A simple equation for simulating C decomposition in a multi‐component pool of soil organic matter

Summary Partitioning carbon (C) pools presents theoretical and practical challenges in soil modelling. In most current models, organic matter (OM) is commonly divided into a number of pools using data‐fitting techniques. It is often not possible to measure the properties of each pool of soil C simulated in this way. Furthermore, there is no effective way in current soil models to properly simulate inputs of OM with variable qualities in terms of decomposability. Here, we describe a simple model, taking the OM as a whole and assuming a rate constant function changing exponentially with time, to simulate C decomposition in a multi‐component OM pool. The model requires fewer parameters to be estimated than current multi‐component models, and the simulated properties of OM are measurable. When changing the quantity and the quality of OM input, the model produces results similar to multi‐component models, but avoids the difficulty and uncertainty of OM partitioning.