The University of California Agriculture and Natural Resources is featuring several books for the month of April to help us conserve water for trees, plants, lawns and other agricultural use. I recommend visiting the UC ANR website to get a look at their publications. You can find out more at . Some of the topics include Monitoring Soil Moisture for Irrigation Water Management. It gives pointers on helping to determine the right amount of water to apply to maintain plant health, how roots uptake water, timing irrigation and how to determine if water is getting deep enough.
With mandatory rationing and the reductions in irrigation frequency or length it is essential to make the best use of what little water is available. Some additional hints to help reduce and retain more of the irrigation water used is to never water during warm daytime periods when much of the water can be lost to evaporation. Mulching around trees and shrubs will also help to retain moisture levels in the soil. A four inch layer of soil will retain more moisture and also reduces heat stress to trees and shrubs. It is important though not to place mulch near the trunks of trees and shrubs because this can encourage root fungi to develop.