不同施肥制度土壤微生物量碳氮变化及细菌群落16S rDNA V3 片段PCR产物的DGGE分析

应用化学分析和变性梯度凝胶电泳（DGGE）技术分离PCR扩增的16S rDNA的方法,研究了不同施肥制度对土壤微生物量碳、氮变化及微生物多样性的影响。结果表明,连续15a长期试验下,土壤微生物量碳（SMB-C）和微生物量氮（SMB-N）的含量大小均为长期撂荒（CK0）土壤高于农田土壤,而在农田土壤中,长期施肥的处理（NPK、NPKM、NPKSt和NPKF）高于长期不施肥处理（CK）,不同的种植制度中,长期复种轮作（NPKF）高于长期复种连作（NPK）;各处理的SMB-C/SOC（土壤有机碳）和SMB-N/TN（全氮）的比值的变化趋势与SMB-C和SMB-N变化一致;从PCR-DGGE分析,长期氮磷钾化肥配施有机肥（NPKM）处理的微生物量碳、氮的含量最高,微生物丰度最高,细菌物种最多,其次为长期撂荒（CK0）,CK处理细菌物种最少。UPGMC聚类分析表明NPK和NPKF处理细菌的群落结构相似,CK和CK0处理细菌的群落结构相似,而NPKM和NPKSt处理细菌的群落结构相似。

Microbial C and N biomass and soil community analysis using DGGE of 16S rDNA V3 fragment PCR products under different long-term fertilization systems

Microbial biomass C and N content and analysis of soil bacteria with different fertilization systems were carried out based on a 15-year long term fertilizer experiment in Drab Fluvo-aquic soil in Beijing. At this site, 13 different treatments were established in 1990. Six treatments were chosen for this work: Four were in a wheat-maize rotation receiving either no fertilizer (CK), mineral fertilizers (NPK), mineral fertilizers plus farmyard manure (NPKM) or mineral fertilizers with maize straw incorporated (NPKSt). One was in a wheat-maize/wheat-soybean rotation receiving NPK (NPKF). The other was abandoned arable land (CK0) growing weeds. The amount of chemical fertilizer per year was N 150 kg hm-2, P2O5 75 kg hm-2, K2O 45 kg hm-2, manure 22.5 t hm-2 and maize straw 2.25 t hm-2. The results showed that microbial biomass C and N in the abandoned arable soil were higher than that in arable soils. Soil microbial biomass C and N in treatments with fertilizer input NPK, NPKM, NPKSt and NPKF were higher than that in CK (without fertilization). The rotation of wheat-maize/wheat-soybean had higher microbial biomass C and N than continuous wheat-maize cropping. The ratio of microbial C to soil organic C (SMB-C/SOC) and microbial N to soil total N (SMB-N/TN) had similar trends to SMB-C and SMB-N. The community structure of bacteria microorganisms was assessed by denaturing gradient gel electrophoresis (DGGE) and Unweighted Pair Group Method Clustering (UPGMC) analysis of the DGGE banding patterns showing that the bacterial community structure was affected by the treatments. The results indicated a significant increase in microbial diversity by fertilization treatments compared to that without fertilizer (CK). However the composition of the bacterial community in NPKM treatment was more complex than that in others. Cluster analysis of the DGGE profiles pointed out that bacteria in the six soils belonged to three clusters. Bacterial communities in CK and NPK soils belonged to one cluster, those in NPKF and CK0 soils to another cluster, and that in NPKSt and NPKM soil to a single cluster. The similarity of bacterial community in soils with six treatments was 53%. This study demonstrated that mineral fertilizer with farmyard manure increased both biomass and diversity of bacterial community in the soil.