Effect of Different Weed Management Practices on Dry Matter Production and Nutrient Uptake by Castor (Ricinus communis L.) and Associated Weeds

Castor (Ricinus communis L.) is an important tropical oilseed crop, but its productivity is greatly affected by weed competition, particularly during the early stages of growth. Although manual weeding is an efficient method of control, the use of herbicides is often preferred due to reduced labor demand and lower operational costs. A field study was carried out during the kharif season of 2020 at the Agricultural College Farm, Bapatla, on clay-textured soils. The findings revealed that the highest dry matter accumulation and nutrient uptake by the castor crop, along with the lowest weed biomass and nutrient removal by weeds, were observed in the treatment involving hand weeding at 20 and 40 DAS. This treatment was found to be statistically comparable with the application of alachlor as a pre-emergence herbicide followed by chlorimuron + propaquizafop or halosulfuron + propaquizafop as post-emergence sprays at 30 DAS. In contrast, the untreated control (weedy check) recorded the lowest crop growth and nutrient uptake, along with maximum weed biomass and higher uptake of nitrogen, phosphorus, and potassium by weeds. This clearly indicates the severe competition imposed by weeds on the crop when no control measures are adopted.