Field‐scale evaluation of struvite phosphorus and nitrogen leaching relative to monoammonium phosphate

Abstract

Struvite (MgNH4PO4·6H2O) is a wastewater‐derived phosphorus (P) fertilizer with potential to reduce P as well as nitrogen (N) losses due its low water solubility. To test hypothesized lower P and N losses from struvite relative to monoammonium phosphate (MAP), field experiments with a randomized‐complete block design were conducted at two locations, on a Endoaquoll‐Argiudoll complex (Urbana, IL) and a Fragiudalf‐Hapludalf complex (Ewing, IL). Fertilizer was broadcast applied in the fall prior to spring planting of soybean (Glycine max L.) at a maintenance rate of 29.5 kg P ha−1 (Urbana) and 22.0 kg P ha−1 (Ewing). In the spring, soil extractable N and Mehlich 3‐P at 0–15 and 15–35 cm depths were determined, and leached N and P were estimated using fall‐installed ion‐exchangeable resin (IER) lysimeters. At Urbana, soil extractable nitrate‐N was higher under MAP than struvite at the 0–15 cm depth. At Ewing, soil Mehlich 3‐P under struvite was lower than MAP at both depths. At Urbana, leached P was 10‐fold lower and leached N was 2‐fold lower under struvite than MAP. Soybean yields were similar between MAP and struvite at Urbana (4.1‐4.3 Mg ha−1) and Ewing (3.2‐3.5 Mg ha−1), but at Ewing were 23% higher under struvite compared to the P‐unfertilized control. Off‐season yield‐scaled P and N losses under struvite were lower than MAP by 51% at Urbana and by 10% at Ewing. Our results support the hypothesized potential of struvite to reduce nutrient losses while meeting crop P needs. Additionally, we identify disproportionally greater reductions in N leaching and yield‐scaled N losses by substituting struvite for MAP in fall applications, indicating that struvite may offer greater relative benefits for N loss reductions than P loss reductions.This article is protected by copyright. All rights reserved

Phosphorus dissolution and diffusion from struvite and its impact on phosphorus availability in Acrisol and Cambisol soils

“…Labile P was primarily detected in the soil treated with struvite around the area where the fertilizer was applied, with P dissolution playing a pivotal role in regulating P lability and mobility. Leon et al (2023) also suggested that P leaching from soil treated with struvite is negligible. These findings indicate that the use of struvite as a P source has the potential to improve nutrient utilization efficiency and mitigate environmental pollution associated with P leaching.…”

Struvite and biodiversity to improve phosphorus use in agricultural fields

“…Although crop nutrient demand may not always be met due to the slow dissolution of struvite in soil, there is one benefit associated with the use of struvite as a fertiliser as it does reduce environmental risks. Both in the greenhouse and in the field, struvite did not increase N leaching compared to the unfertilised control (Leon et al, 2024;Liu et al, 2011). Phosphorus leaching is also less likely to occur as compared to conventional P fertiliser that are highly soluble (Talboys et al, 2016).…”

“…From this soil P test and the amounts of Fe-and Al-(hydr)oxides extracted simultaneously with the same extraction method, it is possible to calculate the P loading α of the soil (van der Zee and van Riemsdijk, 1988). consideration as its slow release likely has environmental benefit with respect to the N biogeochemical cycle (Leon et al, 2024;Liu et al, 2011).…”