A review of stubble burning on Canterbury grain farms has defended the practice as an essential part of crop rotation.
But it has also reminded farmers of the need to operate within the rules when they burn the residue after harvesting.
Canterbury Regional Council commissioned the Foundation for Arable Research to do a report on stubble burning as part of a council review of its air plan.
FAR research director Nick Poole says Canterbury, as the main grain growing region, produces about 700,000 tonnes of crop residue per year,
But farmers burn less than half of that, and it's done to clear the way for seed crops, that are grown after grain.
Mr Poole says alternatives such as ploughing-in or baling the straw after grain harvests can mean increased fuel costs and greater use of chemicals to control weeds.
While the foundation's report acknowledges stubble burning as an essential tool, it says farmers could do more to reduce the smoke nuisance.
The foundation is working with Federated Farmers leading up to the harvesting season, to remind arable farmers of the regulations and an industry code of practice.