Green manure from pruned biomass affect phosphorus adsorption in soil and its uptake by wheat in Albizia procera based agroforestry system

Abstract

To assess the effect of adding pruned green biomass of Albizia procera Benth. on phosphorus sorption capacity of the soil and uptake of P by trees and wheat intercrop, a study was conducted in a well established 8 years old A. pro cera based agroforestry trial consisting of five treatments viz. control (pure crop), pure tree (without inter cropping), zero pruning+ inter cropping, 50% pruning + inter cropping and 70% pruning + inter cropping. The findings revealed that application of Albizia pruning as green manure significantly reduced P sorption capacity of the soil. Langmuir adsorption maxima and binding energy, and Freundlich P adsorption constants were significantly reduced with application of Albizia pruning. The amount of phosphorus adsorbed by soil at 0.2 mg P/L in solution (standard phosphorus requirement) significantly decreased with addition of increased pruning biomass into soil from zero to 70% pruning treatments. The results also revealed that addition of pruned biomass increased available P in soil. Application of pruned biomass as green manure in 50% pruning + inter cropping and 70% pruning + inter cropping treatments significantly improved the grain yield and P uptake of wheat over zero pruning + inter cropping treatment. However, maximum wheat yield and P uptake in control (pure crop) reflected overriding effect of optimal growth condition in pure crop plot on addition of pruned biomass in pruning treatments. Added pruning had significant effect on P accumulation in 8 years old trees as well as treecomponents. Irrespective of tree-components, on an average, maximum P was accumulated in zero pruning while minimum in 70% pruning. Among the tree components, on an average, maximum P was accumulated in roots followed by branches. The study concludes that addition of Albizia pruning increases P availability through reduced P sorption capacity of soil and recycling of P.