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Saving time and saving dollars are the major reasons cover crops have worked so well in no-till rotations for many Virginia growers.
Paul Davis is convinced he’ll eventually be able to meet all of his corn-crop nitrogen needs from the cover crops he seeds each fall. The New Kent, Va., no-tiller has been using cover crops for 6 years, and relied on cereal rye for several years before switching to hairy vetch on much of his acreage.
“One concern may be that the nitrogen from the cover crops may not be available early enough in the cropping season,” he says. “But I think we could still utilize all of the available nitrogen from our cover crops by the time we sidedress corn.”
Davis obtains 60 to 80 pounds of nitrogen from the hairy-vetch cover crop, applies 40 to 50 pounds of nitrogen in starter fertilizer and sidedresses another 60 pounds of nitrogen to harvest 200-bushel corn yields. By no-tilling hairy vetch after full-season soybeans, Davis has dropped nitrogen sidedressing needs with corn from 120 pounds per acre to only 60 pounds.
“We don’t yet have a good answer as to how many pounds of nitrogen we need after a cover crop,” says Davis. “We tissue-test corn plants, along with the amount of biomass in the soil, to determine the precise amount of nitrogen needed for sidedressing. Our goal is to rely on the cover crop to boost soil organic matter and sequester carbon.”