The Natural Resources Conservation Service (NRCS) has produced a video that does an excellent job in less than five minutes describing the relationship between cover crop planting and improved water infiltration.
Click here to view it: http://plantingseedsblog.cdfa.ca.gov/wordpress/?p=6587.
It features Russ Lester, owner of Dixon Ridge Farms and a CalCAN advisor, who discusses the importance of cover crops on his organic walnut orchard near Winters, CA.