水稻秸秆燃烧对土壤有机质组成的影响研究

CHANGES IN COMPOSITION OF SOIL ORGANIC MATTER AFTER BURNING OF STRAW

研究生物质(水稻秸秆)燃烧行为对土壤有机质含量和组成的影响,探讨不同燃烧次数下土壤中胡敏酸(HA)、富里酸(FA)、水溶性有机质(DOM)的含量和结构特征的变化情况。结果表明:土壤有机碳的变化仅在土壤表层几厘米以内,随燃烧频次增加土壤有机碳含量减少量增加,而水溶性有机质及组分则呈现不断增加的趋势。不同来源土壤的腐殖物质对生物质燃烧作用的响应不同,3种供试土样中腐殖物质随不同次数同强度秸秆燃烧并未呈现较一致的变化趋势,但每一种土壤的HA和FA含量及HA/FA、E4/E6值均随燃烧频次的增加呈现规律性的升高或者降低,而且FA含量的变化是影响HA/FA值大小的主导因素。此外,通过红外光谱图可知,随燃烧频次增加,FA中芳香性成分和含脂肪族C—OH、C—O物质增加,而HA由于本身芳香缩和度高而无明显变化。

Effects of burning biomass （rice straw） in the field on content and composition of soil organic matter were studied to explore changes in content and structure of humic acid （HA）, fulvic acid （FA） and dissolved organic matter （DOM） in relation to frequency of burning. It was found that change in soil organic carbon occurred only within a few millimeters of surface soil layer. It decreased in content and the magnitude of the drop increased with frequency of burning, while soluble organic matter and its components increased in content. Humic substances from different sources responded differently to burning. The humic substances in three studied soils didn’t show any consistent variation trend with frequency burning, but HA and FA contents, HA/FA and E4/E6 increased or decreased regularly with increasing frequency of burning. The change in FA content was the leading factor affecting HA/FA ratio. Besides, from the FTIR, it was learnt that in FA aromatic fractions and Aliphatic substances, like C—OH, C—O, increased as frequency of burning increasing, while changes in HA were not noticeable because the aromatic condensation of HA per se is high.