Abstract:By laboratory experiment under controlled temperature and humidity, the effect of addition of biochar and straw were studied on soil biological and physical properties, such as soil crush resistance and soil aggregate stability. Rice straw-derived biochars were obtained under 400℃ charring and with 4 h duration. Five different amendment combinations were selected, i.e., control (CK), 1% biochar (BC), 1% biochar + NPK (BC+NPK), straw, and straw + NPK. The results showed that the decomposition rate of biochar was very slow, and the mean residence time (MRT) of biochar was about 1 400 years by calculation but only 7 years for straw. The decomposition rate could be accelerated by chemical fertilizer, which was proved after 55 d incubation with 25℃ temperature and 40% field moisture capacity. However, Biochar could not improve soil tensile strength and soil aggregate stability (P>0.05), which indicated that biomass biochar can’t improve microbial activity and the stabilization of soil structure as the other organic matters.