(Adds background on Macri reforms, docking services costs)
BUENOS AIRES, Nov 15 (Reuters) - Argentina's government will cut the cost of docking services in the ports of Rosario, the country's main agricultural hub, by 70 percent when it implements a maximum rate for entry and exit guide services in December, an official told Reuters on Wednesday.
The official decision is part of Argentine President Mauricio Macri's crusade to lower the costs of producing and exporting grains to boost economic growth in the world's No. 3 soy and corn exporter.
"By the end of December, we will make the final disposition to apply the maximum rate for navigation services, which we understand will be 30 percent of the current rates," said Jorge Metz, national undersecretary of ports and waterways in the country's Transportation Ministry.
The cost of docking services in Rosario, the point of departure for 80 percent of Argentina's agricultural exports, is about $108,000 per vessel, according to Metz.
That figure represents about 30 percent of the port costs attached to ships that travel to Rosario, Metz said, adding that the ministry has the authority to regulate the rate, thanks to a decree issued earlier this month.
Guillermo Wade, manager of the Chamber of Port and Maritime Activities, said a reduction "is important because it is one of the biggest costs you have, the biggest cost today is the toll, and the second is the docking cost."
The measure will benefit agro-export giants like Cargill Inc and Bunge Ltd, which have their own terminals in the town of Puerto General San Martin, north of Rosario.
As part of the effort to increase productivity in the agro-export sector, the government in September pushed a union that represents dock workers to accept competition from rival companies after decades of monopoly.
Metz said due to the diversification of suppliers of the loading and unloading services for grains, the stowage rate has already registered a 30 percent drop.
Argentina is the world's leading exporter of soy oil and flour and a key global wheat supplier. (Writing by Cassandra Garrison; Editing by Chizu Nomiyama and Jonathan Oatis)