Long term effect of prescription based fertilizer application on soil carbon and potassium dynamics under maize wheat cropping system in an acid Alfisol

Abstract

The present investigation was carried out during rabi, 2014-15 and rabi, 2015-16 to study the effect of prescription based fertilizer application on soil organic carbon and potassium dynamics under maize-wheat cropping system in a long term experiment initiated during kharif, 2007 at the Experimental Farm of the Department of Soil Science CSK HPKV, Palampur. The experiment was laid out in a randomized block design with eight treatments. The soil of experimental field was silty clay loam in texture, pH 5.2, organic carbon 7.2 g kg-1 and available N, P and K status was 236, 41 and 272 kg ha-1, respectively. The soil samples from 0- 0.15 m soil depth were collected before and after harvest of wheat and analysed for some physical, physico-chemical, biological properties, fractions of soil organic carbon and potassium in the soil. Grain and straw samples were collected from each plot and analyzed for total N, P, K and micronutrient contents and uptake. There was an overall improvement in the physical properties of soil under STCR (IPNS) treatments for target 25 and 35 q ha-1. Soil organic carbon, pH, CEC, available N, P, K, enzyme activities and DTPA extractable micronutrients were higher under treatments where inorganic fertilizers along with FYM were applied under targeted yield treatments. The study also revealed that the target yield of 35q ha-1 with FYM resulted in highest wheat grain and straw yield during both the years. However, the highest B:C ratio was recorded in treatment for target yield 35 q ha-1 without FYM followed by soil test based treatment. Higher uptake of N, P, K and micronutrients by wheat were recorded in treatments comprising of target yield 25 and 35 q ha-1 with and without FYM. Continuous application of inorganic fertilizers alone or in conjunction with FYM improved the different fractions of soil organic carbon and potassium significantly. All the passive and active pools of soil organic carbon significantly improved under STCR (IPNS) treatments for target yield 25 and 35 qha-1 in comparisons to unfertilized plots. Among K fractions, non- exchangeable K was found to be the most dominant followed by exchangeable K and water soluble K. Different fractions of soil organic carbon were found to be positively and significantly correlated with yield and soil properties except bulk density, where it was negative. All forms of potassium were positively and significantly correlated with grain and straw yield of wheat, available K and total K uptake by wheat. newline