Phosphorus is essential for global food production, but the rising cost of phosphate fertilisers and reliance on imported resources are creating challenges for agricultural sustainability. Research by Lincoln University, New Zealand, explores the potential of struvite, a phosphorus-rich compound recovered from wastewater, as an alternative to conventional fertilisers. The findings suggest that recovering and reusing phosphorus could improve nutrient uptake by plants while reducing the risk of phosphorus losses into waterways.
Conventional phosphorus fertilisers play an important role in maintaining agricultural productivity, but plants typically absorb only 20–50% of the phosphorus applied. The unused portion can accumulate in soils, increasing the risk of water pollution. In New Zealand, phosphate fertiliser production relies entirely on imported phosphate rock, making the search for alternative domestic sources increasingly relevant amid rising costs and supply-chain uncertainty.
Against this backdrop, Professor Leo M. Condron, Distinguished Professor of Soil Science at Lincoln University, has highlighted research investigating struvite as a potential phosphorus source for New Zealand grasslands. The study combined field trials, controlled-environment experiments and laboratory analyses to assess how effectively plants absorb phosphorus from struvite compared with single superphosphate, a conventional fertiliser.
A two-year field trial found that struvite increased phosphorus uptake by perennial ryegrass by more than 30% compared with single superphosphate. The findings suggest that a similar plant yield could be achieved using approximately one-third less phosphorus. Further experiments found higher plant phosphorus uptake from struvite and indicated that it could reduce immediate phosphorus losses through soil drainage.
The research also highlights the potential environmental benefits of recovering phosphorus from wastewater. Struvite can be recovered from municipal wastewater and industrial waste, including milk-processing waste, while its removal can help reduce the discharge of phosphorus and nitrogen into waterways. However, further research is needed to understand how soil types, plant species and environmental conditions influence its effectiveness and to assess its commercial viability.
As agricultural systems face increasing pressure to improve resource efficiency and reduce environmental impacts, the findings highlight the potential of waste-derived nutrients to support more sustainable fertiliser use. While further work is needed before wider adoption, struvite could offer New Zealand’s primary industries a complementary source of phosphorus, helping reduce reliance on imported fertiliser while improving nutrient uptake and limiting losses to waterways.
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