Soil Physico-chemical Properties as affected by Long-term Application of Organics and Inorganic NPK Fertilisers under Rice-wheat Cropping System in Calcareous Soil of Bihar

A balanced application of organics and inorganic fertilisers could be beneficial to both soil nutrient availability, soil health and crop growth. The experiment was conducted on light textured highly calcareous soil at Research Farm of Dr. Rajendra Prasad Central Agricultural University, Pusa. Four levels of inorganic fertiliser treatments were applied i.e. 50, 100 and 150% of NPK along with no NPK as control as main plot treatments while four levels of organic treatment (i.e. no organics, compost, crop residue and compost+ crop residue) were applied as sub plot treatments in a split plot design with a total sixteen (16) treatments with three replications to investigate the long term effect of application of various doses of recommended fertiliser along with organic amendments on various physico-chemical properties of calcareous soils after 32nd crop cycle . Data was collected on various physico-chemical properties i.e. Soil pH, electrical conductivity (dSm-1), soil organic carbon (g kg-1), free CaCO3 (%), cation exchange capacity [cmol (p+) kg -1], bulk Density (Mg m-3) and water holding capacity (w/w %). The result revealed that soil pH was reduced by 3.9% while electrical conductivity (EC) was reduced by 45% over initial (1988). Both soil pH and EC were reduced by 1.7% and 15.4% respectively in plots receiving combined application of compost and crop residue along with 150% NPK over control. Organic carbon was improves by 33% over initial (1988) which had direct effect on reduction in soil bulk density (32%) and improved water holding capacity (29%) over the control in plots receiving 150% NPK along with combined application of compost and crop residue. Soil cation exchange capacity and free CaCO3 also showed an alternate trend former being enhanced and later being reduced after 32nd crop cycle in rice-wheat cropping system. Application of different levels of NPK along with different organics improved the overall soil physico-chemical properties which further have direct relation with enhanced crop growth and productivity.