长期施肥对宁夏灌淤土土壤微生物多样性的影响

Effect of Long-term Fertilization on Soil Microbial Diversity in Irrigation Silting Soil of Ningxia

灌淤土是含有大量泥沙的黄河水流经长期灌溉而形成,其在宁夏土类中占有一定的比例。为了阐明长期施肥对灌淤土土壤微生物的影响,以宁夏灌淤土土壤肥力监测基地为试验平台,采用平板稀释法和Biolog微生物鉴定系统研究了长期施肥条件下土壤微生物特征的变化。结果表明:长期NP、NK、PK、NPK施肥处理显著降低了土壤细菌数量和土壤微生物总数,细菌数量降低达50%以上。M和1.5NPKM处理增加了土壤放线菌数量,增加的幅度达95%左右,单施氮肥处理显著降低了土壤放线菌数量。NPK和NPKM处理提高了土壤微生物群落对羧酸类、碳水化合物类和酚类碳源的代谢活性,1.5NPKM处理提高了微生物群落对胺类碳源的代谢活性,说明长期的NPK及NPK配合施用有利于土壤微生物活性的提高。施肥处理均不同程度地提高了土壤微生物群落的SHANNON多样性指数但降低了均匀度指数。

Silting soil is formed by the long-term irrlga tion with a large amount of sediment in Yellow River, accounting for a certain proportion in soil types of Ningxia. In order to elucidate the effect of long-term fertilization on soil microbial diversity in irrigation silting soil of Ningxia, the changes in soil microbial characteristics under the f long-term fertilization were studied using plate dilution method and Biolog microbial identification system based on the test platform of fertility monitoring. The results showed that： long-term NP, NK, PK, NPK fertilization treatments significantly reduced the number of soil bacteria and total microorganisms, especially bacteria decreased by more than 50%. The M and 1.5 NPKM treatments significantly increased the number of soil actinomycetes by 95% （P 〈 0.05） compared with the control. While the number of actinomycetes was significantly decreased （P 〈 0.05） under single N treatment. NPK and NPKM treatments improved the metabolic activity of soil microbial community for carboxylic acids, carbohydrates and phenolic carbon sources, 1.5 NPKM treatment improved the metabolic activity of soil microbial community for amine carbon source, which suggested long-term NPK combined with organic fertilizer application are conducive to the improvement of soil microbial activity. The application of fertilizer increased the Shannon diversity index of soil microbial community but decreased the evenness index of soil microbial community.