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October 14, 2019

Deforestation could Disrupt Rainfall Distribution in South America

Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.

Scientists in South America are concerned that continued deforestation along the southern edge of the Amazon Rainforest in Brazil and Bolivia could impact the distribution of rainfall in the grain and beef producing regions of South America.

A recent study by agronomist Leonardo Melgarejo from the Federal University of Santa Catarina in Brazil indicated that much of the rainfall in the grain and beef producing regions of South America originates as transpiration from vegetation in the Amazon Region. If there is less vegetation, then there will be less moisture in the atmosphere.

The vegetation puts the moisture into the atmosphere and the rotation of the earth causes these rivers of moisture to move southward from the Amazon into regions of Brazil, Bolivia, Paraguay, and as far south as northern Argentina and even Uruguay. In a recent scientific meeting held in the city of Santa Cruz, Bolivia, he indicated to Reuters that another 5% deforestation in the region could destabilize the rainfall distribution in much of South America.

The recent fires in Brazil and Bolivia generated worldwide concern because the Amazon Rainforest is considered by many as the "lungs of the earth." For the agricultural community in South America, it is a much more of a local concern because a reduction of moisture coming from the Amazon means reduced rainfall and potentially lower production.

Approximately 80% of the fires in the Amazon region over the recent months were set by ranchers clearing dry pastures in preparation for the summer rainy season. Most of the other 20% were due to slash and burn land clearing by subsistent farmers in the region clearing land for their small family farms.

Very little of the land cleared by the recent fires will be used for grain production. The vast majority will be used for beef production with most of the remainder used by subsistent farmers.

A recent study conducted by Embrapa (the Brazilian Agricultural Research Service) indicated that there are 63.99 million hectares of crop land in Brazil or 7.6% of Brazil's total land area. Forested areas, which are mostly in the Amazon region, occupy 66.3% of Brazil's total land area.

In Brazil, from 1990 to 2019, grain production increased 304% while the increase in the crop area was 66% indicating that increases in productivity and efficiency accounted for most of the increased grain production and not the clearing of new land.