Agricultural practices can lead to fluctuations in soil pH and salinity, likely affecting soil nutrient cycling. Compost addition may reduce the impact of these stresses, leading to more stable and resilient systems. We tested nitrogen (N) and carbon (C) cycling responses to the imposition and relief of an acute stress in an agricultural soil, and whether these responses were moderated by compost. In greenhouse pots, we mixed soil with elemental sulfur (S) and compost in a complete 2-way factorial design and incubated at ambient temperatures. Sulfur induced strong acidity and mild salinity stress. After 70 d, stress was partially alleviated by leaching with liquid lime. We took samples 21 and 42 d after S addition and one week after alleviation, measured enzyme activity, microbial biomass, and soluble organic C and N, and performed N and C cycle assays by incubating subsamples with and without ground legume residues to stimulate mineralization and microbial growth. Net N mineralization increased in response to the applied stress, and declined after alleviation. Conversely, stress reduced most C cycling indicators and inhibited nitrification. Stress limited microbial growth more than respiration. Unexpectedly, compost additions to the stressed soils consistently stimulated net N mineralization compared to stressed soils without compost. Compost thus exacerbated rather than buffered the effects of stress on net N mineralization. Compost addition did not affect microbial growth or respiration in any treatment, or how any C cycle parameter responded to stress. The decoupled C and N responses suggest that the localized stresses associated with intensive agriculture may have important implications for C and N turnover in these systems, and warrant further study. Additionally, they demonstrate that biogeochemical processes should be evaluated concurrently when accessing the effect of stressors in soil systems.

农业实践会导致土壤 pH 值和盐度的波动，可能会影响土壤养分循环。添加堆肥可以减少这些压力的影响，从而形成更稳定和更有弹性的系统。我们测试了氮 (N) 和碳 (C) 循环对农业土壤中急性压力的施加和缓解的反应，以及这些反应是否受到堆肥的调节。在温室花盆中，我们以完整的 2 向因子设计将土壤与元素硫 (S) 和堆肥混合，并在环境温度下培养。硫引起强酸和轻度盐胁迫。70 天后，通过液体石灰浸出部分缓解了压力。我们在添加硫后 21 天和 42 天和缓解后 1 周取样，测量酶活性、微生物生物量和可溶性有机碳和氮，并通过孵育含有和不含磨碎豆类残留物的子样品来进行 N 和 C 循环测定，以刺激矿化和微生物生长。净氮矿化因施加应力而增加，并在缓解后下降。相反，压力降低了大多数 C 循环指标并抑制了硝化作用。压力比呼吸更能限制微生物的生长。出乎意料的是，与没有堆肥的压力土壤相比，在压力土壤中添加堆肥始终刺激净氮矿化。因此，堆肥加剧而不是缓冲压力对净氮矿化的影响。添加堆肥不影响任何处理中的微生物生长或呼吸，也不影响任何 C 循环参数对压力的反应。解耦的 C 和 N 响应表明与集约化农业相关的局部压力可能对这些系统中的 C 和 N 周转具有重要意义，值得进一步研究。此外，他们证明，在访问土壤系统中压力源的影响时，应同时评估生物地球化学过程。