Effect Of Land Use Types And Fertilization Systems On Active Soil Organic Carbon Pool

Through laboratory analysis, a systematic study was made on the quantitative dynamicsof fractions of soil organic carbon in long term experiment of different land use and fertilizepatterns at the aquic brown soil region located in the lower reaches of Liaohe plain. The effectof use and fertilize patterns on turnover rate of soil microbial biomass carbon and soil carbonpool management index and the relationships between soil organic carbon and active soilorganic carbon, among fractions of soil organic carbon and between active and soil nutrientswere also approached. The results as follows:In different fertilization systems, the content of soil microbial biomass carbon with NPKand recycled manure was significant higher than other treatments. Application of NPK andrecycled manure can substantial increase the content of active soil organic carbon. With therising of temperature, the content of microbial biomass carbon, dissolved organic carbon,readily oxidizable carbon and light fraction organic carbon was increased gradually untilharvest time. Season had obvious influence on dissolved organic carbon. So in farm the orderof soil dissolved organic carbon was summer＞autumn＞spring.Under long term experiment of land use, compared mowing field and fallow field withbare field, the content of soil organic carbon increased by 21% and 32% in soil depth from 0to 20 centimeters, but the depth from 20 to 40 centimeters didn't have the trend. According tomethod of adjacent sample field, changing bare field into mowing field or fallow field,content of active soil organic carbon can be highly increased in soil upwards of 20 centimeters.And the same to the depth from 20 to 40 centimeters. But expect content of dissolved organiccarbon, others had no significant difference. With the rising of temperature, content ofmicrobial biomass carbon wasn't great change in bare field. Its content peak of mowing fieldand fallow field appeared during flower season. In addition, with the changing of temperatureand humidity, top layer had bigger microbial biomass carbon scope of variety than underlayerin bare field, mowing field and fallow field. As the behalf of nature ecosystem, fallow field'sdissolved organic carbon had the order which was autumn＞summer＞spring.Datum of microbial biomass carbon based on different fertilization system and land usetypes, microbial biomass carbon turnover time was the longest, which was 2.33a. Turnovertime which was about 1.19a in mowing field and fallow field was equal to it in treatment ofapplying fertilizer. Treatment with NPK and recycle manure had the shortest turnover time, itwas 0.97a. Application of fertilizer for a long time, soil readily oxidizable carbon could be used uprapidly. Then carbon pool management index also fell lower. But recycle manure wasopposite. The treatment can lead to higher carbon pool management index, especiallytreatment of fertilizer along with recycle manure. How much organic matter be back to soilwould influence on changes of readily oxidizable carbon and carbon pool management index.Otherwise, correlation between carbon pool management index and soil chemical propertieswas great higher than it between soil organic carbon and soil chemical properties.There were extremely significant relationships between soil organic carbon and activesoil organic carbon or among fractions of soil organic carbon. These were positive extremelysignificant relationships between active soil organic carbon and soil total N, total P, availableP and available K. Moreover, soil organic carbon had no significant relationships withavailable P.