How Microdrip Irrigation Systems Use Less Water and Could Change Farming Forever

Good News Notes:

On the bone-dry western flank of Arizona, where the Colorado River Basin meets the Mojave Desert, sit 11,000 acres of alfalfa, sorghum, wheat, and Sudan grass belonging to the Colorado River Indian Tribes (CRIT), all destined to be harvested and sold for animal feed. For anything to grow here, irrigation is a must. Less than a quarter inch of rain has fallen so far this year, according to Josh Moore, who manages the farm on behalf of his tribe.

“The reservation is set up on a pretty outdated flood irrigation system,” Moore says. A network of canals built in the 19th century delivers water from the Colorado River, a system that seemed like a better idea before the watershed entered a persistent and increasingly dire state of drought. Although the canals supply enough water to meet CRIT’s farming needs for now, the tribes are planning for a hotter, drier future. This season, black plastic tubing can be seen snaking down hundreds of rows of sorghum: an experiment with microdrip irrigation that could radically reduce the farm’s withdrawals from an overtaxed watershed.

Around the world, most crops depend on rain alone for their water, but in places where rainfall isn’t sufficient, we’re forced to irrigate. Despite all the innovation that’s made its way into agriculture in recent years, from GPS-guided tractors to genetically engineered seedlings, 85% of all irrigation is still done by releasing vast quantities of water across the surface of a field, pretty much the same way it was handled 4,000 years ago in Mesopotamia.

Flood irrigation has hung on because it’s cash-cheap, but from a natural-resource perspective, it’s staggeringly expensive. As much as 70% of the water goes to waste, and overwatered crops can fail to reach their full potential. Excess fertilizer is carried away by the runoff, contaminating streams, wetlands, and lakes.

Microdrip irrigation was supposed to solve all that. In the 1930s, a young engineer named Simcha Blass noticed a tree that had grown much taller than the others in the same row; when he looked closer, he found that its roots were being fed by a tiny leak from a nearby irrigation pipe. Years later, the Israeli used the concept to create a plastic drip irrigation system that went on to be sold under the brand name Netafim. It remains the global leader in its sector.

Today, there are hundreds of drip irrigation companies, but the technology is being applied to less than 5% of irrigated acres globally, usually to big-ticket crops such as almonds, wine grapes, and tomatoes. The limiting factor is cost. As the systems are currently designed, pushing water through hundreds of feet of pipe requires a lot of force, which farmers supply with pumps; electric ones if they have power in their fields, carbon-belching diesel versions if they don’t. The dripper lines are also prone to getting clogged by silt particles or algae found in natural water, so it must be filtered, which adds another expense. The whole setup amounts to at least $2,000 an acre, plus energy bills. For lower-value crops such as cotton or alfalfa, drip irrigation simply doesn’t pay.

The microdrip setup being used by CRIT Farms, however, cost less than $400 an acre to install, and the required pressure is supplied entirely by gravity, which has the advantage of being free and carbon-neutral. To the casual observer, the system doesn’t look like much. But to Moore, the idea of drip irrigating crops for animal feed is nothing short of revolutionary. Assuming, of course, that it actually works.

“When the well’s dry, we know the worth of water,” Benjamin Franklin wrote in a 1746 edition of Poor Richard’s Almanack. He didn’t know the half of it. Today’s global population is 10 times what it was back then, and freshwater sources are in decline. The biggest water hog by far is agriculture, which accounts for almost three-quarters of global use.

Signs of water scarcity are all around us, growing more alarming with each passing year. In August, for the first time in history, the Colorado River was declared by the U.S. government to be in a state of shortage, triggering supply cuts to some of the 40 million people who depend on it. Five million of them get their water courtesy of the Central Arizona Project (CAP), a public utility that delivers river water by canal from the western edge of Arizona to 80% of the state’s population.

Chuck Cullom, the Colorado River programs manager at CAP, has spent the past decade exploring options for increasing Arizona’s water supply, including wastewater-treatment technologies and gadgets that help urban customers curb their use. In 2019, at a conference in Tel Aviv, Cullom met an executive from an Israeli irrigation startup called N-Drip, which was developing a system that promised drastic water savings without the prohibitive costs. “I was superskeptical,” Cullom says. “It sounded like a unicorn solution.”

