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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。
Through the experiment of straw decay, the chemical analysis method was used to study the dynamic changes of soil humic acid chemical characteristics in the process of straw decomposition, in order to enrich the chemical composition, properties and structural changes of humic acid during the straw returning feature. Under the experimental culture conditions, the content of organic carbon in soil increased by 31.71% and the content of humus increased by 51.93%, all reaching the maximum at 90 days. The PQ value (the proportion of HA in HS) at 45 days after straw application decreased obviously, but the PQ value at 90 days and 135 days did not change much at 45 days. The color coefficient (ΔlogK) of soil humic acid decreased gradually with the application of straw, the relative colorimetric (RF) value increased rapidly, and the degree of oxidation and aromatization of humic acid increased. Humic acid elemental composition of carbon-based, content of about 52%, followed by oxygen. H / C ratio gradually decreased, O / C ratio continues to increase. Carboxyl and phenolic hydroxyl groups are the main acidic groups. The content of carboxyl groups decreased first and then decreased with the progress of decomposing. The contents of phenolic hydroxyl group changed inversely with the content of carboxyl groups. The content of carbonyl group increased gradually. The application of straw can cause changes in the chemical composition and structure of humus acid in purple paddy soil.