SWAT Away Wasted Water TRADITIONAL WAYS OF IRRIGATING CROPS ARE CHANGING

UNDER T H E PRESSURE OF WATER SCARCITY AS N E W

TECHNOLOGIES EMERGE,

By Lyn Corum

N ew tech- nologies to control and mod- erate crop

water use have emerged in the past decade and are increasing crop yields, A study published in September 2008 by the Pacific Institute, More with Less: Agricultural Water Conservation and EfFciency in California-A Special Focus on the Delta, reviews the research and, in particular, analyzes four scenarios for improving

I five years or so, the innovations have focused on monitoring soil moisture.

Agriculture consulting companies have been around for

I some time, exp&ins Zoldoske. In the past, neutron probes were used to measure soil moisture, and reports were provided to growers, but that work was time and labor intensive. The latest technology, created by Puresense, uses their programming experi- ence and a lot of science to de- velop reporting techniques using real-time information, building on existing technology, he says.

Bottom line? "You look to water use efficiency: mod- Pure Sense monitoring station powered by solar panel and battery backup see what best fits the application:' est crop shifting, smart says Zoldoske. irrigation scheduling, advanced irrigation study. For example, it notes that regulated There are two types of smart water management, and efficient irrigation deficit irrigation can be used on pistachios application technologies, also known as technology. during the shell-hardening phase that is par- SWAT-those that monitor soil moisture in

The study notes that regulated deficit ticularly stress-tolerant, while the bloom and the root zone, and those that use weather irrigation can be an important tool to both nut-filling stages are not. Studies have also data to estimate the amount of water used by reduce applied water and increase revenues. shown, the study says, that this technique the turf to adjust the irrigation. Soil moisture Deficit irrigation applies water below the might improve crop quality, particularly for monitoring technologies are reviewed here. requirements for traditional, full crop wine grapes. The companies profiled illustrate the evapotranspiration (the movement of water David Zoldoske, Ph.D., director of the technologies available for smart irrigation through the plant and its evaporation). Center for Irrigation Technology at Califor- scheduling and advanced irrigation manage-

Irrigation control technology makes nia State University, Fresno, and a member of ment, including regulated deficit water usage. regulated deficit irrigation possible without Water Eficieng's Editorial Advisory Board, The profiles were not intended to promote introducing water stress to crops, if it is used says irrigation control technologies have the companies themselves. Seventeen com- duringstress-tolerant growth stages, says the been evolving for 20 years, and, in the last pany products have been evaluated by the

26 1 WATER EFFICIENCY

Seelbach says research will continue to expand the model to encompass hu- man uses of water. "People are part of this ecosystem, and we need to have their water budgets better understood:' he says. "We've looked at the hydrology and the fish, but we're weak on the human part."

Lampreys and Ballast Water Another major research thrust involves exotic species admitted to the Great Lakes by shipping. The most notorious alien, the sea lamprey, is a parasitic fish that entered Lake Ontario in the early 19th century and established equilibrium with the native species there. Niagara Falls blocked it from access to the upper lakes.

To allow shipping to bypass Niagara Falls, the Welland Canal was built in the 1820s and 1830s, and rebuilt three times- in the 1840s and 1850s, in the 1880s, and from 1913 to 1932. The 20th-century recon- struction "allowed the direct mixing of wa- ters from Lake Ontario and Lake Erie, and let the sea lamprey into the upper lakes:' says Scarpino. "The lampreys didn't do all that well in Lake Erie, which is relatively shallow and warm. In the colder lakes, they had a smorgasbord available. They were first reported in Lake Huron in 1932, Lake Michigan in 1936, and Lake Superior in 1946. Lamprey populations exploded, and lake trout abundance went into freefall. In the US waters of Lake Huron, the commer- cial lake trout catch was 1.7 million pounds in 1935,940,000 pounds in 1940,172,000 pounds in 1945, and just 4,000 pounds in 1948."

