One day in early October, a group of University of California, Merced, students went to the campus Smart Farm, augurs in hand, to explore the soil for the best spots to locate moisture sensors.
They were not looking in the root zone to monitor how much water is available but instead for areas lower in the soil to study how irrigation and stormwater can travel far enough beneath the plants to recharge the groundwater below.
“The trick is trying to get more water down to the aquifer and verifying that we did it,” said Tom Harmon, UC Merced chair of the civil and environmental engineering department. “We need to figure out how to measure soil moisture deeper. We usually measure to the root zone, but we have to take it past the plant.”
The ability to monitor how much water is recharging the underground aquifer will become more important as growers have to comply with the Sustainable Groundwater Management Act. It requires that local agencies adopt rules to limit pumping to no more than the groundwater can sustain over time.