Characterics Of Soil Physiochemical Properties And Microbial Activities In The Wetland From Returning Farmlands Within Verious Periods In Caizi Lake, Anhui Province

Wetland ecosystems, an interaction ecosystems between terrestrial ecosystemsand aquatic ecosystems, have specially hydrology, vegetation, soil and biologicalcharacteristics. Wetland has tremendous environmental benefits and environmentalfunctions in water conversation, climate regulation, water purification and et al. In thepast few decades, in the middle and lower reaches of the Yangtze River, excessivereclamation leaded to the area of natural wetlands reducing, the biodiversitydecreasing, the soil pollution increasing and the ecological destruction increasinglyserious. Wetlands ecological restoration has been an important and national demandfor the construction of ecology restoration in middle and lower reaches of YangtzeRiver. Returning farmland to lake is a strategic measure for wetland ecologicalrestoration in china now.Soils from wetlands under returning farmland to lake with different periods, theoriginal wetlands and the cultivated soil were sampled, to analyze changes of soilphysical and chemical properties, and Microbial biomass carbon and nitrogenproperties, and Soil enzyme activity properties in Caizi lake along Yangtze River.Thus will provide the changes of microbial activities with different periods ofreturning farmland. The main conclusions are as follows:1. After returning farmlands to lake, soil bulk density increased and thendecreased, but didn’t reach the level of the original wetlands. After returning farmlandto lake, the differences of soil particle composition were significant, during thereturning period soil silt contents and sand contents were higher than those of theoriginal wetlands, and clay content were lower than those of the original wetlands.The water contents were increased with returning periods, indicating that waterconversation increased. Soil pH values of test soils range from4.52~4.99and the surface soil acidity were greater than the layers’. Soil organic matter and totalnitrogen content increased gradually, and available N of tested soils were significantlyhigher; total P generally decreased while available P generally increased afterreturning farmland to lake. Correlation analysis showed that the test water content,soil clay content, total N and total P were significantly correlated（P <0.01）, soilorganic matter, total N, available N total were significantly correlated（P <0.01）. SoilpH and soil organic matter, total N, available N were significantly correlated（P <0.05）.2The soil microbial biomass carbon content range was333.77~700.75mg/kg，while the soil microbial biomass nitrogen range was30.80~64.01mg/kg. Soilmicrobial biomass carbon was highly significantly correlated (P <0.01) with soilorganic matter, total nitrogen and pH, and was significantly correlated (P <0.05) withthe soil clay content; the soil microbial biomass nitrogen was highly significantlycorrelated (P <0.01) with soil organic matter, total nitrogen and bulk density, wassignificantly correlated (P <0.05) with soil pH.3. Soil enzyme activities of tested wetland soils shown that after returningfarmland to lake, soil catalase activity and soil phosphatase activity increased. Thesurface soil enzyme activities were higher than the layer soil. Correlation analysisshowed that soil catalase activity, soil bulk density, water content, clay content andsoil microbial biomass nitrogen were highly significantly correlated (P <0.01); soilcatalase activity, soil organic matter, available P, total N and available N were highlysignificantly correlated (P <0.01); soil microbial biomass carbon, total P and soilcatalase activity were significantly correlated (P <0.05). Soil phosphatase activity，soil bulk density，available P，total N and available N，soil microbial biomass carbonand soil microbial biomass nitrogen were highly significantly correlated (P <0.01).Soil sucrose activities were fluctuation. Soil sucrose activity, soil microbial biomasscarbon and soil microbial biomass nitrogen, soil organic matter, available P,total Nand available N were highly significantly correlated (P <0.01). Soil urease activityand pH were highly significantly correlated (P <0.01); Soil urease activity, total Nand available N and soil microbial biomass nitrogen were significantly correlated (P < 0.05).