Differential Response of Biochar Derived from Rice-Residue Waste on Phosphorus Availability in Soils with Dissimilar Ph

Although use of biochar as an amendment for soil C accretion has received immense prominence, its role on alleviating crop P demand remains largely contentious. Therefore, an incubation study for 60 days was conducted to examine the impact of biochar derived from rice-residue waste and Inorganic-P on phosphorous availability in soils with dissimilar pH (acid, neutral and alkali soil). The experimental soils were treated with 0, 20 g kg −1 (w/w) rice-residue biochar with three rates of Inorganic-P (KH 2 PO 4 ) (0, 25, 50 mg kg −1 ). Application of rice-residue biochar alone or in combination with Inorganic-P in the experimental soils resulted in significant increase in P pools possibly due to greater available P content in biochar itself; biochar impelled decrease in soil P sorption capacity and or; biochar-facilitated release of soil organic matter bound P. Among the Inorganic-P fractions, content of Fe-P and Al-P was greater in acid soil, whereas Ca-P content was higher in neutral or alkali soils, irrespective of biochar and Inorganic-P treatments. Furthermore, ability of rice-residue biochar to decrease phospho-monoesterase activity in the experimental soils was indicative of its significance to act as a long-term source of phosphorous in soil. Therefore, amendment of soil with biochar can be used as an important strategy for sustainable management of surplus rice-residue and fulfilling phosphorous demand in differential pH soils of Indo-Gangetic plains.