Leaching characteristics of electrochemically precipitated struvite compared to other common phosphorus fertilizers in differing soils

Abstract

AbstractPhosphate‐rich struvite (MgNH4PO4·6H2O) can be reclaimed from wastewater as a fertilizer material to help provide clean water and sustainable food production. The objective of this study was to evaluate the leaching characteristics of wastewater‐recovered electrochemically precipitated struvite (ECST) compared to other common fertilizer‐P sources in soils from Arkansas (AR loam and silt loam), Missouri (MO silt loam 1 and 2), and Nebraska (NE sandy loam and silt loam). A bench‐scale, soil‐column experiment was conducted using five fertilizer‐P sources (i.e., ECST, chemically precipitated struvite [CPST], monoammonium phosphate [MAP], triple superphosphate [TSP], and an unamended control [UC]) and leached six times over 15 weeks after fertilizer application. Leachate‐P concentration changes from the UC differed among soil–fertilizer combinations over time (p < 0.05) but only in the AR‐loam, where TSP (2.0–6.6 mg L−1) consistently had a larger leachate‐P change from the UC than ECST (−0.04 to 3.1 mg L−1) in weeks 1–3. Leachate‐NO3‐N concentration changes from the UC among soils occurred only in week 1, where three of the six soils had NO3‐N concentration increases >10.7 mg L−1 from their respective UC. Though inconsistent across the various soils evaluated, P‐leaching losses relative to respective UC treatments were often larger from MAP and TSP than ECST and CPST. Results showed that P, NH4‐N, NO3‐N, Ca, Mg, and Fe leaching potentials differed among soils depending on initial soil pH and texture and fertilizer‐P source; thus, soil characteristics and fertilizer‐P source should be considered to minimize potential nutrient leaching losses.