稻草腐解过程中形成胡敏酸的组成和结构研究

Chemical Composition and Structure of Humic Acids from Decomposited Paddy Straw Residue

通过稻草腐解实验,采用化学分析方法,研究了稻草腐解过程中土壤胡敏酸的化学特征的动态变化,旨在丰富农作物秸秆还田过程中的胡敏酸化学组成、性质与结构变化的特征。在试验培养条件下,施用稻草后土壤的有机碳含量提高了31.71%,腐殖质含量增加了51.93%,都在90d时达到最大值。施用稻草45d时的PQ值(HA在HS中所占的比例)明显降低,在90d和135d时的PQ值与45d时变化不大。施用稻草后土壤胡敏酸的色调系数(ΔlogK)逐渐减少,相对色度(RF)值迅速增大,胡敏酸的氧化程度和芳构化程度增强。胡敏酸的元素组成以碳为主,含量在52%左右,其次为氧。H/C的比值逐渐降低,O/C的比值不断增大。羧基和酚羟基为主要的酸性基团。羧基含量先降低,后随着腐解的进行,其含量不断升高;酚羟基的含量变化与羧基的含量变化趋势相反;羰基含量逐渐增加。施用稻草会引起紫色水稻土胡敏酸化学组成和结构的变化。

In this paper,chemical methods were used to study the humic acids in purple paddy soil applied with rice straw residue,in order to enrich the characteristics of soil humic substances,changing of composition,properties and structure.The content of soil organic carbon and humus were increased about 31.71% and 51.93%,which were the largest during straw decomposition in the 90th day.In the 45th of decomposition of rice straw residue,the PQ was significantly lower,and at the time of the 90th and 135th,the PQ had changed little.After using straw residue,the ΔlogK of the humic acid extracted from purple paddy soil decreased,the RF increased rapidly.In the elemental composition of humic acids,the carbon was the main contents（about 52%）,the oxygen followed.H/C decreased,O/C increased continuously.Carboxyl and phenolic-hydroxyl groups were the main acidic groups.The content of carboxyl group was reduced firstly,with the decomposition of paddy straw,which was going up;the content of phenolic-hydroxyl group changed contrarily with carboxyl group,carbonyl group increased.Chemical compositions and structure of humic acids extracted from purple paddy soil with straw residue were changing.