According to the U.S. Geological Survey, about 70% of the earth’s surface is covered with water; however, only 1% is suitable for drinking. Yet we irrigate with potable water. It is only in the last dozen years that more municipalities are beginning to think about using non-potable water for irrigation.

However, until we get to the point that we can use enough recycled water or desalinated water, we have to rely on potable water as our source. Because water will be scarce, the first restrictions will be on the landscape. Yet, we have hundreds of billions of dollars tied up in shrubs, plants, turf, trees, etc. So, how do we achieve the wanted results using a minimum amount of water effectively and efficiently?

One way you might consider is using special software to schedule your irrigation. By using irrigation scheduling, you provide the end user with a watering guideline based on system, plant, soil, and evapotranspiration data. The schedule should indicate the number of minutes each station on the controller will operate, the number of cycles between irrigations to prevent runoff, and the number of days to skip before irrigation begins again. This scheduling guideline should be created for each month of the year.

Creating an irrigation schedule is not a difficult task; however, it does require a little effort. To begin with, irrigation schedules should be based on site and system conditions. To create a schedule, you must first determine the evapotranspiration rate in the area where the system is installed.

Additionally, you’ll need to gather data on the type of plant material being irrigated, such as the root depth, plant factor or landscape coefficient. You’ll also need to know the type of soil, and calculate the infiltration rate and soil moisture holding capacity.

Once site conditions are determined, you’ll want to calculate the precipitation rate for each zone of the irrigation system to determine its efficiency and distribution of uniformity. Without this information, it is not possible to properly schedule an irrigation system.

In the past, you’d next have to whip out that calculator, and do some number crunching, possibly bringing back bad memories of high school algebra. That’s not the case anymore. Software programs now available are designed to analyze this data, and then calculate an accurate irrigation schedule. You simply enter known information, or select from existing databases of historical evapotranspiration rates, soil types, and plant factors.

In many instances, there may be multiple stations on a controller, assigned to zones with similar requirements. Many software programs will allow you to quickly transfer information from one station on a controller to another. Once the data is entered, you can calculate a monthly irrigation schedule for each station within seconds.

The beauty of the software is that not only does it make creating an irrigation schedule that much easier, but it also helps educate the end user on proper scheduling. You may design and install the most efficient irrigation system possible, but if your client doesn’t know how long to operate the controller, the system will ultimately waste water.

Some believe that scheduling is not the responsibility of landscape contractors; that this places too high a burden on them. But who is better suited for creating the irrigation schedule than the person most familiar with the system, the plant material, and the environmental conditions?

As landscape professionals, we already take steps to protect the water supply with the proper installation of backflow devices, the distribution of water to landscape areas in the most efficient manner possible, and the conservation of water used in landscape irrigation.

Editor’s Note: John DeCell is the owner of Software Republic, a company that specializes in software for the irrigation market.