ISMC2021-8
https://doi.org/10.5194/ismc2021-8
3rd ISMC Conference ─ Advances in Modeling Soil Systems
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Spatiotemporal assessment of phosphorus release from a fertiliser granule and its diffusion into bulk soil: a combined experimental and modelling study

Chiara Petroselli, Katherine A. Williams, Arpan Ghosh, Daniel McKay Fletcher, Siul A. Ruiz, Tiago Gerheim Sousa Dias, Callum P. Scotson, and Tiina Roose
Chiara Petroselli et al.
  • Bioengineering Sciences Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Sciences, University of Southampton

Phosphorus (P) is a limiting nutrient for crops and it is therefore highly managed in human activities such as agriculture. Not only the global phosphate rock reserves are going to be exhausted in a century, but P can also be lost from fields with the runoff ending up contaminating water bodies and causing eutrophication.

This study is aimed at investigating P release from a fertiliser granule at high spatial and temporal resolution to optimise fertilisation timing, match crop requirements and reduce runoff. Experimental data consist of time-resolved P concentration in the soil solution at three different depths and total P concentration profile determined via total soil digestion. We observed a rapid, single-pulse release of P from the fertiliser granule shortly after soil wetting (<2h). The pulse reaches the furthest probe (3 cm) within the same timeframe, then P concentration in the soil solution gradually decreases over the following 150 hours due to adsorption.

As the experimental data did not match the model-predicted P diffusion behaviour, a new modelling approach was used to reproduce the data. The model accounts for P diffusion and adsorption onto soil particles, resulting in the temporal evolution of P concentrations both in the soil solution and adsorbed onto soil particles. As the final total P concentration in soil reflects the initial P concentration profile in the soil solution, the model shows that adsorption onto soil particles happens faster than diffusion. Additionally, the model gives an estimate of diffusion, adsorption and desorption rates, as well as the maximum distance that P can travel from the source.

Combining high-resolution experiments with modelling provided a new insight into P release and diffusion from a fertiliser granule. The results can inform optimal fertilisation timings to improve crop yields while reducing P application rates and undesirable side effects such as eutrophication.

How to cite: Petroselli, C., Williams, K. A., Ghosh, A., McKay Fletcher, D., Ruiz, S. A., Gerheim Sousa Dias, T., Scotson, C. P., and Roose, T.: Spatiotemporal assessment of phosphorus release from a fertiliser granule and its diffusion into bulk soil: a combined experimental and modelling study, 3rd ISMC Conference ─ Advances in Modeling Soil Systems, online, 18–22 May 2021, ISMC2021-8, https://doi.org/10.5194/ismc2021-8, 2021.