Recurrent Changes of Weed Seed Bank Density and Diversity in Crop—Livestock Systems

Abstract

Core Ideas Crop phase can be used to modify weed diversity.Grazing in sod‐based rotations decreased Palmer amaranth seed bank.Weed seed banks respond rapidly to crop phase within diverse rotations. Weeds are important biodiversity components in agroecosystems, but weed competition with cash crops requires farmers to manage weeds, limiting biodiversity within agricultural fields. Crop rotation increases weed diversity, but weeds are still managed in all cash crop phases so yields are not negatively affected. In our research, a bahiagrass (Paspalum notatum Flüggé)–bahiagrass–peanut (Arachis hypogaea L)–cotton (Gossypium hirsutum L.) rotation exhibited recurrent changes in weed seed banks. The bahiagrass crop phases increased, whereas peanut and cotton phases decreased weed density and diversity. Increasing weed seed banks in bahiagrass did not negatively impact the cash crops peanut and cotton. Furthermore, including grazing in the rotation did not affect overall weed seed banks, but caused a 75% reduction in Palmer amaranth (Amaranthus palmeri S. Watson) populations, the most problematic weed species in peanut and cotton. Our results indicate that grazing bahiagrass will promote weed diversity and suppress Palmer amaranth, resulting in better weed management in the peanut and cotton rotation crops.