Abstract:The synergistic effects of biochar properties on soil properties and biota have received much less attention than their effects on soil chemical properties. To investigate how biochar properties and addition amount affecting physicochemical properties and the quantity and activity of microbial in acid red soils, acid red soils (pH value 5.40) were incubated for 50 days by adding different rates (1%~10%) of ashrich rice husk biochar (RHC) and ashlow Camellia oleifera shell biochar (COSC) pyrolyzed at 500℃. The results showed that compared with COSC (3.80% ash content, 0.22 O/C), RHC remained higher ash content (30.69%), greater O/C molar ratio (0.63) and more oxygen functional groups (C-P-O). With the addition of RHC and COSC, soil moisture contents were increased to 17.47%~28.28%, also the pH value was improved to 7.05~7.75. Additionally, 10%RHC treatment significantly increased (p<0.05) soil moisture content and the pH value by 81.98% and 43.52%, respectively. The nutrient elements of acid red soil was increased with the increase of RHC content, and with the addition of 10% RHC treatment, alkali hydrolyzed N, available P and available K in soil were increased by 84.83%, 70.47% and 595.57%, respectively. The 5% and 10% addition of COSC both had a negative correlation effect on the alkali hydrolyzed N content, which was decreased by 14.65%~29.27%, respectively. RHC and COSC both had a positive effect on the quantity of soil microbial communities, and the abundance of microbial was grown first and then dropped with the increase of amount of biochar. 5%RHC had a significant influence on the quantity of bacteria and actinomycetes, which were increased by 1040.05% and 713.59%, respectively. However, 5%COSC had a significant effect on the quantity of soil fungi, as increased by 1 265.00%. RHC and COSC treatment both had a positive influence on soil microbial biomass carbon (MBC) content and microbial activity, which were increased first and then decreased with the increment of biochar addition. Compared with the CK, 5%COSC treatment had significantly increased 11 times of MBC content, and 5%RHC treatment significantly increased the microbial activity by 60.50%. Therefore, adding ash rich rice husk biochar to amend the red soil may improve the physiochemical properties of soil and increase the quantity and activity of microbial community. The results would provide scientific basis for improving acid soil with ashrich biochar.
