Abstract:Taking the aeolian sandy soil in eastern Helan road of Ningxia as the study object, the changes of soil organic carbon (SOC) and active carbon components under the addition of straw and biochar were analyzed in order to provide scientific theoretical basis for determining the best fertilization measures in this area. The results showed that biochar and straw significantly increased the content and storage of SOC, and compared with the control, SOC content increased by 7.7% and 7.5%, respectively. The addition of biochar was beneficial to the accumulation of soil easily oxidized organic carbon and particulate organic carbon, which were increased by 49.6% and 17.5%, respectively. While straw addition was more conducive to the accumulation of soil microbial biomass carbon and soluble organic carbon, which were increased by 25.8% and 59.9%, respectively. The addition of straw and biochar significantly increased soil available nitrogen, bulk density and clay content, significantly reduced the contents of soil total salt and sand particles, and the increase effect of biochar was more obvious than straw. SOC, soluble organic carbon, particulate organic carbon and easily-oxidized organic carbon were significantly positively correlated with available nitrogen content, and negatively correlated with total salt and sand content. Soil soluble organic carbon, particulate organic carbon and easily-oxidized organic carbon were significantly positively correlated with bulk density. However, there was no significant correlation between soil microbial biomass carbon with physiochemical properties. In conclusion, adding biochar to aeolian sandy soil is more conducive to the improvement of soil active carbon pool and physiochemical properties, and the appropriate annual addition amount is more than 7 t/hm2.