Part Two of a two-part series. Part One: Ancient Methods and Lowest-Cost Technology.
A map that estimates the availability of freshwater in the year 2050 shows a belt of red and orange across Northern Africa, the Middle East and India. The colors signify water deficits, meaning that those regions will not have the water they need to grow enough food for their populations.
Managing farmlands well can conserve water, improve harvests and avoid crises during periodic droughts. But as populations grow and the climate slowly changes, even good land management will not be enough for some of the world’s drylands. Those places will have to import their food or find creative solutions to the severe lack of water.
Prototypes and new tools that are just entering the market in developing countries may make things easier. Dryland farms can now benefit from new materials used in old ways, such as superhydrophobic nano coating on fog nets, and known materials used in new ways, such as plastic plates layered to diffuse water around a plant’s root system. Likewise, researchers are improving on old technology, such as the greenhouse, which one organization has made extremely low cost and modular, and others are combining with desalinators to farm with seawater. And the finger, which is how farmers have judged the moisture level of the soil for thousands of years until recently when digital sensors have turned the art into a science.
Innovative irrigation
“In regular agricultural settings you’ve got evaporation, but in deserts it’s a lot more. There’s not much soil moisture. As a result, you’ve got to change practices to be more efficient. For example, innovations that we’re supporting try to figure out how to store water so it’s not lost in soil or evaporated off.” Ku McMahan, who heads the Securing Water for Food Grand Challenge for Development at USAID’s Global Development Lab, told E4C.
McMahan and his team award grants to bump up the development and distribution of technologies that could improve crop yields. Three such innovations at work on dryland farms today make the most of the little water available with creative irrigation.
When birds and other animals eat seeds and excrete them, they don’t just do the plant the favor of transporting its progeny, they also inadvertently improve the seed’s chances. Dung adds moisture to the soil where the seed is dropped and it also creates a moisture-retaining cap around the seed. The Groasis Waterboxx is a water retaining enclosure that mimics animal excrement by protecting seedlings as they grow. Invented by Pieter Hoff and implemented in Jordan with help from the Institute for University Cooperation and Desert Tulip, the device is a 20 liter (5 gallon) barrier placed around the seedlings of fruit trees and shrubs in desert and semi-arid farms. The Waterboxx collects rain and dew in a reservoir under the plant, preventing evaporation and providing water.
The Buried Diffuser is a plastic plate sandwiching a 5mm layer of silica connected to an underground drip irrigation system. The plate, created by Chahbani Technologies, is buried and diffuses water from the drip system around the roots of the crops. In tests on farms in Tunisia, the system reduced the cost of crop production and the amount of water needed by 30 percent compared to traditional drip systems.
The SWAR system is an upgrade for unglazed clay pot irrigation, and has been tested successfully in orchards in dry regions of Andhra Pradesh near India’s southeastern coast. The system requires gravity-fed drip irrigation from a raised water tower above the field. Farmers can capture rainwater or drill boreholes down below the water table and pump water to the tower with manual or treadle pumps. Once in the tower, gravity draws the water down through PVC piping to sealed plastic jugs placed inside of ceramic pots. The pots are buried near the trees and other crops. Water drips slowly out of the jugs into the pots where, as in traditional clay pot irrigation, it seeps efficiently into the soil. Tests suggest that this method reduces water by 80 percent compared to above-ground drip systems. And independent research found that clay pots use one-tenth of the water needed for surface irrigation.
Farming in the digital age
Phones have facilitated the spread of mobile weather and market information services, and those continue to take hold and improve. But other digital tools are coming online that also have the potential to conserve water and change farming methods in the world’s drylands. Soil moisture sensors and other information technologies have seen the fastest growth among the different categories of agricultural innovation, Roberto Lenton, Director of the Water for Food Institute at the University of Nebraska, said in an E4C Webinar.
Moisture sensors take the guesswork out of knowing when to water and when the soil is wet enough. These devices have soared on the market lately, with cheap, handheld versions for home gardeners and state-of-the art, 70kg (150lb) cosmic-ray sensors that count neutrons above the soil to determine its water content. (The University of Nebraska installed one of the cosmic-ray sensors in a tree in an endangered forest in Mapungubwe National Park in South Africa. Its data will support water conservation work by businesses outside of the park.)
Research underway is simplifying the moisture sensor to give farmers more intuitive readouts. Two prototypes in development now are color coded.
IDEO.org is testing its sensors in Kenya and Tanzania, and in Myanmar the organization has teamed with the local firm Proximity Designs to test sensors in the country’s dry region. A day of measurements reveals the land’s drainage rate and soil type and the farmer’s watering methods. Days and weeks of measurement data reveal weather patterns, all useful in planning land management strategies.
In Mozambique, the Australian Centre for International Agricultural Research is testing the Chameleon, a sensor prototype that also gives a visual readout, changing color to indicate moisture levels.
Moisture sensors are an emerging technology that may not have caught on in developing countries quite yet.
