Intercropping with Isaac Madsen

Canola Field

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Contact Isaac Madsen via email at or via phone at (360) 448-9081.

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Episode Transcription:

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.

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Drew Lyon: My guest today is 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. He has been involved in research on soil health, plant root-soil interactions, soil fertility, and alternative crops. His current research focuses on stand establishment and winter survival in canola, as well as alternative cropping practices, such as legume oilseed intercropping, and integrated livestock and dual-purpose cropping systems. Hello, Isaac.

Isaac Madsen: Hello, Drew.

Drew Lyon: To start off today’s conversation, I wonder if you can give us a little idea of what the projections are for oilseed crops in the State of Washington this year?

Isaac Madsen: Yeah, so the National Ag Statistic Service, they have not released numbers for 2020 yet, but I can tell you what they’ve done for the last three years, what we’ve planted in Washington. So, in 2017 we planted 55,000 acres, and then in 2018 that came up to 70,000. So that was a pretty big jump up there. And then in 2019, we came up to 75,000 acres. A lot of this I think is related to the price pulses and the prices of grains. I’m not sure if we’re going to see going much up from the 75,000 number from 2019, but I think it’ll come up a little bit. But I’m not expecting a massive jump this year.

Drew Lyon: Okay, but the — it’s holding steady or maybe slightly growing, versus some other crops like pulses where the price has really discouraged growing them?

Isaac Madsen: Yeah, exactly. I think it really — especially after, you know, the one caveat I should say is with what happened with the garbanzo beans last year, I don’t think anybody wants to get into that situation again. And so I guess there could be some more garb acreage that goes into canola this year. I do know a few people that have done canola in the past who’re actually going into spring grains this year. And so I think it all depends on what your rotation is and what your weed problems are, and then looking at the markets in the future, so.

Drew Lyon: Okay, very good. So, what current projects are you working on these days and what are you most excited about? I know you have lots of things going on, but what are the ones that you’re most excited about?

Isaac Madsen: Yeah. So, like you mentioned, I have a lot of different research projects going on. I’m right now actually writing the field day abstracts, kind of reviewing my last year of work, and getting those abstracts all put together. So, when those come out, I would like to put a plug into everybody to look at those. But I think I’m going to get around six or seven out there actually. So I was looking back and —

Drew Lyon: And those will be available on the Wheat and Small Grains website when they do become available.

Isaac Madsen: Okay, excellent. So, there we go. Go to small — your Small Grains website. Yeah, so I’m — I’m doing some soil fertility work in canola both. So, mostly micronutrients right now. We have a pretty good set of data on the macronutrients or at least nitrogen, and Haiying Tao is working on the phosphorous, so that’s kind of being her domain. But I’m mostly looking at the micronutrients. And we ran these trials in the past that didn’t work super well, and so we ended up — we’re just doing like broadscale scouting, so that’s a lot of what I’m working on. But then I’m working on these, sort of, alternative systems that I’m really excited about. And so that’s the legume oilseed intercrops, and that can be peas, canola, that could be flax, garbanzo beans, and it could be both winter-type and spring-type on the canola, pea. And then I’m also working on some livestock integration, but that — intercropping I think is one of the really exciting projects that I see as something that could potentially be a game-changer in the region, eventually.

Drew Lyon: The topic of intercropping, I hear more and more about it all the time. What — what do you see as the major advantages of intercropping, versus monocropping?

