26年长期施肥对土壤微生物量碳、氮及土壤呼吸的影响研究

Abstract

Soil microbial properties play important roles in soil quality changes and nutrition cycling. The relationship between soil microbial properties and soil quality changes as a result of climate conditions,soil types,tillage and fertilizer.Lots of studies had been done; however,there are not too many reports on loessial soil. Loessial soil is one of the main types of soil on loess plateau. The study about loessial soil plays an important role in getting better soil environment and increasing productivity of dryland on loess plateau. In this paper,the relationship between soil quality and soil microbial properties such as soil microbial biomass carbon,soil microbial biomass nitrogen and soil basal respiration was studied in order to illustrate the function of soil microbial properties as bio-indicators of soil health. The long-term experiment was set up in1984 in Changwu county,Shaanxi province,China. We collected samples from the 0—20 cm soil zone of the long-term wheat cultivation and fertilization system. Nine treatments were carried out in this study: 1) fallow( F); 2) no fertilization as control( CK); 3) nitrogen( N); 4) phosphorus( P); 5) manure( M); 6) nitrogen + phosphorus( NP); 7)phosphorus + manure( PM); 8) nitrogen + manure( NM); 9) nitrogen + phosphorus + manure( NPM). The chemical properties such as p H,organic matter,total nitrogen,and total phosphorus content were analyzed in order to determine to the effects of long-term wheat cultivation and fertilization on soil nutrients. The soil microbial biomass carbon,soil microbial biomass nitrogen,basal respiration and the derivative indices of the arable soil in different long-term fertilization systems were also analyzed. The results showed that different fertilization on loessial soil in 26 years significantly affected soil chemical and microbial properties. Long-time combined application of organic and mineral fertilizers had more effect on soil organic matter,total nitrogen and total phosphorus content than mineral fertilizers alone. All these properties in treatment with fertilizers input NPM were the highest. In different fertilization treatments,the contents of soil microbial biomass carbon changed between 254.65 mg / kg and 745.26 mg / kg,and the contents of soil microbial biomass nitrogen changed from 31.70 mg / kg to 120.54 mg / kg. Long-term fertilization and planting increased the content of soil microbial biomass carbon and soil microbial biomass nitrogen. Especially, organic fertilizers can significantly enhance soil microbial biomass content.Compared with CK,the treatments with organic fertilizers input increased soil microbial biomass carbon,soil microbial biomass nitrogen and soil basal respiration. The soil basal respiration of treatments with organic fertilizer was increased by15.91% to 75.73%. In the meantime chemical fertilizer had no promotion on the soil basal respiration,and decreased the metabolic quotient. Some of soil microbial properties( Soil microbial biomass carbon,Soil microbial biomass nitrogen,Soil basal respiration) were significantly correlated with soil organic matter and soil total nitrogen contents. Soil basal respiration was also significantly correlated with soil total phosphorus content. The correlations between microbial quotient and soil nutrients,metabolic quotient and soil nutrients were not obvious. These results indicate that soil microbial properties reflect the changes of soil quality and thus can be used as biological indices in the evaluation of soil fertility.