Landscape Water Management
By Jutta Thoerner UCCE Master Gardener
I want to improve my irrigation practices this summer. Any tips?
Mike, Templeton.
My 1st tip: Add to your current water supply and make the most of your resources. For example, install a grey water system and add barrels to collect rainwater. If you have areas on your property that flood or have water runoff during a rain event, create soil swells and redirect the runoff water so it stays on your property.
Another tip: Mulch everywhere possible. Mulch suppresses weeds, cools the soil, soaks up excess water, and slows evaporation which reduces the amount of irrigation you need to apply.
March is a good month to install, update or repair existing irrigation systems.
Many different irrigation systems are available: drip tubes, soaker hoses, micro sprinklers, and drip tape are a few popular choices. These need to be checked for leaks, clogged emitters and uniformity when applying water. To find out how much water your system dispenses, set out several small empty cans or containers under the emitters or sprinklers. Set a timer for 60 seconds and turn on the water. Then, empty the cans to measure the water collected. Simple math will tell you how many gallons or ml per hour are dispensed.
To figure out how much water is needed and how often to apply it, several factors come into play. It starts with the soil and its ability to hold onto the water you apply. This is referred to as the Available Water Holding Capability or AWHC. While loamy soil holds onto water the longest, sandy soil has the lowest AWHC % with 3-6% due to its texture and hydraulic charge. If you have sandy soil, applying water more frequently for a shorter duration is important. Another factor to consider is evaporation or how hot is it on the day you irrigate. The measurements for evaporation (ET) may be estimated by current or historical weather data (ETo).
If you are interested in learning how to collect and apply irrigation data, join the Master Gardeners on March 21st, 10 am-12 pm, and learn about the scientific method of calculating how much and how often to irrigate. The workshop will be held in the auditorium across from the garden. Arrive early as seating is limited!