Effect of rice residue biochar on bioavailability of cadmium to indian mustard under combined lead and cadmium spiking in a loamy sand soil

Abstract

A screen house experiment was conducted to study the effect of rice residue biochar (0, 0.5, 1 and 2% w/w) on the bioavailability and accumulation of Cd by Indian mustard (Brassica juncea) in a loamy sand soil spiked with three levels each of Cd (0, 10 & 25 mg Kg−1 soil) and Pb (0, 25 & 50 mg Kg−1 soil) in all possible combinations. Immobilization of Cd by rice residue biochar was assessed by DTPA-extractable Cd in soil and Cd concentrations in shoots of Indian mustard. Mean DTPA-Cd after harvest of crop decreased with increasing rates of applied rice residue biochar. Addition of biochar at its highest level of 2% decreased the mean DTPA-Cd in soil and its concentrations in plant by 59% and 36% over control, respectively. Biochar addition increased dry matter yield (DMY) of Indian mustard and a maximum increase of 18% over control was observed at a level of 1%. However, DMY decreased by 19% with addition of biochar at 2%. It was concluded that rice residue biochar can be used as an amendment for amelioration of Cd contaminated sites as its concentration in plants decreased with increasing levels of biochar application.