Saving soil, farming fish, and greening communities.

How serious is the problem of soil erosion, and what can be done about it?--Brandi, Fort Worth, TX

The "dirt" beneath our feet plays a variety of supporting roles. It gives plants a foothold so they can root, filters rainwater and provides a record of environmental change. But excessive cultivation, erosion and exposure have led to the degradation of more than 17 percent of the world's soils.

The rate of soil loss can be many times higher than that of soil formation. It can take more than a century for less than an in& of soil to be formed, according to the International Soil Reference and Information Centre, whereas degradation--as in the Dust Bowl of the 1920s and 30s--may occur in just a short time. The U.S. Department of Agriculture (USDA) reports that about 1.8 billion tons of soil is lost from cropland each year because of improper management, deforestation overgrazing and industrial activity.

The USDA says the best way to protect soil is through improved farm management techniques, which include crop rotation, wind breaks, preventing compaction and smarter irrigation. CONTACT: International Soil Reference and Information Centre, www.isric. org; USDA National Soil Survey Center, [phone], http://soils. usda.gov/index.htm.

--Becca Manning

Is commercial fish farming environmentally friendly?

--B. Sashaw, Florham Park, NJ

The world's consumers have an ever-growing appetite for seafood. Annually, fishing industries contribute about $7.5 billion to the U.S. economy and $82 billion worldwide. And while the ocean was once believed to house an endless supply of food, it is now evident that years of unsustainable fishing have taken a toll on marine life.

The development of commercial fish farming, or aquaculture, has been hailed as a way to combat overfishing. The industry has grown rapidly since the 1980s, and it is estimated that one in five fish consumed by humans now comes from aquaculture. But as the conservation group SeaWeb points out, the procedures used to raise these fish may have serious impacts on natural ecosystems.

"Large fish farms may displace wildlife and produce runoff high in added nutrients, chemicals and waste, which can suffocate neighboring waterways," says researcher Michael Weber, who has worked with SeaWeb. Many farmed fish are fed diets of fish meal or oil from wild-caught species, so it can take many more pounds to produce what actually ends up in the store. "The net cages that many facilities use can also make it easy for fish to escape--spreading disease and diminishing diversity in local species, says Weber. Genetic engineering of some species may compound the problem.

Some aquaculture systems are "greener" than others, says SeaWeb. The pond-raised catfish industry typically uses static water production, in which ponds are drained every 10 to 12 years into managed systems. Because the water rarely flows outward there is less opportunity for farmed fish, or chemicals or waste, to escape. CONTACT: SeaWeb Aquaculture Clearinghouse, www.seaweb.org/resources/sac.--B.M.

How can a community become sustainable for future generations?

--Christine Graf, Westminster, CO

With growing awareness of the limited natural resources on Earth, there is an increasing emphasis on finding means of living sustainably. So-called "sustainable communities" are being organized in many parts of the U.S. and world to meet this challenge. As the late author Donella Meadows puts it in Beyond the Limits, A sustainable society is one that can persist over generations, one that is farseeing enough, flexible enough, and wise enough not to undermine either its physical or its social systems of support." Such communities try to preserve resources and integrate economic, environmental and social responsibilities to provide a high quality of life.

Whether in the guise of an ecovillage, a cohousing development or a "green" city, specific lifestyle changes can include using energy-efficient technology and making environmentally conscious choices about food and products. The community of Cobb Hill in Vermont, for example, shares an organic farm and works to minimize waste. Some city neighborhoods buy food in bulk to reduce packaging, share compost piles and buy green power. On a larger scale, some cities, including Chattanooga, Tennessee and Portland, Oregon, employ eco-friendly architecture and efficient, user-friendly public transportation.

The EPA's Green Communities Assistance Kit can help you start or improve your own sustainable community. CONTACT: EPA Green Communities Assistance Kit, www. epa.gov/greenkit.--Freya Sachs

Send your questions about environmental issues, from the personal to the political, to Ask E, P.O. Box 5098, Westport, CT 06881, or e-mail [e-mail]. Please keep your questions brief Include your full name, address and a daytime phone number.