为探讨秸秆还田对土壤水溶性碳(WSOC)的影响, 采用田间定位试验, 研究连续免耕、 浅翻、 深翻与免耕秸秆覆盖、 秸秆浅翻及深翻还田方式下, 旱地草甸土WSOC随土层深度变化的荧光特征。 结果表明: 0～50 cm土层, 3种耕法与相应秸秆还田方式土壤WSOC均解析出2类 3个荧光组分, 即类腐殖质组分C1(240/400 nm)和C2(245, 400/465 nm)及类蛋白质组分C3(220, 275/325 nm); 无论浅翻还是深翻, 0～20 cm表土层C1＞C2＞C3, 20～30 cm土层C3组分的变化与C1, C2组分呈负相关, 秸秆还田增加了30～50 cm土层C3组分的含量; 荧光指数分析表明, 土壤WSOC组成为非生物源与生物源的混合物, 10～20 cm土层异源特征明显, 免耕与免耕秸秆覆盖20～50 cm土层自生源特征较强; 秸秆深翻还田40～50 cm土层腐殖质的产生和积累趋势增强, C2/C1比值高于秸秆浅翻还田和秸秆覆盖。

To study the effect of straw returning on composition of soil water-soluble carbon, the fluorescence spectral characteristics of WSOCwith depth were researched onland meadows with continuous no-tillage, shallow turning, deep turning and no-till cover, shallow and deep straw returning methods, and the results showed that the WSOC was all resolved two types of three fluorescent components in 0～50 cm soil layer with 3 kinds of tillage and corresponding straw returning, namely humus-like components C1 (240/400 nm) and C2 (245, 400/465 nm) and protein-like component C3 (220, 275/325 nm). Regardless of shallow or deep returning, the sequence was C1>C2>C3 in 0～20 cm topsoil, butthe change of C3 composition in 20～30 cm soil layer was negatively correlated with C1 and C2 components. It was also founded that the content of C3 component in 30～50 cm soil layer was increased with continuous straw returning. Fluorescence index analysis showed that the WSOC composition is a mixture of non-biological sources and biological sources, which indicated that the heterogeneous characteristics of the soil layer was obvious in 10～20 cm soil. For the reason of no disturbance to the soil in whole growing season with no-tillage and no-tillage straw cover, the self-generated characteristics in 20～50 cm soil layer was much strong. The ratio of C2/C1 in the 40～50 cm soil layer of straw deep returning was higher than that of shallow tillage and straw cover, indicating that thetenth of humus production and accumulation would be increased.