Biochar production through drum method and characterization for soil amendment qualities

Biochar preparation using portable drum technology is an affordable strategy for efficient use of unused and excess crop residues. The aim of this study was to prepare biochar from pigeonpea and cotton residues at farm level and characterising their soil amendment qualities. The fabricated drum for the preparation of biochar suits the needs of small farmer. The slow pyrolysis (350 to 400 oC temp. range) process yields 24.5 and 22.6% of biochar, correspondingly 16.2 and 18.5% ash content from pigeonpea and cotton residues respectively. The physico-chemical properties of both biochars were compared for assessing soil amendment qualities. The pH of pigeonpea and cotton biochar is 9.86 and 9.82 respectively, which indicates the suitability of both biochar for soil acidity amelioration. Bulk density of pigeonpea and cotton biochar is 0.26 and 0.29 g/cm-3 respectively. the lower BD indicating more pore space, which leads to better soil aeration and more water holding capacity. The carbon recovery of pigeonpea (27.6%) and cotton (29.0%) biochar after thermo-chemical conversion indicates the carbon sequestration potential of both biochar in the background of climate change. Besides, both biochar material contains small concentration of major plant nutrients which improve soil fertility. Therefore, production of biochar under modified drum method suits the small farmer. Besides the properties of both pigeonpea and cotton biochar has greatest soil amendment qualities for soil application.