Different Effect And Mechanism Of Various Organic Materials On Soil Organo-mineral Complexes

Soil organo-mineral complex is one of the fundamental characteristic that distinguishes soils from their geological parent materials. Soil organic-mineral is susceptible to external factors due to organic matter. Organic material has the most prominent effect. At the same time, some studies have shown that organic materials produce beneficial effects on the chemical, biochemical and physical quality of soil and its plant nutrition capacity. So, recycling organic materials as soil organic amendment is important for both environmental safety and sustainable agriculture. However, there are many different kinds of organic materials that produced different kind and amount of low molecular weight(LMW) organic compounds in the progress of decomposition. So, it will inevitably lead to different effect on soil properties after application. At present, little research that simultaneously compares different effect of various organic materials on soil organic-mineral complex properties has been done. In addition, investigation on interaction between different LMW organic compounds and mineral research is less. In addition, some evidence shows an alternative understanding of the conformational nature of HS, which should be regarded as supramolecular associations of self-assembling heterogeneous and relatively small molecules deriving from the degradation and decomposition of dead biological material. To deal with those questions, the pot experiment was conducted to study the effect of different organic materials(herb residues, animal remnant, animal excrement, woody residues.) on the composition and properties of organic-mineral complex. In addition, batch adsorption experiment was carried out to investigate three common LMW organic compounds(glucose, phenylalanine, citric acid) interacted with montmorillonite and silica glass imitating soil clay mineral and large soil particle, respectively. The conclusions as follows: 1) Compared with control treatment(CK), animal excrement significantly decreased SSA by 7.33%, and animal remnant, woody residues and herb residues increased SSA by 59.58%, 57.46% and 100.18%, respectively. When pH<6, Qv-pH curves of all treatments were similar. When pH >6, Qv-pH curve of animal excrement was similar to woody residues and Qv contents of them were higher. CK and animal remnant’s Qv-pH curve was similar and their Qv contents were lower. At pH8-10, Animal remnant and animal excrement’s Qvr-pH curve was similar and their Qvr content were higher. Qvr-pH curve of CK was similar to herb residues and Qvr contents of them were lower. Effect of different organic materials on CEC of black soil was also different. 2) Application of herb residues increased content of loosely combined soil humus substances, and it was significantly higher than CK in the first year. Animal excrement increased the content of loosely combined markedly after five years. The content of unitedly combine humus of organic materials was notable lower than CK in the first year, but was significant higher than CK three year later. There was no difference in the content of the stably combined, but the composition was different. Compared to CK, the content of tightly was increased visible after application of organic materials a year later. Herb residues dramatically enhanced the ratio of loosely and tightly. On the contrary, woody residues and animal excrement was observably lower than CK in the first year. There was no obvious difference with increaseing time. 3) Stability of aliphatic structure of HA in soil applied with herb residues was the strongest, and that of animal remnant was the lowest. In addition, herb residues increased aliphatic structure of FA. Application of organic materials enhanced condensation degree of HMc and increased aliphatic compounds of HMc and plant residues had the most obvious role. Organic materials decreased content of hydroxyl and saccharide of HMi, but increased aliphatic compounds. In addition, application of organic materials resulted in significant decrease of carbon(C) and hydrogen(H) of HA, and the role of herb residues was the most obvious. Animal remnant decreased oxygen(O) of HA. At the same time, it increased N of FA. Application of organic materials resulted in a significant decrease of C and H, but enhanced content of O of HMi, and the role of herb residues was the most obvious. At the same time, herb residues increased N of HMi. 4) All LMW organic compounds was adsorbed by montmorillonite and both surface and interlayer was adsorption site. Association between montmorillonite and LMW organic compounds was drove by different weak dispersive force. Adsorption amount of citric acid was the highest, followed by phenylalanine, and glucose showed lower adsorption amount. The adsorption capacity and amount of glucose was the lowest. The kinetic adsorption data of all LMW organic compounds fitted satisfactorily to Elovich models. The equilibrium date of all LMW organic compounds fitted Freundlich equation. However, parameters of isotherm models of different LMW organic compounds were vary. After interacted with LMW organic compounds, montmorillonite had a visible morphology transformation and there was obvious difference among different LMW organic compounds. Shape of montmorillonite interacting with glucose changed from approximately sphere to lump structure, and particle arrangement was more compact. The morphology of phenylalanine-montmorillonite and citric acid-montmorillonite was laminate. 5) Self-assembly of three kinds of LMW organic compound on silica glass was also different. Assembly amount of citric acid was the highest, followed by phenylalanine, and glucose showed lower adsorption amount. The equilibrium date of glucose fitted Langmuir equation, phenylalanine fitted Freundlich equation, and citric acid fitted Temkin equation. In addition, Glucose was scattered in distribution and few aggregates existed, but phenylalanine was interconnected and deposited on silica glass, so did amino acid. Interconnection of phenylalanine was more compact than amino acid, whereas voids were opposite. 6) The LMW organic compounds promoted self-assembly of montmorillonite by silica glass. However, assembly of montmorillonite under different LMW organic compounds was vary. Montmorillonite could be uniformly assembled on silica glass surface in the form of aggregate under glucose and citric acid condition, and montmorillonite aggregate on silica glass surface were bigger under citric acid condition than under glucose condition. Under phenylalanine condition, Montmorillonite on silica glass surface showed long strip shape. Although orientations of long strips were different from one another, they linked to each other to form a compact and dense film that had some local breakdown. 7) When a high concentration of glucose was used, small spherical particles were main shape. At the same time, they could form local aggregate. Similarly, spherical particles were also main shape under a high concentration of amino acid and their dimensions were bigger than that under a high concentration of glucose. A homogeneous film was formed when a high concentration of glucose was used.The above results suggested that various organic materials had different effects on composition and structure of black soil organo-mineral complex, the reason of which was different interaction mechanism and complex between mineral and various LWM organic compounds.