Now lampreys are more or less under control, thanks to their unique and vulner- able life cycle, adds Scarpino. They spawn in certain types of tributary streams, where the larvae live in a non-parasitic form before migrating into open lake waters. Great Lakes Fishery Commission researchers figured out their spawning requirements, and put electric barriers across spawning streams. Later, the researchers developed a lampricide, a selective poison that kills the larvae in spawning streams. "We have to do this forever:' he says. "The lampreys will rebound like a coiled spring as soon as you take the pressure off."

The opening of the St. Lawrence Seaway in 1959 enabled ocean-going freighters to travel directly into the Great Lakes, bringing ballast water taken on in foreign seas all over the world. "With the ballast water comes whatever happens to be living in it," says Scarpino.

Species introduced by ships discharg- ing their ballast water in the Great Lakes include the zebra mussel, native to lakes in southeastern Russia; and the quagga mussel, from the Dnieper River in Ukraine. Both compete with native species by filtering phytoplankton from the water, and they befoul boats, docking facilities, and the wa- ter intake pipes of power plants and water treatment plants.

Another recent arrival, a hemorrhagic fish virus similar to Ebola, is spreading among Great Lakes fish. It ruptures their blood vessels and damages their internal organs. Researchers aren't sure whether it came from the Atlantic coast or Eurasia.

"The Great Lakes compact says they're going to look at getting ballast water under control," says Scarpino. "It's a thorny prob- lem. Even if you require ships to discharge their ballast water outside the St. Lawrence system, they still will have residue in the tanks. Can you force them to chlorinate their ballast water? Who regulates this, how do you do it, and what's the penalty for vio- lations? How do you harmonize all that?"

Nonpoint Sources The 1972 Great Lakes Water Quality Agreement dealt with control of domestic sewage, phosphates and detergents, and other identifiable sources of water pollu- tion. It stimulated the construction of sew- age-treatment plants in the US and Canada and the control of boat wastes.

Scarpino says research published in 1978 disclosed another major threat, pollut- ants deposited in the lakes by wind and rain. Today, the primary concern is with these "nonpoint sourcesn-airborne fertilizers, pesticides, and herbicides.

"One objective of the new compact is to control nonpoint sources, but it's a much harder problem to solve," he says. "With point sources, the problem was figuring out a way to pay for control. It may cost people a little bit more, but if you build a sewage- treatment plant or a factory has to put in its own plant, that doesn't require any citizen to change his lifestyle. Effective control of non- point sources will have an impact on people's lifestyles. It will affect the fertilizer on the lawns of millions of residents."

Broader Issues Blomquist says the new compact and agree- ment symbolize broader issues, including "recognition of the importance and growing scarcity of freshwater supplies throughout

the world," and "the willingness and ability of states and provinces to undertake their own environmental policies, without neces- sarily waiting for their national governments to set policies for them."

Canada's involvement is vital to the success of the new compact and agreement, Scarpino emphasizes. "Canadians are con- stantly figuring out how to get along with their much larger neighbor to the south," he says. "They know they can't control pollu- tion without us. Because of our larger size, we contribute more pollution. If you're a Canadian, the common end might not be the same as if you're an American."

Scarpino says the compact and agree- ment offer an opportunity for Americans and Canadians alike "to take an integrated look at the system, to see it ecologically, rather than iooicing at fisheries, rransporta- tion, and water quality in isolation."

He adds that, for most of the time since the first European explorers arrived in the Great Lakes basin, the basin residents believed that their fishing, farming, and industrial and urban development were socially beneficial.

"Most people believed the basin's resources were limitless," he states. "Until the middle of the 20th century, people did ,

not think ecologically. They didn't real- ize the Great Lakes are an interconnected and interdependent system, and need to be managed that way. It's not that ignorant and greedy people messed things up, but the unintended consequences of things they did have encouraged them to rethink their relationship with the lakes." we

George Leposky is a science and technology writer based in Miami, FL.

