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[目的]评价硝化反硝化作用在果园土壤氮素损失中的贡献率以及N2O的排放量和排放特性。[方法]在室内培养条件下比较研究了3种不同园龄果园土壤及未开垦土壤之间硝化反硝化活性的差异。[结果]培养26天的未开垦土壤、5年、12年和20年园龄果园土壤的氮肥硝化率分别为6.85%、10.26%、13.29%和12.90%。4种土壤硝化活性均相对较低,但随种植年限的延长呈提高趋势,而且与土壤有机质和铵态氮含量呈显著正相关关系(P<0.05),与全氮含量呈极显著正相关关系(P<0.01),与土壤碳氮比呈显著负相关关系(P<0.05),与pH值呈极显著负相关关系(P<0.01)。3种果园土壤N2O排放量显著高于未开垦土壤(P<0.05),其中硝化作用产生的N2O排放量占施氮量的0.03%～0.08%。硝化过程产生的N2O排放量与土壤有机质、全氮、铵态氮含量呈显著正相关关系(P<0.05),而与土壤碳氮比呈显著负相关系(P<0.05),与pH值呈极显著负相关关系(P<0.01)。不同园龄果园土壤之间氮肥的反硝化活性差异显著,表现为20年>12年>5年>未开垦土壤,反硝化损失氮量占施氮量的0.01%～3.11%,与土壤有机质含量呈显著正相关关系(P<0.05)。[结论]我国南方果园土壤硝化水平相对较低,但随种植年限的延长呈提高的趋势;而土壤反硝化水平相对较高,而且随种植年限的延长显著提高。
[Objective] The research aimed to evaluate the contribution rate of nitrification and denitrification to nitrogen loss in orchard soil and the emission and emission characteristics of N2O. [Method] The differences of nitrification and denitrification activities in orchard and uncultivated soils under three different garden ages were comparatively studied under indoor culture conditions. [Result] The nitrogen fertilization rates of the orchard garden in the cultivated 26-day cultivated orchard gardens for 5, 12 and 20 years were 6.85%, 10.26%, 13.29% and 12.90%, respectively. The four kinds of soil nitrification activities were relatively low, but increased with the extension of planting years, and had a positive correlation with soil organic matter and ammonium nitrogen (P <0.05), and had significant positive correlation with total nitrogen (P <0.01), negatively correlated with C and N (P <0.05), and negatively correlated with pH (P <0.01). The N2O emissions of the orchards were significantly higher than that of the uncultivated soils (P <0.05), of which N2O emissions from nitrification accounted for 0.03% ~ 0.08% of the N application. Nitrous oxide emissions from nitrification processes were positively correlated with soil organic matter, total nitrogen and ammonium nitrogen (P <0.05), but negatively correlated with soil C and N (P <0.05) Significantly negative correlation (P <0.01). The denitrification activities of nitrogen fertilizers in different orchard orchard soils differed significantly, which were 20 years> 12 years> 5 years> uncultivated soil, denitrification losses accounted for 0.01% ~ 3.11% of nitrogen application rate, and soil organic matter content There was a significant positive correlation (P <0.05). [Conclusion] The soil nitrification level in the southern orchard in China was relatively low, but increased with the extension of planting years. However, the soil denitrification level was relatively high and significantly increased with the extension of planting years.