Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/1998
Publication Date: N/A
Interpretive Summary: There is considerable interest in developing alternatives to herbicides and tillage for weed control in corn and soybeans. Spring-seeded smother plants may have potential for weed control through management of interplant competition and surface residues. Smother plants are specialized cover crops developed for their ability to suppress weeds without the aid of herbicides. Additionally, smother plants could reduce soil erosion and improve soil quality. Therefore, the objective of our research was to evaluate the feasibility of a spring-seeded smother plant system for weed control in corn and soybean production. Several annual medic species, Berseem clover, and yellow mustard showed variable potential to control weeds when planted in a band over the corn or soybean row at planting. Smother crop establishment and weed control was better in corn than soybeans with weed control ranging from 20 to 90%. Corn and soybean yields also varied among experiments. While results were variable, we feel that the results warrant further evaluation of smother plants as a weed control method for Midwest corn and soybean growers. Beyond their potential as an alternative weed control method, they also provide soil cover and organic matter to reduce soil erosion, increase soil moisture retention, and improve soil quality.
Technical Abstract: Considerable interest exists in the development of alternate weed management options. Spring-seeded smother plants may provide an alternative to current weed management practices through management of interplant competition and surface residues. Experiments were conducted in corn and soybeans in 1995 and 1996 at Sioux Center and Ames, IA. Caliph medic, Santiago medic, Sava medic, Berseem clover, and yellow mustard were evaluated as potential smother plants. The smother plants were seeded and incorporated in a 25-cm-wide band over the crop row immediately after crop planting. Weed suppression from 19 to 90% among the smother plant species was observed. The effect of smother plants on corn and soybean yields varied among locations, years, smother plant species, and weed pressure. In some instances, yields with smother plants were equal to weed-free crops, while at other times yields were as low as the weedy crop. These results imply that smother plants have potential for weed control. However, more research is needed to reduce variability and to gain more insight on biological, management, and competitive interactions among weeds, smother plants, and the harvested crop.