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Title: Agronomic and economic performance characteristics of conventional and low-external-input cropping systems in the central corn belt

Author
item LIEBMAN, M - IOWA STATE UNIVERSITY
item GIBSON, L - IOWA STATE UNIVERSITY
item HEGGENSTALLER, A - IOWA STATE UNIVERSITY
item SUNDBERG, D - IOWA STATE UNIVERSITY
item WESTERMAN, P - UNIVERSITAT DE LLEIDA
item CHASE, C - IOWA STATE UNIVERSITY EXT
item HARTZLER, R - IOWA STATE UNIVERSITY
item MENALLED, F - MONTANA STATE UNIVERSITY
item Davis, Adam
item DIXON, P - IOWA STATE UNIVERSITY

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2007
Publication Date: 5/7/2008
Citation: Liebman, M., Gibson, L.R., Sundberg, D.N., Heggenstaller, A.H., Westerman, P.R., Chase, C.A., Hartzler, R.G., Menalled, F.D., Davis, A.S., Dixon, P.M. 2008. Agronomic and economic performance characteristics of conventional and low-external-input cropping systems in the central corn belt. Agronomy Journal. 100:600-610.

Interpretive Summary: Agriculture in the Midwestern USA is characterized by heavy reliance on agrichemicals, widespread chemical emissions to water, and strong dependence on government subsidies. Diversified low-external-input (LEI) cropping systems offer important opportunities to reduce use of synthetic fertilizers and pesticides, but questions remain as their ability to maintain crop productivity and profitability. We conducted a 9-ha experiment in Boone County, IA, to compare a conventionally managed corn/soybean system with two LEI systems that included small grains (triticale and oat) and forage legumes (red clover and alfalfa) in addition to corn and soybean. Despite large reductions in N fertilizer and herbicide inputs, yields from the LEI systems matched or exceeded yields obtained from the conventional system. Weeds were controlled effectively in all systems. Without subsidies, net returns from one of the LEI systems exceeded returns from the conventional system. With subsidies, this advantage was reduced, but not eliminated. Labor requirements for the LEI systems were higher than for the conventional system. Our results indicate that certain LEI systems can be biologically and economically competitive with conventional systems in regions of high production potential.

Technical Abstract: Agriculture in the Midwestern USA is characterized by heavy reliance on agrichemicals, widespread chemical emissions to water, and strong dependence on government subsidies. Diversified low-external-input (LEI) cropping systems offer important opportunities to reduce use of synthetic fertilizers and pesticides, but questions remain as their ability to maintain crop productivity and profitability. We conducted a 9-ha experiment in Boone County, IA, to compare a conventionally managed corn/soybean system with two LEI systems that included small grains (triticale and oat) and forage legumes (red clover and alfalfa) in addition to corn and soybean. Despite large reductions in N fertilizer and herbicide inputs, yields from the LEI systems matched or exceeded yields obtained from the conventional system. Weeds were controlled effectively in all systems. Without subsidies, net returns from one of the LEI systems exceeded returns from the conventional system. With subsidies, this advantage was reduced, but not eliminated. Labor requirements for the LEI systems were higher than for the conventional system. Our results indicate that certain LEI systems can be biologically and economically competitive with conventional systems in regions of high production potential.