Using landscape irrigation efficiently can significantly reduce overall household water consumption while leaving adequate water in the ground to cover your plants’ needs. One tool that can help is to build up your water savings when rainfall is available.
Approximately half of the water spent by average California homes is used outdoors, mostly for irrigation. Unfortunately, up to half of commercial and residential irrigation water is squandered by evaporation, wind, improper system design, or overwatering, according to the U.S. Environmental Protection Agency.
During the winter in metropolitan San Diego County, healthy soil can absorb water in surprisingly large quantities to be released slowly to plants as they use it during drier months – like using a savings account to pay for expenses over time.
There haven’t been many opportunities in recent years to do so. However, whenever it is possible, there is no need to use the residential water supply on your landscaping when Mother Nature can bank water savings deposits for you.
Balance your water bank account
Water entering the soil – whether as rain or as irrigation – is like a deposit into a soil checking account.
By keeping track of those transactions of water in and water out, it is possible to know how much water in the soil “reservoir” is available in the landscape at any given time for the plants to access.
The initial soil bank balance is determined by direct observation or is assessed after a thorough wetting of the soil by irrigation or winter rains. Every day, plants take small amounts of water from the soil. Rain and irrigation fill up the water bank again. The trick is to make sure this “account” does not get overdrawn.
How can you tell when the account is depleted? Smart irrigation controllers and landscape professionals can calculate this for you. You can also rely on a soil probe, or even testing the landscape by feeling the soil surface with your fingers.
When oxygen and water are balanced in the soil, the amount of water lost through evapotranspiration is similar to paying fees on your savings account. Shading the soil surface with plant materials and mulch protects water in the soil by slowing evapotranspiration and leaving more water in your soil’s account.
This article is part of a year-long series inspired by the 71-page Sustainable Landscapes Program guidebook. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.