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January 25, 2013

Heavy Rainfall Forecasted to Return to Mato Grosso Next Week

After a dryer than normal month of December, January is turning out to be a wet month for much of Mato Grosso. From the 10th to the 17th of the month, it rained nearly constantly throughout the state. Rainfall amounts were not excessive, but the wet weather slowed the early soybean harvest. Fortunately, the rainfall over the last three or four days has been in the form of afternoon showers with sunny breaks in between. This has allowed farmers to resume a more rapid harvest pace. Approximately 3% of the soybeans in the state have been harvested.

The near term forecast is calling for heavy rains to return to the stat starting early next week. Meteorologists from Somar are forecasting a prolonged period of wet weather starting next Tuesday and lasting multiple days. The increased precipitation is the result of moisture moving southward from the Amazon Region encountering a cold front moving northward from southern Brazil. The resulting instability is expected to produce a prolonged period of wet weather across the state.

Any rainfall at this time of the year can delay harvest progress and result in reduced seed quality, but a much more serious problem can develop if the wet weather lasts for several days. At this time of the year, the temperatures across the state are very warm and if the soybean pods stay constantly wet for several days, the soybeans can start to sprout inside the pods. This can result in very poor seed quality and lower yields. In a worst case scenario, the field may not even be harvestable.

In addition to wet weather next week, Somar is also forecasting that the rainy season will start to diminish during the first half of April. Starting by mid-April, the rains across Mato Grosso are forecasted to be lighter and more irregular. The biggest impact from this early end to the rainy season would be on the safrinha corn crop, which is planted after the soybeans are harvested. An early end to the rains may leave the corn crop vulnerable to moisture stresses as the corn completes the grain filling process.

The 2011/12 safrinha corn crop in the state set a record high statewide corn yield of 104 sacks per hectare (6,240 kg/ha or 96 bu/ac). The record yields were the result of rains that continued to fall in the state until the end of June. If the rains end by mid-April as they are predicted, that would mean two and a half months less of adequate moisture for the safrinha corn crop. The result of this reduced moisture would probably be lower corn yields.