Phosphorus (P) is a major contaminant in many wastewater sources and has gained interest due to the role P has in eutrophication of receiving waters. Recycling P from wastewater as the mineral struvite (MgNH 4 PO 4 • 6H 2 O) could be a promising option to reduce P discharge into receiving waters and could potentially provide an alternative fertilizer-P source for crop production. The objective of this study was to evaluate the effects of two struvite materials (i.e., electrochemically precipitated struvite [ECST] and chemically precipitated struvite [CPST]) relative to several other common fertilizer-P sources (i.e., triple super phosphate [TSP], monoammonium phosphate [MAP], diammonium phosphate [DAP], and rock phosphate [RP]) on the response of a pureline rice (Oryza sativa L.) cultivar grown under flood-irrigation in a P-deficient, silt-loam soil (Typic Glossaqualfs) in eastern Arkansas. In 2019, rice grain yield did not differ (P > .05) among fertilizer-P sources, whereas in 2020, rice grain yield was greater from TSP (13.1 Mg ha −1 ) than that from ESCT (11.0 Mg ha −1 ) or CPST (12.7 Mg ha −1 ). Rice aboveground dry matter, aboveground and belowground tissue and grain P and N concentrations, aboveground and grain tissue P uptake, and aboveground tissue N concentration from ECST and CPST did not differ (P > .05) from those from TSP, MAP, DAP, RP, or an unamended control. The similarities in rice responses compared with other commonly used, commercially available fertilizer-P sources suggest that struvite materials have the potential to be an alternative fertilizer-P source option for flood-irrigated rice production.

Fertilizer-phosphorus (P) sources are mainly derived from rock phosphate (RP), which is a finite, actively mined resource. With growing human populations globally, alternative P sources are vitally important to ensure future food security. Precipitation of the mineral struvite (MgNH 4 PO 4 •6H 2 O) from wastewater could be a potential alternative fertilizer-P option from crop production. The objective of this study was to evaluate the effects of chemically precipitated struvite (CPST), compared with triple superphosphate (TSP) and an unamended control (UC) treatment, and irrigation (irrigated and non-irrigated/dryland) on above-(dry matter, yield, and tissue-N, -P, and -Mg concentrations and uptake) and belowground (root tissue N, P, and Mg concentrations) soybean [Glycine max (L.) Merr.] and wheat (Triticum aestivum L.) response in a wheat-soybean, double-crop production system on a silt-loam soil (Aquic Fraglossudalfs) in eastern Arkansas. Soybean aboveground and wheat belowground Mg concentrations were 1.1 and 1.2 times, respectively, greater (p < .05) from CPST than from TSP, while soybean belowground Mg and wheat stem P concentrations were similar between CPST and TSP. Wheat stem Mg and belowground N concentrations were 1.1 times greater (p < .05) from TSP than from CPST. Soybean seed P and Mg concentrations were 1.2 and 1.1 times, respectively, greater (p < .05) under irrigated than under dryland management. Results substantiate the use of CPST as a potential alternative fertilizer-P and -Mg source on a silt-loam soil for crop production. Using wastewater-recovered nutrients in a production-scale setting may offset the need for energy-intensive commercial fertilizers to supply essential plant nutrients.

The perception of wastewater as a resource rather than a pollutant has not been well emphasized. Phosphorus (P) can be precipitated from wastewaters as the mineral struvite (MgNH 4 PO 4 •6H 2 O), which can be a potential sustainable alternative to the limited, rock phosphate (RP)-dependent, traditional fertilizer-P sources for agricultural production. This field study evaluated the effects of electrochemically precipitated struvite (ECST) and chemically precipitated struvite (CPST) compared with other conventional fertilizer-P materials (monoammonium phosphate [MAP],diammonium phosphate [DAP], triple superphosphate [TSP], and RP) on corn (Zea mays L.) response in two consecutive growing seasons in a P-deficient, silt-loam soil (Aquic Fraglossudalf) in eastern Arkansas. Averaged across years, corn yield was numerically largest from ECST (12.9 Mg ha -1 ), which differed (P < .05) from all other treatments and was numerically smallest from DAP (10.1 Mg ha -1 ), which was similar to MAP (10.7 Mg ha -1 ), CPST (10.3 Mg ha -1 ), and RP (10.3 Mg ha -1 ). Corn yield and kernel P uptake from ECST were at least 1.2 times greater (P < .05) than from CPST, TSP, DAP, and RP. Yield from ECST was 1.2 times greater (P < .05) than from MAP. A partial budget analysis showed that, across both years, fertilizer-P treatment net revenues for ECST were greater than those associated with the other fertilizer-P sources. Results demonstrated that wastewater-recovered struvite materials have the potential to be a sustainable source of P for corn production in P-deficient, silt-loam soil from both a technical and economic perspective.

Phosphorus (P) recovery from wastewaters as struvite (MgNH4PO4·6H2O) may be a viable alternative fertilizer-P source for agriculture. The objective of this study was to evaluate the economic and environmental implications of struvite as a fertilizer-P source for flood-irrigated rice (Oryza sativa) relative to other commonly used commercially available fertilizer-P sources. A field study was conducted in 2019 and 2020 to evaluate the effects of wastewater-recovered struvite (chemically precipitated struvite (CPST) and electrochemically precipitated struvite (ECST)) on rice yield response in a P-deficient, silt–loam soil in eastern Arkansas relative to triple superphosphate, monoammonium and diammonium phosphate, and rock phosphate. A life cycle assessment methodology was used to estimate the global warming potentials associated with rice produced with the various fertilizer-P sources. Life cycle inventory data were based on the field trials conducted with and without struvite application for both years. A partial budget analysis showed that, across both years, net revenues for ECST and CPST were 1.4 to 26.8% lower than those associated with the other fertilizer-P sources. The estimated greenhouse gas emissions varied between 0.58 and 0.70 kg CO2 eq kg rice−1 from CPST and between 0.56 and 0.81 kg CO2 eq kg rice−1 from ECST in 2019 and 2020, respectively, which were numerically similar to those for the other fertilizer-P sources in 2019 and 2020. The similar rice responses compared to commercially available fertilizer-P sources suggest that wastewater-recovered struvite materials might be an alternative fertilizer-P-source option for flood-irrigated rice production if struvite can become price-competitive to other fertilizer-P sources.

Struvite (MgNH 4 PO 4 •6H 2 O) 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.