Microbial Characteristics Of The Calcareous Purple Soil Treated By Different Hedgerows On The Hilly Slopes

The present research studied three different types of soils collected from Ziyang City, including Vetiveria zizanioides hedgerow,Amorpha fruticosa hedgerow and soil in the field(as the control).The amount of the three sorts of microbes,the biomass C and N,and enzyme activity in the soil,together with BOXAIR-PCR and 16S rDNA PCR-RFLP methods,were employed to evaluate the differences among three treatments.The results are as the following:(1) Hedgerows planted in the soil can increase the number of the three microbes effectively.Compared with CK,both Vetiveria zizanioides and Amorpha fruticosa hedgerow increased the amount of bacteria at the depth of 1m,3m and 5m to 126.67%, 30.41%,26.45%and 63.33%,21.75%,31.86%,respectively.To the actinomycetes,the number of Amorpha fruticosa is greater than that of Vetiveria zizanioides treatment and control.Things were just on the contrary to the fungi among Amorpha fruticosa and Vetiveria zizanioides treatment.(2) Hedgerows planting can increase the content of soil microbial biomass C and N.In the present study,the microbial biomass C of the Vetiveria zizanioides in the length of 1m and 3m is higher than that of other treatments in corresponding length.However,things are on the contrary in length of 5m.As to the microbial biomass N,Amorpha fruticosa is higher than that of Vetiveria zizanioides treatment and control.(3) The amount of amination soil in both Amorpha fruticosa and Vetiveria zizanioides is much higher than that in control.Compared with the control,in the length of 1m,3m and 5m,Amorpha fruticosa and Vetiveria zizanioides increased the amount of amination soil to 87.99%,37.06%,101.13%and 79.72%,60.78%,79.14%,respectively.However, nitrification soil of Amorpha fruticosa and Vetiveria zizanioides treats is 77.56%and 93.99%of the control,and sub-nitrificaiton is 47.03%and 73.02%of the control, respectively.(4) 41 bacteria and 31 Rhizobium strains were obtained from the present study.Among 41 bacteria,21 strains came from Vetiveria zizanioides,12 from Amorpha fruticosa,and 8 from the control.As to the 31 Rhizobium strains,17 strains came from Vetiveria zizanioides,8 from Amorpha fruticosa,and 6 from the control.(5) BOXAIR-PCR of 16S rDNA revealed that there were four and five genetic groups based on 71%and 69%homology,respectively,and 17 Rhizobium strains from Amorpha fruticosa showed highly genetic polymorphism. (6) 16S rDNA PCR-RFLP analysis revealed that(â…°) in bacteria,there were 13,8 and 7 genetic diversity as to Vetiveria zizanioides,Amorpha fruticosa and the control, respectively.(â…±) in Rhizobium,there were 6,12 and 5 genetic diversity as to Vetiveria zizanioides,Amorpha fruticosa and the control,respectively.Phylogenetic analysis of 16S rDNA sequence showed that 24 bacteria and 6 Rhizobium srains were clustered into 13 and 2 branches,respectively.