Effects Of Different Fertilization Practices On Soil Microbial Biomass Under Poplar Plantations In Jiangsu Province

Soil microbial biomass is an important component in carbon cycle of the terrestrialecosystem. It is very sensitive to the changes of soil conditions, and may be altered in a shortperiod of time, which reflects the soil microorganisms and soil fertility. Therefore, the study ofsoil microbial biomass will help us to understand the relationship between fertilization and soilmicrobial biomass and soil fertility.In order to understand the effect of different fertilization treatments in the poplar plantationsto the soil microbial biomass carbon, nitrogen and phosphorus, We conducted the experimentwith six different fertilization treatments i.e. CK (control), T1(NPK fertilizer), T2(organicfertilizer), T3(biochar), T4(NPK fertilizer plus biochar) and T5(organic fertilizer plus biochar)in Dongtai forest-farm from August2012to June2013. The results showed：1. The soil microbial biomass carbon, nitrogen and phosphorus were decreased with the soildepth under all the fertilization treatments. Fertilization treatment did not change the verticaldistribution, but improved the content comparing with the CK.2. We got a maximum of soil microbial biomass carbon and phosphorus in August and aminimum in December or February with all the fertilization treatments. There was differencebetween the maximum of the soil microbial biomass nitrogen with all the fertilization treatments.We got the maximum of the soil microbial biomass nitrogen with the treatment T1in Octoberwhile the treatment T3in February and the others in August, but the minimum were all inDecember. All the fertilization treatment had decreased the temporal variation coefficient of thesoil microbial biomass carbon, nitrogen and phosphorus. There were significant differences ofsoil microbial biomass nitrogen and phosphorus with all the fertilization treatment in some soillayers, and no significant differences of soil microbial biomass carbon.3. The soil microbial biomass C:N had decreased within the treatment T2, T4and T5, whileit increased in0-10cm and10-25cm soil layers of treatment T1and T3. The soil microbialbiomass C:P increased in the treatment T4and T5, while it was lower than CK in25-40cm soillayer of treatment T1and T2and in0-10cm soil layer of treatment T3. The soil microbialbiomass N:P increased in all the soil layers with the treatment T1, T2and T4, While it decreasedat0-10cm and10-25cm soil layers in the treatment T3and T5.