May 28, 2010
If a La Nina Develops, It Could Impact Crops in South America
Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.
Long range weather forecasts are never certain, but there are more indications now that the waters in the eastern Pacific could transition from El Nino to La Nina sometime during the North American summer. If the forecast is verified, it could have a significant impact on crop production in southern Brazil, Argentina, Paraguay, and Chile.
Not all the impacts of a La Nina in South America are negative. In fact, the first impact could be positive for the wheat crop in southern Brazil. La Nina generally results in dryer and cooler conditions in southern Brazil during June, July, and August. The lower rainfall would be good for the wheat crop because the biggest weather impact on wheat production in southern Brazil is generally too much rain, especially during the harvest period. The cooler temperatures could be a problem though especially if there are temperatures approaching freezing later in August when the wheat crop is headed out and blooming. If the wheat crop encounters freezing temperatures late in its growth cycle, it can impact the quality of the grain resulting in lower quality wheat only suited for livestock feed instead of flour production.
For Brazil's summer crops of soybeans and corn, the impacts could be very different.
The cooler waters in the eastern Pacific generally restrict the southward movement of humid air from the Amazon Region into southern Brazil. This humid air is the source of much of the summertime precipitation in southern Brazil. Without that source of moisture in the atmosphere, the states in southern Brazil are more dependent on moisture moving up from the south which many time is insufficient to meet the crop's moisture needs during the growing season.
As a result, spring and summer rainfall is generally lower than normal in southern Brazil and northern Argentina. This can impact not only soybean and corn production, but also coffee and sugarcane production as well.
If the humid air remains restricted to northern or northeastern Brazil, it usually results in increased precipitation in those regions. Northern Brazil generally receives ample rainfall, so a little more precipitation generally doesn't cause much concern, but northeastern Brazil is semi-arid so additional rainfall in that region would be advantageous.
Meteorologists hope to have a better handle on a potential La Nina by July, so for the time being, a La Nina is still only a possibility.