SAO PAULO, March 15 (Reuters) - Brazil's major farm town Sorriso declared "a state of emergency" last week after heavy rains during the summer grain harvest caused crop losses and damaged local infrastructure, a local government representative told Reuters on Monday.

The city in Mato Grosso, Brazil's biggest soy producing state, declared a state of emergency on March 11 after receiving some 800 millimeters of rain in the preceding 45 days, according to a statement sent to Reuters by a government representative. The downpours damaged part of the town's grain crop and disrupted local roads, making it difficult to move produce and restricting the circulation of people in the area.

The emergency decree will allow the local government to forgo formal competitive bidding to rebuild bridges and roads, the statement said. It also guarantees farmers the ability to renegotiate contracts and debts, the statement said.

The local government of Sorriso estimates losses of 1.5 billion reais ($269 million) for the private sector after the heavy rains. The size of Sorriso's soy planted area is estimated at 620,000 hectares (1.5 million acres).

Nationwide, Brazilian growers harvested 46% of the country's soybean area through Thursday, compared with 59% at the same time a year ago, as abundant rainfall continues to slow harvesting, agribusiness consultancy AgRural said on Monday.

Wet weather has also delayed planting of Brazil's second corn crop, which is sown after the soy is harvested in the same areas. Brazil's farmers have sown 74% of the estimated second corn crop area in Brazil's Center-South region, less than the 89% in the last season, the consultancy said.

In most parts of Brazil, the ideal climate window for planting the second corn crop has closed, according to AgRural.

($1 = 5.5761 reais) (Reporting by Ana Mano Editing by Paul Simao)