不同腐熟程度有机物料对土壤微生物群落功能多样性的影响

Effects of organic matters on metabolic functional diversity of soil microbial community under pot incubation conditions

室内培养条件下,施用有机物料初期土壤微生物群落代谢功能Shannon多样性指数降低,中期又提高。有机物料种类和腐熟水平可明显影响土壤微生物群落对Biolog微平板中碳源的利用能力,土壤微生物群落利用各类碳源的能力随培养试验的延长而降低,在25d内新鲜有机物处理对碳源的利用率的下降速度低于同类腐熟有机物料处理。糖类是各处理土壤微生物群落的主要利用碳源。土壤微生物群落主成分分析表明,在施用有机物料后25d内腐熟水平是影响土壤微生物群落的主要因素,新鲜有机物处理的土壤微生物群落相似,腐熟有机物处理的土壤微生物群落相似,培养50d后各处理的土壤微生物群落无差异。

Soil sustains an immense diversity of microbes. All life forms rely on microbial processes for their survival. Microbial diversity is greater than the diversity of any other group of organisms. Microbes are responsible for diverse metabolic functions that affect soil, plant, animal and human health. Soil biodiversity is essential for the sustainable functioning of agriculture on which human depends. However microbial diversity is in extinction because of encroachment of human activities on ecosystem and increasing intensification of land use to meet demographic and socio-economic pressures. The urgent problem is how to curb the loss and how to modulate soil biodiversity to maintain soil fertility and productivity. It is well known that the application of organic matter can change soil microbial community. The objective of this study is to assess the effects of organic matter on soil functional diversity after the organic matter amendment. The soils that mixed with organic matter at 25g/kg dry soil were incubated at room temperature ranging from about 15 to 35C. The moisture content was adjusted to 60% of the water-holding-capacity by addition of distilled water. Soils were sampled at 5, 25, 50 and 100 days after incorporation of each substrate to soil. The functional diversity of soil microbial community was determined by Biolog method. The results are shown as follows. The application of organic matters into soil reduced the functional Shannon diversity of soil microbial community at early stage （within 5 days） under the present incubation conditions, but increased at middle stage （from 5 to 50 days）. The application of organic matters affected the Biolog substrate utilization potential of soil microbial communities. The Biolog substrate utilization potential of soil microbial communities was reduced with time, and the reduction-rate of the treatments amended with fresh organic matter was lower than that of composted organic matters （10 days）. Carbohydrate was the main carbon source for each treatment. Principal component analysis for soil microbial communities showed that the composted level （fresh or composted） was the main factor affecting soil microbial communities within 25 days, soil microbial communities in the treatments with fresh organic matters were similar and those in the treatments amended with composted organic matters were similar. However, after 50 days of the incubation soil microbial community from each treatment became similar.