After Bryan Racine harvested his corn this year, he turned around and planted rye and two types of clover in the field where he will plant corn again next year. He put in rye and rapeseed where he intends to rotate his crops over to soybeans. Racine has no intention of harvesting or selling rye, rapeseed or clover. They’re just for cover. But there’s a lot packed into that word: cover.
“The clover is giving me free nitrogen and covering the soil in the spring, and I’ll plant corn into that,” said Racine, who is a third generation farmer in Cecil County Maryland. “The rapeseed brings up phosphorus naturally from the soil, and the soybeans like a lot of that, so hopefully I’ll see a bump in yield there.” Since becoming more intentional with his cover crops a couple years ago Racine has seen other benefits, too. “I don’t have the gullies and the washouts like I used to and I’m not burning as much diesel working the ground. And there’s just a lot more variety of birds and bugs and all.”
In the last four decades, research led by AGNR has shown that cover crops—plants grown in the off season—offer an important suite of tools to address many of the challenges farmers face—things like nutrient and water management, increasing herbicide resistance among weeds and the expanding ranges of insect pests and emerging diseases.
The Details Matter
Effective cover cropping is not as simple as spreading some seed at the end of the cash crop season. Different species of cover crops offer different benefits, and things like timing and planting methods can affect a cover crop’s effectiveness. Maximizing the benefit of a cover crop is a complicated dance, and that’s why Racine is working with UMD Extension agents like Sarah Hirsh to find out exactly what will benefit him in different fields and to apply for grants that help him experiment with new cover crops.
“Ideally each farmer should have different cover crops going across different fields if they're thinking about them intentionally,” Hirsh said. “I work with farmers to talk about the history of the field and the issues it might have, like what's the soil type? Do they struggle with compaction? Do they struggle with low organic matter? Then, together with the farmer, we try to design the best cover crop that makes sense for that particular field.”
For a farmer, trying something new can feel like adding an expensive and unnecessary unknown to an already unpredictable business. That’s why Hirsh’s work is so important.
“What you do with cover crops depends on what your goal is,” said soil scientist Ray Weil, who works with Hirsh on farms like Racine’s. “In the case of rye, you have to plant it by October for nitrogen capture, to keep nitrogen from leaching into groundwater. If you plant it late, it really won’t do much for nitrogen capture, but it will establish, and if you keep rye in the ground until May, it can build up carbon in the soil.”
Weil has been studying and experimenting with cover crops for more than 30 years.
In the early-2000s he introduced the daikon radish as a cover crop. He found that the vegetable’s deep-growing root system could break up compacted soil, allowing crop roots to access water and nutrients from deep below the surface.
He’s currently working with farmers to plan multi-species cover crops while the cash crop is still maturing. This allows the cover crop to grow deep roots and take up nutrients when the cash crop roots die off after harvest. He’s also experimenting with extending the season for cover crops up to the day new cash crops are planted in May to improve soil health and provide flowers for pollinators.
Weil speaks around the country and the world about the benefits of cover crops, but he knows changing the way people do things isn’t easy. He only needs to look at the origins of the Maryland State Cover Crop Program, which pays farmers to plant cover crops, to see proof of that.
Leaders in the Field
Today, Maryland is the top state in the nation for cover crop adoption with close to 50% of its commodity agricultural land under cover crops. But 30 years ago few Maryland farmers planted them. In the 1980s, the U.S. Environmental Protection Agency’s Clean Water Act presented the Chesapeake Bay Region with the major task of reducing nutrients running into the waterways. AGNR researchers Kenneth Staver and the late Russell Brinsfield began studying cover crops as one part of the solution, and in 1998 they published a seminal paper showing that cover crops prevented nitrogen from leaching from farm fields into the watershed.
“UMD built the case scientifically that cover crops were absolutely an essential part of getting the nitrogen loads down to the goals for the Bay,” Staver recalled. “And the way it got done was by convincing folks that you had to help farmers pay the cost.”
Backed by AGNR research, the state established a cover crop program, which pays farmers to plant cover crops in the same way they are paid for other conservation practices like planting trees along streams.
“In the Bay Stat Cabinet, we put a lot of attention on cover crops to manage nutrients from agriculture,” said Robert Summers, Acting Secretary and then Secretary of the Maryland Department of Environment from 2007 to 2015 and a member of the Bay Stat Cabinet, which helped guide the governor on Chesapeake Bay issues. “Russ Brinsfield and the university were right there at the table advising us. And just as important, Soil Conservation District personnel and Extension service folks were the ones on the front lines talking to the farmers.”
It’s difficult to overstate the impact of AGNR’s influence on cover crops in Maryland and in the U.S., as many alumni in top government and faculty positions are helping drive science and policy that influences cover crops. But the hard work is not over. Adoption of cover crops is very low in states where subsidies for them are either non-existent or less generous than Maryland’s.
And even where adoption is high, there’s much to be done to ensure that the right species are planted at the right time and in the right fields.
Much More to Explore
Properly executed, cover crops can make a bigger impact on water quality in the region and provide a plethora of benefits that extend well beyond the Chesapeake Bay. The right cover crops can hinder the spread of pests and herbicide resistant weeds. The additional organic material that cover crops build in soil captures water, protecting farm fields from more frequent floods and droughts. Research also suggests cover crops may help sequester carbon in the soil, buffering against climate change.
And that’s why people like Weil, Staver, Hirsh and dozens of their AGNR colleagues will continue working to realize the full potential of cover crops on a grand scale, throughout the state and beyond.
by Kimbra Cutlip: Momentum Winter 2023
