Since the end of the second world war, adding phosphorus to soils in the form of mineral fertiliser has played a crucial role in increasing and maintaining global food production in response to population growth.

However, plants only take up 20-50% of the phosphorus from fertiliser applications.

The unused phosphorus is mainly stabilised through chemical reactions which bind it to soil minerals. It accumulates as “legacy soil phosphorus”, with an increased risk of contributing to water pollution.

In New Zealand, phosphorus for fertilisers is manufactured exclusively from imported phosphate rock. But there is an alternative to using rock-based phosphorus.

Struvite is a phosphorus-rich compound that can be recovered from wastewater treatment processes.

As our research shows, struvite raises phosphorus uptake by plants and may reduce transfer to waterways. It could at least partially replace conventional phosphorus fertilisers.

Recovering phosphorus from waste

A combination of factors has resulted in significant cost increases for mineral phosphorus fertilisers, while economic and geopolitical instability disrupted supply chains and caused further price volatility.

For example, after decades of relative........

© The Conversation