Scientists at University of Canterbury are developing a tool which will allow farmers to measure phosphates in their local waterways.
Phosphate which is a key ingredient in some fertilisers, can enter streams and rivers when run-off from farms ends up in them.
It can cause damaging algal blooms which have flow-on effects for fish and other wildlife.
Associate Professor of physical and chemical sciences Deborah Crittenden said at the moment it was hard to detect phosphate in waterways as it was colourless and odourless.
"Currently there isn't a simple, chemical-free way of monitoring phosphate levels , but we've already developed very sophisticated ways of sensing phosphate in our bodies so we are going to learn from nature to develop novel light-sensitive biosensors."
With the preliminary science done, proving that they could identify phosphates and capture them in waterways, the team wanted to create a useable device for farmers, she said.
"We want to provide farmers with real-time, accurate test kits that will allow them to better monitor and control fertiliser use on their land, with test results sent instantly to their computer or phone.
"Recent nutrient management laws introduced by the government require them to pay if they are predicted to breach certain levels of fertiliser run-off in waterways, and the advice we've received from farmers is that there is strong demand for a tool that accurately measures actual phosphate levels in waterways. That's exactly what we're planning to deliver."
If farmers knew how much phosphate was running off into waterways they could either reduce the amount of fertiliser they used or do more to prevent run-off, Crittenden said.
The project is expected to take three years.