Electrochemically precipitated struvite effects on extractable nutrients compared with other fertilizer‐phosphorus sources

Abstract

Abstract Recovery of struvite, or magnesium ammonium phosphate (MgNH4PO4 · 6H2O), from wastewater streams may provide an alternative to traditional P fertilizers. Little research has assessed the behavior of struvite relative to other commercially available, fertilizer‐P sources in historically row‐cropped soils in the United States. The objective of this study was to evaluate total extractable P and other nutrients from electrochemically (ECST) and chemically precipitated struvite (CPST) compared with triple superphosphate (TSP), diammonium phosphate (DAP), monoammonium phosphate (MAP), and rock phosphate (RP) in a moist‐soil incubation without plants using varying soil textures (loam, silt loam, and silty clay loam). A uniform application rate of 24.5 kg total P ha–1 was used for each fertilizer‐P source. Soil sampling occurred six times over a 9‐mo period (0.5, 1, 2, 4, 6, and 9 mo) to examine the change in soil pH and water‐soluble (WS) and Mehlich‐3‐extractable nutrient concentrations (P, Ca, Mg, and Fe) from their initial levels over time. After 0.5 mo, WS‐P concentrations increased the most in the ECST treatment (41.6 mg kg–1), which did not differ from that of DAP. Throughout the remaining 8.5 mo of incubation, WS‐P concentrations generally decreased in most treatments but were still greater than the initial level by 9 mo and were often similar among ECST, CPST, MAP, DAP, and TSP treatments. Comparable WS‐P concentrations among ECST and MAP, DAP, and TSP under soil conditions near field capacity (∼0.2 g g–1) support struvite's potential as a sustainable fertilizer‐P source, thus warranting further investigation of the plant response to struvite use as an alternative fertilizer‐P source.