A Canterbury farmer has applied a bit of Kiwi ingenuity to turn a high-tech weed sprayer into a very selective fertiliser applicator.
He sees it as another tool to help farmers manage nitrogen levels in pasture and reduce green-house gas emissions.
Craige Mackenzie has re-engineered a weed sprayer that uses sensor technology to automatically identify the weeds so that only they get the spray.
He started investigating sensors and precision agriculture developments on a Nuffield scholarship to the United States two years ago.
After trying out Weed-Seeker equipment on his cropping farm in mid-Canterbury, he modified it to apply fertiliser on dairy pastures while avoiding the patches of urine and dung that are already high in nitrogen.
Mr Mackenzie and his wife and daughter have set up a precision agriculture company, Agri-Optics, to market his Smart-N technology as well as the Weed-Seeker and other equipment.