Wastewater‐recycled struvite as a phosphorus source in a wheat–soybean double‐crop production system in eastern Arkansas

Abstract

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.

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

“…However, averaged across fertilizer‐P treatments, aboveground tissue Mg concentration was 1.2‐times greater ( P = .01) in 2020 than in 2019 (Table 6). In contrast to the results of the current study, Omidire and Brye (2022) documented that aboveground soybean tissue Mg concentration was 1.1‐times greater from CPST than from TSP or the UC, which did not differ.…”

“…Aboveground tissue P uptake from CPST, which was comparable to DAP or TSP, was at least 1.1‐times greater than that from MAP and at least 1.2‐times greater than that from RP or the UC (Table 5). In contrast to the current study, Omidire and Brye (2022) reported no difference in soybean aboveground tissue P uptake among CPST, TSP, and the UC treatment.…”

“…However, averaged across fertilizer‐P sources, aboveground tissue Mg uptake was at least 1.1‐times greater ( P = .02) in 2020 than in 2019 (Table 6). Similar to the current results, Omidire and Brye (2022) reported no difference in soybean aboveground tissue Mg uptake among TSP, CPST, and the UC treatment.…”

“…Aboveground DM ranged from 7.5 Mg ha −1 from the UC in 2019 to 8.7 Mg ha −1 from TSP in 2020 and averaged 8.2 Mg ha −1 across the seven fertilizer‐P sources and both years (Table 4). Omidire and Brye (2022) reported similar results, where there was no difference in soybean aboveground DM among CPST, TSP, and UC treatments in a field study on the same soil and at the same location as the current study. Ylagan et al.…”

“…Consequently, greenhouse potted‐plant studies may have over‐estimated struvite suitability for field‐scale row crops. In a recent study, Omidire and Brye (2022) evaluated the effects of CPST in a wheat–soybean, double‐cropped production system in eastern Arkansas. Although ECST has been previously evaluated in other crops in the field, such as rice (Omidire et al., 2022a) and corn (Omidire et al., 2022b), in the greenhouse with corn and soybean (Ylagan et al., 2020), or in plant‐less soil incubation studies (Anderson et al., 2021a,b,c), field evaluations of ECST have not been previously conducted for soybean.…”