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Water world

(article, Tracy Ilene Miller)

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“In the winter, you want a good tomato so much that you start to think about buying a hothouse tomato,” wrote a commenter on the blog The Inadvertent Gardener this past January. “Thankfully, you were strong and resisted!”

Someday soon, hothouse tomatoes (tomatoes grown in greenhouses) may become not only harder to resist but unavoidable — and perhaps even delicious. The four largest U.S. greenhouse growers (located in Arizona, Texas, Colorado, and California) together make up 67 percent of domestic tomato production. All of them use hydroponic growing systems, in which tomato plants are grown with only water and nutrients. That’s right: no dirt required. 

The hydroponic tomato first hit the U.S. market in the 1960s. By the 1980s, production was still limited; the tomatoes, often wan in color and dull in flavor, tended to be mealy or just plain hard. But beginning in the early 1990s, production of hydroponically grown tomatoes began to increase nationwide. Today, nearly 40 percent of the fresh tomatoes sold at retail around the country are hydroponic. In that time, overall U.S. tomato consumption has exploded; in the past 20 years, our chomping of fresh tomatoes has grown more than 30 percent, to approximately 20 pounds per capita per year. And as demand has increased, growers are trying to find ways to improve the flavor and texture of the hydroponic tomato. 

[%image promo-image float=left width=400 caption="Hydroponic lettuce grown in a greenhouse." credit="Photo: iStockphoto/dstephens"]

Tomatoes are merely the first in what growers hope will be a long line of commercially successful greenhouse-grown products. The sheer volume of tomato production worldwide overshadows all other hothouse vegetables, but greenhouse cultivation of herbs, cucumbers, and salad greens is continuing to expand. Much experimentation is also being done with strawberries, which are highly susceptible to soil-borne diseases that are no longer treatable with the toxic and ozone-depleting methyl bromide. 

Customers focus mostly on greenhouse-grown vegetables in January, but availability isn’t the only motivator behind water-grown produce. Hydroponic growing appears to be the next big revolution in worldwide agriculture. Many believe it has the potential to feed large populations while using fewer chemicals, making better use of resources, worrying less about contamination, and harvesting much higher yields per acre.

h3. Ditching the dirt

Flavor in a vegetable comes from a number of variables, including the plant variety, the conditions it’s grown under, the water and nutrients available to it, how mature it is at harvest, and how much time elapses between harvest and dinner. Much as the French tout terroir, the concept of tasting the place where something was grown or produced, soil in fact contributes very little to a vegetable’s flavor. All dirt does is give a plant a place to put down roots. 

The two primary influences on the taste of hydroponic vegetables are plant variety and mineral content. Decades ago, the tomato varieties that growers first planted in greenhouses were selected not for flavor but for yield and uniformity. But as consumer values have shifted from appearance to taste, greenhouse growers are making a parallel shift. Many smaller hydroponic operations are already meeting the demand for better taste; Todd McWethy, for example, who owns McWethy Farms in Three Oaks, Michigan, is growing hydroponic tomatoes sought out by local chefs and shoppers.

Last year, McWethy experimented with heirloom tomatoes, which are not particularly suited to hydroponic growing. “The heirloom tomatoes have been a big hit, although I was told they would not work,” he says. “The selling point was the beauty, especially as heirlooms are generally gnarly-looking things. Last year I couldn’t keep up with the demand. The quality really shines.”

Once they've chosen which varieties of plants to grow, hydroponic cultivators then manipulate nutrient mixes and growing conditions in order to obtain the healthiest plants and highest yields possible. Many growers also focus on producing tastier veggies. Nevertheless, “no one can produce a better tomato than in your back yard, or like grandma did,” says Gene Giacomelli, the director of the Controlled Environment Agriculture Center at the University of Arizona, Tucson. But that doesn’t mean, he adds, that hothouse tomatoes are necessarily a flavor disaster. 

“They taste different, not bad,” Giacomelli says. “I won’t tell \[consumers\] what flavor is good or bad. That’s constantly being worked on.” Shoppers looking for product reliability, he says, can look to large commercial hydroponic growers to produce tomatoes with a consistent flavor. Maybe the flavor’s not quite what you were hoping for, he says, but at least it’s not a surprise.

Michigan farmer McWethy says that part of the hydroponic image problem is the quality and flavor of the tomatoes coming out of Canada; our northern neighbor, in fact, has been charged with market-dumping its hothouse tomatoes south of the border in winter. Canada’s greenhouse tomatoes, McWethy says, are “marginal.” But he also admits that consumers do not want to pay $6 a pound for premium hothouse tomatoes. And Canada’s hothouse tomatoes do “look pretty good.” 

h3. Hydroponics, then and now

Humans figured out hydroponics — the science and art of growing plants without soil, using only water, light, and nutrients — centuries ago. Although the term “hydroponics” was coined in the 20th century, the Aztecs, Babylonians (those famous hanging gardens), and ancient Egyptians are all known to have practiced it. But the more modern techniques of hydroponics began to be worked out less than a century ago, in the early 1930s, when William Frederick Gericke, a professor at the University of California, Berkeley, began serious experiments with growing vegetables in water tanks. In the 20th century, hydroponics caught on chiefly in places where warm weather is limited, such as in Canada, or where land was scarce, such as in the Netherlands. (The Netherlands, in fact — a tiny nation with twice the population density of New York state — has more than 10,000 acres of greenhouses, or nearly a third of the total hothouse acreage worldwide.)

