Cover Crops in the Corn Belt: An Interview with Sarah Carlson

Marisa Tsai

Sarah Carlson is the Midwest Cover Crop Director at Practical Farmers of Iowa (PFI). Since 1985, PFI has facilitated farmer-led research and information sharing to help farmers from all backgrounds practice agriculture that benefits both people and the environment. Since joining PFI in 2007, Sarah has worked to promote the latest agronomic research on cover crops and small grains by conducting supply chain projects and publishing research reports. Additionally, Sarah uses her own experience as a trained agronomist and past results of on-farm research projects to help design solutions to integrated crop and livestock concerns.

Food Tank had the opportunity to speak to Sarah about her work with PFI, their efforts to support Iowan farmers, and what farmers are doing today to create more sustainable farming systems.

Food Tank (FT): As an organization of and for farmers, what is PFI’s role in supporting Iowan farms and communities? 

Sarah Carlson (SC): PFI was started 30 years ago by a group of farmers who were interested in doing on-farm research so they could use their resources more wisely, whether that was money or making sure they were protecting the soil, or using less pesticides over time but still maintaining yields and profits. That core focus of testing and doing research is still what we do today. We help farmers who want to make changes on their farm but want to use science to make sure they’re making the right changes. PFI is a membership organization and members will say, “I want to try a project that looks like this, and I need some help, how do I set that up on my farm?” and the staff’s job is to help them design a project on their farm. Then we analyze data and assess the project results and then a big part of the second step is to get that information out. The way we do that is to put newsletter articles together, get stuff published in the agriculture media, and help farmers hold field days so they can talk about what the new thing is that they are trying on their farm. And just sort of change the narrative on what are the new things that farmers are trying out on their farms that are working or not working and how other farmers can get started with that.

FT: What are some of the new things that farmers are trying?

SC: We have a big span; we have horticulture farmers and livestock farmers and field crop farmers in our organization. Some are organic, some are conventional, some are big, some are small. And so in the field crop area, which is the area that I work in, cover crops are really hot. It’s a big focus, and actually, cover crops are hot in all of the program areas. So the horticulture farmers are trying some really cool summer cover crops and quick turnaround cover crop projects, how can cover crops break pest cycles for them, help them deal with weeds. Livestock farmers are messing around with cover crops too. Seeing if they can they reduce hay feeding by feeding cover crops to cows, can they help improve corn stalk utilization with their livestock by having that green cover crop there when the cows are grazing in the fall after harvest. And then the field crop farmers, the corn and soy bean farmers, are interested in how they can protect soil quality, build soil health, reduce nitrogen loss, which is a big issue in Iowa with the lawsuit. And also maybe capture some cost savings from cover crops, so could they use cover crops to reduce weed pressure from soy bean rotations, could they reduce herbicide use, which saves them money, could they help break some pest cycles, like reducing sudden death syndrome, which attacks the soybean plant and reduces soybean yield. We’ve seen some preliminary observations that cover crops could break that pest, that disease cycle, and then soybean yields could be maintained, things like that. So it’s a lot of tweaking and evaluating how can this popular practice really works in these systems.

So that’s one that’s been really popular and then another one that we’ve seen sort of from the transition from the acceptance of cover crops is this interest in extended crop rotation. So that would be like growing oats, wheat, barley, rye, as a grain crop not just as a cover crop, because those plants are also used as cover crop seeds but they’re killed well before they would be harvested for seed in a cover crop system. But in a non-cover crop system, when they’re in a third crop system, they’re planted and then they’re taken all the way to harvest, which in Iowa, is usually in the month of July as opposed to September which is when corn and soybeans are harvested. Farmers are trying to find markets for those harvests, either as cover crop seeds or as feed for livestock or as food, like for Cheerios something like that. And then with that third crop, they’re able to grow a really big cover. They almost don’t care about that third crop as much as being able to grow that really big cover crop. Like, really big, sexy 12-way mixes of crazy stuff that the advanced cover croppers in the nation are doing, that we in Iowa haven’t really had the chance to do because corn and soybeans are in the way. They just have a lot more heat units so they can grow these big sexy cover crops.

