GRAINCORP will exit the farm-merchandising sector after a disastrous few years selling fertiliser, chemicals and other rural inputs.

GrainCorp managing director Mark Irwin said the decision was made after reviewing the company's participation in the sector.

"We ... concluded that GrainCorp needed to significantly expand merchandise operations to become profitable," Mr Irwin said. "During the review, we did not find any attractive expansion options."

The company closed merchandise centres at Charlton and Warracknabeal plus six centres in NSW and Queensland. Another 17 stores will remain open only until September.

The merchandising business, once known as Ag Plus, has been a financial drain for GrainCorp.

Last financial year, it resulted in a pre-tax operating loss of $23 million.