[%image tomatoes float=left width=425 caption="Hydroponic tomatoes grown vertically in a greenhouse." credit="Photo: iStockphoto/lesliejmorris"]

Approximately 40 percent of U.S. greenhouse-tomato imports come from Canada, a fierce competitor of U.S. greenhouse growers. (Mexico ships in another 40 percent of our hothouse-tomato imports, and the rest comes chiefly from the Netherlands and then in very small quantities from other countries, such as Israel and Spain.) In the western U.S., the oval yellow, green, and red sticker of BC Hot House, one of Canada’s largest producers, is ubiquitous in grocery stores; the company sells nearly half of its inventory in the western States alone. 

Despite its comparative infancy, the U.S. hydroponics industry now accounts for 30 percent of North American production of hothouse tomatoes. In the early 1990s, when countries such as the Netherlands and Canada had already been producing for more than a decade, the U.S. grew nearly nothing hydroponically on a commercial scale; today, the country produces more than 350 million pounds of hothouse tomatoes every year.

In research circles, hydroponics is referred to as controlled-environment agriculture, also known as space-intensive agriculture. The goal is optimum use of resources while maximizing output through manipulation of all growing conditions. The uniformity of the produce coming out of these controlled environments — where the growing media and the light and nutrient inputs are all carefully calibrated — has made hydroponics commercially viable after the high initial startup costs of greenhouse construction, equipment, and supplies. Growers can therefore turn around and charge more for the privilege of eating perfectly formed tomatoes or peppers in the dead of winter. 

The costs of greenhouse growing vary greatly, depending on location. In Canada, winter growing is more expensive due to the region’s cold weather and short days; there’s simply a greater need for heat and artificial light sources up north in winter. Those needs are the reason why, in this country, huge commercial operations have developed in areas such as Arizona and New Mexico, where sunlight is abundant and warmer weather more frequent.

h3. The basics

Hydroponic produce is grown either in what you might call a giant water bath or soilless media. (Using soilless media isn’t technically hydroponics, but for simplicity, the industry lumps it in with water-only growing.) Some operations use just a water solution, while others use media made from natural materials such as clay pebbles, coconut fiber, perlite, peat, sawdust, and pine bark. There’s also rockwool, one of the most extensively used growing mediums; it’s a manmade fibrous material made from a mixture of cooked volcanic rock, limestone, and coke. 

In both growing systems, nutrients (typically mined or manmade) are mixed in solution with water that flows either directly over the plant roots or over the growing media. This solution includes everything necessary for producing healthy soil-grown plants, including nitrogen, phosphorous, potassium, calcium, and magnesium. (Some smaller hydroponic operations and many research facilities are now linking aquaculture and hydroponics to recirculate the nutrients gained from fish production into hydroponic vegetable beds; this type of system may someday replace the need for mined or manmade nutrients.)

Rockwool, a preferred growing medium for tomatoes, needs to be replaced every 16 to 18 months. As a result, many growers are looking to coconut fiber (or coco peat, as it is sometimes called) to reduce waste, because coconut fiber is organic and can be composted. Overall, however, hydroponic systems are far less wasteful than field agriculture. Nutrients and water, for example, are typically recaptured in hydroponic systems at rates of 50 to 95 percent; they’re recirculated and monitored by computers. Hydroponics, in fact, generally uses just one-hundredth of the fresh water demanded by field-grown crops. 

[%image water float=left width=400 caption="Reclaiming raw wastewater from a hydroponic growing system." credit="Photo: iStockphoto/Down2theXroads"]

In addition to the inherent efficiency of hydroponic growing, McWethy points out that many hydroponic growers use integrated pest management (IPM), a system that relies on beneficial organisms and natural predators to manage insect pests instead of chemical pesticides. When they do occur, most pest outbreaks in a hydroponic environment can be controlled with biologicals (such as parasitic wasps and lady beetles) instead of sprays. 

“Pesticides are significantly reduced with hydroponics,” Giacomelli says. “We can use biological controls more effectively. There are many hydroponic producers that advertise \[themselves as\] pest-free.” Even when current operations are unable to claim pest-free status, the literature in the industry, the conference workshops, and the products sold to growers all point to the industry’s growing focus on providing spray-free crops.

“When \[hydroponic growers\] pay attention to detail, you can have shelf life, flavor, and appearance, besides marketing \[yourself as\] pesticide-free,” McWethy says. “The neat thing about hydroponics is you are gearing the environment and the nutrients to a specific crop, and even with tomatoes there can be a big variance.” The greenhouse allows for minute adjustments for those variances in small spaces, even for different plants growing side by side. 

h3. The future of food?

