Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: November 9, 2000
Publication Date: November 9, 2000
Citation: Delate, K., Cambardella, C.A. 2000. Long-term agroecological research in Iowa:the transition years. American Society of Agronomy Meetings. P.144.
Organic farming has increased to a $6 billion industry in the U.S. and is expanding approximately 20% annually. International demand for organic products continues, particularly from Japanese and European markets seeking non-GMO crops. In 1998, Long-Term Agroecological Research (LTAR) sites were established throughout Iowa to document changes in the agroecology (soil dynamics, plant performance, pest status) and economic services in conventional and organic systems over time. In the first and second transition years at the Neely-Kinyon LTAR site, there were no statistically significant differences between organic and conventional soybean yields (3.3 Mg/ha), with greater economic return in the organic system. Organic feed corn yields (8.8 Mg/ha) were similar to conventional yields in the first year, but organic white milling corn yields (7.5 Mg/ha) were less than conventional corn yields in Year 2. After one growing season under organic management, early improvements in soil quality were manifested as increased microbial biomass C. In the spring of 1999, after one full year of organic management, particulate organic matter C and N, potentially mineralizable N, and macroaggregate stability were higher in the organic systems than in the conventional rotation of corn-soybean. Corn stalk nitrate content was greater in the conventional system, compared with organic corn fertilized with composted manure and through crop rotational effects (alfalfa).