Today some 2.8 billion people face insufficient supplies of fresh water, and according to the United Nations that number is set to increase to half the world’s population by 2030. The UN Food and Agriculture Organization (FAO) reports that 40% of the world’s food depends on irrigation, which accounts for almost 70% of fresh water used.
It makes sense then that farmers are turning to new and old technology in an attempt to manage their water.
Measure twice, pump once
The old business dogma, “If you can’t measure it, you can’t manage it”, holds especially true with water usage. But in many places around the world the amount of water diverted from rivers or pumped from the ground to irrigate crops is not measured. Even California groundwater was totally unregulated until this month.
That’s a political rather than a technological problem, said Peter Gleick, co-founder of the Pacific Institute, an independent research organization focused on water issues. Flow meters to measure water use are neither new nor expensive, Gleick said. But in many places groundwater has long been considered a property right, so farmers have seen no need measure or justify how they use it.
But with drought and over-pumping dropping water tables, some are beginning to recognize that better water use tracking will help to keep a dwindling resource flowing.
Milwaukee, Wisconsin-based Wellntel, a water technology company, is answering that need with a water-measuring system that uses sound sensors to detect the water level in a well – without touching the water or opening the well. The sensors transmit data to the Wellntel website, where customers can log in to private accounts and see their water level at various points: when pumping, after rainfall, and over time.
In an attempt to mollify farmers, Wellntel specifically touts a farmer’s right not to share data on the amount of water used with anyone else.
Waste not, want not
The first place to save water is in conveyance: as much as 60% of the water withdrawn for irrigation is lost through leaks in canals, spillage and evaporation, according to the FAO.
Another part of the problem is flood irrigation – the most common method of field irrigation globally. About half the water on flood irrigated fields isn’t absorbed by crops, according to the US Geological Survey. Instead it runs off, taking with it fertilizers, pesticides and topsoil that pollute water bodies around the world and cause dead zones, areas where too much fertilizer causes algae to bloom, which in turn sucks oxygen out of the water, killing other life.
Flood irrigation is commonplace because it’s cheap. But in response to strained water supplies, some farmers have made the shift to much more efficient underground irrigation or precision micro-sprinkler and drip irrigation systems that deposit tiny amounts of water directly above the roots of crops. These systems also help farmers earn more money by allowing them to plan more acreage while using less water than before.
The up-front cost of a drip system is significant – about $ 500 to $ 1000 per acre, according to the FAO. Even though these investments pay for themselves within a few years thanks to better water-use efficiency and lower irrigation-related energy bills, many farmers don’t have the cash – or credit access – to install them.
However a Middle Eastern firm has developed a new low-tech solution that also places water right at the roots of crops and can work with or without drip irrigation – and comes with a much smaller price tag.
In Israel, where water scarcity has been a way of life for decades, Tal-Ya (“God’s dew” in Hebrew) manufactures trays that capture dew and funnel it to plants, often tree crops. The 28- by 22-inch polypropylene trays trap air underneath themselves as well, insulating plants from extreme temperatures and catching moisture evaporating from the earth to create a perpetually moist soil pocket around the roots. They also block weeds that would otherwise compete with crops for water.
Each tray costs $ 3 to $ 5 apiece.
Mickey Chesla, Tal-Ya’s vice president of marketing and sales, said the trays can reduce water use by up to 90% although 50% is more typical. They can also reduce fertilizer use by 30% because the trays direct the nutrient straight to the plant’s roots.
While introducing more plastic into the environment might not seem like a great idea, Tal-Ya states that its trays last for up to 10 years and are 100% recyclable. Since beginning commercial production in 2013, farmers in Israel, the United States, China, Chile, Georgia, Sri Lanka, and Australia have adopted them according to the company’s web site.
This past spring Tal-Ya was a runner-up in the Imagine H20 food and agriculture competition. Its tray system “improves agricultural yields without increasing resource allocation”, said Scott Bryan, Imagine H2O’s chief operating officer. “These solutions that enable farmers to produce more with less are proving crucial to surviving the California drought”, he said.
Just in time
Another way to avoid waste is to avoid watering when it’s about to rain or the soil is still moist. A variety of systems – including Measure-Tek, Ranch Systems and Pure Sense – use weather-monitoring stations and soil moisture probes that send data via radio or cellular signals to a grower’s computer or smart phone. Some can be programmed to turn irrigation off and on as needed.
Taking this concept to the extreme, Oakland, California-based Fruition Sciences has created a web application that crunches data from more than 40 sensors to determine whether crops need more water. The system tracks crop nutrient uptake, aerial photos, and weather and soil conditions. One special sensor tracks sap flowing through grapevines.
“People are overwatering”, said Thibaut Scholasch, founder and vice president of research and development for the company. “Everywhere we go, from Spain to Argentina to California to Italy to France, we measure a plant response showing that vines are much more resilient than we think.”
“We are teaching people to un-train their eyes: drippy-looking leaves do not mean the plant needs water”, Scholasch said. “Often it simply means the weather is hot even if there is still plenty of water in the root system.”
Fruition Sciences is working with farmers in the Los Angeles Metropolitan Water District on a project to save water. “So far we have saved anywhere from 40% to 100% of water used for irrigation”, Scholasch said. The range reflects a big swing in how much a grower is over-irrigating as well as the spatial variability and climate dryness of a given vineyard.
