Effects Of Amendments On Soil Organic Carbon Fractions And Microbial In Upland Red Soil

To resolve the problems of low fertility and productivity in upland red soils in Jiangxi Province,a field experiment was conducted to study the effects of soil amendments(biochar and calcium peroxide)on soil labile organic carbon,soil enzymes activities associated with carbon cycling,microbial community structure and agricultural production in upland red soil.The experiment included nine doses of biochar and calcium peroxide: CK(blank control),C0Ca1(The amount of calcium peroxide was 60 kg·hm-2·a-1),C0Ca2(The amount of calcium peroxide was 120 kg·hm-2·a-1),C1Ca0(The amount of biochar was 750 kg·hm-2·a-1),C2Ca0(The amount of biochar was 1500 kg·hm-2·a-1),C1Ca1(The amount of biochar and calcium peroxide were 750 kg·hm-2·a-1 and 60 kg·hm-2·a-1),C1Ca2(The amount of biochar and calcium peroxide were 750 kg·hm-2·a-1 and 120 kg·hm-2·a-1),C2Ca1(The amount of biochar and calcium peroxide were 1500 kg·hm-2·a-1 and 60 kg·hm-2·a-1),C2Ca2(The amount of biochar and calcium peroxide were 1500 kg·hm-2·a-1 and 120 kg·hm-2·a-1).Collection of multipoint mixing soil in experiment area and sampling depth of 0-10 cm,10-20 cm,20-40 cm,40-60 cm.The results show that:(1)Biochar of single application and combined application of biochar and calcium peroxide were beneficial to increase the contents of organic carbon and labile organic carbon fractions in upland red soil,and the effect was better than calcium peroxide of single application.The soil organic carbon under C2Ca0,C2Ca1 and C2Ca2 treatments increased significantly.Biochar and calcium peroxide significantly increased the soil labile organic carbon fractions.The content of microbial biomass carbon average increased by 45.22% in C1Ca0 treatment.The content of dissolved organic carbon average increased by 21.34% in C1Ca2 treatment.The content of particulate organic carbon average incerased by 20.72% in C1Ca0 treatment.The content of labile organic carbon average increased by 22.19% in C2Ca2 treatment.Biochar and calcium peroxide index had a better results to improve carbon management index that average increased by 11.09% and 14.07% in 0-10 cm and 10-20 cm soil layer,respectively.(2)The content of oxyhydrate-bound organic carbon and calcium-bound organic carbon were increased in different degrees in all treatments,which was conductive to soil organic carbon accumulation and stability,and had significant effect in 0-10 cm and 10-20 cm soil layer.The effect of application of biochar was better than calcium peroxide of single application,with the effect of C2Ca0 treatment was better.The content of calcium-bound organic carbon was increased by 41.11%,52.42%,10.17%,7.55% in all treatments in 0-60 cm soil layer,with the effect of conbined application of biochar and calcium peroxide was better than biochar of single application.(3)The enzyme activities were promoted with the addition of the biochar in upland red soil,and the effects of the 0-10 cm soil layer was more obvious than 10-20 cm soil layer.The combined application(C2Ca2)significantly improved amylase activity,cellulase activity and ?-glucosidase activity in upland red soil.The C1Ca1 treatment significantly improved invertase activity in upland red soil.(4)Application of biochar and calcium peroxide could increase soil microbial PLFAs and also improve microbial community structure.Biochar of single application and combined application of biochar and calcium peroxide were better than calcium peroxide of single application.Relative abundances of the soil gram-positive and gram-negative bacteria was larger,advantage for strains,followed by actinomycetes.(5)Application of biochar and calcium peroxide were beneficial to increase agricultural production in upland red soil.The effect of biochar of single application on sweet potato yield was superior to calcium peroxide of single application,in which the effect of combined application was best.In summary,the soil organic carbon fractions and microbial community structure could be improved by applying the amendments,which could increase the soil enzymes activities associated with carbon cycling,and effectively increase the yield and economic benefit of the crop.