LAUSR

ABSTRACT Information on phosphorus (P) dynamics in soil is crucial for careful management of phosphorus fertilization in respect to the sustainable development of agriculture in IGP regions. The sorption and desorption of phosphate, different fractions of phosphate, dehydrogenase activity, acid and alkaline phosphatase activity were studied in soils under organic inorganic and integrated nutrient management practices in four different cropping systems. The P adsorption maxima of long-term organic soil was highest (77.52 µg P g−1) under coarse rice-barley-green gram cropping system. The bonding energy of phosphorus in the soil solution varies from 0.38 to 0.20 ml µ−1. Average across the cropping systems, the bonding energy of adsorb P were 68.54% and 39.05% higher under organic and integrated nutrient-managed plots respectively as compared to the inorganic nutrient management. Maximum buffering capacity of phosphate was observed (29.59 ml g−1 soil) under Coarse rice-barley-green gram cropping systems in organic nutrient management practice. Application of organic nutrient management practice increases 26.04% higher water-soluble phosphorus (WSP) as compared to the inorganic nutrient management practice, average across the cropping systems. All other fractions of phosphorus in the soil were higher under inorganic nutrient management that leads to higher amount of total of phosphorus, average across the cropping systems. Long-term application of organic for 14 years increases the bonding energy and adsorption capacity for P in soil but decreased its desorption potential, increasing P availability to the plant and leading to higher P uptake irrespective of cropping systems.