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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #299715
Title: The effect of rare earth elements on phosphorus leaching in intact soil columns

Author
item Church, Clinton
item Buda, Anthony
item Kleinman, Peter
item Saporito, Louis - Lou

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2015
Publication Date: 9/15/2016
Citation: Church, C., Buda, A.R., Kleinman, P.J., Saporito, L.S. 2016. The effect of rare earth elements on phosphorus leaching in intact soil columns. Journal of Soil and Water Conservation. 71:365-376. doi: 10.2489/jswe.71.5.365.

Interpretive Summary: Phosphorus has been linked to eutrophication in surface waters because it is a limiting nutrient for algal growth, and recent studies have shown that phosphorus (P) transfers through subsurface flow is of growing concern. Dairy and poultry manures were amended with lanthanum and ytterbium chlorides to assess the use of rare earth element to reduce phosphorus leaching through intact soil columns and determine the major pathways of applied P leaching. Results point to the efficacy of REE-chlorides in lowering P solubility in liquid manures but indicate limited potential in tracking sub-surface transport pathways of applied manure P in soils.

Technical Abstract: Phosphorus has been linked to eutrophication in surface waters because it is a limiting nutrient for algal growth, and recent studies have shown that phosphorus (P) transfers through subsurface flow is of growing concern. In this study we amended dairy and poultry manures with lanthanum and ytterbium chlorides to assess the efficacy of using rare earth element (REE) chloride amendments in reducing P leaching through intact soil columns and to determine the major pathways of applied P leaching. Significant reductions in dissolved P (DP, 56% – 64%), particulate P (22% – 36%), and total P (41% – 51%) in leachate were seen when dairy manure was amended with REE-chlorides, but no significant reductions in these P fractions were seen in amended poultry litter. Differences in P leaching losses between the two REE-amended manures were likely due to better mixing and dissolution of the REE-chlorides and better precipitation of an insoluble particulate REE-phosphate salt in the liquid manures prior to being applied. Very little vertical transport of REEs was observed in soil leachate over repeated events. Elevated concentrations of REEs along soil macropores at depths greater than 15 cm suggest the importance of this pathway. However, due to the extremely low concentrations of REEs found at depth and the much higher values of soil P, the ability to “label” the manures with REEs to track P through macropores in the soil was only suggestive and by no means conclusive. Results point to the efficacy of REE-chlorides in lowering P solubility in liquid manures but limited potential in tracking sub-surface transport pathways of applied manure P in soils.