沼渣连续施用对土壤微生物量碳、氮剖面分布的影响

通过"棉花+小麦"轮作施用沼渣的定位试验,研究不同年限的沼渣施用对土壤剖面微生物量C、N(MBC、MBN)分布特征的影响。结果表明:在0~50cm剖面上,施用沼渣1年对0~30cm土壤的MBC、MBN影响较大,能显著提高30~40cm土层土壤MBC、MBN的含量,施用沼渣5年时对40~50cm土层MBC、MBN无明显影响。土壤MBC、MBN含量总体随施用沼渣年限的延长而增加,各土层MBC、MBN含量增幅随着施用年限的延长呈现不同趋势。施用沼渣1年,耕层土壤的MBC/MBN值较习惯耕作增加,施用沼渣3年后,其值呈降低趋势。各土层的MBC/TOC、MBN/TN和MBC的变化趋势基本一致,总体随着沼渣施用年限的延长而增加。针对"棉花+小麦"轮作模式,持续施用沼渣3年更有利于改善0~40cm土层土壤肥力。

Effect of Continuous Biogas Residue Application on the Carbon and Nitrogen Distribution Profiles of Soil Microbial Biomass

Effect of different years of biogas residue application on the microbial biomass carbon and nitrogen （ MBC, MBN） distribution profiles in the soil was studied through the ＂ cotton ＋ wheat＂ crop rotation experiment. The results showed that in the 0 - 50cm soil profiles, one year＇s application of biogas residue had greater impact on MBC and MBN in the top 30cm soil layer and could significantly increase the MBC and MBN content in 30 -40cm soil layer, application of biogas residue for five years had no obvious effect on MBC and MBN in 40 - 50cm soil layer. Soil MBC and MBN content increased with increasing biogas residue application period. The increasing rate of MBC and MBN content in each soil layer showed different trends with biogas residue application period. Compared to traditional farming, MBC / MBN ratio increased in topsoil after one year＇s application of biogas residue, but decreased after application for three years. The variation trends of MBC / TOC, MBN / TN and MBC were basically the same in each soil layer, which increased with the increasing period of biogas residue application. For ＂ cotton ＋ wheat＂ crop rotation mode, application of biogas residue for three years can better improve the fertility of 0 -40cm soil layer.