Isaac Madsen: Yeah, so I think intercropping is actually interesting because you’ll see it in a lot of places in countries that don’t have industrialized agriculture yet. And then you’ll see it in the older textbooks for, actually, cropping systems in the U.S. and Canada, but it was sort of prior to what we think of as the Green Revolution practices. So, you know, when — prior to getting nitrogen fertilizers and herbicides, really, are the — are the two big things. I think they kind of — not that monocropping hasn’t been done for a long time, but with those coming along it made monocropping much more attractive because you could supply all the nitrogen without legumes and you could use herbicides to kill out the weeds. So, if you do a really quick look through the intercropping literature what you find is, you find a lot of work that’s being done in, say, places like Africa or India, and then you see it being done in organic systems. But you don’t really see a lot of it in conventional agriculture systems as we see them in — in the United States. And one of the things I think that’s different about trying these Brassica legume intercrops is that rather than having a grass legume, which is kind of what was traditionally done. That grass legume one, you better than anyone know, Drew, that that complicates your weed control immensely, really, because you lose — I don’t know, maybe you lose all your modes of action if you put a grass and legume into an intercrop. But if you put two broadleaves into an intercrop and you’re trying to clean up the grasses in your system, you actually still have some control. So, for instance, one of the things that I see as an advantage is you can still get that grassy weed control, you can use Assure 2 or Clethodim, or you know, most of your grass herbicides on that. There’s actually some broadleaf herbicides that you can use if you use Clearfield canola varieties. Another advantage is the nitrogen supply, that’s the obvious one. You’re putting legumes in, and especially right now with the legume prices being low, right, you can kind of see the canola as something that you can sell off of the system and then the legumes to build some of your nitrogen up. So, that’s a lot of the thought there. They also have — especially, just talking about canola and peas, they have pretty complimentary architectures. So, if you think about plants as focusing in and really specializing on a special area of resources they can take advantage of. Legumes tend to take advantage of the topsoil; whereas, canola works much deeper. And so canola can extract as deep as wheat can. And so you get into this situation where the idea, and this isn’t proved, this is the idea and this is one of the things I’m actually looking at in my research right now, is that the peas can maybe access those top two feet of soil and really make good use of the nutrients and water there. And that the canola would actually go deeper and access maybe that third and fourth foot of nutrients and water. And so you just get a more efficient system is part of the thought there. And then the legumes are, meanwhile, nodulating and providing nitrogen. And so one of the things we’re doing, is we’re actually looking at nodulation in these systems and, you know, are the roots growing together? And just from preliminary results, it looks like the canola roots will grow all over a nodule. And so that’s really interesting. So, there’s potential for actual in-season nitrogen transfers.

Drew Lyon: That’s interesting.

Isaac Madsen: Yeah, I think it’s really exciting. And then one other advantage I wanted to point out is that I’m a huge fan of canola, but one of the difficulties with it is that it can actually reduce your mycorrhizae fungi. What are — which are a kind of fungi that actually — they allow a root to, essentially, explore — well, you can think of it as a network that hooks onto the root and grows out further than the root. And so it allows the — the root system to access a much wider range of nutrients. And so canola, and actually all Brassicas, I believe, if not all, most of them, won’t form a relationship with the mycorrhizae. So, they won’t, essentially, hook up to that network. And so what that means is if you grow canola in a rotation, sometimes you can actually see a decrease in these beneficial mycorrhizal fungi over the course of that rotation. And so we know that legumes, on the other hand, they do form that relationship. So, they will connect to the network. And our hope is that if you’re growing the legumes and the canola together, that essentially that network will be maintained throughout that period, better than if you were just monocropping canola. So, that’s kind of the thought on it.

Drew Lyon: Okay. In your mind, what’s kind of driven the interest in intercropping? What’s changed? Has anything changed, or it’s just — just an idea that through collective talk has grown to be more interesting?

Isaac Madsen: Yeah. You know, I think that’s a really good question because it’s not a new idea.

Drew Lyon: Right.

Isaac Madsen: You know, and — and that’s one of the funny things is I think there’s — part of it is actually maybe a byproduct of the sort of regenerative ag movement. You know, this — this idea that if we mimic nature we’ll come up with more productive, more efficient systems. And I see the point on that side of things. I don’t fully buy into, I don’t think, some of the — some of the ideas going on there. I really like a lot of the practices coming out of that movement, but I think there — there’s some tricks to work out with it still. So, I think that’s maybe one — one thing that’s happening. Price of inputs going up, right? So, a lot of what we’re talking about is potentially, you know, some of the farmers who do this on a large scale have really reduced their herbicide inputs. So, if you can reduce your herbicide inputs, you know, maybe reduce some of your nitrogen inputs.

Drew Lyon: Okay, yeah.

Isaac Madsen: That kind of thing, it might work out better. And I also think there’s probably a role for technology, actually, moving forward, that we’ve got all of these technologies that allowed us to monocrop. But then as we get better at cleaning seeds and — and prescription mapping, and things like that, we might actually get — it might lead us into being able to take advantage of some of these intercrops. Specifically, vary — variation across terrain is a really interesting one, I think, for these because, you know, one — one plant is going to prefer a different part of the terrain to another plant. And so there’s opportunities for tradeoffs there.

Drew Lyon: Okay, interesting. So, we’ve talked about some of the perceived advantages of intercropping.

Isaac Madsen: Yeah.

