26年长期施肥对土壤微生物量碳、氮及土壤呼吸的影响

研究长期小麦连作施肥条件下土壤微生物量碳、氮,土壤呼吸的变化及其与土壤养分的相关性。以陕西长武长期定位试验为平台,应用氯仿熏蒸-K2SO4提取法、碱液吸收法和化学分析法分析了长达26a不同施肥处理农田土壤微生物量碳、微生物量氮和土壤呼吸之间的差异及其调控土壤肥力的作用。长期施肥及种植作物,均能提高土壤微生物量碳、氮含量,尤其是施用有机肥,土壤微生物量碳、氮含量高于单施无机肥的处理,土壤呼吸量也提高15.91%—75.73%,而施用无机肥对于土壤呼吸无促进作用。土壤微生物生物量碳氮、土壤呼吸与土壤有机质、全氮呈极显著相关。长期有机无机肥配施可以提高土壤微生物量碳氮、土壤呼吸,氮磷肥与厩肥配施对提高土壤肥力效果最好。微生物量碳氮及土壤呼吸可以反映土壤质量的变化,作为评价土壤肥力的生物学指标。

Effects of wheat cultivation and fertilization on soil microbial biomass carbon,soil microbial biomass nitrogen and soil basal respiration in 26 years

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 in 1984 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 pH, 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 by 15.91% 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.