Soil Degradation due to Potassium Mining under Intensive Cropping in Uttaranchal Hills

摘要

An investigation was undertaken in the Long Term Fertilizer Experiment (LTFE) located on an inceptisol in VPKAS Farm at Hawalbagh, Almora district of Uttaranchal Hills, with a specific objective of monitoring the changes in total soil K reserve and K availability under continuously followed varying nutrient input systems in 25 crop cycles of an intensive soybean-wheat rainfed cropping system. Potassic fertilizer application for most of the rainfed crops are practically nil because of higher total potassium soil K reserve due to dominance of micacious soil minerals. Though the soils of this long-term experiment are high in total K (4500 mg kg~(-1)) but low in NH_4 OAC-K (53.3 mg kg~(-1)) and responds irregularly since monsoon controls the release of potassium from soil minerals. The depletion of K was found in treatments receiving no K fertilization and even with the optimum K fertilization dose which needs verification after 25 years of cropping. The N+FYM treatment which is called farmers treatment in the region, showed mining of soil K reserve. Possible reasons are discussed in this paper.