When you think about it, the word “sustainable” is a perfectly ordinary and obvious term to use in discussing Earth’s resources — its biodiversity, its drinking water, its useful soil, its people.

After all, “sustainable” refers to using a resource in a way that won’t let it get used up, or damaged beyond repair. If we were stupid enough to use up or damage all our air, water, soil, and plants and animals, we wouldn’t be able to go on living on Earth ourselves. Like eroded soil, we would just dry up and blow away.

Strangely enough, however, there are plenty of people on Earth (and some of them are in high and important positions) who believe the planet and its resources are there simply to be used, with no thought to their protection. They think that even if we pollute our streams and poison the air, something will come along to bail us out. Something always has, they say, and so something always will.

Plenty of other people think this is just an excuse for selfishness. And they believe that humans have been managing their planet for years in ways that are unsustainable. They see rapid rises in extinction rates for plants and animals; they see Earth’s climate changing rapidly. (It has changed many times before, but never so quickly as now. The reason, say scientists, is that this time the cause isn’t some natural disaster like a meteor impact, but human beings and their wild misuse of their planet). These people think Nature has given Earth a treasury of resources, and that we are in the midst of a dangerous spending spree.

“Sustainability” became an important word in 1987 when a group called the World Commission on Environment and Development issued a report named “Our Common Future.” The commission had been created four years before by the United Nations. It was chaired by Gro Harlem Brundtland, the Norwegian prime minister, and is better known as the Brundtland Commission.

The commission’s basic message was that Earth doesn't need to face a future of poverty and environmental decay, even during a period of rapid population growth, but rather has “the power to reconcile human affairs with natural laws and to thrive in the process.” The commission members, half of whom were from less-affluent countries, saw the possibility of “a new era of economic growth, one that must be based on policies that sustain and expand the environmental resource base.”

A new buzzword.
After that, the term “sustainable” came to be applied to virtually all aspects of environmental protection, especially including agriculture. And at about the same time, some scientists and government officials in the United States began using the term “alternative agriculture” to describe what they felt was needed for an agriculture of the future.

To some people, “sustainable” and “alternative” agriculture were terms to use when you didn’t want to say “organic agriculture,” which they feared sounded too much like long-haired hippies with love beads around their necks. But really, the new terms referred to an agriculture that wasn’t so dependent on fertilizers and poisonous chemicals, on monoculture and huge agricultural corporations.

Alternative (or sustainable) agriculture can mean:

using pests’ natural enemies to keep them away from crops. This is called biological control (as opposed to chemical control), or “biocontrol” for short. Such farmer-friendly insects can include lady beetles (also known as lady bugs), lacewings, certain snails (which eat certain other snails), helpful nematodes, and parasitoids, the best known of which are tiny parasitic wasps.

Parasitoids. This subgroup of parasites is currently much in favor among sustainable farmers, who can purchase the creatures in bulk via mail order. The best known of these are tiny wasps. Female parasitoids lay eggs near or on the insect pest. When the eggs hatch, their larvae feed on the host, killing it. Then the parasitoids continue their life cycles and become adults.     Aleiodes indiscretus wasp parasitizing a gypsy moth caterpillar. (Scott Bauer, USDA-ARS) In some cases, the parasitoids force their pest prey to accommodate to their own schedule by altering the prey's life cycles. The adult parasitoid wasp population may be encouraged to stay around by nearby plantings of plants that are attractive to it, such as parsley, Queen Anne's lace, or dill. Some growers buy their wasps by mail order. The tiny parasitic wasps known as Encarsia formosa, for example, are purchased to control greenhouse whitefly. The wasps are shipped on strips of cardboard, a thousand per strip, at $15.50 per thousand.

using pathogens, which are microorganism forms of parasites. As their name suggests, they cause disease. Most of those that serve as biocontrols are very specific about the groups of insects they infect, and they do their dirty work only during narrow stages in the life cycle of the pest.

Farmers spray the commercially prepared pathogens on their fields with standard pesticide equipment. Once inside the target insect, they multiply rapidly, causing sickness or death. Particles of the pathogens are released by the millions from the host, either living or dead, and spread through the environment. The result is an outbreak of the disease caused by the pathogen, also called an epizootic, which can have a serious impact on the pest insect’s population. Some pathogens are used to control weeds.

Pathogens include bacteria, viruses, fungi, and protozoa. Of the bacteria, one of the most popular and widely used is Bt. Bacillus thuringiensis occurs naturally in soil, but also is sold as an insecticide that is applied by conventional spraying. Scientists have discovered several varieties of Bt, each of them effective against specific insect species. These include armyworms, gypsy moth, spruce budworm, cabbage looper, diamondback moth, aquatic insects, and the larvae of the wax moth, which infests honey bees.

Viruses enter the pest’s body by way of the gut, then disrupt the organism’s life processes. Although those that are used to control insects are not believed to be threats to humans or other mammals, viruses are not yet in widespread use. Fungi that are specific to pests operate by penetrating the insect’s cuticle, or skin, then destroying tissue or producing toxins — in some cases so quickly that the victim dies standing up, and so profoundly that all that’s left is just an empty shell.

growing a variety of crops, rather than planting just one variety that could be wiped out by a potent disease or pest invasion. Diversity is good for biodiversity. As one farmer has put it: “The idea is to create the biggest buffer than you can in your system, with the most diversity, so that if one thing fails, you still have all these backups.”

paying attention to timing. For some crops, it is possible to avoid a lot of insect damage simply by timing the planting so that the food hasn't emerged at the time the insects want it, or by planning the growing season so that harvest is complete by the time late-season pests arrive.

using natural substances (such as animal manure or the “green manure” produced by cover crops that are high in nitrogen) instead of synthetic chemical fertilizers. In the days before the synthetics were invented, this form of recycling was the only form available to farmers.

cultivating the land in ways that minimize erosion. (Asian farmers have been doing this for centuries with their terraces of rice plants).

All these techniques, and more, are in use right now by farmers around the world. Farmers praise them because they save money that would otherwise have to be spent on chemicals. Environmentalists like them because they are more “natural” than the harsh methods used by conventional agriculture.

And everybody should like them because they contribute to the sustainability of the planet and the planet’s biological diversity.

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