Beneficial System Outcomes in Organic Fields at the Long-Term Agroecological Research (LTAR) Site, Greenfield, Iowa, USA

Summary

In 1997, Iowa State University established the first U.S. Land Grant University permanent faculty position in organic agriculture to assist farmers in the rapid expansion of organic production in that state. Research agendas, developed in consultation with organic farmers and processors, led to the establishment of the Neely-Kinyon Long-Term Agroecological Research (LTAR) site in Greenfield, Iowa, in 1998 to study the long-term effects of organic production in terms of yield and economic performance, in addition to other system effects. Over nine years of comparison, there was no significant difference in corn or soybean yields in the organic and conventional systems. Organic corn yields in the longest rotation (C-S-O/A-A) over a 9–yr period were 9914 kg/ha compared to 10113 kg/ha in the conventional system and organic soybeans in the same rotation yielded 3043 kg/ha while conventional yields averaged 2906 kg/ha. Soil quality remains high in the organic system, with soil organic carbon and mineralizable nitrogen greater in the organic rotations relative to conventional, demonstrating greater C sequestration potential and N-use efficiency in the organic system. Over nine years, revenues generated from organic corn crops increased average revenues by a factor of 1.67 over conventional corn, while organic soybean revenues were 2.32 times greater than conventional soybean revenues.