Effect of Different Farming Systems on Phosphorus Fractions in an Acid Alfisol of Meghalaya

The effect of eight watershed-based fanning systems consisting of livestock farming (FSW₁), forestry (FSW₂), agroforestry (FSW₃), agriculture (FSW₄), agri-horti-silvi-pastoral (FSW₅), horticulture (FSW₆), natural fallow (FSW₇) and abandoned jhum land (FSW₈) on different forms of P was studied after 17 years of adoption under rainfed condition on hill slopes of Meghalaya. All the forms of P except organic P were significantly highest in FSW₄ followed by FSW₁ and FSW₅ and the lowest values of inorganic P were recorded in FSW₈ followed by FSW₇. The FSW₈ registered the highest value of organic P, which was 60.7% of total P while the contribution of organic P to total P was lowest (32.7%) in FSW₄ suggesting higher P mineralization in this system. Among the inorganic fractions of P, the highest value was recorded for reductant soluble P, followed by AI-P, Fe-P, occluded-P, Ca-P and saloid bound P, respectively, in all the systems except FSW₇ and FSW₈. There was a continuous increase in all the P fractions from top to bottom of the watersheds under different farming systems. The FSW₁, FSW₄, FSW₅ and FSW₆ with terraces in the bottom retained relatively higher magnitude of all the forms of P. Soil pH, ECEC and base saturation showed significant positive correlation with all the forms of P.