Introduction: Sandy soils present significant challenges for crop production due to their low nutrient-holding capacity and susceptibility to phosphorus (P) leaching. Struvite (ST), a slow-release P fertiliser recovered from wastewater, offers a sustainable alternative to conventional fertilisers by providing a steady nutrient supply while minimising environmental losses in such soils.
Methods: This study evaluated the P leaching and diffusion from ST compared to mono-ammonium phosphate (MAP) and Super SR Extra (SSRE) in plant-free pots filled with sandy soil. In a separate experiment, we assessed the plant growth responses to ST compared to soluble fertilisers for chickpea and wheat growth in a glasshouse.
Results: Phosphorus leaching from ST remained extremely low (<2 μg L−1) throughout the experimental period (60 days). Conversely, P leaching from SSRE was moderately low but significantly higher than that from ST and P leaching from MAP was very high from day 8 onwards. At any given time interval (from day 1 to 45), MAP had the largest P diffusion diameter zone visualised around the fertiliser granule, followed by SSRE, with a much smaller for ST. At the early growth stage, chickpea shoot dry weight (DW) was similar for ST and SSRE, both being ~80% higher than MAP, while wheat shoot DW for ST was half of that for MAP and SSRE. Moreover, ST and SSRE produced similar shoot P contents for chickpea, ~60% higher than MAP, but wheat shoot P content was 76% and 66% lower for ST than MAP and SSRE, respectively. Chickpea grain yield was 46% and 15% higher with ST compared to MAP and SSRE, respectively, whereas wheat grain yield was ~30% lower with ST and SSRE compared to MAP.
Conclusions: These findings suggest that ST is a promising alternative P fertiliser in sandy soils, particularly for chickpea, offering both agronomic and environmental benefits.