Hairy vetch is a key
cover crop in a rotation of organic corn, soybeans and wheat now being studied
by ARS scientists in Beltsville, Maryland. Vetches, such as the early flowering
hairy vetch shown here, add nitrogen to the soil. Click the image for more
information about it.
Organic Farming Is a Winner for Sustainability
Comis November 26, 2004
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
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.
Cavigelli, an ARS soil scientist at the
A. Wallace Beltsville (Md.) Agricultural Research Center, and
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. Minimizing losses of nitrogen and other nutrients is a
key element of both environmental and economic sustainability.
Cavigelli and Green used measurements and estimates to get an initial
picture of nitrogen inputs and losses. They are conducting additional studies
to improve their ability to more accurately estimate the amount of nitrogen
added naturally by soybean plants.
The scientists got their poultry litter--both composted and
noncomposted--from commercial farms on Marylands Eastern Shore. They
studied corn-soybean rotations, mostly with winter wheat, using various levels
Green presented this research at the
American Society of Agronomys
recent annual meeting in Seattle, Wash., along with a report on the risk of
phosphorus loss from erosion. He found the risk of losing phosphorus from soil
erosion was similar for both the organic system and land that was
chisel-plowed, but the risk was lower with a conventional no-till system.
ARS is the U.S. Department of
Agricultures chief scientific research agency.