Yield and economics following 5 years of integrated weed management in cotton

Abstract

The implementation of integrated weed management (IWM) practices in conventional management systems involves additional costs and can influence both short-term and long-term cotton (Gossypium hirsutum L.) yields, ultimately affecting economic viability. This study, conducted from fall 2018 to fall 2023 near Marianna, AR, evaluated four IWM practices in a large-plot, fixed-plot factorial design: zero tolerance for weed seed rain, soil inversion deep tillage every third year in the fall, a preplant terminated cereal rye cover crop, and dicamba-resistant cotton technology. Long-term economic impacts were assessed using the 5-year average cost-adjusted yield, with the base program (excluding all IWM practices) serving as the control. Zero tolerance did not influence cotton yield and, due to a significant decline in hand hoeing time over time, had no adverse effect on economic outcomes. Most IWM combinations produced cotton yield comparable to the base program. However, the deep tillage–dicamba combination resulted in a 9% reduction. When costs were incorporated, cost-adjusted yields for the all-present, dicamba alone, and deep tillage–dicamba combinations were 5%–8% lower than the base program. Integration of a cover crop, except when combined with both deep tillage and dicamba, consistently resulted in cost-adjusted yield similar to the base program. While the progressive reduction in labor costs over time enhances zero tolerance practice's practicality as a foundational element within long-term IWM systems, the evaluated IWM practices, whether implemented individually or in combination, generally did not affect cotton yields, and many combinations, including those up to triplet levels, imposed no long-term economic burden.