Optimizing pre-incubation periods for process-based studies in diverse soils

Pre-incubation is a critical step in process-based soil experiments to stabilize microbial activity and chemical conditions following disturbance caused by sampling, drying, and storage. However, the optimal duration required to achieve representative and stable conditions remains poorly defined across soil types. This study quantified stabilization dynamics across twelve contrasting Australian soils by monitoring mineral nitrogen (N), dissolved organic carbon (DOC) and nitrogen (DON), microbial biomass, and respiration during a 35-day pre-incubation following rewetting. Rewetting triggered rapid and consistent responses across soils, including an initial flush of CO 2 and elevated NH 4 + concentrations, followed by rapid declines within 7 days, reflecting microbial immobilization and nitrification. Dissolved organic matter pools exhibited dynamic turnover, with DON and DOC generally stabilizing between 7 and 14 days, while microbial biomass responses indicated an initial growth phase followed by stabilization within 7–21 days. Respiration rates declined rapidly but indicated longer stabilization times in some soils, highlighting differences between apparent and functional equilibrium. Despite variability among soils and variables, stabilization times converged within a narrow window, with a mean of 12.65 days. A pre-incubation period of approximately 10–14 days represents a robust compromise, allowing microbial and chemical stabilization while minimizing artefacts associated with extended pre-incubation.