Weekend rains seen relieving parched Argentine soy and corn areas

BUENOS AIRES, Dec 12 (Reuters) - Rains expected this weekend in Argentina's main soy and corn growing areas will provide some relief to drought-stricken areas in the country's central farm belt, holding out hope that crop losses may yet be minimal, meteorologists said on Tuesday.

Argentina is the world's top exporter of soymeal used in livestock feed and the No. 3 corn supplier. The drought set in around the start of the Southern Hemisphere springtime on Sept. 21 and has threatened late-season soy and corn planting and the development of already sown crops.

"There is a great deal of concern, and these rains will be decisive," Eduardo Sierra, climate consultant to the Buenos Aires Grains Exchange, said in a telephone interview.

Worries about the dry conditions in Argentina lifted Chicago Board of Trade soybean and soymeal futures to four-month highs earlier this month, although they have since retreated on the forecasts for wetter weather.

Argentina's state weather service predicted showers and storms on Saturday and Sunday in the Pampas farm belt, which includes parts of Buenos Aires province, Santa Fe, San Luis, Cordoba, and Entre Rios provinces. It did not give estimates for the amount of rain.

Showers were expected on Tuesday by the weather service, but it warned that those rains would probably be light, putting the onus on weekend precipitation to make the difference between planting or not planting late-season soybeans.

"Every time you fall behind in planting you lose more yield potential. Planting in the second half of December is already different than in the first half. And in the first half of January the potential for soybean yields is very low," said Cristian Russo, analyst at the Rosario grains exchange.

Through last week farmers in the Pampas had planted about 40 percent of the 660,000 hectares they had planned to dedicate to late-season soy, a recent report from the Rosario exchange said.

Only a few days remain before already-planted corn enters its critical development stage, which requires ground moisture.

The exchange estimates a 2017/18 soybean crop of 54.4 million tonnes and a corn harvest of 41.5 million tonnes.

In a monthly report on Tuesday, the U.S. Department of Agriculture left its forecasts unchanged for an Argentine soy crop at 57 million tonnes and a corn harvest of 42 million tonnes in 2017/18. Some analysts had expected a reduction.

(Reporting by Maximilian Heath, Additional reporting by Julie Ingwersen in Chicago, writing by Hugh Bronstein, Editing by Rosalba O'Brien)