The Cementing Mechanism Of Small Molecular Organic Matter On Agglomerates In Artificial Soil

Soil is not only the material base and valuable source of wealth,but also the earliest production data.Soil science after decades of development,the scientific research workers is generally believed that: soil structure can control soil water,fertilizer,gas and heat to keep and migration,it plays an important role in soil erosion,restoration,sustainable utilization and global carbon sink effect;the aggregate is the basic unit of soil structure,such as the cell of the organism,its structure and spatial distribution determine the soil physical and chemical properties,which is an important index of soil quality.Therefore,a bridge between the macroscopic field scale and the microscopic molecular scale of soil aggregates is the best research object for the study of soil.On the basis of artificial soil incubation experiment,this study from the perspective of microstructure,by monitoring the processing of organic matter during different periods of change,based on different periods the aggregate content of water stability change,explore cementation of small molecule organic matter in aggregate form.Expected to drive for the study of cementing material of soil aggregate formation and stability mechanism to provide certain theoretical basis,at the same time,also for improving soil fertility,improve soil structure,guarantee sustainable utilization of land resources to provide scientific guidance.(1)Comparing the artificial soil treatment(AS)and single clay minerals treatment,soil iron,aluminum oxide have stronger fixed and protection of organic matter,and is very important for the formation of soil aggregate contribution.It is speculated that the iron and aluminum oxide in natural soil may have strong fixation and protective effect on organic matter,and may have a very important contribution to the formation of soil aggregates.(2)Compared with other treatments,incubation six months,organic carbon content of montmorillonite group(MT)as the growth of the incubation time reduce is the smallest,can infer that in natural soil expansiveness clay mineral montmorillonite content is higher,the higher the soil fertility may.(3)MT treatment incubation the first month is the rapid propagation of microorganisms,which is a large amount of organic matter is decomposed and a large number of small molecular organic matter are produced.After 1 months MT treatment reached a microbial decomposition using organic matter balance,the balance is probably because microbial decomposition of organic matter and produce a large number of small molecule organic matter,these small molecule organic matter and montmorillonite form micro aggregate/organic-inorganic compound has a good protective effect on organic matter.(4)It is concluded that the content of montmorillonite in natural soil is high,which can promote microbial decomposition and utilization of organic matter,fast-driven the molecular weight of organic matter concentrated in the range of 4300-210Da;it is speculated that in the natural soil montmorillonite combines with organic matter forms micro aggregates/organic-inorganic complex that can produce a fixed and protective effect on organic matter and can improve soil fertility.(5)Combine 2,3 and 4 conclusions,explain why average the content of soil organic matter in northern China is higher than that of southern soil organic matter(such as northern black soil and southern red soil),due to climate factors,the soil in the north is weak in weathering and leaching,montmorillonite content in the soil is higher,the southern red soil by weathering and eluviation is stronger,almost does not contain montmorillonite in the soil,so the montmorillonite is probably caused by main control factors of our country’s large gap between north and south of fertility.(6)The experiment phenomena and data are proved that Six put forward the concept of "large aggregate turnover" model this conjecture: the reactions between minerals,organic matter and microorganisms form micro aggregates and organic-mineral complexes,small molecule organic compounds can promote the formation of micro aggregates and also stabilize micro aggregates;however,there is a need for root and fungal mycelium to form large aggregates between large distances or separated particles.