Long-term integrated nutrient management for enhancing soil quality and crop productivity under soybean-safflower cropping sequance in a vertisol

The dynamics of soil characteristics were studied in an ongoing long-term fertility experiment under All India Coordinated Research Project on Long-Term Fertilizer Experiment with soybean-safflower cropping sequence in a Vertisol (Typic Haplusters) that commenced from 2006–07 at Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani, Maharashtra, India. The present investigation was conducted to study the effect of long-term organic manure and fertilizers on soil fertility, nutrient uptake and productivity under soybean-safflower cropping system. Treatment includes 50% NPK, 100% NPK, 150% NPK, 100% NPK + hand weeding, 100% NPK + ZnSO4 at 25 kg ha⁻¹, 100% NP, 100% N, 100% NPK + FYM at 5 t ha⁻¹, only FYM, absolute control and fallow without crop. The findings emerged out indicated that the grain (3.11 t ha⁻¹) and straw (2.71 t ha⁻¹) yield of soybean were increased significantly with 150% NPK followed by 100% NPK + FYM at 5 t ha⁻¹. Conjoint use of FYM with 100% NPK improved the soil properties with respect to organic carbon (OC) and cation exchange capacity (CEC), pH, EC, available nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) over the initial value of soil. Bulk density and soil pH significantly reduced with the application of 100% + FYM at 5 t ha⁻¹, and bulk density negatively correlated with OC. However, N, P, K and S uptake by soybean were increased significantly with the application of 100% NPK + FYM @ 5 t ha⁻¹ than other treatments. The study indicated that balanced use of the fertilizers continuously either alone or in combination with organic manure is necessary for sustaining soil fertility and productivity of crops.