Savannah Valley District

Irrigation – Never Too Late To Calibrate!

Becky Davis, Water Resources Agent- Savannah District

Introduction – August in South Carolina may conjure up the start of school and football season, but there still may be hot, dry days in which your plants require additional water to yield the optimal benefits.

Irrigation seems simple! Water plants the right amount at the right time. However, that involves many factors, some should be considered before installing the irrigation system, and some factors dictate adjustments during the growing season.

The type of irrigation used should match the plant species desired and the soil type. Irrigation equipment such as sprinklers, spray heads, drip tape, sub-surface drip tape, micro sprinklers, and micro spray heads have different purposes. After installing the proper system and planting is complete, the main irrigation decisions involve when to irrigate and for how long.

There are many irrigation scheduling methods, from manual (touching the soil) to weather apps and soil moisture sensors. However, system calibration is necessary for any scheduling decision to be effective. All types of irrigation should be tested for water output.

Figure 1: Measuring irrigation water output.

If your lawn is suffering from the heat and patches of brown are increasing, it is time to test the spray angles and the system’s output. The most effective way is to set straight-sided cups or cans (such as cat food or tuna) across the yard (Figure 1.).    Run the system for a set time, measure the water in the containers with a ruler, and adjust the spray angles for better uniformity. Also, average the amount of water in the cups and correctly irrigate by adjusting the time the system is on. For example, if the average water level in the cups equals .5″ after 30 minutes, run the system for 15 minutes to irrigate .25″.

Figure 2: Center Pivot Irrigation Test. Becky Davis

Testing the uniformity of center-pivot irrigation systems (Figure 2) is extremely important for farmers to optimize water output and minimize costs. Clemson Extension provides this service.

So, even though summer weather is waning, it will still benefit your plants and budget to adjust your irrigation system again this season!

Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, gender, religion, national origin, disability, political beliefs, sexual orientation, gender identity, marital or family status, and is an equal opportunity employer.