References Texts of the Great Lakes-St. Lawrence River Basin Water Resources Compact and the Great Lakes-St. Lawrence River Basin Sustainable Water Resources Agreement are online at W W W . C ~ ~ ~ . O T ~ / ~ T O ~ ~ C ~ S I W ~ ~ ~ T ! CompactConsent.asp.

For information on The Nature Con- servancy's ELOHA framework, visit WWW.

nature.org/initiatives/freshwater/strategies/ flows.htm.

I IN WATER RESOURCE MANAGEMENT. LEARN MORE AT: I

WATER EFFICIENCY 1 25

Center for Irrigation Technology, featuring shallow roots that require different configu- PureSense's Irrigation Manager. One of the technologies using both soil moisture and rations and shorter moisture probes than critical services Puresense offers is an auto- weather data technologies. These reports are permanent crops like fruit or nut trees. Also, matic frost and heat alert that go directly to available at www.irrigatlon.org. a sandy topsoil layer will not hold water, the growers' cell phones.

but the clay layer underneath will, thereby

A soil moisture sensor being laid in the ground

Information-Based Technology PureSense announced an infusion of $4.5 million in venture capital financing with One Earth Capital, in March 2008, at the same time that it unveiled upgrades to its Irrigation Manager software, its core service offering for efficient water use in agricul- ture. Founded by Craig Buxton and a small team in 2003, PureSense's technology was incubated as a technology spin-off of NASA technology at NASA's Ames laboratory.

In addition to its Jack London Square headquarters in Oakland, CA, PureSense also has a branch at the Claude Lava1 Water and Energy Technology Center in Fresno, CA.

The company provides ongoing turnkey consulting service to growers of irrigated crops with real-time support for irrigation and water use, featuring Web-hosted soft- ware that receives real-time data via wireless communication from its PureSense propri- etary monitoring station. Growers can access the system anytime and from anywhere via computer, phone, and PDA devices.

Richard Gates, chief information officer, explains that the company contracts with each grower, evaluates water and irrigation needs, installs field monitoring stations, activates online software, and maintains and upgrades its online tools. Pricing is based on the growers' acreage, type of soil, crops, and unique field conditions that influence a crop's performance.

For example, row crops like carrots have

requiring deeper moisture probes. This kind of information determines the economics of the service and the most viable cost-effective system.

The monitoring station communicates via a proprietary device to a soil moisture probe that is buried in the soil 18 inches to 1.5 meters, depending on the crop and soil profile. The monitoring station sits on a pole approximately five feet above the surface of the ground up to 30 feet from the probe. It is powered by a small solar panel, 8 inches by 14 inches with battery backup.

The soil moisture probe can read moisture levels every 4 inches at 15-minute intervals 24 hours a day, and the weather components read temperature, humidity, and other climatic variables at the same time, both below and above the canopy of the crop. This raw data is transmitted to the monitoring station, and then by the wireless communicator in hexadecimal language to PureSense's servers. Here Irrigation Manager software reads it and generates reports and trend charts that can be read by the grower to see, anytime and from anywhere, how their crops are using water and to show them when their irrigation system is on or off, as- sisting them with fine-tuning moisture levels.

Gates says the Irrigation Manager works with all types of irrigation systems, whether they are flood, drip, or micro sprinklers. The irrigation systems are on independent timers controlled by the grower and not by

Alerts Improve Efficiency and Sleep In California, growers worry about frost between midnight and sunrise during the winter months. They must know when to use irrigation water to prevent frost damage, like what hit citrus groves in 2006, explains Gates. When temperatures reach the level he chooses, a grower can receive the automatic alert and turn on the water.

One grower with 10,000 acres has 80 moisture sensor probes and 10 weather sta- tions, explains Gates. Now, he turns the water on only when he receives the automatic alerts from PureSense when the temperature reaches 34°F.

"It's a huge leg up, because he's not watering in late winter and early spring:' says Gates.

Also, certain root diseases, like mold and mildew, are prevented once watering is decreased. This is even more valuable in the case of heat alerts when temperatures are rising rapidly; the ground is sensitive to surface moisture and humidity and can easily activate a Petri dish situation for fungus or mold formation.

