Electrochemically Precipitated Struvite Effects on Extractable Soil Nutrients in Multiple Soil Textures

Struvite recovery from wastewater streams may provide an alternative to traditional fertilizer-phosphorus (P) sources, while also providing the benefit of reducing nitrogen and P loads in wastewater effluent and reducing effects of eutrophication in surface waters. The objective of this study was to assess the effects of fertilizer-P source (i.e., synthetically produced electrochemically precipitated struvite [ECST], chemically precipitated struvite [CPST], monoammonium phosphate [MAP], diammonium phosphate [DAP], triple superphosphate [TSP], rock phosphate [RP], and an unamended control [UC]) on water-soluble (WS) and Mehlich-3 (M3)-extractable soil nutrients (i.e., K, S, Na, Mn, Zn, Cu, and B) periodically over a 9-month period (i.e., 0.5, 1, 2, 4, 6, and 9 months) in multiple soil textures. All WS and M3 nutrients were affected by a combination of soil, fertilizer treatment and/or sampling time. Both WS- and M3-S concentrations increased from the initial for all fertilizer treatments, but the increase was the greatest with DAP (26.3 mg∙kg−1 and 23.4 mg∙kg−1, respectively), which differed from MAP and TSP that had increases that were intermediate and were greater than for ECST, CPST, and the UC. Mehlich-3-Na concentrations increased from the initial after 0.5 months before decreasing from the initial after 1 month and steadily increasing until 9 months, at which point M3-Na concentrations had increased the most from the initial (12.26 mg∙kg−1). Changes in WS and M3 nutrients were often similar among ECST, CPST, MAP, DAP, TSP, and RP, supporting the potential for struvite to be an effective alternative fertilizer-P source.