Weed Community Composition and Diversity in Organic vs. Conventional Soybean Fields Under Different Weed Management

Abstract

Weed community composition and diversity were assessed in organic and conventional soybean (Glycine max L.) fields under different weed management practices to understand shifts in species assemblages and ecological structure. Field surveys were conducted across multiple locations, and weed species were identified, counted, and analyzed for density, frequency, and dominance under contrasting management systems. Results indicated higher species richness and diversity in organic soybean fields compared to conventional systems, reflecting reduced chemical disturbance and greater ecological heterogeneity. Broadleaf weeds such as Amaranthus spp., Chenopodium album, and Parthenium hysterophorus were more prevalent in organic systems, whereas conventional fields were dominated by a narrower spectrum of herbicide-tolerant species. Diversity indices, including Shannon–Wiener and Simpson’s index, confirmed greater evenness and community complexity in organic fields. Weed management practices strongly influenced community structure, with mechanical weeding and crop rotation in organic systems promoting mixed weed populations, while herbicide application in conventional fields resulted in simplified and less diverse communities. Seasonal variation further influenced weed abundance, with peak emergence occurring during early crop growth stages across both systems. Competitive interactions between weeds and soybean were more intense in organic fields due to higher weed density, although crop yield impacts were moderated by timely mechanical control interventions. The study highlights the ecological consequences of contrasting weed management strategies and their role in shaping weed biodiversity in soybean agroecosystems. These findings emphasize the need for integrated weed management approaches that balance productivity with biodiversity conservation in sustainable agricultural systems.