Long-term effect of manure and fertilizers on the physical and chemical properties of an alfisol under semi-arid rainfed conditions

The status of nutrients-their depletion and build up in soil and crop productivity after thirty years (1981-2011) of groundnut intensive cropping were studied under continuous use of various inorganic fertilizers and organic manure in an Alfisol. Results showed that application of NPK (20:10:25 kg ha -1 ) +gypsum+zinc sulphate recorded highest pod yield of 1499 kg ha -1 which was on par with NPK+gypsum and FYM alone treated plot. The soil pH and EC did not change significantly but markedly changed the organic carbon and available nutrient contents of the soil. The available phosphorus and potassium were gradually depleted in all the treatments but the magnitude of depletion was less in the treatments which received P and K respectively. Thus, the balanced use of fertilizers continuously either alone or in combination with organic manure is necessary for sustaining soil fertility and productivity of groundnut under rainfed conditions.