施氮对贫瘠红壤定植芒草根际土有机碳矿化过程的影响

为了探究不同施氮量对长期定植芒属植物后酸性红壤中固定的土壤有机碳矿化过程的影响，本研究以长期定植芒草的根际红壤为试验材料，采用控制变量法开展土壤有机碳矿化培养试验。结果表明：施氮极显著降低了土壤有机碳矿化量，随着施氮量的升高而降低，呈现极显著的负激发效应(P<0.001)。与不施氮相比，低氮与高氮处理下土壤有机碳矿化速率在培养后第60天分别降低了35.47%和45.43%,土壤有机碳累积矿化量分别降低了19.04%和27.85%。随着施氮量的增加，土壤pH值、可溶性有机碳、微生物代谢熵呈现下降趋势，减幅分别达10.46%～14.07%,63.00%～68.36%,38.21%～46.44%;土壤微生物生物量、微生物生物量氮和铵态氮在低氮处理下最高，分别为272.62 mg·kg^-1,42.59 mg·kg^-1和33.14 mg·kg^-1。本研究发现，高水平施氮会降低土壤pH值、可溶性有机碳，从而抑制红壤有机碳矿化过程，进一步稳定芒属植物种植对酸性红壤有机碳的积累效应。

Effects of Nitrogen Application on Organic Carbon Mineralization in Rhizosphere Soil of Miscanthus spp .in the Barren Red Soil

The study was designed to explore the effect of different nitrogen application rates on the mineralization process of soil organic carbon in acid red soil of the land after long-term cultivation of Miscanthus spp.The collected rhizosphere soil samples were applied with different N application rates,then incubated using controlled variable method.The results showed that:N application significantly reduced soil organic carbon mineralization,which decreased with the increase of nitrogen application,presenting an extremely significant negative priming effect (P<0.001).Compared with no nitrogen application,the carbon mineralization rate under low-nitrogen and high-nitrogen treatments at 60 d decreased by 35.47% and 45.43%,respectively.Meanwhile,the cumulative mineralization of soil organic carbon decreased by 19.04% and 27.85%,respectively.With the increase of nitrogen application,the soil pH,dissolved organic carbon content,and the metabolic quotient showed a downward trend,with a decrease of 10.46% to 14.07%,63.00% to 68.36%,and 38.21% to 46.44%.The highest soil microbial biomass,microbial biomass nitrogen and ammonium nitrogen were 272.62 mg·kg^-1,42.59 mg·kg^-1 and 33.14 mg·kg^-1,respectively,under low nitrogen treatment.The study found that high level of nitrogen application reduced soil pH and soil dissolved organic carbon,and thereby inhibited the organic carbon mineralization process of red soil,and further stabilized the organic carbon accumulation effect of Miscanthus spp.on acidic red soil.