Effects Of Amendments On The Distribution Of Soil Aggregates And Organic Carbon Component And Content In Reclaimed Soil

In this study,the soil reclaimed for 7 years in Wuyang Coal Mining Area of Xiangyuan County,Shanxi Province was taken as the research object.A series of micro field experiments and indoor culture experiments were set to study the effects of different proportion of peat and humic acid on soil bulk density,distribution and stability of soil mechanical stability and water stable aggregates,the organic carbon composition and content of soil and mechanical stability and water stable aggregates,soil organic carbon functional groups.This study revealed the variation characteristics of soil structure and organic carbon after applying peat and humic acid and discussed the mechanism of peat and humic acid affecting soil structure and organic carbon.The purpose of this study is to provide theoretical basis for improving soil structure,increasing soil organic carbon and applying amendments rationally.The main results of this study are as follows:(1)Peat and humic acid can reduce the bulk density and increase soil porosity of reclaimed soil.At 6 months,the soil bulk density of 3% peat treatment was the lowest,which was 1.10 g / cm3,29.03% lower than that of CK.(2)The proportion of mechanically stable and water stable macroaggregate(> 0.25 mm)in reclaimed soil increased at applying peat and humic acid for 6 months.In the field experiment,the increment of >2 mm mechanical stable and water stable aggregates with 5%humic acid treatment was the largest,which were 23.06% and 224.27% respectively.In the laboratory test,the increment of 2~0.25 mm mechanical stable and water stable aggregates with 5% peat treatment was the largest,which were 84.06% and 31.38% respectively.However,the proportion of mechanically stable and water stable macroaggregates decreased and the proportion of microaggregates(< 0.25 mm)increase at applying peat and humic acid for 1 year.In the field experiment,the increment of 0.25~0.053 mm mechanical stable and<0.053 mm water stable aggregates with 5% humic acid treatment was the largest,which were 100.74% and 25.74% respectively.In the laboratory test,the increment of 2~0.25 mm mechanical stable and 0.25~0.053 mm water stable aggregates with 5% peat treatment was the largest,which were 43.80% and 122.55% respectively.(3)Peat and humic acid could increase the total organic carbon content,the organic carbon of mechanically stable and water stable aggregates of reclaimed soil,and the total organic carbon content increased with the increase of peat and humic acid application.The organic carbon content of >2 mm,2~0.25 mm,0.25~0.053 mm,<0.053 mm mechanically stable and water stable aggregates decreased at applying peat and humic acid for 1 year compared with 6 months.(4)In test base,POC and MOC of soil were mainly concentrated in 2~0.25 mm water stable aggregates.Peat and humic acid can increase the contents of POC and MOC of reclaimed soil and >2 mm,2 ~ 0.25 mm,0.25 ~ 0.053 mm,<0.053 mm water stable aggregates,but they can decrease the distribution ratio of MOC.The distribution ratio of MOC in peat treatment was higher than that in humic acid treatment.In the field experiment and the laboratory test,3% peat treatment and 3% humic acid treatment had the highest distribution ratio of MOC allocation at 6 months,which were 77.71% and 65.80%respectively.(5)Peat and humic acid can increase the contents of carbohydrates,polysaccharides,oxygen-containing functional groups,silicate minerals and functional groups in the reclaimed soil.The higher the proportion of peat and humic acid,the greater the increment of functional groups in these four substances.In summary,peat and humic acid can reduce soil bulk density,increase the proportion and the organic carbon content of mechanical stable macroaggregate and water stable macroaggregate,the content of carbohydrates,polysaccharides,oxygen-containing functional groups,silicate minerals and functional groups in substituted aromatic substances.That mean peat and humic acid can improve the soil structure and increase organic carbon,and the effect of humic acid is better than peat.However,the effect of peat and humic acid decreased at applying amendments for 1 year compared with 6 months,so peat and humic acid should be added to the soil in time.