Multiple Cover Crop Varieties Amplify Soil Health

Multiple cover crop mixes are touted as the next step toward advancing soil health at a more rapid pace.

Chase Brown spoke of his decade-long experiences utilizing cover crops in an Illinois Cover Crop On-Farm Network-hosted summer webinar series. He farms with his father and uncle and also operates Brown Seed Sales.

“The journey there started in the 2012 drought," Brown says. "We have cattle and started exploring cover crops and really enjoyed it, spent the last 10 years into cover crops, regenerative ag practices and learning as much as I can and being part of groups like we have here. I don’t want to sit here and dive into specific mixes and saying you need to put this species and that species in. Frankly, in my opinion, there is no right or wrong mix. That’s up to you and your goals and your customers’ operations of what species you think you need to be putting in. No-till is better than full tillage. Cover crops is better than no-till, and as we progress in a soil health journey, mixes are the next step.”

Using a mix of cover crops is also beneficial from a risk management standpoint.

“When we do a monoculture cover crop, we see some failures from time to time, whether it’s due to a dry spell or we’re wet," Brown says. "In a mix, we have multiple species to help fill those voids. So, if we have a seeding problem, if we have a germ problem, we have a weather pattern, by putting in a mix we can help alleviate some of that. I really like it from that risk management standpoint. It sure makes our cover crops look much more successful out there when we have multiple species. It can fill in a lot of mistakes. One of the reasons I always say that is mixes can get very expensive. As we start adding these species in, we can get some costs on them.”

Brown noted a mix he’s working on that also involves a cost-share program. Seed costs for the mix range from $35-$50 per acre.

“When a grower is spending $50 for seed versus $15 for cereal rye, they want to start seeing some real response," Brown says. "As we all know in soil health and in cover crops, the response can sometimes be hard to see and hard to put a dollar amount on.

“So, before we really dive into complex mixes with a grower, I want to make sure that they understand what we’re doing and why we’re doing it. We’re blessed here in the Midwest with some unbelievable soils, and the glacier sure helped us, but the reason we have these amazing soils, high carbon soils, is the native prairies that we had here for thousands of years. If you’ve ever been in a native prairie patch, there is all sorts of diversity. That’s what we’re trying to mimic with these mixes. You see tall plants, you see short plants, you see forbs, you see legumes, you see warm season grasses and cool season grasses. We’re trying to mimic that diversity.”

Brown referred to a cover crop mix as “steroids for soil biology.”

“Not that no-till isn’t helping soil biology, not that monoculture cover crop isn’t helping soil biology, but when we put that mix in, all of a sudden we’re giving it a steroid and we can advance the soil health practices so much more rapidly,” Brown says.

Application

A starting point for moving into cover crop mixes is application method — aerial, drill or broadcast application — and seed size.

All seeds sizes are not the same, and a mix of very small seeds and larger seeds could create problems when, for example, a seeding drill may bury a smaller seed too deep.

Mix

When Brown selects a cover crop mix, he tries to include a grass, brassica or forb, and legume. To take it a step further, one needs to understand the plant types, root types and structures.

“I don’t want to plant sun hemp, sunflowers and sorghum sudan grass," Brown says. "That would check all three of those boxes — a grass, a legume and a forb — but I don’t want to plant all three of those because they have the same type of structure. They’ve very tall. They’re very upright.

“I like having those three in, but we need to have something a little shorter statured, a little broader leaf, to make some canopy. We want to cover all different heights, sizes. So, really understand the plant structure and the root structure types. Cereal rye or some of the cereal grains have a pretty fibrous root system. They complement very well with the brassica that has more of a tap root.

“It goes back to that diversity. Let’s add not only multiple, but let’s add some diversity into our plant and root structure types, as well. At the end of the day, we’re trying to capture sunlight, we’re trying to capture carbon. Let’s get some diversity in our types of plant structures.”

Cost Share

Most farmers are eligible for cover crop incentive payments through the Natural Resources Conservation Service.

In recent years, thousands of U.S. farmers have received payments in support of cover crops through the NRCS Environmental Quality Incentives Program.

“These payments are intended to help farmers being the process of cover cropping," Brown says. "They should not be looked at as a long-term subsidy, but they can be helpful during a three-year transition period to cover cropping,” according to the Sustainable Agriculture Research and Education program."

The NRCS cover crop payment rates for basic and multi-species programs vary by state.

Seeding Rates

The NRCS office Brown works with in Mason County uses the Midwest Cover Crops Council seeding rates.

