Show Notes & Resources Mentioned:
- Oilseed Cropping Systems
- Don’t Guess Soil Test Timely Topic
- Soil & Water Resources
- Soil & Plant Sample Testing & Interpretation
- Post-Harvest Nitrogen Use Efficiency Calculator
- Dryland Wheat Nitrogen Fertilizer Calculator
- Spring Canola Nitrogen Rate Calculator
- Oregon State Soil Test Interpretation Guide
- Whatcom County Soil Testing
- Soil Essential Nutrients
For questions or comments, contact Isaac Madsen via email at firstname.lastname@example.org or via phone at (360) 448-9081.
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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 podcast app and leave us a review so others can find the show too.
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Drew Lyon: My guest today is Dr. Isaac Madsen. Isaac is a soil scientist and native of the Northwest. He currently serves as the extension agronomist for the Washington Oilseeds Cropping Systems Project at WSU. His current research focuses on stand establishment, soil fertility, and winter survival in canola. Isaac hopes to see sustainable oilseed production continue to expand and bring crop diversity to the inland Pacific Northwest. Hello, Isaac.
Dr. Isaac Madsen: Hello, Drew.
Drew Lyon: So we hear and read about how fertilizer prices have just been skyrocketing over the last year. Some I’ve heard double, triple prices. So at these high fertilizer prices, it’s probably more important than ever to apply the right amount of fertilizer. Can you tell us about the resources available for making fertility decisions at WSU?
Dr. Isaac Madsen: Yep. First off, when you start getting questions from your friends who aren’t in agriculture. I had somebody the other day say, “Well, who are we going to run out of fertilizer and all starve?” [laughter] So that’s when you know fertilizer prices have got bad. When when your non nonagricultural friends are asking you about fertilizer prices. Yeah, but tools at WSU the part to start with is just don’t guess. Soil test is something that we like to say in soil science. So the whole idea being that if you don’t have the right information to make a nutrient management decision on, right, you can’t make the right decision. So collecting the right information in most of our dryland cropping systems is actually soil testing. So I would really encourage folks who haven’t soil tested before to start thinking about soil testing. You might have a lot more fertilizer in the ground already, right? Nitrogen hanging out in the soil that you can actually utilize and so this is a really good year to take stock of what’s in the soil and try not over apply and and try and maximize that way. The other thing I was going to say is on the Small Grains extension website, there’s a number of resources. So you might get that soil test and get the results back and then say, what what in the world do I do with this and I get a lot of phone calls like that actually from people who have a soil test but have no sort of way to calibrate it to a management action. And so we have some resources for that. There’s a Soil Test Interpretation Guide on the website. And then there’s three calculators that are specifically focused on nutrients and mostly on nitrogen. And those are the the Wheat Nitrogen Application Calculator, the Post-harvest Nitrogen Use Efficiency Calculator, and then a Spring Canola Nutrient Calculator. And those are all under tools and calculators on the Small Grains website. So if you’ve never used those before, I really encourage people to jump on there and at least play around with them. They all have different goals. The Wheat Nitrogen Applicator– Application Calculator, sorry, and the Spring Nutrient Calculator, the Spring Canola Application Calculator, those both focus on how much nitrogen do I apply if I have a given yield goal versus the Post-harvest Nitrogen Use Efficiency Calculator, the goal of that is to sort of see of my previous practice how efficient was it? So how much nitrogen might I be leaving in the field? Right. And so I think in the past when nitrogen was maybe one of our cheaper inputs, we could kind of not care about efficiency as much. But now with how expensive it is, it’s really a good time to maybe get on there and see how efficient your application is is being and if you’re, you know, if you’re over applying and you have excess nitrogen in the soil might be a good year to use some of that up.
Drew Lyon: You mentioned soil testing.
Dr. Isaac Madsen: Yes.
Drew Lyon: Don’t get soil test. If somebody’s not familiar with how the soil tests are the resources on the Wheat and Small Grains website to help them figure out how to go about soil testing or where would they find that information?
Dr. Isaac Madsen: So Oregon State has a guide on on how to soil test. And actually I was looking for a guide on our Small Grains website, and I think maybe we need to write up a little short one on, you know, just how to take samples, where to take samples. I couldn’t find anything that was really up to date on that. And there’s also — there’s a guide from Western Washington, I think, but it’s more focused on the sort of the small acreage organic production sorts of systems. So less focus on the large scale dryland cropping systems. So I think that would actually be a great addition for us is to to write up a little guide on on where and how to soil test because I wrote that timely topic earlier this spring on that topic of soil testing. And I was looking around for guides and I couldn’t find one easily, so maybe one exists, but I think we should really look into updating that probably.
Drew Lyon: Okay. Something to put on your to do list, Isaac.
Dr. Isaac Madsen: [laughter] Yeah.
