Effect of different organic materials on the structure of humus in black soil revealed by thermal (TG-DTA) analyses

Differential thermal analysis (TG-DTA) was conducted to study the effect of animal excrement, animal remnant, herb residues and woody residues on thermal nature of humic acid (HA), fulvic acid (FA) and humin. The results showed as follow: Stability of aliphatic structure of herb residues-HA was the most strong, and stability of animal remnant was the lowest. Compared with control treatment (CK), apart from herb residues, other organic materials decreased condensation of aromatic of HA, and there was difference among different treatments. Stability of aliphatic structure of animal remnant-FA was the lowest, and herb residues increased aliphatic structure of FA, at the same time, stability of it was enhanced. Application of organic materials resulted in decrease of condonsation of aromatic ring of FA, but enhanced condensation degree of humin linked to clay (HMc), and there was difference among various treatments. Use of organic materials reduced stability of aliphatic structure of HMc, and the role of animal remnant was the most obvious.