So the third crop is this new project, where we are trying to involve the market to stabilize permanence of this practice. Let’s get this practice permanently on the landscape and that’s only going to happen if we can have an established market saying, yes I demand that product, I can use that product, continually, this is what I’d use it for, this is how it’d work, and sort of build that permanence of that need for that product in the market.

FT: Practical Farmers of Iowa provides resources and information in response to members’ needs, including the use of cover crops. Why are cover crops important and what benefits do they offer to the farmer? 

SC: These are grains that farmers in Iowa have grown in the past-- farmers across the Corn Belt used to grow oats, used to grow wheat, used to grow barley, in rotation with corn and soybeans, that was pretty common up until the 1970s and 1980s. And so those grains, since the 80s or so until today have really left the landscape. Cereal production worldwide has been on the decline because corn and soybeans have taken a lot of acres worldwide. And so what we find is when we grow corn and soy beans in really short rotations-- a two-year rotation, either we grow corn corn all the time or corn soybean all the time-- we have reduced corn and soybean yields over time because we have issues from diseases and pests and we have expenses. It’s more expensive to grown corn in some of these systems. And so if we can work in small grains-- the oats, rye, wheat, the things we used to grow prior to the early 90s basically, we get the breaks in those pest cycles, we get the breaks in those weed cycles so we get to grow corn at a much cheaper rate because we’re growing it with those big fancy cover crops that farmers are excited about. So to the farmer, those are really the benefits. They’re basically finding a better way to grow corn and soybeans when it’s in an extended rotation with small grains.

There’s definitely water quality benefits, we see less phosphorus loss, less nitrogen loss, less erosion, in this extended rotation. We need less fertilizer, less pesticides to grow that same amount of soybean when we grow those oats with that red clover or oats with the diverse cover crops, things like that because that green manure cover crop is really serving that purpose for the system that maybe chemicals would’ve done. And also because we’re reducing fertilizer so much we’re also reducing greenhouse gases. Data from Iowa state shows they reduce fertilizer by 88 percent which is a pretty big reduction in greenhouse gases when we cut fertilizer to that amount since fertilizer is such a big greenhouse gas emitter in the system. So benefits are really improved water quality, improved soil quality and soil health, reductions in greenhouse gases. And the water quality is reduced eco-toxicity. That’s what it really is at the end of the day.

FT: What is green manure?

SC: A green manure cover crop would just be growing your own nitrogen. It’s a way for farmers to use plants to grow nitrogen for the following corn crop as opposed to depending on and buying manufactured fertilizers.

FT: Small grains can be used as cover crops or as a cash crop. Could you explain the differences between the two uses?

SC: When I say cover crop, there is not a product from that. There isn’t a sold product, although the word crop is in there, there isn’t a product that comes from cover crops. It’s just a placeholder. It’s just a plant that grows on the landscape and covers up the soil, and might fix some nitrogen to provide nitrogen to a corn crop but it’s not marketed. The small grains, which is confusing because a small grain could also be a cover crop when it’s just a cover crop and not marketed, could also be a third crop, or cash crop, when it’s taken all the way to harvest. And harvest is usually in July.

So it’s the same plant -- either I plant it and then I kill it before it harvests grain because I’m going to plant corn or soybean next, or I’m going to plant it and I’m going to let it go all the way to grain harvest and not plant corn or soybeans next. With that small grain crop, is where I grow that green manure cover crop. We’re really talking about the same plants, just used in different ways.

FT: A major concern of farmers when making changes to their farm system is whether or not it will be a successful investment. Who, currently, are the major consumers of small grains and do you envision that market changing?

SC: We want to look for markets for these small grain crops-- when they’re crops, not just cover crops, but when they’re actually crops that we’re harvesting and eating or feeding the animals. We are working on this new project that we received funding for from the federal Natural Resources Conservation Service (NRCS) fund. Also the state of Iowa NRCS gave us a grant to do this in Iowa specifically, the federal one is to work in Minnesota and Wisconsin as well. Our goal is to work with an organization called Sustainable Food Lab (SFL), who is a food and beverage company member organization. And they will work with food and beverage companies who are interested in making some sort of change. They’re very similar to PFI in that they’re driven by what their membership wants, their staff work on what their members want, their members just happen to be food and beverage companies as opposed to farmers. So it’s a really cool partnership.

