While adoption of mixed cover crops is slowly rising, the best management practice still isn't getting the respect it deserves. That's why it's the cover story of the soon-to-arrive October issue of American Agriculturist.
Since timing of fall-seeded cover crops is crucial and the window is narrowing, notes from Rachel Onuska of the Bucks County (Pennsylvania) Conservation District are worth a read. She reports that crop yield increases following cover crops are "evidence of the non-nitrogen benefits of cover crops in general, not just clover."
The root systems can improve infiltration plus contain and recycle nutrients – a big bonus in no-till fields. Manure nutrient availability for fall application doubles if there's a cover crop. And, top growth of cover crops can reduce soil and nutrient erosion.
In a 2007 Centre County study, corn planted after red clover had a 17-bushel per acre yield increase. Other studies have shown a 10% average yield increase. Also, the residue left 62 to 144 pounds of nitrogen per acre, with 80 to 100 pounds being the norm. If red clover was harvested for forage before planting corn, nitrogen availability was reduced to 30 to 50 pounds per acre.
One big reason why wheat and cereal rye are most common cover crops, says Onuska, is that they tolerate a mid- to late-fall planting. But this month, she's watching a Bucks County farmer's experiment with planting the following cover crop plots: Crimson clover, red clover, hairy vetch plus wheat, Austrian winter pea plus ryegrass, tillage radish plus wheat, and buckwheat plus ryegrass.