长期施肥对黄土旱塬农田土壤微生物丰度的影响

以长武黄土高原农业生态试验站的长期定位试验为平台,通过荧光实时定量PCR (real-time PCR) 技术,研究不同施肥制度下的黄土旱塬农田土壤微生物群落丰度,揭示长期不同施肥制度对土壤微生物群落的影响规律.结果表明: 单施化肥处理细菌数量较CK裸地增加21％,古菌增加32％;化肥配施有机肥处理细菌数量增加37％,古菌数量增加36％.化肥配施有机肥处理显著增加了土壤细菌和古菌的丰度.30年长期施氮肥处理导致氨氧化细菌(AOB)的增幅达7.13倍,而氨氧化古菌(AOA)的增幅仅为0.2倍.AOB对施肥的响应程度较高,尤其是对氮肥具有较高的敏感性.与单施氮肥和氮肥混施有机肥处理相比,施磷肥处理显著增加了固氮酶铁蛋白和甲烷氧化菌含量,撂荒地的固氮酶铁蛋白、亚硝酸还原酶和甲烷氧化菌含量显著高于耕作土壤.结合土壤基本理化性质的相关性分析结果,pH、全氮和有机碳含量是影响土壤微生物群落丰度的重要因子.总之,长期施肥显著改变了黄土旱塬农田土壤各微生物丰度,不同施肥模式、耕作方式对微生物群落丰度具有显著影响.

Effects of long-term fertilization on soil microbial abundance in farmland of the Loess Plateau,China

Based on a long-term experiment in the Changwu Agro-ecological Experimental Station, the real-time PCR analysis was used to examine the soil microbial abundance and to reveal the effects on soil microbial community under different long-term fertilization systems. The results showed that compared to the CK (barren field), the population of bacteria increased by 21% and archaea by 32% in treatment with inorganic fertilizer application. The abundance of bacteria in the treatment of chemical fertilizer combined with organic fertilizer increased by 37% and archaea by 36%. The treatment with chemical fertilizer mixed with organic fertilizer significantly increased the abundance of bacteria and archaea. The soil AOB increased by 7.13 times while the soil AOA only by 0.2 folds after 30-year application of chemical nitrogen fertilizer. AOB was highly responsive to fertilizer application, especially to nitrogen fertilizer. Compared with the single nitrogen application and the application of nitrogen fertilizer mixed with organic fertilizer, phosphorus fertilizer significantly increased the abundance of nifH and pmoA. The content of nifH, nirS cd and pmoA in the abandoned land was significantly higher than that in the cultivated soil. Results from the correlation analysis on soil basic physical and chemical properties indicated that soil pH, total nitrogen and organic carbon were key factors affecting soil microbial community abundance. In conclusion, long-term fertilization significantly changed soil microbial abundance, and fertilization patterns and cultivating methods had significant effect on microbial community abundance.