Organic Corn Production Techniques w/ Dr. Erin Silva, PhD
Interview with Erin Silva, Associate Professor at the University of Wisconsin–Madison
How can farmers improve their organic corn production? Dr. Erin Silva of the University of Wisconsin–Madison shares her research on corn production techniques, such as cover crop interseeding, wide-row spacing and integrating cover crops with reduced tillage and cultivation.
Learn more about Avé Organics: www.aveorganics.com
Learn more about Erin Silva at the University of Wisconsin–Madison: www.plantpath.wisc.edu
Connect with our guest on LinkedIn
INTRO: Welcome to Organics Unpacked, a podcast for the business-minded organic grower, where we hear from top experts in the commercial organic industry. With a focus on the business elements of organic growing both in and out of the field, you will gain insight and grow your operation. This show is brought to you by Avé Organics, a Wilbur-Ellis company. Here’s our host, Tom Buman.
Research in Organic Corn Production
TOM: One of the things I wanted to talk to you about today was organic-grown corn and some of the new things you’ve been looking at. Are there any new things that you’ve been looking at in the production of organic corn?
ERIN: Two main focuses of our research related to organic corn is interseeding, so that’s interseeding cover crops into standing corn. We’ve been looking at doing that with row spacing of both 30 inches and 60 inches, so looking at the challenges and benefits of more standard-row corn spacing and the wide-row corn spacing, as well as looking at using reduced tillage and cultivation practices using cover crops for organic corn production. So, with our interseeding work, one of the challenges that farmers face, both organic and conventional, here in the Upper Midwest is being able to implement cover cropping systems that use a diversity of cover crop species. We have a fairly limited growing window after harvest, which often limits us to winter cereal rye for any cover crop that’s going to put on any sort of growth that would potentially offer soil health benefits. But by interseeding into earlier stages of corn growth — and we’re looking at, specifically, about the V3 to V5 stage — we’re able to implement a wider range of species within our cover crop practices and be able to get those cover crops established earlier, that we might be able to accomplish greater soil health benefits by integrating those cover crops into the systems. So a lot of this research has been done in the Mid-Atlantic area, where it’s been found that, especially in conventional systems but organic systems as well, that interseeding cover crops around the V5 stage is an adequate window to allow for those cover crops to germinate and potentially persist after the corn is harvested. But initial work in Wisconsin found that planting at the V5 stage doesn’t allow for enough time for sunlight to reach into that canopy and really allow for those cover crops to establish.
So, in recent years, we’ve been looking at ways to push that cover crop planting window even earlier to about the V3 stage of corn, where the canopy is still a little bit more open, and seeing what sort of mixtures and species of cover crops might be best suited for that production system, as well as how do we implement weed management strategies to allow for cover crops to establish and persist but still manage weeds? So we’ve been looking at different ways to, again, integrate different cover crop species and weed management techniques, like the rotary hoe, and potentially eliminate some of our row cultivation. And we’ve had some initial successes there, so we’re very excited about that opportunity. And also, looking at the 60-inch corn spacing, there has been some pioneering research out of Iowa and some other Midwestern states that have shown the value of potentially widening our corn row spacing but keeping the populations the same. So we’re not compromising the number of plants per acre but instead looking at increasing the density within a given row. So, ideally, maintaining or even increasing yields by increasing light interception and enhancing photosynthetic capacity. But widening that row and allowing for alternative management between the rows with cover crops and having that additional light coming into that canopy could allow for additional cover crop growth and photosynthetic capture. That, then, leads to carbohydrate synthesis and potentially carbon being, then, returned back into the soil, as well as other compounds that could enhance soil biology. And we found some successes there, as well. Widening that row spacing and looking at growing crops in between, that could be used for, again, either soil health purposes or other purposes related to grazing or harvesting that crop for other purposes. So that’s been some really cool work that we’ve been doing over the last two years or so.
Cover Crop-Based No-Till for Organic Corn
ERIN: Additionally, we’ve been trying to take our successes with organic no-till soybean and cover crop-based no-till and translate that to corn. That’s been a challenge, to be able to use roll crimp cover crops in our corn systems, and that’s for a variety of reasons. With the rolled rye soybean system, soybeans being a legume and being able to fix their own nitrogen, we certainly have the advantage with respect to being able to capitalize on the fact that the cereal rye actually sequesters some nitrogen and immobilizes nitrogen, which is beneficial from the weed management standpoint but not beneficial from the standpoint of trying to grow a cash crop that doesn’t fix nitrogen into that system. So, with corn, our alternative is to use a legume as the cover crop versus cereal rye or another winter cereal grain. The challenge there is that we have very few legume cover crops that are able to be planted in the late summer period that put on enough biomass, as well as overwinter consistently, that we’re able to have a successful rolled crimp system. Hairy vetch is one of the few cover crops that do provide those characteristics that make it a potential rolled crimped crop in Wisconsin, but it has its other challenges with respect to management including a very late termination date. We can’t successfully terminate hairy vetch until the mid part of June, which is very late for planting even organic corn. So we’ve been looking at some alternative strategies of new equipment that allows for later termination of hairy vetch such as between-row crimpers, integration of some cereal rye to enhance some deficits with respect to biomass and also some living mulch systems where we’ve been growing red clover and then looking at some strip-till techniques to be able to plant corn into that red clover and seeing how, with organic methods, we can suppress that red clover so that the corn can establish and still be competitive even with that living cover crop being maintained between the rows.