Another farmer slept in his field and woke up each hour to check the temperature, says Gates. Now he can sleep in his own bed until 2 a.m., when-and if-he gets an automated alert from PureSense. Another big grower with five irrigation managers never knew if they turned on the irrigation system

WATER EFFICIENCY 1 27

Irrigation control technology makes regulated deficit irrigation possible wzthout introducin water stress to crops, $it is use f during stress-tolerant growth stages.

power from the controller. Acclima's proprietary system allows multiple sensors and other devices to receive power and maintain communications over just two wires.

The moisture sensor is buried about 2-3 inches in the soil and wired to the valve box on the irrigation system. The cable containing the wire is buried 8 inches deep in the soil. The customer then has complete control over operation of the irrigating system

when the grower told them to. Once he had systems. Unknowingly, the plants were being the PureSense system installed along with starved for water. pressure switches in the drip lines to indicate He used to turn his drip irrigation on when water was going through, he could see for about 12 hours and saturate the soil the pressure switch signals, and soil moisture around the roots and shut off the water for

when he was on vacation in Hawaii. His but for shorter periods. As a result of this irrigation managers now know he is looking adjustment, moisture stays constant around over their shoulders. the root system. The result is that yields have

John Kontrabecki is the owner of the doubled. The vineyard is now producing TriValley Vineyard in Livermore, CA. The 4-4.5 tons per acre, up from 2-2.5 tons vineyard has been growing six varietals per acre.

"The vineyard has never looked better:' says Kontrabecki.

This example em- phasizes a point Gates makes: "Overwatering is just as bad for a crop as underwatering:' he says. "However, a more important result is that, by carefully monitoring the irriga- tion system cycles and the soil moisture read- ings, you can increase

? the yield of your crop. 3 a' "You may be us-

A i-ureaense cnan maps me amounr or molsrure reralnea In me SOII. Ine ing the Same amount top row is a summary of measurements of the three depths. The horizon- of water, but you are tal lines spike up, illustrating increased moisture after irrigation starts, as indicated by the pressure switch marks in the bottom row. producing more food

and more value for of wine grapes on 100 acres since 2002. yourself:' adds Gates. Kontrabecki says he was having problems getting the yield he expected. The fruit qual- Automatic Control Technology ity was high, but the volumes of grapes were Acclima, headquartered in Meridian, ID, has below expectation. He enlisted PureSense been selling the Digital TDT Soil Moisture to improve the yield. PureSense installed a Sensor and irrigating with it since 2001. It moisture probe and monitoring station in functions using a patented, digitized time

- -

each block that grew an individual varietal. domain transmission signal that company According to Kontrabecki, they discov- founder, Scott Anderson, developed.

ered that because the plants were grown on The moisture sensor measures the abso- a hillside with soil composed of adobe clay, lute water content of the soil under all condi- the water was running off. When the soil tions of temperature and soil chemistry, and dries out, it can shrink and damage the root communicates with and receives electrical

and can modify its operating hours. Acclima also sells five models of closed-

loop irrigation control systems, each paired with its sensor. They are capable of covering six to 12,24 to 36, or 64 zones depending on the model and are designed to allow for one

Acclima's suspended time controllers al- low timers to be set up based on the amount of precipitation needed. The timer has set start times and durations, but the system will be inhibited if there is sufficient moisture in the soil. For example, the SCX suspended cycle add-on device can be used on any 24-V timer. It can interrupt conventional timers, and do auto setup and performance reporting.

Alternately, with water-on-demand ir- rigation, the controller requires no schedule programming and turns water on only when the soil moisture level falls below a set threshold. The high-end commercial control- lers are also capable of controlling watering within restrictions set by local governments.

For new systems, a single wire pair or multiple wire pairs can be used to mark the limits of the property and intercon- nect all sensors, valves, flow meters, and such attached to that two-wire network. It conveys 24-V power to the valves and other devices on the system, and it conveys signals to maintain communications with the same devices.

