Scientific irrigation
scheduling
Randy Newhard, president/owner
New Way Professional Landscape Services
San Diego, California
1995 sales: almost $2 million

With about 80% of his work as maintenance, Randy sees xeriscaping as his up and comer. Xeriscaping is seriously scientific landscape water management/irrigation. To make this happen, Randy added Don Shultz, one of California's leading landscape water management experts, to his staff. "Don has pretty much seen it all as far as what exists out in a landscape irrigation system."

One of the most important functions of irrigation is proper scheduling to make sure the proper amount of water is applied based on evapotranspiration (ET) rates. This is the rate at which plants and the soil lose water. Water evaporates from soil. The process which plants lose water is called transpiration.

As you might suspect, the ET rate changes with the humidity, temperature and amount of sunshine, etc. Knowing the ET rate and how to use it lets you accurately predict how much irrigation should be applied.

"Through Don, we set up landscape water budgets for our in-house clients, and we monitor that on a weekly basis based on head spacing, line spacing, plant materials, acres. Then we read the irrigation meters to be sure what we are applying is right. It takes a lot of time."

Randy says most people guess watering rates, and they guess wrong. "People will say, 'It has been hot this week...Let's bump a station from 15 minutes to 30 minutes.'" This increases water usage 100% while ET rates may have increased a minimal amount. In Don's previous government job, he monitored ET rates vs. various irrigator's water bills. In most cases, plants were either overwatered or underwatered.

"You are going to get grubs and fungus problems if you start overwatering, and lose plant material. The plants get addicted to that water too. So you have to slowly cut the water down." Besides the damage, overwatering costs big bucks. "We saved one client 12.3 million gallons, $21,000-something like that-in 2 years."

Randy gets ET rates once a week from the California Irrigation Management Information Systems (CIMIS). He accesses CIMIS ET rates through a modem connected to a computer. He recommends contractors in other areas look to their universities or farm extension offices. Farmers use ET rates in their irrigation scheduling.