Impact of long-term integrated nutrient management on the availability of calcium, magnesium and sulphur macronutrients and their removal by wheat on a mollisol in North India.

摘要

In a long-term experiment on a mollisol in North India, the availability of Ca, Mg and S nutrients was enhanced under integrated nutrient management (INM) conditions, but depleted in the case of continuous rice-wheat-cowpea cropping for 28 years without nutrient input (control), suggesting the need for the regular estimation of these macronutrients in soils under intensive cropping. The soil was still able to supply crop needs for Ca and Mg, but the soil became S-deficient (8.9 mg kg-1) when S-free diammonium phosphate (DAP) fertilizer was applied. Its availability increased 5-fold (45.3 mg kg-1) after the application of S-containing single superphosphate (SSP) fertilizer and improved further when this was combined with farmyard manure (FYM) in an INM system. The wheat response to S was 0.36 and 0.45 t ha-1 for the grain and straw yields, respectively. The highest removal of Ca, Mg and S was observed with INM (21.36, 27.52 and 13.38 kg ha-1, respectively) and the lowest in the unfertilized control.