Sand Culture Growing Success
Growing plants and vegetables in sand culture is not a new idea, but it appears to be both practical and economical now that plastics and commercial water-soluble fertilizers are so common. It also could be part of the solution to feed a growing human population.
For the Aztecs of Mesoamerica, a lack of arable lands didn’t stop them from farming. Instead they exercised their wits and made land of their own in the form of floating gardens along lakeshores and in canals. Although the Aztec civilization ended nearly 500 years ago, many of their agrarian concepts of growing squash and beans in a sand medium can still be found in contemporary culture.
Utilizing materials at hand, the Aztecs used plant roots to lash together rushes and reeds, which they then covered with sand laden with nutrient-rich organic debris dredged up from the lake bottom. Called chinampas, these early sand-culture rafts were home to vegetable crops and flower beds whose roots pushed downward into the water for sustenance. Tied together into floating islands sometimes 200 feet long, the chinampas were often poled close to a market place where shoppers could walk up and purchase fresh produce straight from the garden.
Modern Sand Culture
Despite the demonstrated success of crop cultivation in a hydroponic fashion, most of the work done with soilless growing prior to the early 1900s was low-key, consisting mostly of laboratory experiments with specific plants. The standard definition of sand/gravel culture at that time came from Merriam-Webster: “Growing plants in an artificial medium using sand/gravel to support the roots and supplying mineral nutrients in an aqueous solution.”
Then Dr. Merle Jensen came along. Jensen, a lauded plant scientist from the University of Arizona who was born and raised on a farm in Washington, is recognized worldwide as an eminent research horticulturist. Jensen’s concern in helping to find new ways to feed an ever-growing population (around nine billion estimated by 2050) made him a missionary of sorts. He has spent a good portion of his lengthy career growing vegetable crops in harsh desert climates around the world, from Mexico and Latin America to Asia, the Middle East, and North Africa. His trial-and-error efforts have resulted in new ways of growing nutritious crops in sand. He took agricultural concepts and reassembled them into a form that redefined sand culture to mean growing edibles in sand dunes in arid and inhospitable parts of the world. This is concurrent with Maximum Yield’s definition that the process is “thought to be more efficient than traditional hydroponic methods because sand decreases the risk of botanical ailments such as verticilium and fusarium.”
Jensen eschews the classic deep flow hydroponic system, where plants are supported while their roots hang in a nutrient solution, as well as nutrient film technique and the concept of aeroponics. Instead, he likes aggregate hydroponics where a solid, inert medium such as sand, coconut coir, sawdust, or variations involving peat, vermiculite, perlite, stone wool, or polystyrene beads, provide support for the plant while nutrient solution is delivered directly to the plant root.
“Sand is an anchor and if you make it plant-friendly, it does extremely well,” says Jensen. Although his comment is a contemporary one, he initially made it back in 1973, the year he supervised building The Land Pavilion for Disney’s Epcot Center, when he prophesied “an exciting future for sand culture.”
Also, while sand in its pure state is not an ideal medium for plant culture because of an inability to retain water and nutrients, most natural sand has silt particles and some organic matter (sandy loam), making it one of the cheapest grow mediums because it can be washed easily and recharged with nutrients.
Jensen proved his point with experiments that integrated the production of vegetables, electricity, and desalinized water in the soil-poor deserts of the United Arab Emirates. He called his growing of food on Saadiyat—a sandy, essentially barren, uninhabited island—his version of sand culture and proved it could work in an area buffeted by strong prevailing winds and rainfall of less than two inches a year. A previous prototype in Puerto Penasco, Mexico, where plants were seeded into plots of beach sand or peat moss/vermiculite and drip-irrigated, also proved the efficacy of the concept.
“There are over 20,000 miles of desert coastline worldwide that, if made habitable, could feed millions of people,” he says. “In most cases, edibles could be seeded directly into leached beach sand and, once growing, be irrigated with constant liquid-feed solutions of commercial-grade fertilizer. Current growth of food production will not keep pace with need unless we extend it into new areas and toward that end, the day will come when the world’s deserts must be cultivated.”
While noting that sand culture is “not a new concept,” Jensen says that “with plastics and commercial water-soluble fertilizers now common, it appears to be both practical and economical.” His prescience has been proven true. “There’s lots of sand in the world and we’ve proven we can grow plants in some of the harshest areas in the world,” he says.
“Growing in sand is a technique we might even be using some day on the moon,” adds Jensen. “In the interim, it’s allowing us to bring vitamins and minerals to some very harsh environments. We now have the ability to extend balanced diets in those parts of the world, places like the Gobi Desert, where Chinese farmers are already cultivating 50,000 hectares using sand or cinders.”