What’s the best way to schedule irrigation?

Researchers at California State Polytechnic University, Pomona (Cal Poly), compared different irrigation scheduling methods.

The research, on hybrid bermudagrass, maintained as a golf course fairway, compared soil moisture sensors from Toro (Turf Guard Soil Monitoring System), Rain Bird (Integrated Sensor System), and Tucor Inc. (Soil Moisture Monitoring) with an evapotranspiration-based (ET-based) schedule.

Photo: Toro

The goal was to determine potential water savings between a soil moisture sensor and ET-based irrigation scheduling. The experiment results demonstrated that soil moisture sensors effectively reduced overall water consumption at golf course fairway settings while maintaining an excellent hybrid bermudagrass fairway.

When soil moisture sensors maintained gravimetric water content at or above 15 percent, the resulting turfgrass quality consistently received visual color, quality, and density ratings of minimally acceptable levels or above. These results suggest optimal turfgrass growth is possible under irrigation regimes based on in-ground SMS readings.

Higher volumetric water content in ET plots resulted in slightly better overall turfgrass growth and performance based on both clipping yields and turfgrass visual ratings.

Moisture sensor technology effectively reduces water consumption by roughly 30 to 50 percent of ET while maintaining acceptable turfgrass conditions.

Overall water savings vary from season to season. Water savings between treatments were most substantial in the hot summer season. The contrast in water savings between ET-based irrigation and soil moisture sensor scheduling was far less dramatic during the cooler fall seasons.

The results show that moisture sensor technology reduces water more effectively than ET-based irrigation scheduling. Soil moisture sensors were most effective at reducing overall water usage during the hot summer when water demand was highest.

Soil moisture sensor technology may prove a more helpful tool for golf course superintendents in the southwestern U.S. in reducing overall water consumption on larger golf course fairway areas while still maintaining a quality turfgrass stand.