Weed Community Structure and Diversity in Long-Term Monocropped vs. Rotated Maize Fields

Abstract

Weed infestation remains a major constraint in maize-based cropping systems, with long-term agronomic practices significantly influencing weed community composition and diversity. The present study evaluated weed community structure and species diversity in long-term monocropped and crop-rotated maize fields to understand the impact of cropping systems on weed dynamics. Field surveys were conducted during the active growing season, and weed species were identified, counted, and analyzed using standard ecological indices including species richness, Shannon diversity index, and evenness. Results indicated that monocropped maize fields exhibited higher dominance of a few competitive weed species, leading to reduced overall diversity but increased population density of dominant weeds. In contrast, rotated maize fields supported a more diverse and balanced weed community structure, with lower dominance and higher species evenness. Monocropping systems favored the proliferation of persistent and adaptive weed species due to continuous selection pressure and reduced habitat variability. Crop rotation disrupted weed life cycles and reduced the abundance of crop-specific weed assemblages, thereby enhancing weed community heterogeneity. Seasonal variations further influenced weed composition, with higher diversity observed during peak vegetative stages of maize growth. Environmental factors such as soil moisture and nutrient availability also contributed to variations in weed community structure across treatments. The study highlights that long-term monocropping leads to simplified but aggressive weed communities, whereas crop rotation promotes ecological balance and reduces dominance of problematic weeds. These findings emphasize the importance of diversified cropping systems as a sustainable strategy for weed management in maize agroecosystems. Overall, weed community structure is strongly shaped by cropping practices, and crop rotation serves as an effective cultural tool for maintaining weed biodiversity and reducing long-term weed pressure.