A Federated Farmers leader says the use of fertiliser on hill country farms is not likely to improve in the near future.
The Agricultural Aviation Association says last year was the worst period in a continuing trend of hill country farmers choosing not to fertilise their land.
Topdressing planes flew 21,000 hours last year, half as much as they did five years ago.
About 65% of hill country farms are in the Manawatu-Whanganui region, where meat and fibre chair Tony Gray says farmers simply can't afford to put as much fertiliser on their land as they used to.
He says returns will have to improve before hill country farmers can increase their use of fertiliser and topdressing planes.
The Agricultural Aviation Association says the industry depends on the business from sheep and beef farmers, as topdressers have few strategies available to get more work.