Researchers at CSU have teamed up with NASA to test water-saving technology on California crops

By Vinnee Tong

Near the Central Valley town of Los Banos, Anthony Pereira opens a tap to send water into the fields at his family’s farm. Pereira grows cotton, alfalfa and tomatoes. And he is constantly deciding how much water is the right amount to use.

“Water savings is always an issue,” he says. “That’s why we’re going drip here on this ranch. We gotta try to save what we can now for the years to come.”

Thanks to some new technology, that might get a little easier. To help farmers like Pereira, engineers at NASA and CSU Monterey Bay are developing an online tool that can estimate how much water a field might need. Here’s how it works: satellites orbiting the earth take high-resolution pictures — so detailed that you can zoom in to a quarter of an acre.

“The satellite data is allowing us to get a measurement of how the crop is developing,” says CSUMB scientist Forrest Melton, the lead researcher on the project. “We’re actually measuring the fraction of the field that’s covered by green, growing vegetation.”

Those images are combined with data they’re collecting right now at a dozen California farms from Redding to Bakersfield and from Salinas to Visalia.

In Pereira’s fields a tractor carrying tomato seedlings leads the way as farm workers nestle the plants into the dirt. Alongside them the researchers drill holes in the ground to put sensors underneath and around the crops. The sensors measure wind temperature, radiant energy from the sun and how thirsty the soil may be on a given day.

Walking through the field, researcher Chris Lund is carrying equipment that will collect all that data.

“Once a minute it’ll take a measurement of all the sensors that are attached to this,” he explains, “the soil moisture sensors, the soil water potential sensors, and in this case the capillary lysimeter, which measures how much water is going out the bottom of the system.”

[module align=”left” width=”half” type=”pull-quote”]”We have to figure out how to use whatever limited water each place has to the best possible extent.”[/module]

Using this information with the satellite images that are updated about once a week, the researchers have come up with a formula that can estimate how much water a field might need. Farmers will soon be able to access estimates for their fields online and eventually they’ll be able to use their cell phones.

That means Pereira will no longer have to rely on the old-school way of deciding how much water to use.

“Before, everything was furrow-irrigated or flood-irrigated, and we’d just schedule depending on what the weather is,” he told me. “If it’s warm, we say, ‘OK we’re going to try to irrigate every two weeks.’ If it’s cooler, then let’s try to stretch it out another week, 10 days or so to make the water stretch out more.”

The California Department of Water Resources estimates water savings could amount to hundreds of dollars per acre, and the crop yield could be better, too. The joint research team sees its water-saving tool as something that could be used by any farmer. At the Ames Research Center in Mountain View, NASA’s Rama Nemani studies a map of the world mounted on a wall.

“If you look at the map like this, there are a lot of areas that are like California that are starved for water but need to still produce food,” he says. “So we have to figure out how to use whatever limited water each place has to the best possible extent.”

This online water saving tool could be available at no cost to farmers around the state as soon as next year, and eventually to farmers around the world.

Hear the radio version of this story from KQED’s The California Report.