长期施用有机无机肥对潮土微生物群落的影响

微生物群落结构是土壤生态系统变化的预警及敏感指标，可用于表征土壤质量及其生态功能变化。本文用磷脂脂肪酸法研究了有机肥和NPK肥料长期施用对华北平原潮土微生物群落结构的影响及其变化特征。结果表明：长期施用有机和无机肥不仅提高了土壤有机碳、全氮、速效磷和速效钾等含量，改善了土壤酸碱度，而且显著增加了土壤微生物生物量，其中以有机肥的效果最为明显，增幅达到15.4%。长期施用肥料有机肥也改变了土壤微生物的群落结构，提高了细菌数量，降低了放线菌含量，而对真菌数量没有明显影响，导致真菌与细菌的比值下降。主成分分析表明，长期施用有机肥的土壤，细菌以含a19:0、br14:0、16:1w5c和17:1w9而真菌以含18:1w10c的微生物为优势种群，NPK处理土壤中细菌以含18:1w7、i19:0、br18:0、16:1w7t和a15:0的微生物为优势种群，CK处理中没有明显的优势种群。

The influence of the long-term application of organic manure and mineral fertilizer on microbial community in calcareous fluvo-aquic soil

Soil microbial community reflecting soil quality affects the soil ecosystem functions and has been suggested as the sensitive indicator for predicting change of soil ecosystems. To understand the influence of organic manure and chemical fertilizers on the microbial biomass and community in soils of the North China Plain, soil samples were collected from the 0-20 cm tilled layer in a long-term experimental field at the Fengqiu state key agroecological experimental station, Fengqiu County, Henan Province, China, and used to measure the phospholipid fatty acid profiles of microorganisms. The study included three treatments with four replicates: control (CK, without fertilization), organic manure (OM) and chemical fertilizer NPK (NPK). The long-term application of fertilizer NPK and particularly organic manure significantly increased the concentrations of soil organic C, total N, available P and available K, and reduced soil pH compared to treatment CK. This finding indicates that organic manure application or balanced fertilization of N, P and K could efficiently improve the soil fertility, and the growing conditions were more suitable for crops and soil microorganisms. The long-term application of organic manure significantly increased the amount of total microbial PLFAs by 15.4% compared to the value in the CK treatment, but the addition of fertilizer NPK had no significant effect. Manuring significantly increased the amount of bacterial PLFAs from 41.03 nmol g-1 soil in the CK treatment to 48.03 nmol g-1 soil in the OM treatment, but did not change the amount of fungal PLFAs, which resulted in the significant reduction of the ratio of fungi to bacteria. Fertilization slightly, but not significantly, increased the amount of bacterial PLFAs and reduced the amount of fungal PLFAs, resulting in the slight decrease of the ratio of fungi to bacteria. However, manuring and fertilization dramatically reduced the magnitude of actinomycetal PLFAs, indicating that organic manure and chemical fertilizers both inhibited the growth of actinomycete in arable soils. After the 21-year (1989-2009) application of organic manure and chemical fertilizers, only 52% of total PLFAs showed similarity among the three treatments. Principle component analysis (PCA) of PLFA was used to describe changes in microbial community ,and the result showed that change in microbial community among three treatments was mainly driven by the application of fertilizers and could be attributed to the first and second principal components, which accounted for 43.1% and 30.9% of the total variation, respectively. Three treatments were located in different quadrant: the OM treatment distributed in the fourth quadrant, whereas the NPK treatment in the third quadrant and the CK treatment in the second quadrant. In the OM treatment, bacteria containing a19:0, br14:0, 16:1w5c and 17:1w9, and fungi containing 18:1w10c were dominant microorganisms, while bacteria with 18:1w7, i19:0, br18:0, 16:1w7t and a15:0 for treatment NPK. In contrast, no dominant microorganisms could be identified in the CK treatment.