Influence of phosphorus levels, application timing and methods on productivity and profitability of soybean (Glycine max L.) under Vertisols of Chhattisgarh state

The field experiment was conducted during kharif seasons of 2005–06 and 2006–07 at the Instructional Farm, College of Agriculture, Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh, India. The experimental soil was clayey in texture (Vertisols), low in available nitrogen, medium in available phosphorus and organic carbon, and high in available potassium. Soybean (Glycine max L.) cultivar JS-335 was grown in both the years. The experiment was comprised of ten treatment combinations which were arranged in a split-plot design with three replications. The main plots consisted of two phosphorus application levels: 40 kg P₂O₅ ha⁻¹ and 60 kg P₂O₅ ha⁻¹ and the sub-plots included five phosphorus application schedules and methods: (i) broadcast (ii) drilling (iii) two equal splits (50% basal as drilling + 50% side dressing at 30 DAS) (iv) two equal splits with blending in FYM (50% basal as drilling after blending with FYM + 50% side dressing at 30 DAS after blending with FYM), and (v) three splits (50% basal as drilling + 25% side dressing at 30 DAS + 25% side dressing at 50 DAS). Results indicated that application of 60 kg P₂O₅ ha⁻¹, in combination with two splits (with or without FYM blending), consistently produced significantly higher seed yield, straw yield, harvest index, phosphorus recovery index, phosphorus use efficiency, gross returns, net returns, and benefit-cost ratio in both the years. The highest return per rupee invested on phosphorus fertilizer was recorded under 40 kg P₂O₅ ha⁻¹ with two splits (with or without FYM blending) or drilling application.