Here�s the progression of innovation in irrigation technology from spray, to low energy precision application, to drip irrigation to subsurface drip irrigation.  The question we�re asking in arid Saudi Arabia is can we use the sun to power enough desalination to support enough desalination to grow crops in the desert.  Saudi Arabia�s problems aren�t much different from those of our arid southwest.  In many places, agriculture is living on borrowed time:  Saudi Arabia�s aquifers and our huge Ogallala aquifer are being drained  -- and are not being recharged � that�s the definition of a fossil aquifer.