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采用室内培养方法研究了灭菌及未灭菌条件下施用氮肥对石灰性土壤p H值、矿质态氮含量和CO2释放量的影响。结果表明:土壤CO2释放量随施氮量增加而显著增加,培养结束时未灭菌土壤CO2累积释放量比对照增加了21.8%~103.5%,平均增加62.7%,这与施氮促进有机质矿化及降低土壤p H值促进无机碳分解有关。采用哌嗪-1,4-二乙磺酸(PIPES)缓冲的Hg Cl2溶液灭菌后,培养期间不同施氮量下土壤铵态氮与硝态氮含量稳定,说明灭菌处理抑制了硝化作用的进行,灭菌效果良好。灭菌处理显著降低了土壤CO2释放量,但相比对照,施用氮肥也使CO2释放量增加了5.3%~17.8%,说明施用氮肥也促进了培养过程中土壤无机碳的释放。因此,应重视大量施用氮肥对石灰性土壤无机碳释放的影响。
The indoor culture method was used to study the effects of nitrogen fertilizer application on the p H value, mineral nitrogen content and CO2 emission of calcareous soil under sterile and non-sterile conditions. The results showed that the amount of soil CO2 emission increased significantly with the increase of nitrogen application rate, and the cumulative released amount of CO2 in non-sterilized soil increased by 21.8% -103.5% at the end of cultivation and increased by 62.7% on average, which was related to the N mineralization And reduce soil p H value to promote the decomposition of inorganic carbon. After being sterilized by PIPES buffer Hg Cl2 solution, the contents of ammonium nitrogen and nitrate nitrogen in soil were stable under different N rates during the cultivation, which indicated that the sterilization treatment inhibited the nitrification The sterilization effect is good. Sterilization treatment significantly reduced soil CO2 emissions, but compared with the control, application of nitrogen fertilizer also increased CO2 emissions by 5.3% ~ 17.8%, indicating that application of nitrogen fertilizer also promoted soil inorganic carbon release during culture. Therefore, attention should be paid to the effect of nitrogen fertilizer on the release of inorganic carbon in calcareous soils.