There’s a dual explanation behind the growth of the U.S. hydroponics industry: an increase in the number of greenhouse acres devoted to vegetables and herbs, and an increase in the amount of food produced per acre in those greenhouses. Continuous tweaking in the hothouse has led to incredible yields. 

“In 1990, yield was about 50 percent of today on a per-plant or per-area basis,” Giacomelli says. One of the reasons for the yield increase, he says, is that growers have simply gotten better at growing, using plants developed to do best in a greenhouse environment. Researchers at the Cornell Hydroponics Facility, for example, have produced lettuce heads in central New York greenhouses at 20 times the rate of California field-grown lettuce — without applying pesticides or other chemicals. The yield estimates run to about 80 lettuce heads per square foot per year. 

In the southwestern U.S., home to most of the country's commercial greenhouses, hothouse productivity (measured in dollars) can easily be 10 times greater per acre than that of field-grown crops. Hothouse crops also mature much faster; lettuce, for instance, can be ready for market in 20 to 40 days, or two weeks earlier than field-grown lettuce. There’s also no need to wash the produce or worry about soil-borne contamination such as E. coli.

According to the USDA, there’s really no contest, yield-wise, between greenhouse growers and field growers. Greenhouse growers can produce 15 times more food per acre than field growers, and 90 percent of that food (compared with approximately 40 to 60 percent in field production) is marketable. Tomato production in a field can average 20 to 25 pounds of fruit per plant; in a hothouse, that figure can go as high as 55 pounds per plant. 

Hydroponics in Europe and North America are high-tech, but the principles are also being used in the developing world in low-tech ways. In Las Gaviotas, a sustainable village established in Colombia in the 1970s, windmills, energy-efficient turbines, and manual water-extraction pumps are used in hydroponic systems in place of high-tech computers and nutrient-meting systems used by growers in wealthier areas. As a high-efficiency system, hydroponics can mean not only commercial success but agricultural security for a planet that, by 2050, is estimated to harbor nearly 9 billion people. Giacomelli says that hydroponics is a partial solution to the problem of feeding ourselves, an increasingly important companion to field-growing.

Hydroponics do require higher doses of nutrients, and power outages could threaten crops. But field-growing is not necessarily energy-efficient; farms require petrochemicals and big agribusiness relies on synthetic fertilizer. In field growing, there’s little to no recapture of resources, along with lower yields, longer growing times, and greater variances in crop yields due to weather and other environmental impacts. 

Todd McWethy, the Three Oaks farmer, may represent the farmer of the future, whose science and technology link a love of growing to a type of production that’s financially viable for small growers.

If not for a hydroponics class he took as part of his landscape-design degree at SUNY-Cobleskill, McWethy’s path back to the family farm might have been diverted. Instead, he ended up doing an internship on the Caribbean island of Anguilla, where he studied with Howard Resh, a hydroponics pioneer who developed the greenhouses that supply salad, vegetable, and herb crops for the CuisinArt Resort and Spa on Anguilla.

“After doing both, I don’t know why I would ever grow in soil again, mostly because of soil-borne diseases and insects,” McWethy says.

Freedom from soil-borne diseases is a compelling reason to go hydroponic. In the past 20 years, most of the nation’s outbreaks of food-borne disease have been linked to fresh produce — specifically to soil-borne bacteria such as salmonella (present in chicken manure) and E. coli (present in cattle manure).

[%image fridge float=left width=200 caption="Hydroponics for the home: the VEGE hydroponics unit from Electrolux."]

One challenge for McWethy and other environmentally conscious hydroponic growers is that they’re currently unable to identify themselves as organic. The USDA organic regulations state that any produce grown with the formulations of fertilizer and refined minerals central to successful hydroponic growing cannot be labeled “organically grown.”

“In my opinion, the whole organic \[issue\] has to be worked out,” McWethy says. “What \[organic\] actually is and what people perceive it as.”

Hydroponics is regarded by some as having the potential to bring chemical-free vegetables and fruits to those who formerly couldn’t afford them. And as recently reported in Popular Science, there are even visions of bringing the farm to the city: Microbiologist Dickson Despommier has proposed designs for hydroponic farms as vertical skyscrapers in urban areas that will capture water, filter wastes, and feed people. 

After all, the farms of the future will probably have to produce far more food with far fewer resources. 

The basic simplicity of hydroponics invites experimentation. “This is a new industry of an old industry,” Giacomelli says. “We see it as a new way of bringing in a whole new generation who have the science of agriculture but no tradition of the farm.”

p(bio). [ "Tracy Ilene Miller"] is a freelance writer and teacher of journalism courses at the University of Oregon and Northwest Christian College. She has been an organic gardener for nearly 20 years, with a special interest in intensive, high-yield gardening.

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