Every year 22,000 tons of dust is blown from the Sahara Desert to the Amazon Rainforest. Long, long ago, the Sahara Desert used to be a lake, and the dust and sand left behind are rich in phosphorous. This is quite fortunate, as this phosphorous-rich dust is carried through the skies to the Amazon rainforest, which is surprisingly in need of fertilizer. The rainforest loses just about as much phosphorous as it gains because it all gets washed away through streams, creeks, and the Amazon River.