But agriculture accounts for the vast majority of Arizona’s freshwater use, so Cullom was willing to try N-Drip. In 2020, CAP provided the system to CRIT Farms for use on 40 acres of sorghum. They found that it cut water use in half, while slightly improving the quality of the crops: a staggering result, albeit on a very small scale. This year, CAP expanded the pilot to about 200 acres of sorghum and cotton across Arizona, and, if all goes well, hopes to deploy the system regionally by 2023, continuing to cover the cost of the equipment for farmers who install it.

N-Drip is the brainchild of Uri Shani, a professor of soil physics at the Hebrew University of Jerusalem and a former chairman of Israel’s water authority. He set out seven years ago to devise a microdrip irrigation system cheap enough to make sense not just for lettuces and berries but also commodity crops such as soy and corn, which make up the bulk of the world’s agricultural output.

Shani is 72 years old, with short salt-and-pepper hair, wire-rimmed glasses, and an avuncular manner. He was born in 1950, on a kibbutz suffused with an angst peculiar to life in an arid country committed to agricultural self-sufficiency. “My father was an engineer who worked primarily on water. I grew up thinking about water and water solutions all my life,” Shani says, speaking by Zoom from N-Drip’s office in Tel Aviv.

After completing his military service with an elite commando unit, Shani went on to Hebrew University, Israel’s preeminent research institution, and got a master’s degree in soil physics. For his Ph.D. work, he moved to Kibbutz Yotvata, in the desert in Israel’s far south. The area gets less than an inch of rain each year and has only brackish groundwater for irrigation purposes: the outer limits of agriculture. He began there as a grad student and ended up managing the kibbutz.

Shani later became a professor, and in 2006 was tapped to become the first head of the newly created Israel water authority. The role was complex, spanning engineering, management, politics, and economics, and he took it on with the country experiencing its worst-ever drought. Shani turbocharged investment in water recycling and desalination. To pay for it, he significantly—and controversially—raised the price of water.

“Around the world, the reason why there are so many water problems is very few countries are prepared to charge consumers the real price,” says Seth Siegel, N-Drip’s chief sustainability officer and the author of a 2015 New York Times bestseller, Let There Be Water, that recounts Israel’s rise as a leader in water conservation and technology. In 2012, Shani left office with Israel in a freshwater surplus. “It was extraordinary what he pulled off.”

A private citizen once again, Shani began ruminating on the growing threat of water shortages worldwide. More than a quarter of the world’s population lives in water-stressed countries, and the United Nations estimates that water scarcity could displace 700 million people by the end of the decade. The most significant contribution he could make, he decided, would be to help drip irrigation go mainstream. That meant inventing a system that ran without filters and pumps.

To understand Shani’s challenge, you first must understand what’s happening inside those humble black plastic dripper lines. Along each one is a series of holes, and fastened inside every hole is a plastic widget about the size of a Tic Tac, called an emitter. Water moves through an exceedingly narrow, maze-like channel inside the emitter, regulated so it comes out in measured droplets. The resistance produced by those emitters is the reason so much pressure is required to move water from one end of a field to the other in a traditional system.

Shani conceived a new kind of emitter, one that offered so little resistance that the water pressure provided by gravity alone—accrued during the 1- to 2-foot descent from the irrigation canal to the field below—would be enough to propel the water all the way down hundreds of feet of tubing and out into the ground. First, he experimented with weaving plastic and metal fibers into various three-dimensional lattice structures. But it was on a hike one day, he says, that the breakthrough came: Instead of a zigzag channel, his emitter would consist of a rod suspended inside a cylinder, with water flowing through the tube shape formed between them. Unlike with a traditional emitter, now, no single particle of debris could block the water’s flow. “Boom,” Shani says. “I was absolutely convinced it would work. Then we developed all the mathematics.”

Once he fine-tuned the concept, Shani needed to commercialize it. He contacted Eran Pollak, a former finance ministry official with whom he’d worked closely as water chairman, and told Pollak he’d invented drip irrigation that used only gravity. Pollak was skeptical. He’d grown up on a kibbutz, too, and he knew about irrigation; there was no such thing as zero-pressure drip….”

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