Space and time‐resolved monitoring of phosphorus release from a fertilizer pellet and its mobility in soil using microdialysis and x‐ray computed tomography

Abstract

Phosphorus (P) is an essential nutrient for crops and precise spatiotemporal application of P fertilizer can improve plant P acquisition and reduce run-off losses of P. Optimizing application would benefit from understanding the dynamics of P release from a fertilizer pellet into bulk soil, which requires space and time-resolved measurements of P concentration in soil solution. In this study, we combined microdialysis and X-ray Computed Tomography to investigate P transport in soil. Microdialysis probes enable repeated solute sampling from one location with minimal physical disturbance, and their small dimensions permit spatially-resolved monitoring. We observed a rapid initial release of P from the source, producing high dissolved P concentrations within the first 24 hours, followed by a decrease in dissolved P over time compatible with adsorption onto soil particles. Soils with greater bulk density (i.e. reduced soil porosity) impeded the P pulse movement, which resulted in a less homogeneous distribution of total P in the soil column at the end of the experiment. Model fit to the data showed that the observed phenomena can be explained with diffusion and adsorption. Results showed that compared with conventional measurement techniques (e.g. suction cups), microdialysis measurements present a less invasive alternative. The time resolved measurements ultimately highlight rapid P dynamics that require more attention for improving P use efficiency.

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Identifiers

ORCID for Katherine Williams: orcid.org/0000-0001-6827-9261

ORCID for Daniel Mckay Fletcher: orcid.org/0000-0001-6569-2931

ORCID for Tiina Roose: orcid.org/0000-0001-8710-1063

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