Effects Of Organic Material Application On Soil Organic Carbon Fraction And Fertility Characteristic Of Farmland

Organic materials amendment in different forms to agricultural soil is one of the main ways to increase soil organic carbon content and soil fertility.With the current situation of farmland fertilizer and agricultural waste utilization in the pearl river delta region,a pot study was carried out by adding different content of crop straw(rice straw(DC)and banana stalk(JG)),livestock and poultry excrement(pig manure(ZF)and chicken manure(JF))and crop straw biochar(straw stalk biochar(BDC),banana stalk biochar(BJG)and tobacco stalk biochar(BYG))to investigate the impact of different organic materials amendment component contents of soil organic carbon of farmland in the pearl river delta region,and thus to quaulify the effects of adding different kinds and contents of the organic Materials on the farmland soil structure,fertility conditions in the pearl river delta region.The main results are as follows:(1)Soil organic carbon(SOC)increased markedly as affected by adding different kinds of organic Materials(p?0.05),and incresment was positive correlation with the organic materials amendment rates.The content of soil humic acid(HA)increased significantly with the amendments of DC,JG and ZF,while the content of soil humic acid(HE)showed opposite effects and the content of Humin(Hu)showed positive effects with the application of biochar.The different amendment rates of poultry and animal feces and crop straw can all increase the content of soil labile organic carbon(LOC)and its allocation proportion,and the incresments was significant in the treatment applied by DC,JG and ZF with the amendment rate of 2.0%.Compared with the control treatment,the content of LOC increased by 101%,114% and 102%,respectively,but the effects of biochar was not significant.the application of biochar to the contents of soil particulate organic carbon(POC)and light fraction organic carbon(LFOC)have pronounced ascending effect,and the contents of coarse particle organic carbon(CPOC)and fine particle organic carbon(FPOC)increased respectively by 718%,773%,1239% and 397%,415%,197% in the treatment applied BDC,BJG and BYG with the adding amount of 2.0% as compared with control treatment,and increased the soil light fraction organic carbion(LFOC)by 373%,446% and 459%,respectively.(2)The distribution of mechanical stability of soil aggregate is dominated with diameter?5mm,2 ~ 5mm,which accounted for 34.7~58.8% and 17.3~22.9% of total aggregates,respectively.Compared with control treatment,the increase of?0.25 mm aggregate in the treatment of applying DC,JG and JF with the amendment of 2.0% increased by 4.6%,5.2% and 5.9%,respectively;The distribution of water stability of soil aggregate is dominated with diameter?0.25 mm,which accounted for 32.7 ~ 50.1% of the total aggregates.Compared with control treatment,the largest increase of?0.25 mm aggregate of water stability in the treatment of applying DC and JG with the amendment rate of 2.0% increased by 11.4% and 10.2%,respectively.Meanwhile,the treatments of adding DC and JG on the mechanical stability and water stability of soil aggregate mean weight diameter(MWD)and geometric mean diameter(GMD)promotion effect is more apparent than the treatments of applying ZF and JF.but the effects of biochar was not significant.in the crop straw applied treatment,SOC and POC were significantly positively with MWD and GMD,while negatively correlated with PAD and D of soil aggregates(p?0.05).(3)The aboveground vegetable organic Materials of the first crop was significant positive correlatied with the SOC and its various components(p?0.05),while SOC and its various components have great influence on indicators such as soil bulk density,porosity,pH,alkali-hydrolyzale nitrogen,available kalium and available phosphorus,and FPOC,Hu,SOC,LFOC have more influences on the targets of the above.CPOC,LFOC and FPOC have the most sensitive reaction on the soils changes caused by human disturbance and management measures such as fertilization,and the sensitivity index was 1.45,1.08 and 0.89,respectively,which were 3.7,2.7,2.3 times of the SOC.Compared with control treatment,the carbon pool management index(CPMI)was significantly promoted in the treaments applied with DC,JG and ZF by 128%,140% and 129%,respectively,and whereas the improvement in the treaments of adding biochar was not significant.Overall,the effect organic materials made from different feedstocks on soil fertility was different due to the nature diversity of different organic materials.Thus,in the short term,crop straws have more advantages than livestock and poultry manure and crop stalk biochar for soil fertilization by stimulating the activity of soil,and improve soil quality by the management measure of adding the organic materials.