SAO PAULO Aug 4 (Reuters) – A key highway for transporting soy and corn to ports in northern Brazil still has about 237 kilometers (147 miles) of unpaved road, while some paved stretches are in poor condition, soy growers association Aprosoja said on Tuesday.

The BR-163 highway is unlikely to be fully paved until 2017, Aprosoja said in a statement after a 1,300-kilometer technical expedition from Sinop, in northern Mato Grosso state, to Santarem on the Amazon River in Para state.

The road is the main artery through Mato Grosso, which accounts for a quarter of total grain output in Brazil. In addition, major grain exporters are building river terminals at its northern end in Para that connect to new ports on the northern coast.

Cargill has operated in Santarem since 2003, relying mostly on a distant river port in Rondonia state to bring soy from Mato Grosso. Last year, Bunge inaugurated a terminal farther south in Miritituba.

Aprosoja says once the new road is fully operational, exporters could cut 34 percent off freight costs in comparison to what they pay to truck grains to Brazil’s largest port of Santos in the southeast. Half of the new northern route is by river barge rather than road.

President Dilma Rousseff said last year that BR-163 would be paved in 2016, though the project to do the work has been delayed repeatedly since 2009. The jungle dirt road was opened in the 1970s.