Fertiliser co-operative Ravensdown is prepared to sell less fertiliser if that is what it takes to get better environmental outcomes for streams and rivers, it says.
General manager for customer relationships Bryan Inch said he noticed the conversation had changed at Fieldays this year.
He said people were starting to acknowledge that what was happening to the environment was not OK.
"They want to do better around the whole environmental management and nutrient space... so smarter farming for us is what it's about going forward.
"In many cases that will mean less fertiliser sales and if that's what it means to get optimum long-term benefits for New Zealand, then that's great."
Twenty or thirty years ago fertiliser was very widely used and without too much consultation, but now that was changing, he said.
"We've always known that fertiliser helps grow grass. Whether we like it or not, water has become the litmus test for whether we are putting on too much."
New tool for farmers
Ravensdown has launched a new nutrient decision-making tool called HawkEye to help farmers make smarter fertiliser decisions.
Mr Inch said the challenge facing modern farming was to avoid drowning in a sea of data.
HawkEye will integrate three perspectives of pasture production: imagery from the air, nutrient input and pasture quantity on the ground, and the diagnostic status of the soil, he said.
"There's been a huge focus on precision agriculture and the focus has been around understanding what nutrients are landing where.
"It's one thing doing it by precision, but if you know where the wrong nutrients are landing that does actually help."