Microdialysis probes and digital twins reveal the rapid removal of fertiliser phosphate from the soil solution with an impact on crop nutrition in the short-term

Global food production depends on the application of phosphorus (P) fertilisers, usually sourced from rock phosphate, a non-renewable resource. Optimising P use to ensure sustainable P application is necessary to supply food worldwide and to protect the environment from P runoff. However, standard models used to guide P application on fields are limited due to assumptions that fail to consider the short-term dynamics of P in the soil solution. This study combined time-resolved microdialysis sampling with 4D spatial information from X-ray computed tomography to inform an image-based model for assessing P-soil-plant interactions over the start of a growing season. The time-resolved microdialysis measurements revealed that P released from the granules is rapidly removed from the soil solution in the short-term. We demonstrate that the standard equilibrium models typically used to characterise P transport in soil are not representative of the experimental system on the time scales considered. Instead, an Absorption-Diffusion model, where a single sink term accounts for all the processes removing P from the soil solution was required to correctly characterise experimental observations. Our study provides the basis for a model which could be adapted to predict within-season fertilisation scenarios in different soil conditions, and provides a conceptual description of plant/crop yield response to P fertilisation.