Soil Water Tension, a Powerful Measurement for Productivity and Stewardship

A fundamental way to schedule irrigation is through the monitoring and management of soil water tension (SWT). Soil water tension is the force necessary for plant roots to extract water from the soil. With the invention of tensiometers, SWT measurements have been used to schedule irrigation. There are different types of field instruments used to measure SWT, either directly or indirectly. Precise irrigation scheduling by SWT criteria is a powerful method to optimize plant performance. Specific SWT criteria for irrigation scheduling have been developed to optimize the production and quality of vegetable crops, field crops, trees, shrubs, and nursery crops. This review discusses known SWT criteria for irrigation scheduling that vary from 2 to 800 kPa depending on the crop species, plant product to be optimized, environmental conditions, and irrigation system. By using the ideal SWT and adjusting irrigation duration and amount, it is possible to simultaneously achieve high productivity and meet environmental stewardship goals for water use and reduced leaching. Irrigatedhorticultureisessentialforhuman health and welfare. Improved human nutrition can be achieved through improved horticul- tural productivity and quality, which in turn is often related to irrigation practices. Fresh water for horticulture production is increas- ingly in scarce supply and facing competition from alternative water demands from cities, industries, and interest groups that want water left in-stream to support fish and other aquatic organisms. Water quality is also becoming more important. It is widely recognized that precise irrigationisa key tohigh horticultural productivity, efficient water use, and water quality protection.