Nutrient content, Uptake, Soil Enzymatic Activity and Available Nutrient status of Sweet sorghum as influenced by Nutrient Management in Agri silvi culture system

Sweet sorghum (SSV-84) was grown under two year old Pongamia grafts in red sandy loam soil with different nutrient management options viz., application of FYM 10 t ha⁻¹, 100% RDF (80-60-40 NPK kg ha⁻¹) alone, and in conjunction with 75% RD N with 25% N through FYM, Poultry manure, Vermicompost; also with biofertilizers @ 5 kg ha⁻¹ Azospirillum and VAM. Grain and stover yield of sweet sorghum was significantly affected by different treatments over control. Maximum grain and stover yield (30.78 and 92.25 q ha⁻¹) was recorded by the 100% RDF (80-60-40 NPK kg ha⁻¹) followed by integrated use of 75% RD N + 25% N through Poultry manure (28.5 and 84.65 q ha⁻¹) and lowest being control (18.38 and 48.88 q ha⁻¹). Quality parameters such as brix and sucrose content in green stalks, influenced significantly among various nutrient sources in comparison to control. Among different combination treatments, the highest brix content was recorded in conjoint use of 75% RD N + 25% N through Poultry manure (12.14%) on par with 100% RDF (11.8%). In case of sucrose content the trend was in the following order 75% RD N + 25% N through Poultry manure (9.86%) > 75% RD N + 25% N through Vermicompost (9.29%) > 75% N through FYM (9.07%) > 100% RDF (8.85%). Pertaining to nutrient content, the integration of 75% RD N + 25% N through poultry manure was superior practice which resulted in significantly higher N, P, K content in both grain and stover ((1.41, 0.319, 0.46 and 1.36, 0.282, 2.68%) and uptake (58.86, 8.79, 12.53 and 38.90, 7.78, 73.85 kg ha⁻¹) respectively in comparison with 100% RDF.