Inhibition of phosphorus sorption on calcite by dairy manure-sourced DOC. (October 2017)

• Record Type: Journal Article
• Authors: Weyers, Eva; Strawn, Daniel G.; Peak, Derek; Baker, Leslie L.
• Is Part Of: Chemosphere. Volume 184(2017)
• Page Start: 99
• Page End: 105
• Publication Date: 2017-10
• Subjects: Manure -- Phosphorus -- Calcite -- Calcareous soils -- Hydroxyapatite -- P L-edge XANES -- P K-Edge XANES -- Dissolved organic matter; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2017.05.141
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: In confined animal feeding operations, such as dairies, manure is amended to soils at high rates leading to increases in P and organic matter in the soils. Phosphorus reacts with soil-Ca to form Ca-P minerals, which controls P availability for leaching and transport through the watershed. In this research, the effects of manure sourced dissolved organic matter (DOM) on P sorption on calcite were measured at different reaction times and concentrations. Reactions were monitored in 1% and 10% manure-to-water extract solutions spiked with P. When manure-DOM was present, a significant reduction in P sorption occurred (2–90% absolute decrease) compared to samples without manure-DOM. The greatest decrease occurred in the samples reacted in the 10% manure solution. XANES spectroscopic analysis showed that at 1% manure solution, a Ca-P phase similar to hydroxyapatite formed. In the calcite samples reacted in the 10% manure solution, K-edge XANES spectroscopy revealed that P occurred as a Ca-Mg-P phase instead of the less soluble hydroxyapatite-like phase. Results from this study suggest that in manure-amended calcareous soils, increased DOM from manure will decrease P sorption capacity and increase the overall P concentration in solution, which will increase the mobility of P and subsequently pose greater risks for impairment of surface water quality. Graphical abstract: Highlights: Dairy manure added to calcareous soils releases dissolved organic carbon (DOC) and phosphate to the soil solution. Dairy-manure sourced DOC greatly reduces P sorption. High DOC levels promote formation of more soluble Ca-Mg-P minerals. Mg substituted amorphous hydroxyapatite minerals occur on calcite minerals exposed to dairy manure extract.