Liming is a common agricultural practice to improve crop yields by raising soil pH. Liming also modulates the production and consumption of greenhouse gases (GHGs) in soils, but the direction and strength of such effects are largely unknown. Since lime application is not a dichotomous variable (application or not), but rather can be dosed according to crop requirements, a critical research gap is whether liming effects on GHG emissions are linear or follow alternate relationships. Based on two-years of data from a long-term field-liming experiment (initiated in 1942), we show that the relationship between an established soil pH gradient (pH of 3.77, 4.92, 6.39, and 6.84 in 1 M KCl extracts) and the emission of GHGs deviates from linearity. Liming increased carbon dioxide (CO₂) fluxes from ecosystem respiration, but there were no differences between limed treatments. The increased respiration was due to higher plant carbon (C) inputs and root respiration, enhanced decomposition activity (β-glucosidase) and increased abundance of specific microbial groups (e.g., cellulose-decomposing bacteria). Liming decreased nitrous oxide (N₂O) emissions due to increased N₂O reduction via denitrification and by promoting plant growth. Compared with native acidic soil, lime application stimulated methane (CH₄) oxidation, but the highest liming rate was least stimulatory. This aligned with the soil CH₄ oxidation potential, which was modified by liming-induced changes in soil microbial structure as indicated by phospholipid fatty acid analyses. There were no differences in soil organic C (SOC) content between liming levels, apparently because increased ecosystem respiration rates compensated for higher plant C inputs from limed plots. Overall, our results reveal a fundamental ecological trade-off: applying lime at a rate that maximizes crop yield with low N₂O emissions may increase CO₂ emissions (not compensated by higher SOC in a sandy soil) and decrease CH₄ oxidation compared to liming applications below this level.

撒石灰是通过提高土壤pH值来提高农作物产量的常见农业实践。石灰还调节土壤中温室气体（GHGs）的产生和消耗，但是这种作用的方向和强度在很大程度上尚不清楚。由于石灰的施用不是二分变量（施用与否），而是可以根据作物需求进行配量，因此关键的研究差距是石灰对温室气体排放的影响是线性的还是遵循交替关系。基于长期野外试验（始于1942年）的两年数据，我们显示了已建立的土壤pH梯度之间的关系（1 M KCl提取物中的pH值为3.77、4.92、6.39和6.84）温室气体的排放偏离线性。石灰增加的二氧化碳（CO ₂）从生态系统呼吸的流量，但石灰处理之间没有差异。呼吸增加的原因是较高的植物碳（C）输入量和根部呼吸，分解活性（β-葡萄糖苷酶）增强和特定微生物基团（例如，分解纤维素的细菌）的丰度增加。由于通过反硝化和促进植物生长而增加的N ₂ O减少，石灰使减少的一氧化二氮（N ₂ O）排放减少。与天然酸性土壤相比，石灰的施用刺激了甲烷（CH ₄）的氧化，但最高的增钙速率却刺激最少。这与土壤CH ₄对齐氧化电位，这是通过石灰诱导的土壤微生物结构的变化引起的，该变化通过磷脂脂肪酸分析表明。石灰水平之间的土壤有机碳（SOC）含量没有差异，这显然是因为增加的生态系统呼吸速率可以补偿石灰土地上较高的植物碳输入。总的来说，我们的结果揭示了一个基本的生态平衡：与低N ₂ O排放相比，以最大的农作物产量施用石灰可以增加CO ₂排放（未被沙质土壤中较高的SOC补偿）并减少CH ₄氧化。将应用程序限制在此级别以下。