Leaching of Sulphate From Biochar and Phosphogypsum-Biochar for the Treatment of Acidic Red Soil

Abstract

Recycling of solid waste resources for agricultural applications is one of the best strategies to tackle environmental and agricultural problems. Biochar is a solid carbon-rich material (mainly alkaline pH) produced through thermal heating in the absence of oxygen from waste biomass. On the other hand, phosphogypsum is an acidic sulphur-rich (calcium sulphate dihydrate) waste generated from phosphoric acid plant. It is generally applied in the alkaline or sodic agricultural soil as calcium sulphur fertiliser. The major limitation of phosphogypsum is that it cannot be used for acidic soil due to its acidic pH. To target this challenge, the application of biochar-phosphogypsum composite (BPC) material produced through co-pyrolysis of banana peduncle biomass and phosphogypsum at 700°C was studied for acidic red soil. The short-term (41 days) leaching experiments were conducted for evaluating the sulphate leaching from the BPC treated acidic red soil. The results showed an increase in sulphate leachability from the BPG with time, which indicates its potential to replenish sulphur in acidic red soils.