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ARS Home » Midwest Area » Morris, Minnesota » Soil Management Research » Research » Publications at this Location » Publication #61962

Title: MULTI-YEAR VALIDATION OF A DECISION AID FOR INTEGRATED WEED MANAGEMENT IN ROW CROPS

Author
item Forcella, Frank
item KING, ROBERT - UNIVERSITY OF MINNESOTA
item SWINTON, SCOTT - MICHIGAN STATE UNIVERSITY
item Buhler, Douglas - Doug
item GUNSOLUS, JEFFREY - UNIVERSITY OF MINNESOTA

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: A team of ARS and University of Minnesota weed scientists and economists examined the long-term agronomic and economic consequences of using a computerized weed management decision aid. The decision aid, known as WEEDSIM (weed simulation), made weed management recommendations for continuous corn, rotation corn, and soybean based upon either the density of weed seeds in the soil during early spring and/or the density of weed seedlings emerging with the crop. The management recommendations could be no control, mechanical control (i.e., rotary hoeing), or herbicides, which could be applied preplant incorporated, preemergence, or postemergence. Results were compared to standard farming practices for western Minnesota. Repeated use of WEEDSIM recommendations, which differed every year, resulted in somewhat higher weed populations in comparison to standard farming practices, but yields were not affected. This occurred regardless of whether the weed seed density or weed seedling density versions of the decision aid were used. Because herbicide applications were reduced appreciably through WEEDSIM recommendations, weed control costs were considerably lower and profits were higher ($20/acre) than those for standard farming practices. Furthermore, the environmental risks associated with herbicide applications were lessened through the use of WEEDSIM recommendations. Decision aids, like WEEDSIM, eventually may permit highly objective and profitable weed management decisions for producers in the Corn Belt.

Technical Abstract: WEEDSIM, a bioeconomic model for the management of annual weeds in corn and soybean, was field-tested for four years in Minnesota. The model makes two categories of management recommendations: (a) soil-applied plus postemergence (Pre+), based on estimated weed seedbank composition and density; and (b) postemergence (Post), based upon observed weed seedling composition and density. Weed densities, weed control, herbicide use, environmental impact of herbicide use, weed management costs, crop yields, and economic returns that resulted from Pre+ and Post recommendations were compared to those associated with standard herbicide management (Herb)for the region. After four years of continuous use of WEEDSIM on the same plots, there were no increases in annual weed densities or decreases in weed control or crop yields, compared to the Herb treatment. WEEDSIM recommendations resulted in average annual herbicide applications of 1.1 kg/ha for Pre+ and 1.0 kg/ha for Post, compared to 3.5 kg/ha for Herb. The environmental impact quotients associated with Pre+, Post, and Herb treatments were 0.75, 0.71, and 0.54, with the lowest value indicating greater environmental risk than the two higher values. Similarly, average weed management costs were $24, $33, and $77/ha for Pre+, Post, and Herb, respectively. Lastly, based on crop prices of $94/Mg for corn and $220/Mg for soybean, the average profits were significantly higher for Pre+ ($509/ha) and Post ($522/ha) than for Herb ($455/ha). WEEDSIM made recommendations that adequately controlled weeds, maintained crop yields, reduced herbicide use, decreased environmental risk, lowered weed management costs, and increased profits compared to the use of standard herbicides.