Temporal assessment of nutrient bioavailability in rice using different organic inputs

An investigation into nutrient dynamics was carried out through field trials during the kharif growing seasons of 2019 and 2020. The research was conducted at the experimental fields of Sardar Vallabhbhai Patel University of Agriculture and Technology’s Crop Research Centre in Meerut. Initial soil analysis indicated a sandy loam with neutral reaction conditions, with deficient organic carbon and nitrogen levels, while phosphorus and potassium concentrations were moderate. The experimental design incorporated fourteen distinct treatments, exploring various combinations of organic and inorganic nutrient sources. These treatments evaluated nitrogen substitution rates of 25% and 37.5% using dhaincha and vermicompost. The organic materials were incorporated at three different timings: at planting, five days before planting, and ten days before planting. The remaining nutritional requirements were fulfilled through conventional fertilizers providing nitrogen, phosphorus, potassium, and zinc. The study followed a randomized block design with three replications, using the Pusa basmati-1509 rice variety. Analysis of soil samples throughout the growing period demonstrated significant variations in the availability of major nutrients (N, P, K) and micronutrients (S, Zn) across different treatments and growth stages. The highest residual soil fertility was observed in plots where 37.5% of nitrogen was provided through vermicompost applied on the planting date. The two-year study findings suggest that rice farmers can effectively substitute 25% of their crop’s nitrogen requirements through either dhaincha incorporation at planting time or vermicompost application ten days before planting. These organic amendment strategies demonstrated notably superior yields compared to treatments T2, T4, T7, T8, and T11.