Drew Lyon: So you mentioned the Canola Nitrogen Rate Calculator. Can you describe a little bit about how to use the calculator?
Dr. Isaac Madsen: Yeah. So the calculator is — so the method for developing the calculator that we have is you enter a yield goal and then from that yield goal, you try and estimate the amount of nitrogen you’re going to need and then you estimate your nitrogen supply from the soil and the amount of fertilizer you need to apply is the nitrogen required minus the nitrogen supply. So that’s that’s sort of the underlying of it. And so what we have you enter as a user is basically the variables that we need to estimate the requirements. So the amount of nitrogen you’re going to pull off and the amount of nitrogen that your soil might supply. And so the requirements for canola are a bit funny. So it’s we use what’s called the Unit Nitrogen Requirement, which is for every 100 pounds of canola, we’re going to require a certain amount of nitrogen. And for wheat that’s a really sort of stable number, but for canola, that actually changes depending on your yield. And so it might be anywhere between it actually can get as high as ten and then as low as six. So that’s pounds of nitrogen per 100 pounds of canola. So we do all those calculations in the background. So all you need to know is put in your yield goal. So that would be the first thing to put in is just put in the amount of yield you’re trying to hit and then look at a soil test and from the soil test it’ll ask you to put in the amount of nitrate you have. So nitrate, nitrogen, ammonium nitrate, ammonium nitrogen, sorry, and then also the mineralizable nitrogen. And that mineralizable nitrogen is the nitrogen that comes from organic matter. So if a soil has higher organic matter we sort of have this equation where we multiply the amount of organic matter times and some conversion factor that changes whether it’s no till or till. And then that gives you the amount of nitrogen that’s going to be provided from the organic matter because nitrogen– a lot of the nitrogen we get over the growing season, especially in a natural system, isn’t in plant available forms at the start of the season. So it’s not there as nitrate, it’s not there is ammonium, it’s there as soil organic matter. And so then it mineralized is over the growing season and it converts into that nitrate and ammonium and then those can be taken up by the plant. And so that’s sort of the overall outline of how the supply works. There’s one other factor of supply, which is your rotation. So if you’re growing in rotation with winter wheat or spring wheat versus a spring legume, so the legume is going to provide what we call a credit. And so it’s going to add some nitrogen to that system. And winter wheat is actually going to be a debit. The straw, as it breaks down, it’s going to pull nitrogen out of the soil. And so you have to take those those factors into account. So that’s sort of how we calculate nitrogen supply. It’s the mineral nitrogen, which is ammonium nitrate, plus the mineralizable nitrogen, which is from the organic matter, plus or minus your rotation. And that’s the basic sort of equation there. You don’t have to worry about how it works if you’re using the calculator so much, all you have to do is look you soil test, put in those numbers, know you’re rotation — so put in your rotation — and know you’re yield goal and then it’ll from that it’ll calculate a fertilizer rate. So how much fertilizer you need to use.
Drew Lyon: Okay. And is it different between winter canola and spring canola or does the calculator work for both?
Dr. Isaac Madsen: So the calculator right now is built off spring canola data. We’ve tried to do a similar thing for winter canola data and to no avail. There have been a lot of research projects done here and we had a lot of trouble developing what’s called that Unit Nitrogen Requirement, which we abbreviate as the UNR, and so in our research, I think there was — I can’t remember the exact number. I think it’s seven or eight trials done all over Eastern Washington. These are really intensive small plot trials that are done. And there was not a sort of consistent response to the nitrogen application in winter canola, which really means we’re probably underestimating the nitrogen supply. So some of those yields were quite high yields and they weren’t seeing any response to additional nitrogen fertilizer. So we’re talking like 4000, 5000, I think. I think one of them actually was pushing 6,000 pound winter canola and it was with zero extra nitrogen applied. [laughter] So so you know that there’s sort of, you know, that you can’t grow 6,000 pounds of canola, you know, without additional nitrogen. And so there is some source that we’re not really taking into account there. And so that that is a little bit concerning and with that, that probably gets back to the mineralized side of things. So this organic matter in the nitrogen release from there and we have these ways of estimating it but it’s a natural system, right, so it involves all of these bacteria in the soil and it involves basically the you know, what kinds of organic matter you have there. And so I think it’s difficult. And then all of that process is also dependent on the temperature and the moisture, you know, and not having too much moisture so you still have oxygen in the soil. So it’s a complex sort of biological reaction we’re talking about. And I think that’s probably where the error is. And so we’re working on it with winter canola. I don’t know why it’s harder than spring canola.
Drew Lyon: It could have to do… winter canola, I assume has a taproot, maybe gets down deeper below maybe where you’re sampling or are you sampling to a pretty good depth?
