Mixing of biochar with organic amendments reduces carbon removal after field exposure under tropical conditions

This study aimed to evaluate the decomposition of three exogenous organic amendments (buffalo manure, its compost and vermicompost), mixed with biochar or not, under tropical climate conditions. Litterbags containing pure substrates or mixtures were exposed to soil under natural rainfall conditions during one year. Most of C and N of exogenous organic matters (EOMs) and biochar were removed rapidly in the first 16 weeks of incubation. After one year, in case of applying alone, only around 30% of C of EOMs and 40% of C of biochar remained. Our data highlighted that in mixture, the presence of biochar led to about 40% higher amounts of C remaining, most probably related to aggregate formation preventing physical disintegration and/or leaching losses. Consequently, this study demonstrated the interest of mixing organic substrates with biochar for preventing C removal from soil immediately after field exposure. (C) 2016 Published by Elsevier B.V.