In mid latitude regions of North America, many soils are subjected to freeze-thaw conditions (Fr–Th) during the late winter and early spring months. Fr–Th events are usually accompanied by flushes of C and N mineralization, yet, the concomitant response of nitrification has not been consistently characterized. A laboratory experiment was conducted on three soils that differ in their annual history of exposure to freeze-thaw events, and where both ammonia oxidizing bacteria (AOB) and archaea (AOA) are capable of contributing to nitrification activity at 10 and 16 °C under NH₄⁺ replete conditions. Emergence and rates of N mineralization/nitrification were compared between soils frozen at −20 °C, with non-frozen soils stored at 4 °C. In all soils N mineralization commenced immediately (<1 d) in the Fr–Th soil treatments. Rates and/or amounts of mineralizable N released during the flush differed between soils, but rates for each soil were the same at 10 and 16 °C. Only ammonia oxidizing archaea (AOA)-driven nitrification emerged immediately (<1 d) from the Fr–Th treatment of the two soils with a history of freezing; these rates were higher at 16 than at 10 °C, and were not NH₄⁺ limited. No AOB activity was detected in these soils for up to 3 d. AOB contribute the vast majority (88–92%) of nitrification under NH₄⁺ replete conditions in the soil that rarely freezes. In this soil AOA did not contribute to nitrification in the Fr–Th treatment, and the emergence of AOB activity was delayed for 3 d at 10 °C unless supplemental NH₄⁺ was provided, but commenced immediately at 16 °C with or without supplemental NH₄⁺; however, rates of nitrification at 10 and 16 °C did not differ. The dominance of AOA activity immediately after Fr–Th in soils with a history of freezing suggests that AOA handle the transition during the freeze-down phase, and/or recover during the freeze-thaw phase with less constraint of NH₄⁺ availability and temperature, than the AOB.

在北美中纬度地区，许多土壤在冬季末期和春季初月份经历了冻融条件（Fr–Th）。Fr–Th事件通常伴有C和N矿化的潮红，但是，硝化的伴随响应并未得到一致的表征。在三种土壤中进行了实验室实验，这三种土壤的年度暴露历史与冻融事件不同，并且氨氧化细菌（AOB）和古生菌（AOA）都能够在10和16°C的温度下促进硝化活性。 NH ₄ ⁺条件充实。比较了在-20°C冷冻的土壤和在4°C储存的非冷冻土壤的氮矿化/硝化的出现和速率。在Fr–Th土壤处理中，所有土壤中的N矿化立即开始（<1 d）。冲洗期间释放的矿化氮的速率和/或量在土壤之间有所不同，但每种土壤的速率在10和16°C时相同。从Fr-Th处理两种有冻结历史的土壤中，只有氨氧化古细菌（AOA）驱动的硝化作用立即出现（<1 d）。这些速率在16时高于10℃，并且不受NH ₄ ⁺限制。在长达3 d的土壤中未检测到AOB活性。在NH ₄ ⁺下，AOB占硝化作用的绝大部分（88–92％）土壤中很少冻结的充足条件。在这种土壤中，AOA在Fr–Th处理中没有促进硝化作用，除非提供补充的NH ₄ ⁺，否则AOB活性的出现在10°C的环境中延迟了3天，但在有或没有补充的情况下在16°C时立即开始。 NH ₄ ⁺ ; 但是，在10和16°C下的硝化速率没有差异。在具有冻结历史的土壤中，在Fr–Th之后紧随其后的AOA活性占主导地位，这表明AOA可以在冻结阶段处理过渡，和/或在融化阶段恢复生长，而对NH ₄ ^+的可用性和温度的约束较少，而不是AOB。