Irrigation Scheduling and Nutrient Management in Green Gram Cultivation: An Evaluation of Yield and Water Productivity, Soil Water-Nutrient Dynamics, Energy Budgeting and Profitability

Green gram is an excellent pulse crop with high economic and nutritional values. Optimal water and nutrient application can boost yield, water productivity, nutrient use, energy indices, and economic gains. The field experiment comprising three irrigation schedules (one irrigation at pre-flowering, two irrigations at pre-flowering and pod formation, and three irrigations at branching, pre-flowering and pod formation stages) and four nutrient management (control, 100% recommended fertilizer (RDF), farmyard manure at 5 t ha-1, and 100% RDF + FYM at 5 t ha-1) was arranged in a split-plot design with three replications during the summer seasons of 2016 and 2017. Based on the principal component analysis technique and economic assessment of all the treatments studied, three irrigations at branching, pre-flowering and pod formation stages with the recommended fertilizer plus FYM resulted in the maximum growth, yield components, seed yield (784 kg ha-1), stover yield (2288 kg ha-1), highest NPK uptake, total output energy, net energy gain, greatest gross return (USD 749.7 ha-1), net return (USD 331.7 ha-1) and higher BCR (1.79). However, maximum crop water productivity and irrigation water productivity (0.55 and 0.96 kg m-3, respectively) were recorded with a single irrigation at pre-flowering stage in tandem with full recommended fertilizer and farmyard manure. A linear relationship was detected between seed yield and seasonal crop evapotranspiration (ETc) at different nutritional levels. Seasonal water consumtion of 178 mm corresponding to an irrigation amount of 170 mm with a yield of 620 kg ha-1 and CWP of 0.36 kg m-3 was a balance for optimum seed yield, ETc and CWP. The 0-30 cm depth of the root zone profile contributed 80-84% while the 30-60 cm depth accounted for 16-20% of total soil moisture depletion. Based on the physical and financial outputs, a three-irrigation schedule coupled with the full recommended fertilizer and manure was identified as the best management strategy for green gram production and can thus be recommended to farmers of non-saline coastal soils in eastern India.