氮肥和羊粪对内蒙古典型草原土壤多糖含量及组成的影响

采用三氟乙酸(TFA)水解、糖醇乙酸酯衍生、气相色谱法测定土壤多糖含量,研究了内蒙古羊草草原围栏封育并连续5年施用氮肥和羊粪的表层土壤的多糖含量和组成特征。结果表明:长期施用氮肥显著降低土壤多糖含量6%～19%;施用羊粪显著提高土壤多糖含量20%。施氮肥或羊粪都降低了(半乳糖+甘露糖)(/阿拉伯糖+木糖)(GM/AX)和甘露糖/木糖(M/X)的比例,表明施肥降低了微生物多糖对土壤多糖的贡献,但是施氮肥的土壤降低幅度大于施羊粪的土壤。这表明,长期施氮肥和羊粪都将改变土壤多糖含量和组成。

Effects of Nitrogen Fertilizer and Sheep Manure Application on Quantity and Composition of Soil Polysaccharides in Typical Steppe

Soil samples were collected from a typical grassland plot in Inner Mongolia which was fenced and excluded from grazing since 1999. N fertilizer and sheep manure was applied for 5 years was to evaluate the impacts of fertilizer addition on polysaccharide content and composition of surface soils. Gas chromatographic determination of individual sugars was applied after hydrolysis using trifluoroacetic acid (TFA). For GC analysis, the monosaccharide units were derivatised by reduction to alditols and subsequent acetylation. In sheep manured sites, the content of neutral sugars was about 20% higher compared with unfertilized sites, whereas N fertilization decreased the content of neutral sugars between 6%-19%. GM/AX and M/X rations indicated soil sugar was mainly of microbial origin across all sites, and a strong contribution of microbial-derived sugar in the sheep manured sites compared to the N fertilized sites. It could be concluded that addition of mineral N fertilizer and sheep manure affected polysaccharide content and composition.