The Midwest Cover Crops Council website features recommended seeding rates for each species. The percentage of mix varies with the numbers of species.

For example, the seeding rates using two cover crop species would be 50% of each. If three species are used, the rate would be 33% of each.

“I feel this is a great starting place and it works very well,” Brown says.

He offered a word of caution that is grounded by the “why” specific cover crops are selected. If a grower has been using cereal rye for several years for weed and erosion control on his rolling farm and is ready for a mix, be aware of cutting rye proportionately when adding two other species to the cereal rye.

“All of a sudden I go from a 50- or 60-pound seeding rate for cereal rye, and I throw in a few pounds of rapeseed and a radish," Brown says. "Using this method I’ve cut my cereal rye down to, say, 30 pounds. While it’s still doing some good, the brassicas are going to winter kill and come spring we’re going to have about 30 pounds of rye out there, and he’s going to be really upset because the weeds are going to come through. He’s not going to get the effectiveness of having a 60-pound rate. So, we need to keep in mind what a grower’s ‘why’ is. This is a great starting point, but we need to be a little flexible and say, ‘He really likes his weed control. I can back off that rye a little, but we’re going to keep it up there, too. We aren’t going to go to the full 25% rate using this method.’"

Power Mix

Brown noted his experiences with an organic cover crop mix seeded in July after wheat. The mix included sunn hemp, cowpeas, radish, rapeseed, oats, balansa clover and flax.

“That kind of covered all the different styles, from root styles to upright plants to broadleaf plants," Brown says. "We got a tremendous amount of growth that we don’t normally get in some of the cooler season mixes. We put this mix out as our organic fertilizer for our corn crop that is currently growing out there. Considering how dry we were in June, the corn looks absolutely incredible. This was not the sole source of nitrogen. We did put some turkey litter down, but it is noticeable enough that we had neighbors who don’t do any cover crops comment that the corn looks really good. And I put a huge value on this cover crop mix.”

Nutrient Benefits

Doing a cover crop analysis, it was determined that Brown’s cover crop mix raised 53 pounds of nitrogen per acre, 25 pounds of phosphorous and 82 pounds of potassium.

“When we have growers that want to start peeling back on some of their inputs, this is the power of the mix," Brown says. We raised 50 pounds of nitrogen out there. When I talk about growers getting a little shell-shocked when they hear a price for cover crop seeds, when we can show 50 pounds of nitrogen, 25 pounds of phosphorous and 82 pounds of potassium, we can pay for that seed mix very quickly. We just have to get them to understand what that mix has to do, and we have to allow it to have time to do what it’s supposed to do. We have to give it the best opportunity and when we start working with these mixes we can start making some changes in our management, but we certainly want to crawl.”

Keep It Simple

“I’m always one who’s very focal on keeping it simple, keep it basic," Brown says. "If you’re doing one or two species, let’s add. If you’ve been doing oats and radish, let’s try to add in a clover. If you’ve been doing a cereal rye, let’s try to add a winter camelina, and when we get comfortable with that, we can continue to add species, and as we get very familiar and comfortable with these mixes, the sky is the limit. We hear of guys doing 10 and 15 species blends. When we get to that level, that’s when we can really start pushing things and doing a lot better job.”

Brown was asked at what point in cover cropping that he recommends moving toward multiple species integration.

“It’s like getting us to take the leap to do cover crops the first time," Brown says. "At some point you have to say we’re ready and you have to jump in. Keep it simple. You can do a five, six species blend if keep the species within that blend simple. It’s no different than I have a new cover cropper and I’m not going to tell them to put out 70 pounds of cereal rye.

"We’re going to plant green, we’re going to let the soybeans come up and we’re going to roller crimp it. That’s a little advanced. That’s a couple years down the road. Let’s start basic. Let’s do a winter-kill of oats and radish, and once they get comfortable with that, we can progress to rye and terminating it early in the spring. Once they get comfortable with that, we’ll progress to planting green, and then we’ll progress to roller crimping. At some point you have to jump in, but let’s understand our species so we don’t have a mess, we don’t have something getting away from us or a species going to seed and creating a bigger mess for us.

“Let’s start building. Let’s start stacking and adding. If we did two species this year, let’s add three or four. Seeing results help with that, as well. If we’re doing a winter-kill and we decide to do an over-wintering and put in a clover, and we see that clover in the spring and see it worked, let’s build on that. Let’s have some small wins and successes. I’m big on just keep building, keep stacking.”