pistachios and almonds are desert plants to begin with, right? how can they need so much water?
These plants grow in oases, which occur in areas where winds converge and blow away much or all of the sand so the water table is at the surface, or just below the surface. As such, they usually occur in geomorphic depressions. More on the geology of oases here: http://www.britannica.com/EBchecked/topic/423497/oasis
Thanks, that makes sense. There's a reason these nuts are planted in SoCal instead of bananas, for instance - they do well in the dry, hot climate, but they need water reaching the roots.