The systems aren’t cheap however. Costs range from $ 40 to $ 5,000 for a “site” which can be as large as 50 acres – if the field is planted with a single crop – but is often much smaller.
The expense has so far limited the appeal of Fruition Sciences’ system to use with wine grapes. But Scholasch said the firm is currently testing the technology with other cash crops.
From restraint to reuse
An even more nuanced way to manage watering is a strategy called regulated deficit irrigation. The goal is to irrigate crops just enough to maximize crop-water productivity by reducing irrigation at the point of diminishing returns. For example, reducing water by 50% might result in a yield reduction of just 10%. Some crops, such as wine grapes and certain nuts, actually benefit from water stress during drought-tolerant life stages.
Regulated deficit irrigation can be implemented with any type of irrigation system. It is sometimes used with rain-fed crops, adding a bit of irrigation during droughts or in sensitive growth stages, such as when the plants are producing vegetation and during final ripening.
Reuse is also growing in appeal, with urban wastewater being lightly treated and directed to landscaping, industry, power plant cooling, groundwater recharge – and crop irrigation.
“In Monterey and Salinas Valley, much of the strawberries and artichokes are grown with recycled wastewater effluent”, said David Sedlak, a professor of civil and environmental engineering at the University of California at Berkeley.
A new technology from Calgary-based Livestock Water Recycling is treating animal waste for reuse on row crops in what amounts to a little sewage treatment plant. The nutrients in the treated sewage benefit the crops by reducing the need for fertilizer inputs, and reduce pollutant runoff because the plants absorb some of the nutrients.
It’s an improvement over the common lagoon system, in which waste sits in a pool for multiple months, to allow solids to settle out before being sprayed on crops. These pools emit toxic gases and can leak into nearby water bodies.
Farmers can also capture flood irrigation runoff and reuse it. This kind of reuse is easier and more cheaply done in organic farming, where the water contains fewer fertilizers and pesticides, than in more conventional agriculture.
And dry-land farmers have developed many strategies to collect rain via barrels and cisterns for direct use, and to resupply groundwater using bioswales (land features that filter water), buffer strips, off-stream storage reservoirs and natural wetlands.
Not all countries or regions may be able to be self-sufficient in food production. Fifty-one percent of the world’s population may rely on food imports in 2050, according to a study last year in Environmental Research Letters. Certain crops need less water and are well suited to dry environments, whereas others such as rice, cotton, or alfalfa – notoriously thirsty crops – are probably better left to wetter regions. Choosing to grow the right crops for the climate – right-cropping – is important in making the most of available water.
Countries in the Persian Gulf are turning increasingly to international food imports after decades of depleting their groundwater.
Israel, too, is spending more of its limited water resources on industries other than agriculture, earning money to buy food internationally. “There may be no countries in the Middle East that have enough water to be self-sufficient in agriculture,” said Gleick of the Pacific Institute.
However, some countries are buying land in wetter countries to grow their food, a practice that can jeopardize local food security, environmental justice and human rights. A study last year in the Proceedings of the National Academy of Sciences found land grabbing inextricably linked to gaining water rights, with 60% taken by the United States, the United Arab Emirates, India, the United Kingdom, Egypt, China and Israel. Forty-seven percent of such land purchases occurred in Africa and 33% in Asia.
There is also a growing debate over whether some non-food crops should be grown at all in an increasingly water-scarce world. Feedstocks for biofuels, for example, take hundreds of gallons of water per gallon of fuel to produce. The International Energy Agency predicts a 317% percent increase in water consumption by biofuel crops by 2035.
Happy soil, happy plant life
While modern industrial agriculture has tended to treat soil merely as a medium that props up plants – first bombing it with insecticides and pesticides, then applying fertilizer to pump up the plants – healthy soil has built-in plant nutrients, absorbs water more deeply and retains it better.
Many traditional agricultural practices – such as reduced tillage, crop rotation, planting cover crops, applying compost, manure, or mulch – nurture the microscopic critters that live in soil. But ways to increase soil moisture and water efficiency are also coming to conventional farming.Polymer soil additions have been researched for 20 years as a means to help soil retain moisture. The idea is that when the farmer irrigates, the polymer absorbs water that would otherwise run off and holds it around the seed.
Bay Area-based mOasis, which produces a soil polymer called BountiGel, claims its product is a significant advance on this concept: it doesn’t break down before the plant can use it, said Steven Hartmeir, mOasis’ CEO. But it does break down. It’s harmless to soil microorganisms because it is highly diluted in the soil at about 10 parts per million, he said.
Made of ingredients already approved for human use and consumption, BountiGel has been approved for use by the California Department of Food and Agriculture. Roda Group, a venture capital firm based in Berkeley, Calif., has invested more than $ 5m in mOasis.
In use the polymer has shown the potential for 25% higher crop yields due to decreased stress on plants, 25% reduced water use overall, and 15% savings on water-related energy utilities, Hartmeir said. “We had a tomato grower this year that would normally drip-irrigate every seven days, and with our product, they stretched it out nine to 11 days”.
Although BountiGel costs about $ 150 an acre, an average grower can generate about $ 900 more per acre thanks to increased yield and water savings, according Hartmeir.
The farmers he works with, like farmers nearly everywhere around the world, “need to figure out how to grow more with less water”, Hartmeir said. “We have a water problem in California, and it’s not going away”.
This piece was published in conjunction with Climate Confidential.
Erica Gies is an independent reporter who covers water and energy for The New York Times, The Economist, Scientific American and other publications.
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