Soil bacteria live in patchy and dynamic environments where cells in adjacent microhabitats may realize vastly different generation times ranging from hours to years within small soil volumes. This study links bacterial population demographics with soil conditions to better estimate mean bacterial cell ages by tracking individual lineages over space and time using a mechanistic model of bacterial life in soil. Results show heavy-tailed distributions of generation times that follow a power law across all hydration conditions, implying no simple definition of mean soil bacterial age where soil volumes may harbor cells with very broad range of ages living side by side. The study highlights ubiquitous conditions that support a “genetic reservoir” of physiological traits for each bacterial species that may be preserved in soil cold spots and reintroduced during episodic reunification events (soil wetting).