Study On Chemical Composition And Structure Of Extracts From Plants At Different Evolutionary Stages And Humic Substances Of Different Sources

Humic acid(HA)is a kind of humus(HS).Some achievements have been made in the adsorption of harmful substances in the environment by humic acid or humic-like acid,formation characteristics of humic acid or humic-like acid structure under different environmental conditions and the effect on crop yield of humic acid or humic-like acid.However,few studies have been do ne on the alkali extracted and acid precipitated substance from plants by alkali extraction from plants by the method of extracting humic acid.In order to un derstand the structural characteristics and their structural relationships between h umic acid,like humuic acid and alkali extracted and acid precipitated substanc e from plants,and their structural relationship,the different humic acids and the different humic-like acids,plants at different stages of evolution,alkali extrac ted and acid precipitated substances from different types of plants,humic acid from black soil and alkali extracted and acid precipitated substance from plants,alkali extracted and acid precipitated substance from plants and their humic-like acid after rotting were used for experimental comparison respectively.The components of organic matter were separated by humus composition modification method,and the IHSS method recommended by the International Humic Subst ance Society was used to extract and purify the humic acid,humic-like acid and alkali extracted and acid precipitated substance from plants.Potassium dichro mate external heating method was used to determine the content of organic car bon and organic matter of various experimental materials,and then elemental analysis,infrared analysis and thermal analysis were utilized to determine the str uctures of humic acid,humic-like acid and alkali extracted and acid precipitate d substance from plants.The results are as follows that:1)The humic acid cont ent of the material with longer humification time is higher,the humidification degree is higher and the condensation degree of humic acid is higher and the oxidation degree is lower than that of humic-like acid;2)The chemical structu re of plants materials at different stages of evolution is different in condensation degree and oxidation degree;3)The content of organic carbon and organic matter of different types of plants are different.The functional groups of alkali extracted and acid precipitated substance from different types of plants are similar,but the content of functional groups is significant difference,and the condensation degree and oxidation degree are also obviously different;4)The co ntent of organic carbon and organic matter in black soil is very different from that in plants,and the kinds of functional groups are similar between humic acidand alkali extracted and acid precipitated substance from plants,but the content of functional group is different significantly between black soil and alkali extracted and acid precipitated substance from plants,and the content of humic acid in black soil is different from that in alkali extracted and acid precipitat ed substance from plants.Higher degree of condensation and higher degree of oxidation;5)The content of organic matter decreased obviously after leaf matu ration,the content of organic matter increased obviously after straw maturation,and the content of alkali extracted and acid precipitated substance increased af ter plant maturation.The condensation degree of humic acid was higher than t hat of alkali extracted and acid precipitated substance.The degree of oxidation is lower.