What connects Earth’s largest, hottest desert to its largest tropical rain forest? The link: Dust, specifically phosphorous and other nutrients, picked up by the wind from the Sahara Desert and spread half a world away. Much of this falls into the ocean, but about 27.7 million tons settles over the Amazon River basin.
Even though the Amazon has plenty of nutrients, rain and flooding washes away a lot of the phosphorous in the soil, a fertilizing nutrient critical to plant growth. The phosphorus that reaches Amazon soils from Saharan dust, an estimated 22,000 tons per year, is about the same amount as that lost from rain and flooding.