Growing demand for soybeans threatens Amazon rainforest
"Some 3,000 years ago, farmers in eastern China domesticated the soybean. In 1765, the first soybeans were planted in North America. Today the soybean occupies more US cropland than wheat. And in Brazil, where it spread even more rapidly, the soybean is invading the Amazon rainforest," writes Lester R. Brown, president of the Earth Policy Institute, in a December commentary.
Since 1950 the world soybean harvest has climbed from 17 million tons to 250 million tons, a gain of more than 14-fold. This contrasts with growth in the world grain harvest of less than fourfold. Soybeans are the second-ranking US crop after corn, and they totally dominate agriculture in both Brazil and Argentina.
Satisfying the global demand for soybeans, growing at nearly six million tons per year, poses a challenge. The soybean is a legume, fixing atmospheric nitrogen in the soil, which means it is not as fertiliser-responsive as, say, corn, which has a ravenous appetite for nitrogen. But because the soy plant uses a substantial fraction of its metabolic energy to fix nitrogen, it has less energy to devote to producing seed. This makes raising yields more difficult.
Although the US area in corn has remained essentially unchanged since 1950, the area in soybeans has expanded fivefold. Farmers get more soybeans largely by planting more soybeans. Herein lies the dilemma: how to satisfy the continually expanding demand for soybeans without clearing so much of the Amazon rainforest that it dries out and becomes vulnerable to fire.