Deliveries of grains via trucks were totally paralyzed at Brazil's main port of Santos on Tuesday, the second day of a truck drivers strike, although exports are continuing, the port authority said.
Some two thirds of grains are delivered to Santos by trucks. Brazil has not developed train networks and waterways the way the Western hemisphere's other agricultural powerhouse, the United States, has.
Despite fewer deliveries, shipments continued because exporting firms hold grains in private storage units to minimize the effect of interruptions in ground transport, according to Codesp, the Santos Port authority.
Exports had slowed due to frequent rains in the past few weeks, meaning stocks in silos near the ports had increased. Truckers protesting on the Anchieta highway that links Sao Paulo to Brazil's main Santos port triggered a 4-kilometer (2.9-mile) traffic jam, according to the highway operator Ecovias.
MUBC, as the most influential truckers union in Brazil is known, said protests linked to the strike were also occurring in parts of top coffee-growing state Minas Gerais, the main sugar producing state Sao Paulo, top soybean producer Mato Grosso, as well as in Espirito Santo, Bahia, Rio de Janeiro, Parana and Rio Grande do Sul.
The federal government secured an injunction on Monday that prevents protesters blocking federal highways, which could limit the impact of the protests.
MUBC's demands include a subsidy for diesel fuel, exemptions on highway toll payments for drivers and the creation of a new federal government department of cargo transportation.
The union last went on strike for a week in July 2012, disrupting the flow of goods in the country's heavily populated southeast region and raising concerns over food inflation.
Brazil is moving the last of a record soybean harvest to its ports, and shipments of sugar and corn picked up, data from the trade ministry showed on Monday.
The strike is scheduled to end on Thursday, according to the MUBC.