Irrigation calculator and CIMIS data - California Avocado Commission
Irrigation Efficiency - from UCAVO web site
Irrigation water requirement studies of citrus and avocado trees in San Diego County, California, 1926 and 1927 - 1930. Beckett, S.H., Blaney, Harry F., Taylor, Colin A.
Tensiometers - from UC Davis
Tensiometer Use to Schedule Crop Irrigation - by Ted Sammis New Mexico State University
Tensiometer Service, Testing and Calibration - A.G. Smajstrla and D.J. Pitts - Bulletin 319, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: April 1997.
Estimating Soil Moisture by Appearance and Feel - by Norman Klocke and Paul Fischbach - University of Nebraska Cooperative Extension
Water relations - Home page of Professor E. Steudle - Institute of Plant Ecology