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

A 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.