“Theoretically, soil moisture measurement could work, but practically, I haven’t seen any in place. I work with farmers and I have yet to see anyone implement any of the data science solutions in the field yet,” says Khanjan Mehta, Director of the Humanitarian Engineering and Social Entrepreneurship (HESE) Program at Pennsylvania State University and an E4C Contributing Editor.
But in spite of the skepticism for sensors, Mehta’s team is developing a different digital tool for farmers: a knowledge database. The database is compiling local agricultural knowledge among farmers in Sierra Leone, information like plant types, farming techniques, seasonal patterns and so on. But rather than throwing it all in the cloud and hoping that farmers with phones can find it, the team is controlling the informational chaos, sending the database to Amazon Fire tablets for roving experts to reference while they talk with farmers.
And the Water for Food Institute has been instrumental in creating another digital farming tool: the Global Yield Gap and Water Productivity Atlas. The Atlas estimates yield gaps – the gap between a region’s potential and its actual crop production – for major crops around the world, identifying targets for improvement.
Desalination and fog nets
Seawater desalination is necessary for the near future of farms in desert countries in the Middle East, according to a 2014 research paper in Consilience: The Journal of Sustainable Development. The prospect may be expensive, but farms irrigated with desalinated water are already operating in desert climates, and projects are underway in developing countries. A company called Seawater Greenhouse combines solar desalination with greenhouses and evaporative cooling to grow tomatoes and other crops on desert coasts, with one facility planned for Somaliland.
And the Israel-based Arava Institute is testing a solar-powered desalination prototype for small families in Gaza, among many other examples.
Fog nets work where fog is thick, but they lag in drier climates. To capture water from the air for irrigation even where the fog is lighter, the engineering firm NBD Nanotechnologies is giving the nets an upgrade. NBD is testing its superhydrophobic coating on nets in the semi-arid hills of San Francisco. Data suggest that the coated nets yield five times as much water as uncoated nets. And 50 of them in heavy fog may capture up to 19,000 liters (5000 gallons) of water per day.
Silos, fridges and other storage
“Storage enables us to deal with temporary scarcity. I like to think of storage not only in terms of physical storage, but also in virtual storage. Food storage, for example,” Lenton says.
After the harvest, storage silos can prevent loss to insects, rodents, mold and even theft. Pests account for 10-40 percent of food loss worldwide, the World Resources Institute reports. New research into food storage in developing countries has revived old silo designs and developed power-efficient refrigeration.
The Zero-Emission Fridge for Rural Africa protects grains inside a triple wall of woven bamboo sandwiched between layers of clay. Inside, herbal repellants keep insects at bay and the base has built-in mouse traps. It joins other passive storage solutions such as the thick-walled, antimicrobial Purdue Improved Cowpea Storage bags, and the ISSB Granary built with interlocking stabilized soil bricks.
Taking storage a step further, although in a smaller space, evaporative coolers chill produce inside a container that is surrounded by water. As the water evaporates it draws heat from inside the pot and lowers the temperature. The clay Zeer Pot is a simple example. Mitticool is a larger version, shaped like an electric refrigerator but made of porous terracotta. It stores water in an upper container and cools its contents while the water evaporates.
The Thermogenn Cooler takes a step up the technological ladder, employing a highly absorptive mineral called zeolite to draw water out of a reservoir sandwiched between layers of stainless steel, lowering the temperature inside its storage chamber by a similar principle. The mineral must be heated later to restore its absorptive power.
On the upper end of the low-cost storage technology spectrum, Wakati One ventilates and humidifies produce stored inside a tent. Its 3w solar panel, fan and water reservoir can keep perishable foods intact for more than a week.
And Chotukool is a fan-cooled thermoelectric cooler that consumes half of the power of similar-sized electric refrigerators.
The challenges ahead: Climate change, urban farming and “process innovation”
Dryland farms already slip across the line from sustainability into famine from time to time, but a changing global climate threatens to upset this already precarious balance.
“We expect that unless we can come up with technology advances that can store water when it comes in huge deluges, or just use less water, then there will be greater impact from climate variability,” says McMahan at Securing Water for Food.
And urban farming should figure among the technological advances that developing countries focus on in the coming years, McMahan says. It’s not yet practical to produce food at a large scale in hydroponic farms using recycled water, but that would be a boon for the world’s growing number of city dwellers.
“As people move to cities you want to reduce the need to move food at great distances. Especially in developing countries where people are moving to cities away from farms,” McMahan says.
That issue of moving food and moving things in general might be key to solving the food problem. Distribution of goods and of information is a problem that doesn’t get nearly enough attention, says Mehta at Penn State.
“There is enormous opportunity for process innovation,” Mehta says. “Everybody is focused on designing new products, but not on the channels to reach the farmers. In a place where people don’t know how to grow the most basic things a tomato costs $1 or more. Not many people know how to grow them and if something goes wrong they don’t know how to fix it. As we design new products, we need to design ways to get the information and products there.”
If they’re right, the new targets for design could improve how we deliver tools to farms and how we move farms to cities. Regardless, we’ll see changes on farms in the next 30-40 years whether or not we guide them. The uncertain effects of climate change and the inexorable climb toward 9 billion people will demand them.
