Effect of irrigation schedule, residue incorporation and nutrient management on system productivity and profitability of soybean (Glycine max)-wheat (Triticum aestivum) cropping system in Vertisols of Rajasthan

A 3-year field experiment was carried out at Kota, Rajasthan during 2015-16 to 2017-18, to study the effect of irrigation schedule, residue incorporation and nutrient management on system productivity and profitability of soybean [Glycine max (L.) Merr.]-wheat (Triticum aestivum L.) cropping system in Vertisols of Rajasthan. The treatments consisted of 24 combinations of 2 irrigation schedules in soybean, viz. 1 irrigation at flowering stage and 2 irrigations at flowering and other pod-development stages -in main plots; 4 wheat residue-management practices, viz. sowing of soybean after wheat-residue burning, wheat-residue incorporation without irrigation, residue incorporation with irrigation and application of urea @ 25 kg/ha and residue incorporation with irrigation and application of urea @ 25 kg/ha + cellulolytic microbes @ 2.0 kg/ha in subplots; and 3 nutrient-management practices, viz. 75% recommended dose of fertilizers (RDF), 100% RDF (20 kg N, 40 kg P₂O₅, 40 kg K₂O/ha) and 125% RDF in subsubplots. The experiment was laid out in a split split-plot design with 3 replications. Wheat crop was sown every year with the adoption of recommended package of practices. Pooled data of 3 years revealed that 2 irrigations at flowering and other at pod development stages-in soybean crop significantly increased dry-matter production, unitarea efficiency, branches/plant, pods/plant, seeds/pod, seed index, seed and straw yields and net returns of soybean, grain yield of wheat, soybean-equivalent yield (SEY), profitability, production- and economic-efficiency of system, available N, P and K status of soil after harvesting of wheat and soybean as compared to 1 irrigation at flowering stage. However, available K status of soil after harvesting of soybean was found non-significant in relation to irrigation. Wheat-residue incorporation with irrigation and application of urea @ 25 kg/ha + cellulolytic microbes @ 2.0 kg/ha resulted in the highest growth and yield attributes, seed and straw yields and net returns of soybean, water-use efficiency (WUE), water productivity (WP), soybean-equivalent yield (4.51 t/ha), system profitability (96,520/ha), production (12.35 kg/ha/day) and economic (264/ha/day) efficiency of system, organic carbon, bulk density of soil after harvesting of soybean and N, P and K status of soil after harvesting of both soybean as well as wheat over wheat-residue burning. Application of 125% RDF resulted in the maximum growth and yield attributes, seed (1.51 t/ha) and straw (2.17 t/ha) yield, net returns (25,700), benefit: cost ratio (1.09) of soybean and SEY (4.44 t/ha), system profitability (95,740/ha), production (12.15 kg/ha/day) and economic efficiency (262/ha/day), bulk density (1.42 Mg/m³), N (282, 288 kg/ha) P₂O₅ (24.6,25.9 kg/ha) and K₂O (293, 299 kg/ha) of soil after harvesting of wheat and soybean respectively.