a very good correlation. So, and, of course, you don’t want to, you know, overapply, because you don’t want to end up with high protein concentration.
Drew Lyon: Okay. Dave, do you have anything to add to that?
Dr. Dave Huggins: Yeah, sure. Yeah, I think a couple of things that are really important to consider, and one, anyone that’s gone out and actually had to harvest and sampled with depth to try to see, well, how much did I leave behind, sampling itself is not an easy thing to do to get a representative type of sample for your, for your field. Right? You’ll find quite a bit of variability across the field in terms of how much is left. Also, we’ve found that you can, particularly if you banded nitrogen in the spring, for instance, for a spring wheat crop or another crop, some of those residual bands might show up in your sampling after harvest, simply because, you know, basically the crop dried out the surface with use of water, and you stranded nitrogen in those bands still. And so we’ve found upwards of 300 pounds of nitrogen because we hit a band. Right? In that top foot. And so sampling becomes an issue, particularly that top foot. And the recommendations there are to sample across basically the row in order to get so, you’re not just hitting a band and saying, oh, my gosh, because that’s not representative of the field. Right? You want to get a sample that actually captures the places in between those bands, et cetera, and to put it into more of a proportionally correct type of sample. So, sampling becomes important. And I think like Haiying mentioned, if you, you know, if you had a drought situation, or you applied too much nitrogen, you really should consider crops that are good scavengers of nitrogen to follow, like canola is one of those, you know, very excellent at scavenging nitrogen up. Or consider some of our hard red wheats, et cetera, that require, you know, higher protein levels, and consequently, you know, more nitrogen of the profile to help promote some of those, some of those protein goals that we have.
Drew Lyon: Okay. Well, we can’t get through the remainder of our questions because we’ve run out of time. But I think we’ve had a very good discussion of those questions we did have. And I really appreciate having you two on my inaugural episode of Ask An Expert podcast. Thank you very much.
Dr. Dave Huggins: Yep. Thanks for having us.
Dr. Haiying Tao: Thank you for having us.
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Drew Lyon: Thanks for joining us and listening to the WSU Wheat Beat podcast. If you like what you hear don’t forget to subscribe and leave a review on iTunes or your favorite podcasting app. If you have questions or topics, you’d like to hear on future episodes please email me at drew.lyon — that’s email@example.com –(firstname.lastname@example.org). You can find us online at smallgrains.wsu.edu and on Facebook and Twitter @WSUSmallGrains. The WSU Wheat Beat podcast is a production of CAHNRS Communications and the College of Agricultural, Human and Natural Resource Sciences at Washington State University. I’m Drew Lyon, we’ll see you next time.