So we work with SFL and they’ll bring companies to Iowa that want to think about how to make changes in their supply chain. How could they meet some more sustainability goals? There’s a big cultural shift in these companies who are saying, well why can’t we help reduce greenhouse gases, why can’t we help improve water quality? Why can’t we reduce overextending the aquifer? You know, whatever the environmental issue might be, why can’t we as a company have a positive impact on the land? Maybe we need to work within our supply chain to see if there are changes that we can support and make a transition to. And maybe it’s not transitioning to organic, maybe they’re not ready to take that step because their brand is not an organic brand, but maybe they want to be a little bit lighter on the landscape. And we know that there are obviously negative externalities of agriculture, I mean the Gulf of Mexico really shows that there’s a canary in the coalmine, there’s obviously something going on. The system is not sustainable when its leaking that amount of phosphorus and nitrogen at those rates, something is wrong. So, SFL will work with us and say, I’ve got company X, they’re a protein company, like they’re a livestock company, or they buy some protein product, and they want to explore how could they influence their supply chain to maybe feed pigs in a different way, or feed cows in a different way for milk products or yogurt. So then we work with farmers on the ground, who might be in Iowa to try a pilot project.

So something like, okay, these pigs in this farm are going to be fed this alternative option that has this small grain. The farmers in that area are going to grow this small grain and PFI is going to work with those farmers to see what are some barriers to growing this small grain, what are barriers for good yield, what are ways to make sure they’re successful. And we’ll use our farmer to farmer info sharing research model to help those farmers make those changes to grow really good small grains and get it to market which will be the pigs or cows, or turkeys or chickens. And then with the with the companies, test out, okay these pigs were fed these alternative rations with small grains and these other pigs a non-alternative ration, what differences do we have? Are we having more cost? Are we having less cost? Are we improving the health of the animals? Are we having less animals dying? Are we having more pigs alive at the end of this project in the alternative barns vs. the non-alternative? And so that’s what we want to figure out.

Published research might tell us one thing--we have a good hypothesis going in that says more than likely we will have positive results. We do a literature review to make sure our suggested alternative is going to probably be successful. But then we want companies to actually go through this alternative and test it out in their business model and see-- is this actually not that big of a deal, and this change would mean that their customer might buy more product from them, or their customer might pay them a premium, or something like that in the market.

FT: Part of your work as an agronomist involves finding solutions to integrated crop and livestock concerns. What are some of the major challenges and benefits to integrated crop and livestock production systems?

SC: The biggest challenge is the market. That’s exactly what this agreement is working on. It’s how can we make sure that we have markets that support farms that grow a diversity of crops on the farm, maybe have a diversity of livestock-fed alternative rations, that’s a big challenge is the market.

There’s benefits to an integrated system, whether the farmer actually owns the crop and the livestock or has a close relationship with another farmer who has that other enterprise. So sometimes we have, within a family they grow both crop and livestock. Sometimes we have two families-- one is really into the livestock the other is really into the crops but they share resources. So that’s great too. The benefit of having those two systems highly integrated is so that we better manage nutrients. So when we grow crops, if they have a place to be fed to the livestock, then we’re more likely to have a diversity of crops because we have a market for them through the livestock. And then the waste from the livestock, manure, isn’t just disposed of in a fashion as if it was garbage, it’s reincorporated back onto the cropland. And so then that’s a way to offset purchased manufactured fertilizer, which means the livestock farmer has a place for their manure, which is good for the soil and it’s at rates that are tolerable for the soil to receive. When we have too many animals in one area, it’s too much for the soil around them. We get loading, just too many nutrients on soil. When we have better coupled crop and livestock systems, then we have a better balance of those systems and it’s a win-win for everybody. There’s less loss of nutrients, better utilization of nutrients, which means there’s less purchased fertilizer by the farmer which means they all make more money. That’s the real benefit and why we want to make sure we have these really tightly coupled crop and livestock systems.

FT: Practical Farmers of Iowa has been helping farmers move towards more sustainable practices for over 30 years. What are some of the biggest differences in the needs and desires of farmers then and now? 

