Analytical models of soil and litter decomposition: Solutions for mass loss and time-dependent decay rates

► Single and multiple-cohort decomposition studies require different model solutions. ► A unifying theory to describe both is presented and applied to 8 common models. ► This theory yields temporal changes in mass loss and apparent decay rate. ► We found that litter and SOM data are best described by different models. ► The apparent first-order decay rate declines over time during decomposition.