Effects Of Long-term Fertilization And Land Use Patterns On Bacterial Community Diversity In An Anthropogenic Lou Soil

The objective of this study was to explore the effects of long-term different fertilization and land use patterns on soil bacterial community diversity and its mechanism in an anthropogenic Lou soil. Based on a long-term fertilization experiment(24 years) on “National Monitoring Base of Soil Fertility and Fertilizer Efficiency on Loess Soil” in Yangling, Shaanxi province, Effects of different fertilizations and land use patterns on soil bacterial community diversity were studied by T-RFLP(Terminal restriction fragment length polymorphism) technique and high throughout sequencing technique. 11 treatments were used as: 1) without fertilization(CK), 2) only chemical N fertilizer(N), 3) chemical N and K fertilizer(NK), 4) chemical P and K fertilizer(PK), 5) chemical N and P fertilizer(NP), 6) chemical N, P and K fertilizer(NPK), 7) chemical NPK fertilizer together with straw return(SNPK), 8) chemical NPK fertilizer together with low amount of organic manure(M1NPK), 9) chemical NPK fertilizer together with high amount of organic manure(M2NPK), 10) Set aside(LH), and 11) Fallow(XX). The results showed as below.1. The effects of different fertilization and land use patterns were different on soil bacterial community diversity on Lou soil. Compared with CK, the Shannon indices of NP, NK, PK, SNPK and M1 NPK decreased significantly as 16.6%, 11.8%, 3.2%, 3.2% and 9.2% respectively, the evenness indices of NP, NK, PK, SNPK and M2 NPK decreased significantly as 4.2%, 3.1%, 2.1% and 1.0% respectively, while XX could increase soil bacterial diversity richness index and dominant index when measured by T-RFLP technique. Soil bacterial diversity richness indixes of N, M2 NPK, LH and XX were lower than that of CK significantly by high throughout sequencing technique.2. The effects of different fertilization and land use patterns were different on soil bacterial community structure on Lou soil. Measured by T-RFLP technique and compared with CK, soil bacteria could be enriched such as Bacillus and Pediococcus under long-term N, NP and PK treatments, Pediococcus under NK, Gemmata under NPK, and Geobacillus、Bacillus、Pediococcus under M1 NPK, while soil bacteria could be inhibited, for examples, Lactobacillus under N treatment, Bacteroidales, Halomonas, Kocuria and Lactobacillus under NP, Bacteroidales、Firmicutes、Halomonas、Kocuria、Lactobacillus under NK, Kocuria under SNPK, Gemmata under M2 NPK. Soil bacteria could be enriched such as Bacillus, and could be inhibited such as Bacteroidales under XX treatment. Measured by high throughout sequencing technique, soil bacteria could be facilitated such as Proteobacteria under NP, Cyanobacteria and Chloroflexi under PK, Bacteroidales under NPK, Proteobacteria and Bacteroidales under SNPK, Proteobacteria, Bacteroidales and Firmicutes under M1 NPK and M2 NPK. soil bacteria could be inhibited such as Actinobacteria under SNPK and M2 NPK,Chloroflexi、Armatimonadetes under M2 NPK. Soil bacteria could be facilitated such as Proteobacteria under LH, Actinobacteria under XX, while they could be inhibited such as Planctomycetes under XX.3. Long-term different fertilization and land use patterns had a significant effect on bacterial community structure in an anthropogenic Lou soil, and the main causes were the shifts of main soil chemical properties. PCA of data from T-RFLP showed that, soil bacterial structure of N, NP、NK、PK、SNPK、M1NPK,LH、XX were all changed significantly compared with that of CK. By high throughout sequencing technique, all treatments could be divided into 2 classes, in which one of them was LH, CK、XX、PK、N and NK, the other was M1 NPK, M2 NPK, NPK, NP and SNPK.4. NPK and M2 NPK were beneficial to maintain soil bacterial structure diversity on Lou soil, SNPK, M1 NPK, M2 NPK and XX had positive effects, while N, NP, NK, PK and LH had opposite effects from T-RFLP analyses. N and LH had a negative effect, while NP, NPK, SNPK, M1 NPK and M2 NPK had a positive effect on soil bacterial structure diversity, and NK and PK could it from high throughout sequencing analyses.