Effect of Organic Sources on Phosphorus Fractions and Available Phosphorus in Typic Haplustept

Abstract

Phosphorus (P), as an essential plant nutrient for crop production, acts as energy currency in plant, cell elongation, respiration, promotes root growth, early plant maturity and stalk strength, and imparts resistance to stress conditions. Apart from its importance in crop production, it is also a costly input across the globe. The use efficiency of P rarely exceeds 20 per cent because of P-fixation often due to iron (Fe) and aluminium (Al) in acid soils and calcium (Ca) in alkaline soils. Use of organic materials such as crop residues and by-product of sugarcane industries have a positive response on labile P in soil. Decomposition of organic materials produces different organic acids, which help in mobilizing non-labile P in soil into labile P. Phosphorus uptake is enhanced by the addition of organics due to production of organic acids like citric, lactic, gluconic and oxalic, which in turn, transform P from non-utilizable form to plant utilizable form (Ivanova et al. 2006). Thus, incorporation of organic materials improves soil health and crop yield (Dotaniya 2012). The exudation of low molecular weight carboxylates is an important P acquisition strategy by plants, particularly in strongly P-fixing soils. The enhancing properties of P availability of citric acid are not only due to acidification of the plant rhizosphere, but also for its Al and Fe complexing capacity (Drouillon and Merckx 2003). The objective of the present study was to investigate the effect of organic residues on P fractions mainly Al–P, Ca–P, and available P in soil during a one year incubation period.