Databases of soil pH values today not only guide the decisions of land managers but also the biogeochemical models and experimental designs of microbiologists and soil ecologists. Soil acidity underpins fundamental properties and functions in the soil, such as the solubilities of exchangeable ions and nutrients, or bacterial use of gradients of internal and external acidity to generate ATP and turn flagellar motors. Therefore, it is perhaps unsurprising that soil pH has emerged as the strongest predictor of soil bacterial community composition. However, the measurement of these particular values today does not address whether soil pH accurately represents the in situ acidity of soil microhabitats where microorganisms survive and reproduce. This study analyzes and compares soils of a large-scale natural soil pH gradient and a long-term experimental soil pH gradient for the purposes of testing new methods of measuring and interpreting soil acidity when applied to soil ecology. We extracted and prepared soil solutions using laboratory simulation of levels of carbon dioxide and soil moisture more typical of soil conditions while also miniaturizing traditional methods using a centrifuge for extractions. The simulation of in situ soil conditions resulted in significantly different estimates of soil pH. Furthermore, for soils from the long-term experimental soil pH gradient trial, the simulated soil pH values substantially improved predictions of bacterial community composition. We offer suggestions and cautions for researchers considering how to better represent soil acidity.

今天的土壤 pH 值数据库不仅指导土地管理者的决策，而且指导微生物学家和土壤生态学家的生物地球化学模型和实验设计。土壤酸度是土壤基本特性和功能的基础，例如可交换离子和养分的溶解度，或细菌利用内部和外部酸度梯度来产生 ATP 和转动鞭毛马达。因此，土壤 pH 值已成为土壤细菌群落组成的最强预测因子，这可能不足为奇。然而，今天对这些特定值的测量并没有解决土壤 pH 值是否准确地代表原位的问题。微生物生存和繁殖的土壤微生境的酸度。本研究分析和比较了大规模自然土壤 pH 梯度和长期实验土壤 pH 梯度的土壤，目的是测试应用于土壤生态学时测量和解释土壤酸度的新方法。我们使用实验室模拟更典型的土壤条件的二氧化碳和土壤水分水平来提取和制备土壤溶液，同时还将使用离心机进行提取的传统方法小型化。原位模拟土壤条件导致对土壤 pH 值的估计存在显着差异。此外，对于来自长期实验土壤 pH 梯度试验的土壤，模拟的土壤 pH 值大大提高了对细菌群落组成的预测。我们为考虑如何更好地代表土壤酸度的研究人员提供建议和注意事项。