Long term effect of chemical fertilizers and amendments on chemical pools of nitrogen in maize-wheat cropping system in an acid Alfisol

Abstract

The present investigation was carried out in the ongoing long term fertilizer experiment at Department of soil science, CSKHPKV Palampur. The influence of thirty six years of cropping with different chemical fertilizers and amendments on the contents and total N, inorganic N and organic N fractions at 0-0.15 m and 0.15-0.30 m depths was investigated in an Acid Alfisol. Continuous combined use of chemical fertilizers and FYM and manual weeding in 100% NPK treated plots resulted in significant increase in the soil organic carbon content compared to rest of the treatments. However, higher organic carbon content was recorded under surface soils. Continuous application of chemical fertilizers either alone or in combination with FYM or lime influenced different organic and inorganic nitrogen fractions significantly except non hydrolysable-N at both the depths. Hydrolysable ammonical-N was found to be the most dominant organic nitrogen fraction. Different organic and inorganic –N fractions at surface and subsurface soils were significantly and positively correlated with available N.