SC: It’s amazing to me that we’re really still asking very similar questions. At the core of what our work is, that is, research and outreach of that research by the farmer-- that core request is still there. They still want to do research projects about questions that they have on their farm, and they still want to talk about it with their neighbors, and want help with getting all that accomplished. And that core, that core still stays there. And I notice that when we work with other farm groups, they maybe don’t have that same model. And when those farmers are at meetings that I’m at, I’ll just say “If you ever want to do some on-farm research, don’t hesitate to reach out to us, you can become a member and we’ll help you do on farm research.” And we’ll get those other farm groups’ members into our membership because there is this desire to be curious on farms, there’s a desire to test things out in a meaningful way and then talk about it to their neighbors. So it’s really basic. And that really still continues. It’s really interesting to me that that curiosity is maybe in the blood of all farmers.

Of the specific content, on the specific questions that their asking, I’d say, some of the ones who have maybe done research for 30 years maybe aren’t asking exactly the same questions, but as we get new farmers in the organization and new farmers on the land, they then are asking those questions that they’ve seen other farmers ask. They’ll go to field days and maybe learn from a veteran farmer on how did you do this, what were you studying, what was your population, what was your program for this crop production system? But they still want to test it on their farms in their soils to kind of ground truth in what they’ve read.

So, we are regurgitating a lot of stuff. Like all the cover crop stuff we’re doing today, is stuff we did 15 years ago. Farmers are asking the same questions they asked 15 years ago, and we’re kind of doing it again but they’re doing it on their farms and we’re able to talk about it. And a lot of times we have new observations from it, so it’s not just an exercise in worthlessness—there are new observations that come from it. But it is interesting that we do a lot of the things over again.

FT: What do you see as the greatest opportunity to improve the food system?

SC: The greatest opportunity is really holding the food and beverage companies’ feet to the fire. If they’re going to make claims on sustainability goals, and say they want to meet sustainability goals, like, X pounds reduction of greenhouse gases in their supply chain, X pounds reduction of nitrates in water bodies, then there are ways to really accomplish this. And they can change the way farmers farm rather quickly as long as they actually do it. And so that means they need to figure out ways to be smarter about making purchases, smarter about their procurement. 


And farmers are not opposed to any of this-- they’re quite happy to grow what the market wants. And I feel, when we talk about small grains with them, like if I talk about oats with farmers that are like 55 or 56 years old, they’re kind of saddened that they can’t really grow oats anymore and they can’t grow it because they don’t have a market for it. It’s a crop they grew up with. It’s one where maybe they remember their grandpa doing a lot more of and their dad did a little bit, and then it was gone. So they’re kind of sad about it-- it’s kind of funny. And so it’s not like they’d be opposed to this. What is interesting about this is that by holding those companies’ feet to the fire, it’s not like we’re talking about totally getting rid of what we’re doing today-- it’s just some tweaks of what we’re doing today. It shouldn’t be a huge shakeup in the supply chain. I mean, what we’re even asking is for just a million acres of oats out of 23 million acres of corn and soybean. Just reduce corn and soybean production by a million acres and grow a million acres of oats and have markets for that and then put cover crops on 10 million acres of corn and soybeans. That right there will solve Iowa’s water quality problems and have a huge reduction in greenhouse gases. Because a million acres of corn will have received 50 percent less manufactured fertilizer. And Walmart could just say, all our ham is going to have come from pigs that were fed 10 percent of their ration as oats. That’s what it is. Or, all their ham from Iowa. I mean a lot of their pigs are going to come from Iowa no matter what. Pigs from Iowa and North Carolina, they’re going to have 10 percent of their ration be oats.


If companies are actually serious about their supply chains having an impact on sustainability goals, then they need to do some bold things. And they obviously need to be business smart and not just make crazy demands that will put farmers out of business but if there’s a thoughtful way, working with farmers on what can happen, farmers would be all in. Especially the under 45-year olds because they’re new, they’re back on their land, they’ve gone through some good times and now they’re back to these bad times, and it’s the bad times their grandfather spoke about and they want to avoid those extremes and how do they do that? Well, cutting fertilizer is a good way to control costs, cutting inputs is a good way to control costs which helps them be successful profit-wise over time and adding a third crop is a way to really control those costs.