Interactive effects of synthetic fertilizer and organic residue inputs on soil fertility and wheat crop under various moisture regimes

Excessive use of chemical fertilizers causes nutrient losses, environmental pollution and reduced economic returns. Integrating organic resources with reduced dose of chemical fertilizers is important to release the nutrients fixed to soil colloids to improve and sustain soil fertility. In greenhouse and two-year field experiments, the effect of six different fertilizer treatments including control; recommended NPK; 1/2 NPK of recommended + mung bean straw; 1/2 NPK of recommended + rice straw; mung bean and rice straw under different water regimes was determined on soil fertility and wheat production. Fertilizer treatments caused remarkable increase in soil organic carbon (SOC), available nitrogen (AN), phosphorus (AP) and potassium (AK), wheat chlorophyll contents (Chl), dry biomass and grain yield, especially under 14 days of alternate wet dry cycles. Incorporation of mung bean straw resulted in increase of SOC, AN, AP, Chl and wheat dry biomass, while maximum increase in AK was observed with 200-150-100 kg NPK ha^-1. Highest C/N ratio and lowest soil pH were observed with rice straw. Maximum (up to 33%) increase in grain yield was achieved with 100-75-50 kg NPK ha^-1 + mung bean straw during both years. In conclusion, alternate wet/dry cycles with integrated fertilizer options increased soil nutrients availability, wheat growth and yield.