A long stretch of little-to-no rain since the beginning of the year in center-west Brazil is starting to worry soybean farmers, who fear productivity losses from the expected record crop.

Meteorologists say an atmospheric block is stopping cold air from advancing from the south, preventing widespread rain in the top producing region of the world's No. 2 soy grower.

"All areas are showing a hydric deficit; it's only raining in micro-regions," Somar's agro meteorologist Marco Antonio dos Santos said of conditions in the center-west.

In Goias state, responsible for 10 percent of the national crop, some areas have not seen any rain since Christmas, said Cristiano Palavro, technical consultant from Senar Goias.

Where rains have occurred they have been less than needed, he said, explaining that soy plants can go up to 15 days without rain before productivity losses are seen.

Somar says the blockage could break up for the end of the month, bringing needed rain. The soy crop is in the early stages of harvesting in some areas.

Rainfall in general has been better in the center-west grain belt than in the southeast coffee and cane areas, but southern Mato Grosso state is on track for below-average rain in January, Somar said.

Some 94 millimeters (3.7 inches) have fallen there so far compared with the 256 millimeter average for the month.

Planting in the center-west was delayed this season due to a dry period in September and October, meaning most of the crop was planted around the same time.

"The lack of scaling exacerbates the problem, most of the crop is at the same stage," said Senar's Palavro.

Nery Ribas, technical director of farmer's association Aprosoja in Mato Grosso, said January would be a critical month.

"Rains are essential for development, this defines the productivity of the crop and could compromise the initial estimates," he said in an Aprosoja statement.

Analysts said it is too early to estimate potential losses. Government and private forecasts expect a record crop of at least 94 million tonnes.

In southern growing areas, where more rain has fallen, conditions are quite favorable. In the second-largest growing state Parana, 89 percent of the crop is in "good condition," the state's agricultural department said.

In No. 3 soybean-growing state Rio Grande do Sul "climate conditions are favorable" for strong yields, the state's agricultural entity Emater said.

Source - http://news.yahoo.com