Long term effect of integrated nutrient management on potassium fractions and their relationship with yield of cotton + greengram (1:1) intercropping system in Vertisols

A field study was conducted during kharif 2019-20 at Research field of AICRP for Dryland Agriculture, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra to assess the long term effect of integrated nutrient management on potassium fractions and yield of cotton+greengram(1:1) intercropping system in Vertisols. The eight treatments replicated three times in randomized block design comprised of control, 50% and 100% RDF, 50% N ha-1 through gliricidia/FYM, 50% N fertilizers + 50% N ha-1 gliricidia/FYM + 100% P2O5+ 100% K2O ha-1 fertilizers and 100% N ha-1 gliricidia + 100% P2O5+ 100% K2O ha-1 fertilizers. The results after 33rd cycle indicated that application of 50% RDN through FYM in combination with 50% N + 100% P2O5 + 100% K2O ha-1 through inorganics recorded higher cotton+greengram yield and was on par with the application of 50% N through gliricidia + 50% N +100% P2O5 + 100% K2O ha-1 through fertilizers. However, the significant improvement in potassium fractions was recorded with application of 50% N through gliricidia + 50% N + 100% P2O5 + 100% K2O ha-1 through fertilizers and was on par with 50% RDN through FYM in combination with 50% N + 100% P2O5+ 100% K2O ha-1 through fertilizers. Among the various potassium fractions, the exchangeable and lattice K was highly correlated with yield of crops. Hence, it is concluded that the integrated application of 50% N through gliricidia / FYM + 50% N + 100% P2O5 + 100% K2O ha-1 through fertilizers resulted in improvement in potassium fractions and yield of cotton + greengram (1:1) intercropping system in Vertisols under rainfed conditions.