AE437, a 5-page illustrated fact sheet by Michael D. Dukes, Mary Shedd, and Bernard Cardenas-Lailhacar, is part of the Smart Irrigation Controllers series. It describes how soil moisture sensor systems work, rules for installation, setting the sensor threshold, and programming the irrigation timer. Includes references. Published by the UF Department of Agricultural and Biological Engineering, February 2009.
http://edis.ifas.ufl.edu/AE437