Shallow root systems result in plants being stressed even in short periods of water deficit. On the other hand, excessive irrigation can leach nutrients from the soil and encourage the development of diseases and nutrient deficiencies. The rooting depth of various vegetable crops is listed in the table. It is important that shallow-rooted crops receive more frequent irrigations. Preferred Minimum Soil Moisture.
Soil moisture is measured with a tensiometer or soil block.
The former is preferred for sandy soils and the latter for clays and loams. Tensiometers report soil moisture in centibars. Suggested soil tensions for various vegetables are reported below. Irrigation amounts and the time between irrigations are critical to efficient irrigation practices. Some suggestions for amount and timing of irrigations are presented in the table.