What is in this article?:
- Drip irrigation provides far more than water use efficiency
- Watch every drop
- Winter rains, early dam releases and optimistic water delivery allocations by federal and state irrigation water providers point to an exciting year for California producers.
- Drip Irrigation systems not only delivery water efficiently, they reduce tailwater.
Watch every drop
That’s why, even with the possibility of a good water year ahead, Sano and his irrigation manager, Jesse Sanchez, watch every drop that goes into – and out of – Sano Farms’ drip irrigation system. Sano and Sanchez irrigate with buried bury drip lines under the farm’s processing tomatoes, and run surface drip in the Sano almonds, pomegranates and pistachios.
It was another kind of water efficiency – minimizing back flush water from the 45 water filters that protect the farm’s drip system – that led them to low-back flush filtration technology.
When Sano invested in drip, he knew he had tapped into a powerful tool for the efficient delivery of water and fertilizer.
“In processing tomatoes, yields of 36 to 38 tons used to be good,” he says. “Then we used to figure on 42 to 44 tons on average, and now we shoot for 50.”
By fastidious maintenance of the operation’s buried lines, he and Sanchez have been able to eke five seasons or more out of the farm’s original drip tape, and they’re aiming for seven or eight. Part of that maintenance involves regular flushing of the lines. Another vital element is protecting them from the sand that can be pumped up with well water and the algae that can develop in canals.
Variable water quality can be a challenge for many filtration systems – some technologies that are good for capturing hard materials like grit or sand, for instance, have more trouble with softer materials like algae or bacterial buildup. Sano and Sanchez knew they didn’t want back flush-intensive sand media systems, and an experiment with another technology didn’t provide the flow or flexibility they were looking for.
Then Sanchez came across automatic self-cleaning screen filters at the World Ag Expo. The technology, like drip irrigation itself, was developed in Israel, and was strongly geared toward water efficiency, notes Matt Aguiar, the Merced-based national sales manager for Amiad Filtration Systems, which manufactures the systems.
When a target pressure differential is reached between the clean and dirty sides of the filter screen, a flush valve opens, Aguiar explains. Water begins rushing from the pressurized inside of the filter to the lower atmospheric pressure of the flush valve, pushing trapped particles, or filter cake, with it. The system focuses that back flush action through small suction nozzles, which concentrate the cleaning action on one square inch at a time. The nozzles are mounted on a scanner that spirals down the screen, ensuring that every square inch of the screen is cleaned during the cycle. Meanwhile, the filter continues trapping new particulates as irrigation water continues flowing through the system.
“Water efficiency should carry through every aspect of a good drip irrigation system, all the way through back flushing the filters,” Aguiar says. “This suction scanner technology uses up to 75 percent less water for back flushing than sand media systems do, which has a double benefit – not only a water savings going into the process, but also a reduction in the amount of tailwater coming out.”
Sano knew from the start that tailwater was going to be a challenge multiplied by each of the nearly four dozen filters he needed to install on his operation.
“The problem with sand media is they waste a lot of water when they flush,” Sano says. “Over here, that’s expensive, and there’s hardly any water. Also, in this part of the Valley, we have no drainage system – we have to re-circulate all our water. You have to have reservoirs and pump the tailwater back into the system.”
Managing tailwater was easier to do when Sano furrow-irrigated his row crops, though the reservoirs took up acres of valuable space. When he put drip under his row crops, he began focusing his small amount of tailwater on his pomegranate orchards, which can tolerate lower-quality water. Then he reclaimed acres that had once been dedicated to storing excess water.
“We used to have 10 reservoirs with concrete ditch lines to all of them,” Sano says. “Now we have two, and we only pump out of them maybe once a year, when we flush our lines. We filled up the others and planted them with the rest of the field, or used them as storage or cleaning areas – 8 to 10 acres’ worth.”
As with his drip lines, Sano believes in a meticulous maintenance program for his filters. He says the self-cleaning screen systems look complicated, but actually have far simpler – and less leak-prone – plumbing than sand media tanks do.
“Once you get to know them, it’s easy,” he says. “You have to acid-bathe the screens in muriatic acid every year in this part of the world, and we do an annual lubrication of the moving parts. We have to replace solenoids every once in a while, but it’s not hard.”
The compact size of the Amiad filters – they’re less than five feet long and easy to lift with a fork or bucket – is another benefit over multi-tank sand systems, Sano adds. “We can easily pop these filters out and move them to another ranch,” he says.
For Sano, it all comes down to efficiency. “We got tired of dealing with water issues,” he says. “A minimal amount of drainage – that’s the key out here.”
The 2011 season will surely present its challenges, from late-planted triticale cover crops that need to be burned down to make way for Sano’s conservation-tilled tomato transplants to the constant challenge of battling morningglory. But even with the water supply looking promising, Sano says his biggest long-term concern remains water – the water he brings or pumps onto the farm, and the water that can’t leave.