Response of Soybean to Integrated Nutrient Management in Cotton and Soybean Intercropping System

A field experiment was conducted to study the integrated nutrient management on growth components of soybean, resource use efficiency and economics of cotton and soybean intercropping system. The study was conducted at All India Coordinated Research Project on soybean, Main Agricultural Research Station, University of Agricultural Sciences, Dharwad, Karnataka (India) during Kharif 2015 and 2016. The experiment was laid out in a randomised complete block design with three replications and twenty treatments. As per the treatments, the organic manure (FYM) and green leaf manures (gliricidia and pongamia) were applied 15 days before sowing of the crop. Vermicompost was spot applied to soil before dibbling of seeds in cotton and soybean intercropping system in 1:2 row proportion, soybean introduced as intercrop in cotton with row spacing of cotton 120 cm and soybean 30 cm. Results of the study indicated that significantly higher soybean growth attributes were observed in sole soybean than intercropped soybean, except for plant height. Among the intercropping system, T3 (150% recommended dose of fertilizer for cotton and soybean) recorded significantly higher number of branches per plant, leaf area per plant, leaf area index, dry matter production and the total number of nodules per plant. Intercropping of cotton and soybean resulted in more efficient utilization of resource. Among the intercropping system, T3 (150% recommended dose of fertilizer for cotton and soybean) recorded higher biomass and leaf area of cotton and soybean intercropping system. Among the different treatments, significantly higher gross returns and net returns were recorded in T3 (150% recommended dose of fertilizer for cotton and soybean) and it was on par with T2 (125% recommended dose of fertilizer for cotton and soybean) and T17 (T1 + Vermicompost 1.25 t ha-1 + Gliricidia 2.5 t ha-1) during both years and in pooled data. Among the different treatments, significantly higher benefit cost ratio was recorded in T16 (T1 + Gliricidia 2.5 t ha-1 + Pongamia 2.5 t ha-1) compared to rest of the intercropping systems and sole cotton and soybean during both years and in pooled data. However, T16 was on par with T2 (125% recommended dose of fertilizer for cotton and soybean) during 2015-16. Farmers can adopt a fertilizer dose of 125: 62.5: 62.5 N, P2O and K2O kg ha-1 in cotton and soybean intercropping system or 100: 50: 50 N, P2O5 and K2O kg ha-1 along with Gliricidia + Pongamia 2.5 t ha-1 each for cotton and soybean intercropping for profitable yields in rainfed situation.