Quasi-steady uptake and bacterial community assembly in a mathematical model of soil-phosphorus mobility

•We create a simple three-species model of phosphorus and carbon uptake.•We show how nutrient dynamics can manifest as bacterial and plant community shifts.•We show how under sufficient nutrient supply, additional nutrient benefits bacteria with satiation in the plants.•We theoretically predict experimental community reassembly results between bacterial species.•Under certain parameter regimes, population and nutrient oscillations occur as has been observed in literature. We mathematically model the uptake of phosphorus by a soil community consisting of a plant and two bacterial groups: copiotrophs and oligotrophs. Four equilibrium states emerge, one for each of the species monopolising the resource and dominating the community and one with coexistence of all species. We show that the dynamics are controlled by the ratio of chemical adsorption to bacterial death permitting either oscillatory states or quasi-steady uptake. We show how a steady state can emerge which has soil and plant nutrient content unresponsive to increased fertilization. However, the additional fertilization supports the copiotrophs leading to community reassembly. Our results demonstrate the importance of time-series measurements in nutrient uptake experiments.