The Argentine government will call for a national and international public tender to privatize its stretch of the Paraguay-Parana waterway through a 30-year concession, cabinet chief Guillermo Francos said.The waterway, a natural river corridor that extends through the Parana and Paraguay rivers, is a key transport route to the sea from inland areas of Paraguay, Bolivia and southern Brazil.Argentina uses the 3,400 km-long (2,100 mile-long) waterway to move nearly 80% its foreign trade, including its massive farm exports such as processed soybeans, corn and wheat.Francos said the concession wou