The effect of brewery sludge biochar on immobilization of bio-available cadmium and growth of Brassica carinata

Biochar has gained an attention in reducing the bio-availability of toxic heavy metals and minimize threat of entering into food chain from contaminated soil. This study was aimed at evaluating the potential use of brewery sludge biochar (BSB) as a soil amendment for reducing cadmium bio-availability and uptake by Brassica carinata in a pot experiment. In this pot experiment, artificially cadmium spiked, moderately fertile, and slightly basic silty-loam soil was used. The biochar was produced by pyrolyzing of the brewery sludge at 500 °C. The obtained biochar was sieved with 0.5 mm mesh size and applied at the rate of 4 % (w/w) on the Brassica carinata grown cadmium spiked soil. The additions of BSB to the soil contributed a significant reduction of the bio-availability of cadmium in the soil and its accumulation in the shoot of Brassica carinata by 86% and 93%, respectively. Besides, it remarkably increased the dry weight of the edible part of Brassica carinata by 228%. The results revealed that BSB is very effective additive in cadmium immobilization, in turn, significantly (p-value = 0.00) promoting vegetable (Brassica carinata) growth. Therefore, BSB can be used as agricultural soil remedy for cadmium contamination and as safe disposal of brewery sludge.