Soil profile distribution of nutrients in contrasting soils amended with struvite and other conventional phosphorus fertilizers

Phosphorus (P) can be recovered from wastewater and used as an alternative fertilizer, namely, struvite [MgNH₄PO₄·6(H₂O)]. However, the soil mobility of wastewater-derived P and other nutrients needs to be evaluated. The objective of this study was to compare the vertical distribution of water-soluble (WS) soil P and other nutrients from a synthetic-wastewater-derived electrochemically precipitated struvite (ECST) to that from a chemically precipitated struvite (CPST), triple superphosphate (TSP), monoammonium phosphate (MAP), and a control in six soils from Arkansas (AR; loam [L] and silt loam [SiL]), Missouri (MO; SiL 1 and SiL 2), and Nebraska (NE; sandy loam [SL] and SiL). A column-leaching experiment was conducted with the six soils and five fertilizer-P treatments. Water-soluble (WS) P from the two struvite materials generally did not differ (p > 0.05) and was similar to that of MAP in the depths of 0–3, 3–6, and 6–10 cm, but was greater than that of TSP in the top 6 cm in four of the six soils. WS P from CPST in the MO-SiL 2 and NE-SL soils (6.6 and 12.7 mg kg⁻¹, respectively) was larger than that from ECST, MAP, and TSP. In the AR-L and MO-SiL 1 soils, TSP was the only fertilizer-P source that had increased WS P concentrations in the top 6 cm relative to the other fertilizer-P sources. Results showed that ECST-derived, WS P had similar soil profile distributions in the top 10 cm, suggesting that ECST will be equally protective of environmental health and leachate quality across multiple soil textures as other common fertilizer-P sources.