Denitrification is a major source of the greenhouse gas N₂O. As a result of spatial heterogeneity of organic carbon, oxygen and nitrate, denitrification is observed even under relatively dry conditions. However, it is unclear whether denitrification potentials of microbial communities exhibit spatial patterns relative to variations in distance to soil pores facilitating oxygen exchange and nutrient transfer. Thus, we determined genetic and process-level denitrification potentials in two contrasting soils, a cropland and a grassland, with respect to the distance to air-filled pores. An X-ray computed tomography aided sampling strategy was applied for precise sampling of soil material. Process-level and genetic denitrification potentials in both soils were spatially variable, and similar with respect to distance to macropores. In the cropland soil, a minor increase of process-level potentials with distance to pores was observed and related to changes in NO₃⁻ rather than oxygen availability. Genetic denitrification potentials after the short-term incubations revealed a certain robustness of the local community. Thus, distance to macropores has a minor impact on denitrification potentials relative to the observed spatial variability. Our findings support the notion that the impact of macropore induced changes of the environmental conditions in soil does not overrule the high spatial variability due to other controlling factors, so that the rather minor proportion of spatial heterogeneity of functional genes and activity potentials related to macropore distances in soil need not be considered explicitly in modelling denitrification.

反硝化作用是温室气体N ₂ O的主要来源。由于有机碳、氧和硝酸盐的空间异质性，即使在相对干燥的条件下也能观察到反硝化作用。然而，尚不清楚微生物群落的反硝化潜力是否表现出相对于促进氧交换和养分转移的土壤孔隙距离变化的空间模式。因此，我们确定了两种对比土壤（农田和草地）中相对于充满空气的孔隙的距离的遗传和过程水平反硝化潜力。应用 X 射线计算机断层扫描辅助采样策略对土壤材料进行精确采样。两种土壤的过程水平和遗传反硝化潜力在空间上是可变的，并且在与大孔的距离方面相似。在农田土壤中，观察到过程水平电位随着距孔隙距离的增加而略有增加，这与 NO ₃ ⁻的变化有关，而不是氧气可用性的变化。短期孵化后的遗传反硝化潜力揭示了当地社区的一定稳健性。因此，相对于观察到的空间变化，到大孔的距离对反硝化潜力的影响较小。我们的研究结果支持这样的观点，即大孔引起的土壤环境条件变化的影响并不能排除其他控制因素导致的高空间变异性，因此与大孔距离相关的功能基因和活动潜力的空间异质性比例相当小在反硝化建模中不需要明确考虑土壤中的污染物。