The new dust transport estimates were derived from data collected by a lidar instrument on NASA's Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation, or CALIPSO, satellite from 2007 though 2013.
An average of 27.7 million tons of dust per year – enough to fill 104,908 semi trucks – fall to the surface over the Amazon basin. The phosphorus portion, an estimated 22,000 tons per year, is about the same amount as that lost from rain and flooding. The finding is part of a bigger research effort to understand the role of dust and aerosols in the environment and on local and global climate.
Research: The fertilizing role of African dust in the Amazon rainforest: A first multiyear assessment based on data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations
Journal: Geophysical Research Letters
Link to paper: http://onlinelibrary.wiley.com/doi/10.1002/2015GL063040/full
Here is the YouTube video.