Sarah Hirsh, an Extension educator at University of Maryland, shared cover cropping case studies from Maryland’s Eastern Shore at a recent Northeast Cover Crop Council meeting.
The case studies are part of a multiyear grant which includes support from USDA-NRCS and the National Fish & Wildlife Foundation.
The grant encourages farmers to branch out and try different types of cover crops based on site factors and the farmers’ goals. Hirsh and other Extension agents offer financial and technical assistance for these field scale trials.
“Basically, the idea behind this project is to try to take cover cropping to the next level in Maryland. Maryland already has the highest percent of cover crop acreage, but still the most common cover crop in Maryland is wheat. And farmers tend to just plant the same cover crop across all of their fields or acreage regardless of other factors,” Hirsh said.
Primarily, Hirsh has been working with grain farms, but the project recently received some additional funding to expand statewide and include four farm types: grain, vegetable, micro and grazing.
Case Study 1: Following a Wheat & Vetch Cover Crop with Corn & Soybeans
This farm’s primary goals were to use cover crops to build organic matter and to cut back on how much imported nitrogen they needed to apply on their corn crop.
In early September 2023, using an aerial ground rig, the farmer planted wheat and vetch into a standing soybean crop. He harvested the soybeans on Nov. 18. By Dec. 12, the cover crop stand contained about 340 lbs./acre of biomass (dry matter). By May 2024, it contained about 8,500 lbs./acre of biomass.
In spring 2024, he planted half of the cover cropped ground to corn and the other half to soybean.
Ahead of the soybean, the farmer crimped the wheat and vetch when it was about chest height. He let the crimped crop continue to grow for the next two weeks, and then planted soybeans in late May. Post-planting, he terminated the wheat and vetch with an herbicide.
Hirsh said, “After that you could see a really nice layer of mulch underneath that soybean all the way into August. You could see no soil showing.”
For the corn acreage, he let the wheat and vetch grow to waist height. Using a planter with shark teeth, he planted corn directly into the cover crop stand. The planter helped to knock down the crop and mat the vetch. Hirsh noted that this method probably wouldn’t have worked without the specialized planter. Three days after planting the corn, he terminated the cover crop stand with an herbicide.
Case Study 2: Taking a Nuanced Approach to Aerial Seeding
“A lot of times farmers would say, ‘Oh, I’m aerial seeding, I have to just do the same cover crop across all my land or across the whole field,’” Hirsh said.
The farmer in this study, however, asked the pilot to split a 150-acre field into two sections. On Sept. 10, the pilot aerial seeded a combination of radish and triticale into the stand of corn, and on Sept. 30, a combination of radish and vetch into a stand of soybeans.
The farmer chose to plant the cover crop into the corn earlier than the soybeans so he could do a better job of getting through the corn and soybean canopies. He chose radish and vetch for the soybean because he followed the soybean with corn and hoped for the vetch to provide nitrogen to the corn.
Farmers utilizing aerial seeding should consider that differentiation is possible. “This shows an example of a farmer strategizing and doing different cover crop species and timing based on the cash crop rotation with the aerial seeding,” Hirsh said.
At a field day, a farmer shares his approach to aerially seeding cover crops. Photo courtesy of Elizabeth Beggins
Case Study 3: Supporting High Yielding No-Till Corn
This farmer has a no-till continuous corn rotation. On Oct. 25, 2023, post-corn harvest, he drilled a combination of rye (84 lbs./acre), hairy vetch (8 lbs./acre) and Keystone winter peas (20 lbs./acre).
“He separated out the winter pea in one box, and the hairy vetch and rye in the other box. He found that this worked better at getting the stand he wanted,” Hirsh said.
Since the cover crop was planted fairly late, there was very little growth by December. The peas were only about two inches tall. By April, however, the density of the stand had greatly increased.
Hirsh commented that the longer the cover crop can be left in spring, the more benefits the cover crop will provide.
Case Study 4: Preparing Corn & Soybean Ground on Certified Organic Ground
Ahead of an organic soybean crop, in late October, this farmer planted half of the ground to 55 lbs./acre rye plus 8 – 10 lbs./acre Balansa clover. The other half was planted to 55 lbs./acre rye plus 12 lbs./acre crimson clover and 5 lbs./acre Balansa clover. The planting occurred in late October.
He worked the field, then aerial seeded the clovers, and then drilled the rye. “So, kind of a combination between planting methods. He found that the clovers do well aerial seeded since they don’t need to be planted deep. By drilling the rye, it helped establish the clover with the movement of the soil,” Hirsh said.
When Hirsh measured the biomass about a month after planting, it weighed about 300 lbs./acre. By mid-May, though, the cover crop was yielding nearly 3,000 lbs./acre.
by Sonja Heyck-Merlin
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