Irrigation Based on Soil Suction Measurements

Abstract

Abstract Soil suction (soil moisture tension) from zero to 0.8 bar is explicitly indicated by tensiometers. Higher values can be measured by suitably calibrated soil moisture resistance units. An irrigation program, both as to timing and duration of applications, can be carried out based on day‐to‐day records of soil suction at two or more depths in the root zone of the crop involved. Available moisture depletion is a commonly used basis for recommending irrigation practices. Curves are presented which show that, when irrigation timing is based on a given value of available moisture depletion, irrigations may be applied at widely differing values of soil suction if soil texture varies. A layered soil experiment shows the usefulness of soil suction measurements for evaluating relative moisture conditions in soils of varying texture. Examples are given of irrigation practices by avocado growers which are based on tensiometer readings. When related to soil suction measurements, an irrigation program is adapted to soil, climate, and plant variables.