Long term effect of different land use systems on phosphorus adsorption behaviour of an acid Alfisol on hilly slopes of Meghalaya, India.

Phosphorus adsorption behaviour of five land use systems viz. Livestock based land use (FS1), Forestry (FS2), Agriculture (FS3), Agri-horti-silvi-pastoral (FS4) and Natural fallow (FS5) regularly receiving/not receiving fertilizer P and manure was studied after 17 years of their establishment on an acid Alfisol on hilly slopes. The soils of various land use systems varied widely in their P sorption behaviour with variable P built up in different systems. The P sorption was higher in the soils of the natural fallow land use system and progressively decreased with the application of manures/P + manures in livestock, agri-horti-silvipastoral and agriculture land use. Phosphate sorption data fitted well to the classical Langmuir adsorption isotherm equation. Different land use systems had no effect on adsorption maxima (b) while, bonding energy (k), maximum phosphate buffering capacity (MPBC) and standard P requirement (SPR) were highest for natural fallow followed by forestry land use. In contrast, livestock, agri-horti-silvipastoral and agriculture land use recorded lower values of these P adsorption parameters indicating higher P availability in these systems. The P fractionation before and after equilibrium with added P showed a wide variation in the build up of various forms of P in different land use systems. This is which reflected in the variable adsorption of P in these land use systems under study. [ABSTRACT FROM AUTHOR]