Development and Evaluation of Soil Fertility Gradient under STCR Framework with Exhaust Crop Sorghum (Sorghum bicolor)

Abstract

A critical requirement for this approach is the development of a soil fertility gradient through graded fertilizer application, which helps to establish reliable relationships between soil test values and crop response with minimizing external influences. Field experiment was conducted at Norman E. Borlaug Crop Research Centre, G.B.U.A.&T., Pantnagar during kharif 2024 under AICRP on Soil Test Crop Response (STCR) to establish and evaluate soil fertility gradient. The experimental field was divided into three strips treated with graded doses of fertilizers: N₀P₀K₀ (Strip-I), N₁₀₀P₁₀₀K₁₀₀ (Strip-II), and N₂₀₀P₂₀₀K₂₀₀ (Strip-III).  Nitrogen, phosphorus, and potassium were supplied through NPK fertiliser mixtures and urea. Sorghum bicolor was cultivated as an exhaust crop following the recommended agronomic practices, and the forage yield was subsequently recorded. Plant samples were analysed to determine nitrogen, phosphorus, and potassium concentrations, and the total nutrient uptake was calculated accordingly. Post-harvest soil samples were also analysed to assess the available nitrogen, phosphorus, and potassium status of the soil. Results revealed significant variation in forage yield, total nutrient uptake, and soil fertility status across the strips, confirming successful establishment of soil fertility gradient. Gradient establishment is prerequisite for developing precise STCR-based fertilizer recommendations to improve nutrient use efficiency and sustain crop productivity.