Abstract:In this study, biochar was made at 500 ℃ from tea residues produced during tea production process and used in a 112 d incubation experiment to study its impacts on the distributions, stabilities and organic carbon contents of soil aggregates in three typical tea garden soils (purple soil, paddy soil and yellow soil) of Ya'an, Sichuan Province. In total fifteen treatments were designed with five applying rates of biochar (0, 0.5%, 1%, 2% and 4%). Soil aggregate size distribution and their organic carbon contents were determined. The results showed >0.25 mm aggregates were increased in the three soils with the increase of biochar applied. >2 mm aggregates increased most in purple soil (increased by 12.71%), 0.25-2 mm aggregates were increased most in paddy soil and yellow soil (increased by 8.25% and 8.19%, respectively). Biochar increased mean weight diameters (MWD), geometric mean diameter (GMD) and macro-aggregate content (R0.25) significantly, indicating biochar can improve the stability of soil water-stable aggregates, and the effect is intensified with increasing biochar input. Biochar increased organic carbon contents in all size aggregates in the three soils significantly, and the effect is intensified with increasing biochar input. The differences were significant (P<0.05) between different treatments. Organic carbon content increased most in <0.053 mm aggregates in purple soil (increased by 96.35%), in 0.053-0.25 mm aggregates in paddy soil (increased by 74.22%), and in >2 mm aggregates in yellow soil (increased by 334.79%). The relative contribution rate of SOC was the highest in 0.25-2 mm aggregates in the three soils. In general, biochar of tea residues can increase large soil aggregates in tea gardens, improve the stability of soil aggregates, and significantly promote organic carbon contents in all size soil aggregates.