Phosphorus (P) is an essential nutrient for all life forms and plays a vital role in a variety of fundamental reactions within organisms. Plants in particular need P for photosynthesis, nitrogen fixation, and seed development. Due to its key role in plant nutrition, in US Mid-Atlantic agricultural soils, P is applied to fields in the form of chicken manure and fertilizers. The repetitive addition of P leads to a buildup of the nutrient and results in soils with excessive levels of legacy P. Through leaching, erosion, and runoff, P makes its way into bodies of water where it may contribute to eutrophication. Eutrophication is caused by the over enrichment of nutrients, promoting algae growth whose decomposition leads to anoxic and hypoxic conditions that can cause fish kills. There are many different P species found within soil, each having differences in solubility and bond strength. By introducing soil taken from agricultural fields throughout the Mid-Atlantic region of the US to various extracting solutions, we can, to an extent, mimic the ionic strength of soil pore water (KCl extractable), acid rain (HNO3 extractable), and ligand exchange mechanisms (0.1 mM SiO4 2- extractable) to determine the rate at which P desorbs. By pairing the phosphorus desorption data with Mehlich-III extractable P, total P, and soil textural classification, we can begin to understand legacy phosphorus mobility in these soils. Additionally, we compared these bulk, wet chemical data with high resolution, micro X-ray fluorescence (µ-XRF) maps of the soil to determine P co-location with other elements of interest (Si, P, S, Al, Fe, Mn, Ca, and Mg). We then used micro X-ray absorption near edge structure (μ-XANES) spectra of P hotspots to help determine the solid phase P speciation at the micron scale. Comparison of the u-XRF maps with µ-XANES spectra show that the majority of P species probed in the soil are associated with Ca, potentially in the form of fluorapatite. Understanding the legacy P mobility and speciation in soils will help inform improved P management practices and reduce negative environmental impacts.

Legacy phosphorus desorption from U.S. Mid-Atlantic agricultural soils

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.