Changes in soil fertility status of maize-wheat system due to long-term use of chemical fertilizers and amendments in an alfisol

The present study was undertaken to quantify changes in the status of soil nutrients, their depletion and build-up after continuous long intensive cropping for last 36 years in a permanent manorial trial which has been in progress since 1972 in an alfisol of western Himalayas. The rotation was maize-wheat which included various combinations of N, P, K, Zn and FYM (farmyard manure). Continuous cultivation influenced pH, OC (organic carbon), available N (nitrogen), P (phosphorus) and K (potassium). An increase in the status of organic carbon was observed in 100% NPK + FYM treatments for more than three decades from initial value of 7.9 to 12.0 g/kg. The use of either FYM or lime alongwith 100% NPK sustained crop productivity or improved nutrient status. However, imbalanced use of nutrients i.e. NP or N alone is adversely affecting the fertility of soil by aggravating the problem of soil acidity. Application of S free P fertilizer DAP (diammonium phosphate) drastically reduced the yield of both the crops. Thus, continuous use of balanced fertilizers is necessary for sustaining soil fertility and productivity of crops.