Influence of Nutrient Supply Systems on Productivity of Soybean-Wheat and Soil Fertility of Vertisol of Madya Pradesh

To study the effect of nutrient supply exclusively through organic manure on soil productivity and to compare with chemical fertilizer, field experiments were conducted in farmer's participatory mode for 3 years with four nutrient supply systems on soybean-wheat cropping system. The nutrients were supplied in 4 modes viz., i) farmyard manure (FYM), ii) poultry manure (PM), iii) farmyard manure-cum-chemical fertilizer, and iv) chemical fertilizer. The data on seed yield of soybean and grain yield of wheat revealed that in all 4 nutrient supply systems, the seed yield of soybean was at par within a year which suggests that soybean can be grown by using the organic sources of nutrients alone without any loss in yield. But the potential yield of wheat could not be achieved by application of nutrients through organic source alone. Wheat yield with application of organics alone was always lower than the chemical fertilizers. However, integrated use of farmyard and chemical fertilizer not only sustained the yield of wheat at higher level but also improved the soil nutrient status. The three years’ average yield of wheat with application of FYM and PM was 3.87 and 3.69 t ha⁻¹, respectively, whereas with application of nutrients through fertilizer alone and with conjunctive use of FYM and fertilizer the yields were 3.98 and 4.32 t ha⁻¹, respectively. The study further revealed that the combined application of organics and chemical fertilizers also led to larger biological N fixation by soybean in addition to more profit to the farmer. Nutrient supply through integrated plant nutrient supply module may also bridge the gap between nutrient removal by crops and the supply by enhancing the biological N fixation by legumes.