Effect Of Biochar Application On Soil Aggregates Distribution And Organic Carbon Fractions

Biochar(BC) refers to the highly aromatic substance remaining after pyrolysis of biomass under complete or partial exclusion of oxygen.Its application to soil has been considered to be one of the important practices in improving soil properties and increasing carbon sequestration.However, tructural properties of biochar vary from the different Feedstock, Production temperature and the Production conditions.Therefore, the Biochar was produced from wheat straw under four different temperature of 300,400,500 and 600℃. All kinds of characteristic indexes included surface functional groups,elemental analysis and heat stability of the different Biochars are detected and analyzed by using Elemental analyzer,Fourier Transform Infrared Spectroscopy(FTIR) and Thermogravimetric analyzer.For the sake of finding the best preparation temperature of the required biochars and analyze the relationship between the preparation temperature and the surface properties of the biochars.At the same time,Applying biochar produced from different temperature into soil to execute Incubation test.In order to investigate the effects of the biochar application on soil aggregates distribution and its organic matter content. In addition,the biochar produced by apple tree twigs was applicated with three rates(10, 20, 30 t·hm-2) into orchard soil to investigate the effects of the biochar application on soil aggregates distribution and its organic matter content.Various particle-size fractions of soil aggregates were obtained with the dry-screening method and wet-screening method,and then analysis the content of different aggregate size.Meanwhile,the contentof soil organic carbon(TOC),microbial biomass carbon(MBC),dissolved organic carbon(DOC) and readily oxidized organic carbon(ROOC)were measured.Correlations of contents of total organic carbon(TOC) and dissolved organic carbon(DOC), microbial biomass carbon(MBC) and readily oxidized organic carbon(ROOC)were also analyzed. and It aimed at providing certain scientific basis for comprehensive understanding of soil eco-environmental effect of biochar on promoting semiarid farmland soil qualities and agricultural.The main results are as follows:1)The increasing temperature(from 300 to 600℃) increased biochar C content(50.27-65.68%) and heat stability,while decreased the content of O, H and N,acidic functional groups.With the temperature increasing,The alkaline functional groups first increased andthen decreased,and the most is in applying 500℃produced biochar(0.39 mmol?g-1).2)The execute Incubation test showed that applying biochar produced from different temperature to lou soil increased the content of >0.25 mm soil aggregates,while decreased the content of <0.25 mm soil aggregates.At the same,its increased MWD and decreased PAD 、ELT.The increasing test time increased >2mm soil aggregates.Among different temperature produced biochar,the content of >2mm large aggregates were the most in applying500℃produced biochar,and the 300℃produced biochar were the least.3)A 1-year orchard experiment showed that applying biochar produced by apple tree twigs decreased the content of 5-8mm、<0.25 mm loessial soil aggregates,while increased the content of 1-2mm 、 2-5mm soil aggregates.Among them,the content of 1-2mm aggregates increased sharpest and it With the amount of biochar increased significantly.biochar application significantly increased soil organic carbon content in aggregates, especially in 1-2mm aggregates which increased by >70% compared to CK.4)Applying biochar significantly increased the content of soil organic carbon and its activated carbon component( microbial biomass carbon,dissolved organic carbon,readily oxidized organic carbon) content. With the biochar application rate the SOC,MBC,DOC and ROOC increased significantly.Among different temperature produced biochar,the The increase of SOC was the most in applying 500℃produced biochar and it reached184.29%.The contents of DOC, MBC and ROOC increased with biochar produced from different temperature are expressed as 300 ℃>400 ℃>500 ℃>600 ℃. The relationship of SOC,MBC,DOC and ROOC were significantly or very significantly.