长期不同施肥对潮土芽胞杆菌数量的影响及其优势度的季节变化

以河南封丘潮土养分平衡长期定位试验地为研究对象,于各季节分别采集耕作层土壤样品,比较不同施肥处理潮土芽胞杆菌数量及其占细菌总数的比例,并解析其与土壤养分之间的关系.结果发现,与不施肥对照相比,长期施肥尤其是施用有机肥和磷肥的处理土壤有机碳与速效氮、有效磷、速效钾等的含量趋于升高,除不施磷肥处理(NK)外其他施肥处理土壤有机碳含量在四季的增幅范围为0.91 ～7.00 g kg-1.长期不同施肥后土壤细菌与芽胞杆菌在数量上也发生了明显分异,且在各季均呈现稳定的梯度规律,即施肥处理(除NK外)显著高于不施肥处理、施有机肥处理显著高于施化肥处理、平衡施化肥处理高于缺素施肥处理,除NK外其他施肥处理与不施肥对照相比在四季的增幅范围力0.02～0.54 lg(CFU g-1).长期施化肥的处理芽胞杆菌占细菌数量的比例(即优势度)在冬、夏季高于春、秋季,而施有机肥的处理在不同季节保持相对恒定.相关性分析显示,芽胞杆菌数量与土壤有机碳和有效磷含量均呈极显著相关(p＜0.01).长期施用有机肥更有利于提高土壤肥力、促进土壤微生物生长繁育,且芽胞杆菌的数量可敏感地反映土壤肥力.

Effect of long-term fertilization regime on population of bacilli and seasonal variation of its dominance in fluvo-aquic soil

Soil samples were collected in every season of a year from the plow layer of a long-term fertilization experimental field at the Fengqiu Agro-ecological Experimental Station, Fengqiu County, Henan Province, China, for investigation of effects of fertilization regimes on population of soil Bacilli and its proportion to the total of bacteria, and for analysis of relationship between population of Bacilli and soil fertility. The long-term fertilization experiment consisted of seven treatments, i.e. organic manure (OM), half the rate of organic manure plus half the rate of N fertilizer (1/2OMN), fertilizer NPK, fertilizer NP, fertilizer NK, fertilizer PK, and the control (without fertilizer), of which each had four replicates. Results show that long-term fertilization, especially in treatments that involved organic manure and fertilizer P, increased the contents of soil organic C, total N, mineral N, available P and available K, and the increase in soil organic C varied in the range of 0.91~7.00 g kg-1 in all the fertilization treatments, except Treatment NK. Regime of the long-term fertilization also significantly affected populations of Bacilli and soil bacteria, which showed steady gradients in all the seasons, that is, the populations were significantly higher in all the fertilization treatments, except NK than in the control; in the treatments involving organic manure than in the treatments involving chemical fertilizers only; and in the treatment of balanced fertilization than in the treatments missing any one element. The population of Bacilli increased in all the treatments except Treatment NK by a range of 0.02~0.54 lg (CFU g-1) as compared that in the control. The ratio of Bacilli/bacteria was higher in summer and winter than in spring and autumn in all the chemical fertilizer treatments and relatively stable throughout the year in the treatments involving OM. Correlation analysis that the population of Bacilli was closely related to the contents of soil organic carbon and available P (p<0.01). All the findings demonstrate that, long-term application of organic manure is more conducive to build-up of soil fertility and growth and propagation of soil microbes, and that the population of Bacilli is a sensitive indicator of soil fertility.