Corn School: Does planting into green cover crops work?

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Planting corn directly into a living cover crop before it is killed by herbicide or tillage is not something growers would have considered 30 years ago, says Ontario Ministry of Agriculture, Food and Rural affairs soil management specialist Jake Munroe.

More and more farmers, however, are now willing to take the leap thanks to advances in planter technology, herbicide options and a greater awareness of cover crop benefits to soil health. But does it work? Can growers realize the agronomic benefits while also harvesting reliable and reasonable yields?

Munroe worked with five farmers across Ontario in 2023 to help answer these questions. On this episode of the RealAgriculture Corn School, he shares observations from the individual farms, identifies common challenges, highlights differences across soil types, and defines key elements to success.

Overall, Munroe concludes that planting corn into green cover crop mixtures can work in Ontario. When yields were tallied for the five plant green farms that he followed in 2023, they yielded an average 193.7 bu/ac at 15.5% moisture, surpassing the county average yield for the fields by almost 30 bu/ac.

Success, however, requires an advanced level of management, and can carry a higher level of risk, Munroe says. In the video, he discusses his key takeaways, which include targeting modest spring cover crop growth to maximize benefits while reducing planting challenges. It’s also important to consider cover crop seeding rate, date, number of overwintering species, and nutrient availability from manure. (Story continues after the video.)

Modifying the planter for better corn stands, especially in a no-till-plant green environment, is another key consideration — pneumatic downforce enables adjustments from the cab based on conditions, while hydraulic downforce helps place seed at the proper depth in thick, living plant material. Munroe also notes that all the farmers he followed employed some form of aftermarket closing wheel system to achieve seed slot closure.

Applying a higher-than-standard upfront nitrogen rate is also favourable. Four of five growers applied an upfront nitrogen rate over 45 lbs/acre. Munroe says ample early nitrogen is critical when planting green to help overcome nitrate tie-up by non-legume cover crops and compensate for cooler, slower-to-mineralize soils. He also recommends banding nitrogen and protecting any surface-applied N with a urease inhibitor. Check out Munroe’s full report at Field Crop News.

Tap here for more Corn School videos.

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