By enhancing the edge effect of pressure between different medias, in this case, wind and sand, the extension pattern creates the dish form that then shelters the plantings at the lowest point. It shelters them from the wind itself and from the extended shade in the lower position closer the water table. Combined this reduces evaporation, extends productivity, and reduces input requirements.
These systems can be permanent with no reduction in fertility if the scale and order of the appropriate pattern size relationship is carefully observed and applied as the guiding principles of design, implementation, establishment and permanent maintenance.
This is classic permaculture design :-)
January 25 at 8:32am ·
Photograph by George Steinmetz @geosteinmetz One of the last great examples of pit agriculture in a remote part of the Algerian #Sahara. Here the water table is just below the surface, and is drawn up by hand and donkey to sustain date #palms in the midst of a sea of mobile sand dunes. This ancient method of cultivation was once found throughout the Middle East, but increasing population and electric pumps are causing the water table to drop.