Impact of long-term fertilization on the microbial biomass carbon and soil microbial communities in paddy red soil | 长期施肥管理对红壤稻田土壤微生物量碳和微生物多样性的影响

Chinese. 【目的】土壤微生物在地球化学循环及维持土壤肥力和作物产量方面发挥了重要作用,为了研究长期不同施肥制度对土壤肥力状况的影响,明确施肥制度与土壤微生物的关系。【方法】采用土壤熏蒸和磷脂脂肪酸分析方法,研究了湖南宁乡不施肥处理、施用化肥、常规施肥、秸秆还田、30%有机肥+化肥和60%有机肥+化肥6个长期肥料定位试验的土壤微生物量碳及磷脂脂肪酸。【结果】与不施肥对照相比,施用化肥、秸秆还田及有机肥与化肥配合施用可以显著的提高土壤微生物量碳及总磷脂脂肪酸的量。长期施用化肥后,群落中含有iC15:0的微生物明显增多,长期施用有机肥和秸秆还田后,群落中含iC15:0微生物明显减少,而含aC15:0微生物则显著增加。通过对21种测得磷脂脂肪酸进行主成分分析,结果表明,前两个主成分可以解释总变异的87.6%。除C12:0和C15:0外,大部分的非饱和脂肪酸和环式脂肪酸的变异可以在第一主成分中反映出来。从肥料处理的主成分分析结果看,第一主成分及第二主成分可以解释肥料处理变异的89.8%,相比较而言,化肥处理和常规施肥处理相互间的差别较小,60%有机肥处理与秸秆还田处理几乎重合。【结论】不同施肥处理对土壤微生物量碳和微生物多样性有重要影响,肥料处理差异可以在微生物结构与多样性变化上得以体现。

English. 【Objective】 Soil microorganisms are involved in various biochemical processes and play a vital role in maintaining soil fertility and plant yields. The impacts of different long-term fertilization treatments on soil microbial community structure were studied to clarify the relationship between them. 【Method】 Soil samples were collected from long-term fertilization experimental plots receiving no fertilization, chemical fertilization, chemical fertilization as normally applied by local farmers, harvested residue return, 60% organic manure plus chemical fertilization and 30% organic manure plus chemical fertilizer. Total microbial biomass carbon was determined by chloroform- fumigation-extraction. Phospholipid fatty acid (PLFA) profiles for each treatment were used to characterize the microbial community structure and were analyzed by principle component analysis. 【Result】 Compared with the unfertilized control, all fertilization treatments showed significant increases in total microbial biomass carbon and PLFAs. The iC15:0 fatty acids significantly increased under long-term application of chemical fertilizer but decreased under both organic manure and residue return fertilization. In contrast, under organic manure and residue return, the aC15:0 fatty acids increased. Principal component analyses of the 21 PLFAs detected in the six treatments showed that 87.6 % of the total variance of the individual PFLAs could be explained by two principal components. All unsaturated and cyclopropyl PLFAs except C12:0 and C15:0 were highly weighted on the first principal component. The first and the second principal components could also explain 89.8% of the total variance of fertilization treatment. There was a very little different between the chemical fertilizer treatment and the treatment receiving chemical fertilizer as typically applied by local farmers. There was also almost no difference between the treatment that received residue return and the treatment that received 60% organic manure plus chemical fertilizer. 【Conclusion】 Long-term fertilization can significantly impact soil microbial biomass carbon and influence microbial community structure. PLFAs reflect soil microbial community structure and can be used to detect shifts in response to fertilization.