Dr. Isaac Madsen: So those samples, I believe, went down to six feet in that study, which there are a little bit of nitrogen that, well, you can see the nitrogen draw down a little bit and six feet from canola. So it is pulling from that depth. But how much it’s pulling, it’s hard to tell. [laughter]
Drew Lyon: Like I said, 6,000 pounds with no head nitrogen. It’s finding something somewhere isn’t it?
Dr. Isaac Madsen: [laughter] Yeah.
Drew Lyon: So it seems like there’s been a lot of focus on nitrogen because of its price. But can you talk a little bit about other nutrients of interest in your canola systems?
Dr. Isaac Madsen: Yeah, so plants, all plants require the essential nutrients or elements, right. So 14 of those come from the soil and there’s macronutrients which is nitrogen, phosphorus, potassium, magnesium, calcium, sorry, nitrogen and phosphorus, potassium and sulfur, magnesium, calcium and sulfur. Those are the macronutrients. And then there’s a bunch of micronutrients also, and we can sort of think of these micronutrients or sometimes I think subconsciously we think of them as less important, but all essential nutrients are essential. So they’re all important for the plant to grow. It’s just that the micronutrients are taken up in smaller quantities, so the plant doesn’t need as much. It doesn’t mean it’s less important. So take something like Boron, which is a micronutrient, for instance, if you have no boron in the soil at all, you still can’t grow a plant and you won’t complete the plants life cycle. So we’ve been interested in the other macronutrients. So things like phosphorus and potassium. and Dr. Haiying Tao was doing work on phosphorus trials in winter canola prior to moving back to the East Coast, and hopefully that that work is ongoing and so hopefully it’ll be published in the next few years. By and large, what we were finding is that in most instances the sort of most of our soils where she was going and sampling on grower fields actually have enough phosphorus in them. So it seems like people are doing a really a pretty good job of sort of a replacement strategy, just making sure that when they’re pulling phosphorus off, they’re putting some phosphorus on to and then potassium generally our soils are really rich in potassium here. So it’s not a huge concern. But there are a few micronutrients that if you sample around the state, most of our shows are are shown deficient in, and that’s boron and zinc. And those have been really, really tricky. So we’ve we’ve tried to like develop some rate calculations for those. And we really haven’t got to the point where we can give some really good recommendations. And specifically in canola, we know boron is really important because it’s important for pollen to tube development in flowering. And so right that’s how you get a good yield and can cause is having that flowering. And so we we’ve tried to develop recommendations and really haven’t been able to do that from the data. We’ve actually in some instances seen declines in yield when you’re applying around flowering foliar which boron can be toxic also, so it’s this really narrow range between sufficiency and toxicity that you’re playing with and the Canadians have seen really similar sorts of problems occur where they might their soil might show itself as deficient, but then they don’t necessarily get a yield bump from adding boron so it’s it’s a little bit mysterious still around boron and zinc. The last thing I would say this kind of fun is in one of our variety trials where we are sampling for tissue tests I think we’re not sure yet, but we were looking over the data, the tissue tests, and it looks like we found a nickel deficiency across the field, which is is really rare to find so it’s I wouldn’t say people need to go out and be concerned about their nickel in their fields. But it was kind of exciting to see that from a researcher perspective like, oh, wow, because nickel was the last of the essential nutrients where they discovered it was essential, I believe. So it was it was added later than the rest to the list. And so we found these this trend in the field between decreasing nickel and decreasing yield. And then I went and started digging through the literature. And sure enough, we were getting below the levels that you want to have where that yield was trending down. So I don’t I’m not really thinking people need to go out there and apply a whole bunch of nickel or anything like that. But it was kind of a fun result from a research perspective and definitely something that I’ll keep an eye on now, moving forward.
Drew Lyon: Here are these are the prices for these micronutrients increasing like the macronutrient prices have, do you know?
Dr. Isaac Madsen: I actually don’t know because I’ve been mostly tracking the nitrogen price and nitrogen is obviously related directly to natural gas for production. And then most of these micronutrients come and the other macronutrients come from some mining process, right? So I believe boron. I think a lot of it’s actually mined in California, and I may not be right on that, but so they’re going to be you know, they’re not going to have the same dependency on the energy market as the nitrogen, although everything’s connected to the energy market at the end of the day, right? So you’re sure driving mining equipment, you’re using a lot of energy. So I would say they’re probably dealing with similar supply chain issues to a lot of our other commodities, not commodities, but a lot of our other inputs. But if I had to guess, it would be a little less than nitrogen. And if somebody from, you know, a fertilizer company knows more than that, they’re welcome to comment and reach out to me and tell me what the percentage has gone up.
Drew Lyon: All right. Well, very informative, very important topic, particularly this year. Thanks for your work on this, Isaac, and thanks for being my guest today.
Dr. Isaac Madsen: Thank you, Drew.
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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 podcast 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.
The views, thoughts, and opinions expressed by guests of this podcast are their own and does not imply Washington State University’s endorsement.