Influence of Phosphorus and Sulphur Levels on Nodulation, Growth Parameters and Yield of Soybean (Glycine max L.) Grown on Vertisol

A field experiments were conducted for two consecutive years during 2009-10 and 2010-11to study the effect of phosphorus and sulphur levels on soybean (Glycine max L.) at Research Farm, Department of Soil Science and Agril. Chemistry, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani (M.S.) on Vertisol (Typic Hapluster) deficient in phosphorus and sulphur. The treatments consisted of four levels of sulphur (S₀, S₂₀, S₄₀ and S₆₀ kg ha^-1) and four levels of phosphorus (P₀, P₃₀, P₆₀ and P₉₀ kg P₂O₅ ha^-1) applied through elemental sulphur and DAP, respectively. Results revealed that due to increase in the phosphorus and sulphur levels, there was effective improvement in nodulation, fresh weight of nodules plant^-1 and growth parameters viz., plant height, leaf area, ischolar_main length, ischolar_main dry weight plant-1 and number of pods plant^-1 at various growth stages of soybean. The yield i.e. grain, straw and total biological yield of soybean increased significantly with increasing levels of both phosphorus and sulphur. Further, synergistic effect of phosphorus and sulphur interactions on straw and total biological yield was highest at 90 kg P₂O₅ + 60 kg S ha^-1 followed by 90 kg P₂O₅ + 40 kg S ha^-1, 90 kg P₂O₅ + 20 kg S ha^-1 and 60 kg P₂O₅ + 60 kg S ha^-1 in straw yield and 90 kg P₂O₅ ha^-1 with 60 or 40 kg S ha^-1 produced significantly higher yield over S application with 30 and 0 kg P₂O₅ ha^-1 in total biological yield.