Effects of Cover Cropping In Organic Systems Including Organic No-till.

Organic farming may be perceived as promoting poor soil stewardship because of the amount of tillage needed for weed management that may contribute to excessive erosion and overall soil degradation. Conservation tillage, including no-till crop production, addresses these concerns and has led to improvements in soil quality; however, conventional no-till relies on synthetic herbicides as the primary form of weed management, which is prohibited in organic production. Instead of herbicides, organic farmers utilize cover crops and crop rotations for preventative weed management. In the organic no-till system, cover crops are terminated through mechanical rolling/crimping. In 2007, in Iowa, no-till organic soybeans in a rolled/crimped cover crop of hairy vetch and rye yielded 3.02 Mg/ha, compared to 3.36 Mg/ha in the tilled organic soybeans, but no-till organic corn was not competitive, with yields as low as 0.63 Mg/ha. In 2009, yield results were similar, with no-till organic soybeans averaging 2.62 Mg/ha, compared to 2.89 Mg/ha in the tilled organic soybeans. No-till organic corn only averaged 1.82 Mg/ha compared to the tilled organic corn averaging 6.20 Mg/ha.  Winter rye biomass averaged 15,449 kg/ha preceding soybeans, while hairy vetch averaged 5933 kg/ha preceding corn.  In 2010, a study was conducted involving planting organic corn into hairy vetch, winter rye, winter triticale, Austrian winter peas, and a hairy vetch/winter rye mixture, using both conventional tillage and organic no-tillage.  Due to late planting from wet weather, corn was harvested as silage with the tilled plots yielding 54.8 Mg/ha of corn biomass and the no-tillage plots yielding 14.56 Mg/ha.  Cover crop biomasses ranged from 3429 kg/ha of hairy vetch to 7907 kg/ha and 8288 kg/ha of winter rye and winter triticale, respectively.  Economic and soil quality analyses are underway to determine effects from cover crops and tillage systems.