Effect of improved nutrient management on quality and nutrient uptake of castor (Ricinus communis)

field experiment was conducted at the Agronomy Instructional Farm, Chimanbhai Patel College of Agriculture, Sardarkrushinagar Dantiwada Agricultural University, Gujarat, during the kharif seasons of 2020–21 and 2021–22 to evaluate the “Impact of Green Manure and Nutrient Management on Quality and Nutrient Uptake in Castor (Ricinus communis L.)”. The experiment involved 20 treatment combinations, consisting of four green manure treatments (Control, Sunhemp, Clusterbean, and Cowpea) and five nutrient management treatments (100% Recommended Dose of Fertilizer (RDF), 75% RDF + 1% Banana pseudostem sap foliar spray at 30, 60, and 90 DAS, 75% RDF + 1.5% Banana pseudostem sap foliar spray at 30, 60, and 90 DAS, 100% RDF + 1% Banana pseudostem sap foliar spray at 30, 60, and 90 DAS, and 100% RDF + 1.5% Banana pseudostem sap foliar spray at 30, 60, and 90 DAS). A split-plot design with three replications was used. Results showed that the sunhemp green manure treatment significantly increased oil yield upto 1665 kg/ha and nutrient (N, P, K) uptake by the castor stalk. The application of 100% RDF combined with a 1.5% Banana pseudostem sap foliar spray at 30, 60, and 90 DAS led to significantly higher nutrient uptake by both seed and stalk compared to other treatments. However, the combined application of green manuring and nutrient management did not significantly affect nutrient uptake by seed and stalk. Although nutrient management treatments did not affect oil content in castor seed, the highest oil yield and nutrient uptake were observed with 100% RDF + 1.5% Banana pseudostem sap foliar spray at 30, 60, and 90 DAS, followed by the 1% sap foliar spray treatment. Overall, growing sunhemp as green manure at 45 DAS, followed by 75% RDF application and 1.5% Banana pseudostem sap foliar spray at 30, 60, and 90 DAS, improved oil yield and nutrient uptake in castor.