新疆绿洲棉花长期连作土壤氨基糖积累特征

研究长期连作棉田土壤中氨基糖的含量和组成变化,旨在评价棉花长期连作及秸秆还田对土壤有机质转化积累的微生物群落的影响。采用棉花长期连作定位试验,通过气相色谱法测定了棉花连作9、14、19、24、29年棉田土壤不同土层中氨基葡萄糖、胞壁酸和氨基半乳糖的含量。结果表明：随棉花连作年限的逐年增加,棉田土壤中总氨基糖、氨基葡萄糖和氨基半乳糖含量均逐渐增加,而胞壁酸含量为先降低后增加,以氨基葡萄糖的转化积累具有明显优势,占土壤氨基糖总量的70.4%~71.1%;在土层0~30 cm范围内,总氨基糖及3种氨基单糖的含量随着土层深度的增加而降低;土壤中GluN/MurA值随着棉田连作年限的增加呈增大趋势,对0~20 cm土层影响较大。棉花长期连作及秸秆还田可促进土壤中总氨基糖及3种氨基单糖的积累,土壤有机质的转化过程逐渐以真菌占主导作用,长期连作棉田土壤向着真菌为优势群体的环境转变。

Characteristics of Amino Sugar Accumulation in Long-term Continuous Cropping Soil of Cotton in Xinjiang Oasis

To investigate soil amino sugar content and composition change in long-term cotton continuous cropping field, and evaluate the effects of cotton continuous cropping and straw returning on the microbial community of soil organic matter (SOM) transformation and accumulation, the long-term cotton continuous cropping field experiment was conducted combined with modern gas chromatography to determine the contents of three kinds of amino monosaccharides (glucosamine, muramic acid and galactosamine) in different soil layers of cotton field for different years of continuous cropping (9, 14, 19, 24 and 29 years). The results showed that the contents of total amino sugar, glucosamine and galactosamine in cotton field soil gradually increased with the increasing of cotton cropping years, while muramic acid content decreased first and then increased. The transformation and accumulation of glucosamine had obvious advantages, which accounted for 70.4%-71.1% of the total amino sugar. In 0-30 cm soil layer, the contents of total amino sugar and three kinds of amino monosaccharides decreased with the increasing soil depth. The GluN/MurA value in cotton continuous cropping field increased with the increase of continuous cropping years, and had a great effect on 0-20 cm soil. Long-term cotton continuous cropping and straw returning could promote the accumulation of soil total amino sugar and three kinds of amino monosaccharides. Fungi gradually play a dominant role in the transformation process of SOM, and the soil of cotton continuous cropping field changes to the environment with fungi as the dominant population.