The Effects Of Different Fertilizers On The Functional Diversity Of Soil Microbes In A Poplar Plantation

Soil microbes participate in many ecological processes and is an important part of soil ecosystem. The functional diversity indicates the ecological function of soil microbes. The effects of different fertilizers on the functional diversity of soil microbes were investigated using Biolog-Eco methods in a 5 years old poplar plantation in a coastal area of eastern china. We fertilized in June 2012, June 2013, and set up six fertilizing treatments i.e. no fertilizer(CK), NPK chemical fertilizer(T1), Manure fertilizer(T2), Biochar(T3), NPK fertilizer plus biochar(T4), Manure fertilizer plus biochar(T5). The amounts of fertilizations were 1040kg·ha-1 NPK fertilizer, 2080kg·ha-1 manure fertilizer and biochar, respectively. The experiment was carried out by randomized blocks design. We collected soil samples in August 2014, October 2014, December 2014 and March, 2015,respectively. The results showed as follows.(1) T1, T3 treatments didn’t change soil p H, and T2 treatment decreased p H, while T4, T5 treatments increased p H. All treatments increased soil DOC content. Except for T2 treatment, other treatments increased TC, and T4, T5 treatments increased TC/TN ratio.(2) The soil microbial biomass was closely related to soil p H, DOC and TC. Fertilizer applications increased SMBC and SMBN, and the microbial biomass with T4 and T5 treatments were significantly higher than other treatments. T1 decreased Simpson index, Shannon index, and T5 significantly increased Mc Intosh index and T4 increased Simpson index. All of these showed that fertilizations promoted growth of soil microbes and changed the community structure. T1, T3, T4 treatments changed the seasonal variation of SMBC; T1, T2, T4, T5 treatments changed seasonal variation of SMBN, and only T2 changed seasonal variation of SMBC/SMBN ratio.(3) Carbon utilization ability of soil microbes was closely related to soil moisture, SMBC/SMBN and TN. Fertilizer applications altered the functional diversity of soil microbial community, T5 treatments improved soil microbial activity and carbon utilization capacity of soil microbial community, and carbon utilization ability of T5 treatment was the highest, especially the utilization abilities of carbohydrate, polymer, phenolic acid were higher than others.(4) The carbon utilization ability in spring and summer were significantly higher than that in autumn and winter. T5 changed the seasonal variation of carbon utilization ability, and utilization abilities of some carbon sources in spring were significantly higher than that in summer.To sum up, fertilizer applications changed soil chemical properties and promoted growth of soil microbes. T5 treatments improved soil microbial activity. And T1, T3, T4, T5 changed the functional diversity of soil microbes which manure plus biochar mostly changed. Biochar plus NPK fertilizer, biochar plus manure fertilizer application increased decreased nutrient and water loss because of the adsorptivity, porosity, huge surface area of biochar. Biochar plus manure fertilization had the most significant influence on soil properties, microbial biomass and functional diversity.