Effect of Five Years of Rice-Wheat Cropping and NPK Fertilizer Use with and without Organic and Green Manures on Soil Properties and Crop Yields in a Reclaimed Sodic Soil

A field experiment was initiated in 1994 on a reclaimed sodic soil (Aqnic Natrustalfs) at the Central Soil Salinity Research Institute, Karnal involving use of NPK fertilizers with and without organic and green manures (Sesbania aculeata) on rice-wheat cropping sequence. Application of N and P significantly enhanced the yield of crops. There was no significant response to K application. Addition of NPK and its combination with green manuring and FYM increased the rice and wheat yields significantly. Application of 150 per cent recommended NPK increased rice yield by 9.4 per cent and decreased wheat yield by 4.0 per cent over 100 per cent recommended NPK. Use of inorganic fertilizers with and without organic and green manures significantly enhanced the available N, P, K and organic carbon content of the soil. Where N alone was applied, available P and K declined from the initial level of 11.8 and 220 kg ha⁻¹ to 7.5 and 183 kg ha⁻¹, respectively. Application of N, P and K enhanced the uptake of these elements by both crops, the effect being more pronounced with integrated use of organic and green manures.