Drew Lyon: What do you see as some of the biggest challenges with intercropping?

Isaac Madsen: Logistics is — I would say that’s the number one challenge. You know, you — I’ve talked to a lot of farmers about this. A lot of them that are really interested. In fact, we actually planted a strip trial this week. But the question is always, “So what do I do when I harvest this?” You know, so for this year, I’m taking care of that. You know, I’m — I’m probably going to harvest it and take it somewhere for feed, most likely, and use the samples to clean out and see what percentages of peas I’m getting and what percentage of canola. But I that — that’s the real major issue. And I think that kind of highlights the need, if this is really going to take off and become a major — a major production system. I think there has to be somebody in the grain handling side of things who sees value in what’s going on and is willing to either store mixes or facilitate the cleaning and the — the separation. Because I think that’s — that’s going to be one of the big challenges. Another challenge is planting. Generally, at least with fall-seeded crops, you — you plant peas way deeper than you plant canola. So, you know, we’re — we’re looking at some sort of wing-typed openers, and you know, could we put the canola out the side of the wings and the pea down the middle? You know, what sort of options are out there? And I think those are — those are going to be some of the — most of the challenges are going to kind of be on the logistics side of it.

Drew Lyon: Okay.

Isaac Madsen: So, I think the economics are going to have to look really, really good if you try it, you know, in order to — to make it actually work out well.

Drew Lyon: Okay. So, some pretty — pretty nifty ecological ideas. And just I can see the benefits, it’s just making it all come together.

Isaac Madsen: Yeah.

Drew Lyon: That’s going to be difficult. Okay, but you’re out there trying and there’s a lot of growers out there trying. And so collectively, hopefully, you’ll make some — some progress. What’s some of the research you’re — research you’re going to be conducting to assess the feasibility of intercropping in the region?

Isaac Madsen: Yeah, so we’re starting with really basic, you know, just planting it out there and seeing, hey, does it grow? You know, do the peas massively outcompete the canola when it’s young? We — we had a field where I actually saw that happen, where the peas came on really fast, you know, and just kind of outcompeted the canola. So, just sort of observations like that. And that’s what we’re trying to do at a larger scale. So, we got a strip trial out this week, and there was a field out that wasn’t mine, but it was a field man had going last year. And then I’m doing small plot studies to look at the nutrient-use efficiencies and the land-use efficiencies. So, really, you know, for this to work you have to demonstrate that per acre, acre-per-acre of intercrops, you can grow more than you could acre-per-acre of monocrop, because otherwise it’s — it’s not worth it. So, you have to — you have to save money on the inputs and you have to over yield is my thinking on this. And so that’s really what we’re looking at right now, is we’re looking at nitrogen rates and can you grow a good yield of canola with peas in it without adding any nitrogen? That would be a big first step. So, you know, can we really reduce that fertilizer input? And then the second would be, after that, what — what is this yield on the land, you know, acre-per-acre, which one of these yields better, and then start looking at the economics from there. So, that’s kind of what I have going on right now. What I’d really like to see and start working on, and I need to bring a microbiologist on to work with this, is, you know, we have some stuff starting in the works with Maren Friesen and Tarah Sullivan, is to start looking at what are the microbial communities doing in this intercrop versus not. And, specifically, with that mycorrhizae, you know, is the mycorrhizae, you know, colonizing? Especially in the following wheat crop, you know, that’s where we get a lot of this concern. Does wheat following pea-ola have more mycorrhizae than wheat following canola would be, I think, one of the really major things to look at.

Drew Lyon: Okay, very interesting work. You mentioned the dryland abstracts that will be coming out. One place people can go to find this information. Where else can they go if they want to read more about what you’re doing?

Isaac Madsen: Yup. Yeah. So, the Small Grains website is great. And then Washington Oilseeds also will have information up. And that’s also just another great resource.

Drew Lyon: And what — what’s that URL?

Isaac Madsen: It’s — think it’s, at this point.

Drew Lyon: Okay.

Isaac Madsen: We’ve talked about changing it, but it’s the same for right now.

Drew Lyon: Okay, very good. Well very interesting work, Isaac. I’ll be curious to see how this all pans out this year. Thanks a lot for being my guest today.

Isaac Madsen: Thanks, 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 podcasting app. If you have questions or topics, you’d like to hear on future episodes please email me at drew.lyon — that’s –( You can find us online at 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.