Acclima also offers irrigation manager software. It allows multiple controls and monitoring of irrigation controllers from a central location. Maps of sites can be imported, and the irrigation system can be viewed including zones. Reports and sensor graphs are also available.

Saving Water While Improving Plant Growth Kingsley Horton, western states sales man- ager for Acclima, describes a study done at a Florida housing development that had been warned by local authorities about

28 1 WATER EFFICIENCY

different contractors installed TO LEARN MORE ABOUT SWAT GO TO schedule was modified from six Acclima systems, and water usage hours straight, to three hours in was tracked. The Acclima system early mornings and three hours reduced water usage 62%, com- pared to areas where irrigation timers were used with no Acclima systems.

At the Idaho State Capital, Horton says the company installed one controller with three sensors, at a cost of $2,400. That con- troller saved enough water to pay back the cost in 3.8 months, despite a leak caused by a broken pipe behind the water meter causing runoff into the street all night. Apparently, the managers had opted to not install flow meters that would have shut the water off. 33- ' -- f k ? about the advantage of a flow meter, since it could have saved even more water.

Roger \\later, a landscape architect specializing in water and soil management, installs Acclima smart controllers regularly. He originally installed controllers that use weather data and ran into various kinds of problems. The radio that needed a signal sent to it would lose the signal, antennas and radios broke, and wire contacts went bad on solenoids.

"I need to have customers not be aware of the irrigation system," he says.

And when things break, the customer becomes aware. In a number of gardens and landscaped residential estates, he replaced those systems with Acclima's probes and controllers, and got much fewer callbacks.

However, \%'ater says he would install the weather-based wireless \\'eatherTRAK system in areas where there is too much hardscape to run the wires needed foi- the Acclilna system.

"You do save an awful lot of water," says M7ater, of the Acclima system. He I-ecently replaced a weather database system that had been in place for three to four years, with an Acclima controller at a winery in Napa, CA. The owner is now saving one million gallons of water annually.

These savings came after M'atel- cleaned out the irrigation system a year ago, moving heads around to improve coverage, and

The owner told him the plants have never looked better.

John Paz is a grower-manager at hlilano Flower Farm that grows cut flowers and cut greens in Carlsbad and Oceanside, CA. Cut greens are plants such as myrtle, boxwood, and ruscus. Paz installed one Acclilna control- ler and six probes in October 2007 in the 325-acre Oceanside farm he manages. Over 20 types of plants are grown and all take differ- ent water requirements.

"The biggest thing we've learned is how ~ w q . s ; l \ . s @ a z - ~

The well water is high in sodium, and he was increasing the amount of water to leach it out, but he wouldn't see any increased mois- ture in the probes unless it rained heavily. The reason? \\later was running off the fields. The effect on plants was burned leaves- something unacceptable in the cut flower and greens business.

in late afternoon. "It's a mindset about continuous watering," he says. "This learning was due to the probe."

The next step for Paz and his colleagues is an experiment. They are adding three more probes in one field. One part of the field will get one percentage of water while another part of the field will get a different percentage of water, so they can determine how much water the plants actually require.

Horton says customers in Europe, South Africa, and Australia have installed the com-

~ a n ~ - i l o g ; ~ 4 n e ~ _ I ~ ~ ~ b u t ~ r ~

has sold 300 systems without technical sup- port. The systems are very popular in Florida; in hot pockets in Michigan, Minnesota, Ohio, and \4Tisconsin; throughout the IVest; and in Texas. WC

California-based Lyn Corum is a technical writer specializing in energy topics.

reducing the number of controllers from six to four. Water usage plummeted from 8,000 gallons per day to 3,700 gallons per day dur- ing a period that included a 1 10°F heat spell.

\%%en he installed the Acclima system

w w w . w a t e r e f f i c i e n c y . n e t I WATER EFFICIENCY 1 29

four to five months ago, he reduced the number of controllers further, to two.

I I