UPDATE 1-Brazil's truckers begin strike; limited impact so far
* Truck protests cause traffic jam on road to Santos port
Exports continuing as normal, thanks to stocks
* Drivers walked off the job in five states
(Adds update from union, port, highway operator)
RIO DE JANEIRO, July 1 (Reuters) - Brazil's trucking union started a 72-hour strike that might delay the movement of record soy, corn and sugar crops to ports, but the impact was limited on Monday and the action was unlikely to stop exports.
A spokeswoman for the MUBC trucking union headquarters in Rio de Janeiro said drivers were off the job in at least five states: Sao Paulo, Rio de Janeiro, Minas Gerais, Espíritu Santo and Mato Grosso.
Truckers protesting on the Anchieta highway that links Sao Paulo to Brazil's main Santos port triggered a 2-kilometer (1.4-mile) traffic jam, according to the highway operator Ecovias.
The protests slowed traffic into the port, but exports were continuing as normal on Monday, according to the Santos Port Authority (Codesp), which manages the port's public corridor.
Most exporting companies keep grains in private storage units to minimize the effect of interruptions in ground transport and analysts say it would take more than a few days of paralyzed truck traffic to slow shipments.
Brazil saw its largest protests in 20 years in recent weeks over issues ranging from education to corruption in politics, but a general strike failed to materialize on Monday as feared.
MUBC's demands include a subsidy for diesel fuel, exemption 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. However, the strike did not affect the export of bulk commodities.
Brazil is moving the last of a record soybean harvest to its ports, and shipments of sugar and corn are picking up.
(Reporting by Alonso Soto, Gustavo Bonato and Caroline Stauffer; Editing by Lisa Von Ahn and Andrea Ricci)