An organic crop rotation is at least as sustainable as no-till farming or chisel tillage in terms of nitrogen loss and corn yields, according to an Agricultural Research Service (ARS) study. The five-year study showed that a three-year rotation of organic corn, soybeans, wheat and a legume cover crop had nitrogen losses and corn yields similar to those on land where either chisel-tillage or no-till farming had been used.
The organic rotation relied on poultry litter, soybeans and a hairy vetch legume cover crop as nitrogen sources. The study showed the highest risk of leaching nitrogen to groundwater was on fields with no-till or chisel tillage where both commercial fertilizer and poultry litter had been used. Future studies are planned to measure or estimate leaching losses.
Michel Cavigelli, an ARS soil scientist at the Henry A. Wallace Beltsville (Md.) Agricultural Research Center, and Steve Green, an ARS soil scientist research associate, are studying nitrogen losses with organic and other farming systems. The study is part of a farming systems project begun in 1996 to compare the sustainability of organic and conventional farming.