Iowa Gov. Chet Culver (D) has exempted weight limits on trucks for 60 days on carriers of farm products for the harvest season.

The temporary extension is aimed at harvests of corn, soybeans, hay, straw and stover by 10% per axle without requiring carriers to acquire a special permit, the governor’s office said.

The proclamation signed Tuesday covers all Iowa roads, but does not include interstate highways. The Iowa Department of Transportation will monitor the temporary extension.

Corn and other farm products are “a critical component to the state’s economy,” Culver said in a statement, adding that last year Iowa farmers exported about $9 billion worth of corn.

Iowa Corn Growers Association President Dean Taylor called the temporary extension a “privilege,” the Associated Press reported.