Soybean growth and production as affected by struvite as a phosphorus source in eastern Arkansas

Struvite (MgNH₄PO₄·6H₂O) has been precipitated from liquid waste streams to recover valuable nutrients, such as phosphorus (P) and nitrogen (N), that can be used as an alternative fertilizer-P source. Because prior research has focused on greenhouse studies, it is necessary to expand struvite evaluations to the field-scale to include row-crop responses. The objective of this field study was to evaluate the effects of two struvite materials (electrochemically precipitated struvite, ECST; and chemically precipitated struvite, CPST) relative to other common fertilizer-P sources (diammonium phosphate, DAP; triple superphosphate, TSP; rock phosphate, RP; and monoammonium phosphate, MAP) on soybean [Glycine max (L.) Merr.] response and economics in two consecutive growing seasons in a P-deficient, silt-loam soil (Aquic Fraglossudalfs) in eastern Arkansas. Averaged across years, soybean aboveground tissue P uptake was largest (P <.05) from ECST (28.4 kg ha⁻¹), which was similar to CPST (26.7 kg ha⁻¹) and TSP (25.9 kg ha⁻¹) and was smallest from RP (21.4 kg ha⁻¹). In 2019, seed yield was largest (P <.05) from ECST (4.1 Mg ha⁻¹), which was similar to DAP, CPST, RP, TSP, and MAP, and was smallest from the unamended control (3.6 Mg ha⁻¹). In 2020, seed yield was numerically greatest from CPST (2.8 Mg ha⁻¹) and was numerically smallest from ECST (2.2 Mg ha⁻¹). Results showed that wastewater-recovered struvite materials have the potential to be a viable, alternative fertilizer-P source for soybean production in a P-deficient, silt-loam soil, but further work is needed to confirm struvite's cost effectiveness.