Effects Of Sod-cultural Practices On Soil Microbial Diversity In The Carya Cathayensis Forest

With rapid development of hickory industry and increasing of intensive management indensity, soilproperty changed and ecological environment damaged day by day in Carya cathayensisforest.According to its bioecology characteristics which is deciduous tree species, the type of coolseasonal green manures were planted in Carya cathayensis forest for improving the soil. We still need toinvestigate whether green manures can improving soil fertility and enrich soil microbial diversity inCarya cathayensis forest. To evaluate the potential of sod-culture to improve soil fertility and microbialactivities of Carya cathayensis forest land, a field trial was conducted over two years in Caryacathayensis ecological demonstration, in Linan. White clover, rye grass, oil rape seed, milk vetch,natural weeds and clean tillage (as CK) six treatments with three replications and random lay out wereused for this study. Sod-culture affect to soil nutrients in the Carya cathayensis forest land weremeasured. The rule of annual dynamic changes of soil microbial functional diversity and bacterialcommunity structure diversity were also evaluated by Biolog method and PCR-DGGE technology. Themain results are follows:(1) Sod-culture improved soil nutrient contents. Contents of soil organic matter,total N,total P, totalK, available N, available P and available K with grass were higher than that of clean tillage（CK）. Soilorganic matter content with grass increased remarkably in April and July; total elements contentincreased obviously, especially total P reached the highest growth rate in October; available N and Pcontent increased higher in April and July and available K content increased higher in July and October.Sod-culture changed soil chemical properties. Considering the whole growth process, the legume plantshad a better effect of improving soil properties than that of gramineous plants.(2)Analysis of Biolog Eco showed that there was an impact of soil microbial richness,microbialcarbon utilization type and capacity with different sod-culture treatments. White clover, natural weedsand milk vetch handle a greater impact on soil microbial metabolic activity than that of other treatmentswith a higher average well color development value. Diversity index analysis showed that there was nosignifcant difference between grass area and clean tillage area in January and April, yet diversity indexwith grass are higher than that of clean tillage in July and October(except oil rape seed treatment).Theprincipal component analysis showed that there was some differences in the type of soil microbial carbon utilization in different seasons, but the main carbon sources were the carbohydrate, polymers andamino acids in different seasons.(3)Analysis of PCR-DGGE showed that soil bacterial diversity with sod-culture was very rich, andthere were more than30different bands and no less than6common bands in four seasons. The highestrichness of soil bacteria was in April with39different bands. Cluster analysis revealed that in Januaryand April, all samples clustered into a group with the similar value of0.49and0.46and the similaritywas low. This can explain that soil microbial community were quite different in the two seasons andthere was a significant impact on soil bacterial community structures with sod-culture. In July andOctober, all soil samples clustered into a group with the similar value of0.55and0.65and the similaritywas high. This can reveal that there was no significant difference in soil microbial community structuresamong different treatments, and there was a significant impact on soil bacterial community structureswith sod-culture. The similarity analysis showed that compared with the other treatments, the duplicatesof natural weeds, oil rape and white clover treatments had better consistency.