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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.
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This content will become publicly available on March 1, 2026
Why Does Overapplication of Phosphorus Fertilizers Occur: Insights from North Carolina Farmers
To minimize environmental damage, conserve global diminishing fertilizer reserves, all while maximizing food production, it is essential that farmers apply phosphate fertilizers at the optimal rate. The purpose of this study is to assess grower attitudes and behavior, with respect to proper application of phosphorus, and to investigate how certain exogenous factors might influence such applications. Data were analyzed from a survey conducted in North Carolina, USA, with 122 farmer participants. The findings reveal that annual phosphorus applications consistently exceed recommendations, which indicates overapplication, leading to economic inefficiency and environmental concerns. Overapplication is neither due to knowledge gaps in nutrient concentrations in the soil nor the lack of interest in soil sampling, as 99% of farmers submit soil tests as frequently or more frequently than every two years. Only 36% of growers indicated that they would not apply phosphorus if their soil report indicated that levels were sufficient, and that none was required. Additionally, overapplication is not strongly influenced by price effects, as only nine percent of growers abandoned applications in 2021, following a dramatic spike doubling fertilizer prices. The adoption of reduced phosphate fertilization will depend on strong local trusted technical assistance and continued extension education.
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- Award ID(s):
- 2019435
- PAR ID:
- 10608733
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Agriculture
- Volume:
- 15
- Issue:
- 6
- ISSN:
- 2077-0472
- Page Range / eLocation ID:
- 606
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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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 (MgNH4PO4·6H2O), 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 to 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 Fraglossudalfs) in eastern Arkansas. Averaged across years, corn yield was numerically largest from ECST (12.9 Mg ha–1), which differed (P < 0.05) 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 < 0.05) than from CPST, TSP, DAP, and RP. Yield from ECST was 1.2 times greater (P < 0.05) 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.more » « less
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