Interseeding Cover Crops in Organic Corn
TOM: I want to jump back to one of the things that you were talking about, and that’s interseeding cover crops into corn earlier. How do you do the interseeding? What equipment do you use? What rates do you use to accomplish that?
ERIN: The equipment we use for interseeding, we do have a specific interseeder from Underground Ag. So we are able to actually plant the cover crops between the rows. So we’re not broadcasting the cover crops, and we’re planting two rows of cover crops between each row of corn. There are certainly other methods to do that, through broadcasting and then, potentially, rotary hoeing to incorporate that seed to some degree. Depending on equipment and resources, there are other ways to get the cover crop established, but we are using an interseeder from Underground Ag. The rates we’re using, we’re using a bunch of different rates, depending on the crops and the mixtures, that don’t deviate, necessarily, substantially from a lot of the recommendations you’d see when planting those species as cover crops. So there are some great tools out there. Green Cover Seed has some great cover crop seeding tools. The different cover crop councils like the Midwest Cover Crops Council, their website has a great tool. So there are a lot of resources out there to be able to look at ranges for cover crop seeding rates, and we’re using cover crop seeding rates within those ranges.
Wide-Row Spacing for Organic Corn
TOM: Then on your wide rows of your corn, what’s the anticipated benefit? Is it getting more sunlight deeper into the canopy by spreading those? I know that you’re doing it, in part, because of cover crops, but is there an advantage of getting light deeper into that canopy by spreading those rows out? What’s the real advantage in doing the wide rows?
ERIN: The hypothesis with the wide-row corn is that there will be greater photosynthetic efficiency because of the fact that sunlight is able to get down between the rows and be able to be intercepted by a greater surface area of the corn plant and, with that greater photosynthetic capacity, that potentially we could see more carbohydrate being partitioned into the corn ear and be able to get higher yields. The results there still have been quite variable, at least within the literature that I’ve seen. So how that hypothesis actually translates to what is happening in the field and how that relates to corn variety, looking at flexier varieties versus semi-flex varieties. And there’s still research, I think, that needs to be done to clarify, again, how that hypothesis plays out on farm fields across environments. The opportunity to do more cover cropping and the recognized benefits of cover cropping with respect to soil health. In organic systems, being able to put legumes in the system to be able to get a nitrogen credit. The potential benefits with respect to weed suppression and then many farmers that are experimenting with 60-inch rows, they are doing it because they do have integrated livestock systems or maybe do some custom grazing and do see the benefit of being able to get those animals out on the field in the fall and really having that diversified crop/livestock system that is really a foundation of regenerative ag systems.
TOM: On the wide rows, it would seem to me that it’s going to be important which direction you run the rows, right? North or south or east or west. Have you found that at all?
ERIN: We have not done research related to orientation of rows. There is thought that orientation of rows might be important, whether it is for light interception or potentially looking at disease management and airflow through the canopy. A lot of our fields, which I think is often the case with a lot of farms in Wisconsin, were kind of limited by topography and field shape. So we don’t have a ton of options with respect to being able to have flexibility in row orientation. But that is an area that people are interested in and are thinking about with respect to optimizing the system.
Small Grain Challenges in Organic Farming
TOM: In organic farming, obviously, thinking about small grains and legumes is always important. Whereas maybe in our commercial agricultural world, we think of corn and beans largely in the Upper Midwest. So let’s talk about some of the small grain opportunities and challenges that exist in organic farming.
ERIN: The opportunities with small grains and the challenges are very much regionally dependent. So, speaking from a Wisconsin perspective, having small grains in the rotation is really important for successful organic grain management for a variety of reasons, specifically winter-grown cereal grains. Those can be quite competitive against weeds, crops such as winter cereal rye and winter wheat. Looking at how do we integrate different cash crops that are planted in different planting windows, harvested in different windows? By altering different planting dates and harvest windows, we’re able to mix up what we’re doing on the field and being able to more effectively manage weeds by going in there at different times, by harvesting the cash crop at different times and being able to look at putting on cover crops at different times. So having those winter cereal grains really allows us a pretty profound shift in terms of planting and harvest dates that can be very, very important for weed management. Also, the row spacing having more of a drilled crop, a solid-seeded crop versus having a 30-inch row crop, is really important with respect to successful weed management across the entire crop rotation. So, again, those winter-planted cereal grains allow us an opportunity to come in and harvest those crops in July or early August. And that allows us to also remove some weeds that are notoriously challenging in Wisconsin, such as giant ragweed, before they go to seed, so a very important ecological management tool with respect to weed management.
We certainly can grow successful cereal grains, both winter-seeded cereal grains and spring-seeded cereal grains, but a major challenge we have here in Wisconsin is disease pressure, particularly with fusarium, which can lead to vomitoxin and high levels of a compound that can potentially make that cereal grain crop not usable. It’s either feed-grade cereal grain or food-grade cereal grain. Looking at challenges for growing cereal grains in organic rotation Wisconsin, looking at identifying varieties that have disease resistance in our more humid climate, as well as looking at potential management or other inputs that also allow for disease management, it can be very, very hard in Wisconsin to be able to meet food-grade specs for cereal grains. And that’s really where you get that extra market value. It’s certainly not impossible, and we have some farmers that are doing it very, very successfully. But in Wisconsin, it’s definitely more challenging than in some of the states west of us that have a more dry climate where those diseases are a bit easier with respect to management and a bit less of a risk.
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