Farm Soil Determines Environmental Fate

BirdJust 20 years ago, the soils of the Amazon basin were thought unsuitable for large-scale agriculture, but then industrial agriculture — and the ability to fertilize on a massive scale — came to the Amazon. What were once the poorest soils in the world now produce crops at a rate that rivals that of global breadbaskets. Soils no longer seem to be the driver — or the limiter — of agricultural productivity. But a new Brown University-led study of three soybean growing regions, including Brazil, finds that soils have taken on a new role: mediating the environmental consequences of modern farming.

The study focuses on the relationship between soils and phosphorus, a key agricultural nutrient. Typically in short supply, particularly in tropical soils, phosphorus is unique among fertilizer requirements. It is finite, irreplaceable and mined in just a few places around the world.

“If that suggests scarcity, which is a concern, the overuse of phosphorus can also pose another problem, causing harmful algal blooms in waterways,” said Stephen Porder, assistant professor of biology in the Department of Ecology and Evolutionary Biology and co-author of the study in the January 2013 edition of BioScience, posted early online. “It’s a bit of a Goldilocks problem — too much and our waterways are choked with algae, too little and we cannot produce enough food.”

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