Influence of phosphate retention capacity on the potential plant availability of struvite fertiliser in acidic grassland soils

Abstract

Context. Sustainable agricultural production relies on efficient phosphorus (P) management due to the finite nature of phosphate rock reserves, increasing fertiliser costs for farmers, and environmental concerns associated with P losses. Struvite, a P fertiliser recovered from wastewater, appears to be an alternative to conventional water soluble-P fertilisers. Aims. We aimed to evaluate changes in the concentration of soil available P in response to the application of struvite in three New Zealand acidic soils with varied P retention capacities. Methods. A plant-less incubation was carried out for 63 days where struvite, two water soluble-P fertilisers, and reactive phosphate rock were applied at two rates to three contrasting soils. Key results. Regardless of soil type, struvite significantly increased Olsen-P concentrations, comparable to conventional P fertilisers. P retention capacity influenced P release patterns, with Pallic soil exhibiting the highest Olsen-P increases due to its low P retention. P release from struvite was rapid but showed sustained availability in Pallic soil compared to declines in Allophanic and Brown soils. Conclusions. Struvite showed similar fertiliser-P behaviour in soils with contrasting P retention capacity generating changes in Olsen-P like those from watersoluble P fertilisers. Implications. Further research is necessary to investigate the suitability of struvite as an alternative P fertiliser source for New Zealand agriculture.