Soil Chemical Property Changes over Time from Struvite Compared to Other Fertilizer-Phosphorus Sources in Multiple Soils

Abstract

Studies have shown that phosphorus (P) recovered from wastewater as the mineral struvite [MgNH 4 PO 4 &#183; 6(H 2 O)] may be a viable alternative fertilizer-P source. This study aimed to compare the effectiveness of electrochemically precipitated struvite (ECST), reclaimed from synthetic wastewater, to other commercial fertilizer-P sources in cultivated soils from Arkansas [AR; silt loam (SiL) and loam (L)], Missouri (MO; SiL), and Nebraska [NE; SiL and sandy loam (SL)]. A plant-less, moist-soil incubation experiment, including ECST, chemically precipitated struvite (CPST), monoammonium phosphate (MAP), triple superphosphate (TSP), and an unamended control (UC), was conducted to quantify soil pH, nitrate (NO 3 -N), ammonium (NH 4 -N), and Mehlich-3 (M3)-P, -Ca, -Mg, and -Fe concentrations at 0.5, 1, 2, 4, and 6 months. All measured soil properties differed ( P < 0.05) among fertilizer-P sources within soils over time. Soil-fertilizer combinations generally had an acidifying effect over time, with pH change from the initial lower at 6 than at 0.5 months and lower than the initial soil pH. Soil NO 3 -N generally increased among fertilizer-P sources, ranging from an increase of 10.1 to 221 mg &#183; kg -1 for AR-L-TSP after 1 month and NE-SiL-MAP after 6 months, respectively. Soil M3-P ranged from -29.6 mg &#183; kg -1 in the AR-L-UC after 1 month to 429 mg &#183; kg -1 AR-SiL-TSP after 0.5 months. Results showed that, over time, ECST had comparable pH and soil NO 3 -N, NH 4 -N, and M3-P, -Ca, -Mg, and -Fe behavior compared to CPST, MAP, and TSP across various soil textures.