Measuring the growth rate of a microorganism is a simple yet profound way to quantify its effect on the world. The absolute growth rate of a microbial population reflects rates of resource assimilation, biomass production and element transformation—some of the many ways in which organisms affect Earth’s ecosystems and climate. Microbial fitness in the environment depends on the ability to reproduce quickly when conditions are favourable and adopt a survival physiology when conditions worsen, which cells coordinate by adjusting their relative growth rate. At the population level, relative growth rate is a sensitive metric of fitness, linking survival and reproduction to the ecology and evolution of populations. Techniques combining omics and stable isotope probing enable sensitive measurements of the growth rates of microbial assemblages and individual taxa in soil. Microbial ecologists can explore how the growth rates of taxa with known traits and evolutionary histories respond to changes in resource availability, environmental conditions and interactions with other organisms. We anticipate that quantitative and scalable data on the growth rates of soil microorganisms, coupled with measurements of biogeochemical fluxes, will allow scientists to test and refine ecological theory and advance process-based models of carbon flux, nutrient uptake and ecosystem productivity. Measurements of in situ microbial growth rates provide insights into the ecology of populations and can be used to quantitatively link microbial diversity to soil biogeochemistry.

测量微生物的生长速度是量化其对世界影响的一种简单而深刻的方法。微生物种群的绝对增长率反映了资源同化、生物量生产和元素转化的速率——生物体影响地球生态系统和气候的多种方式中的一些。环境中的微生物适应性取决于在条件有利时快速繁殖的能力，并在条件恶化时采用生存生理学，这些细胞通过调整其相对生长速率来协调。在种群水平上，相对增长率是衡量适应性的敏感指标，将生存和繁殖与种群的生态和进化联系起来。将组学和稳定同位素探测相结合的技术能够对土壤中微生物组合和单个分类群的生长速率进行灵敏测量。微生物生态学家可以探索具有已知性状和进化历史的分类群的生长速度如何响应资源可用性、环境条件和与其他生物相互作用的变化。我们预计，关于土壤微生物生长速率的定量和可扩展数据，加上生物地球化学通量的测量，将使科学家能够测试和改进生态学理论，并推进基于过程的碳通量、养分吸收和生态系统生产力模型。原位微生物生长速率的测量有助于深入了解种群的生态学，并可用于定量地将微生物多样性与土壤生物地球化学联系起来。