× Expand Photo courtesy of Ars Electronica, The Window Project

Q: What are the environmental benefits of the hydroponic growing of lettuce and other crops?

A: While organic agriculture is all the rage, growing by leaps and bounds to meet increased consumer demand for healthier food, another option that's less well known but just as healthy is hydroponics, whereby plants are grown in nutrient-fortified water-based solutions without a soil substrate whatsoever. Besides not needing chemical fertilizers or pesticides (most of which are toxic as well as derived from petroleum), hydroponics also take up much less space than traditional agriculture, meaning that even an apartment window can yield impressive amounts of food throughout the calendar year.

In traditional forms of agriculture, soil facilitates the process of providing the mineral nutrients that plants need to grow. Organisms in the soil break down the nutrients into inorganic basic forms that the plants can then take up accordingly and put to use photosynthesizing. Of course, some of the organisms the soil attracts are unwelcome, and not every speck of soil is ideal as a growth medium, so we have come up with ways to kill off unwanted pests (pesticides) and pump up the ground's productivity (fertilizers).

But growing fruits and vegetables hydroponically obviates the need for fertilizers and pesticideslet alone soilaltogether. "Without soil, there is little to no microbial activity, so the plants depend on direct nutrients from nutrient solutions," reports Alexandra Gross in E – The Environmental Magazine. "And because hydroponics occur in a highly controlled space and microbial activity is at minimum, pesticides, insecticides and herbicides are not needed."

In most hydroponic systems, the nutrient solutions include inorganic salt fertilizers and semisoluble organic materials such as bat guano (manure), bone meal and fish emulsion. Since growing hydroponically does not require chemical fertilizers and pesticides, the method is inherently "organic," although the federal government doesn't recognize it as such officially. Hydroponic farmers are trying to get the U.S. Food & Drug Administration to take soil out of the equation when it comes to defining organic so that their products can bear an organic certification label on store shelves and appeal to a quickly growing segment of green-minded consumers.

Hydroponic methods are becoming especially popular with a new wave of urban gardeners. When artist Britta Riley began growing her own food hydroponically in the window of her fifth-floor Brooklyn apartment in 2009and sharing her findings with like-minded folks all over the world via the Internetthe Windowfarms Project was born. In less than two years, some 13,000 people have joined the online community. Members can download free how-to instructions for homemade hydroponic systems.

Along with the Windowfarms Project, a couple of good sources of hydroponic growing information, inspiration and supplies include Hydroponics Online and Simply Hydroponics and Organics.

Send your environmental questions to: EarthTalk®, c/o E – The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; earthtalk@emagazine.com. E is a nonprofit publication. Subscribe: www.emagazine.com/subscribe.