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Title: LONG-TERM AGRONOMIC PERFORMANCE OF ORGANIC AND CONVENTIONAL FIELD CROPS IN THE MID-ATLANTIC REGION

Author
item Cavigelli, Michel
item Teasdale, John
item Conklin, Anne

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2007
Publication Date: 5/8/2008
Citation: Cavigelli, M.A., Teasdale, J.R., Conklin, A.E. 2008. Long-term agronomic performance of organic and conventional field crops in the mid-atlantic region. Agronomy Journal. 100:785-794.

Interpretive Summary: There is growing interest in organic grain crop production among farmers and government agencies. However, there is little information on expected crop yields and production challenges in organic grain production, especially in the mid-Atlantic region. A long-term cropping systems trial, the USDA-ARS Beltsville Farming Systems Project (FSP), was established in Maryland in 1996 to better understand production challenges in organic grain production. Corn and soybean yields in organic systems were, on average, 76 and 82% lower in organic than in conventional systems. There were no consistent differences in wheat yields among systems. Weed competition alone accounted for differences between organic and conventional soybean yields. Both weed competition and N availability accounted for lower corn yields in organic than in conventional systems. Crop rotation length and complexity did not affect soybean and wheat yields in organic systems but had an effect on corn yield. In general, corn yield increased with increasing crop rotation length and complexity because there were fewer weeds and more available nitrogen in longer rotations, especially when hay was included in the rotation. Since this project is one of only a handful of long-term projects that includes organic grain production and because it is one of the first studies to integrate weed and nitrogen impacts on organic grain production, the results will be of interest to a national audience of farmers, agricultural professionals and government agencies involved in organic grain production. Specific results will be of particular interest to those working in organic grain production in the mid-Atlantic region.

Technical Abstract: Despite increasing interest in organic grain crop production among farmers, government agencies and others, there is little information on expected crop yields and production challenges in organic grain production, especially in Coastal Plain soils of the mid-Atlantic region. The USDA-ARS Beltsville Farming Systems Project (FSP), a long-term cropping systems trial, was established in Maryland in 1996 to address these needs. The five FSP cropping systems include a conventional no-till corn (C)-soybean (S)-wheat (W)/S rotation, a conventional chisel-till C-S-W/S rotation, a two-year organic C-S rotation, a three-year C-S-W rotation, and a four-to-six year organic C-S-W-hay rotation. The impact of weed competition on corn and soybean yields was determined using paired weed-free and weedy subplots. Nitrogen impact on corn yield was evaluated using the relationship between estimated N availability and estimated weed-free corn yield. Corn and soybean yields in organic systems were, on average, 76 and 82 % of those in conventional systems. There were no consistent differences in wheat yields among systems. Weed competition alone accounted for differences between organic and conventional soybean yields, as indicated by similar estimated weed-free soybean yield among all five systems. Both weed competition and low N availability contributed to lower corn yields in organic than in conventional systems. Crop rotation length and complexity among organic systems had no impact on soybean and wheat yields, but corn yield, in general, increased with increasing crop rotation length and complexity due to both lower weed competition and greater N availability in longer rotations, especially when hay was included in the rotation.