Total extractable phosphorus in flooded soil as affected by struvite and other fertilizer‐phosphorus sources

Abstract

AbstractA sustainable P source is imperative to ensure that food production can supply a growing global population. Wastewater‐recovered struvite (MgNH4PO4 · 6H2O) has emerged as an attractive option because of the ability to recover P from waste streams. This study aimed to evaluate total extractable soil P from electrochemically precipitated struvite (ECST) compared with other fertilizer‐P sources [chemically precipitated struvite (CPST), diammonium phosphate (DAP), and rock phosphate] in two soil textures (two different silt loams and a silty clay loam) over time in a flooded soil environment. An equivalent fertilizer rate of 24.5 kg P ha–1 was used. The change in water‐soluble (WS) and Mehlich‐3 (M3)‐extractable nutrient concentrations (P, K, Ca, Mg, and Fe) from their initial concentrations was determined five times over a 4‐mo period. After 0.5 mo, WS‐P increased the most from the initial value with DAP (27.6 mg kg–1), which did not differ from CPST or ECST. After 0.5 mo, M3‐P increased the most in ECST (82 mg kg–1), which did not differ from DAP. After 1 mo and thereafter under flooded conditions, M3‐P increased the most from the initial value and was similar among ECST, CPST, and DAP. After 3 and 4 mo, WS‐P was greater than the initial value in DAP only, but remained similar to CPST, ECST, and rock phosphate, which did not differ from the initial value. Comparable WS‐ and M3‐P concentrations among ECST, CPST, and DAP under flooded conditions support struvite's agronomic potential as a prospective sustainable fertilizer‐P source.