土壤碳水化合物的转化与累积研究进展

碳水化合物虽然仅占土壤有机质的10%~20%，却是土壤中最活跃的有机碳库，是微生物的主要能源和碳源，并参与土壤团聚体的形成，是土壤有机质和土壤性质研究中的重要指标和对象。本文综述了土壤碳水化合物种类、来源和在团聚体中的分布特征、微生物群落结构对碳水化合物的转化和积聚的影响，同时讨论了耕作、施肥等农业措施对碳水化合物含量和分布的影响。从现有文献资料来看，碳水化合物的含量因土壤粒级不同而异；外源碳水化合物在土壤中的转化和累积与微生物群落结构特征密切相关，细菌在单糖等简单碳水化合物的转化中起主要作用，而复杂碳水化合物则首先在真菌的作用下水解成单糖；真菌和革兰氏阳性菌丰富的土壤更有利于碳水化合物来源碳的累积，但是详细的转化过程和存在形态认识有限，有待深入研究。

Progress in the study on transformation and accumulation of carbohydrates in soil

Carbohydrates are readily biodegradable substrates, though accounting only for 10%~20% of soil organic matter (SOM), they are considered as an important indicator in the research of SOM and soil properties. Soil carbohydrates, including monosaccharides, disaccharides, polysaccharides and sugar derivatives, are essential components of and energy sources for microorganisms in soil. Polysaccharides are also important binding material for the formation of soil aggregates. Neutral sugar is commonly used to evaluate stability of SOM, while the amino sugar is used to predict C source from microorganisms in SOM. The processes of absorption and conversion of carbohydrates were related to structure of soil microbial community and biomass of soil microorganisms. Monosaccharides and disaccharides are generally assimilated by bacteria firstly, while polysaccharides are hydrolyzed into simple sugars by fungi. Decomposition of SOM is closely related to distribution of carbohydrates in soil fractions as well as their combination with mineral particles. The turnover of SOM, which including microbial, chemical and physical processes, is very complicated, however, all these processes can be boiled down to the dynamical process of carbohydrates partly. The accumulation of carbohydrates in soil is also affected by soil microorganisms, and fungi and G bacteria are much more conducive to the accumulation of carbohydrates. The effects of soil tillage and fertilization on carbohydrates depend on the content of SOM. This paper reviewed the factors that affect the distribution and transformation of carbohydrates and pointed out future direction of the research on soil carbohydrates.