How Sustainable Agriculture Works

By: Dave Roos
Sustainable agriculture helps crops help themselves grow. See more green science pictures.
Sustainable agriculture helps crops help themselves grow. See more green science pictures.

Food prices may be on the rise, but in the United States, food has never been cheaper. In the 1930s, Americans spent roughly a third of their income on food [source: Bureau of Labor Statistics]. Today, we spend less than 10 percent. For less than five dollars, we can buy a fast-food meal that weighs in at 1,200 calories -- more than half of our daily recommended intake. But all of that cheap food comes at huge costs to our health, our environment and our farmland.

Over the course of the 20th century, the introduction of chemical fertilizers gave rise to the factory farm. With a prescribed amount of chemical inputs, farmers could increase their yields (and therefore their profits) year after year, abandoning the ancient agricultural practices that had conserved the soil and ensured its continued fertility.


As far back as the first century A.D., the Roman writer Columella wrote about soil building techniques like rotating crops between grain, legume and fallow fields and applying animal manure for fertilizer. "The earth neither grows old, nor wears out, if it be dunged," he wrote [source: Gold].

But who needs mountains of stinking manure and profit-killing fallow fields when you have cheap nitrogen, phosphorus and potassium in a bag? Corn growers, with generous subsidies from the U.S. government, can pump out over 150 bushels of corn per acre by pumping in 10 million tons (about 9 billion kilograms) of fertilizer per year [source: Walsh]. Unfortunately, run-off from these fertilizer-soaked farms travels down the Mississippi River into the Gulf of Mexico, where it creates a seasonal "dead zone" covering over 7,000 square miles (18,130 square kilometers) of ocean, killing all sea life in its reach [source: Associated Press].

The glut of cheap corn is then fed to cows, pigs and chickens crammed into concentrated animal feeding operations (CAFOs). As their collective manure stagnates in massive lagoons, the hogs, cows and chickens are injected with high doses of antibiotics to protect them from the dangerous bacteria that thrive in such confined, unsanitary conditions. Seventy percent of the antibiotics administered in America are given to animals, not humans, speeding the evolution of drug-resistant bacterial strains [source: Walsh]. Still want that Big Mac?

Fortunately, there is an alternative to the factory farm system that is threatening our health and our environment. Sustainable agriculture is nothing new. Its methods have been practiced, even if not fully understood, for millennia. On the next page we'll discuss the goals of sustainable agriculture and how they can serve as an instruction manual for fixing a broken food system.

Goals of Sustainable Agriculture

The definition of sustainable agriculture is hard to pin down. It is both a philosophy and a set of concrete farming practices. Although practiced by conscientious and prosperous farmers since day one, the term sustainable agriculture didn't come into widespread use until the 1980s. In the 1990 Farm Bill, Congress proposed a definition of sustainable agriculture as an "integrated system of plant and animal practices" that work toward the following overarching goals:

  • Satisfy human food and clothing (cotton, wool, leather) needs
  • Enhance environmental quality and natural resources
  • Use nonrenewable resources more efficiently
  • Take better advantage of on-farm resources
  • Employ natural and biological controls for pests and disease
  • Sustain the economic viability of farming
  • Enhance the quality of life of farmers and society as a whole [source: Gold]

If there is a single overarching goal in sustainable agriculture, it is to work with natural processes rather than against them [source: McRae]. Let's use soil fertility as an example: In nature, the soil is fed by the slow decomposition of organic matter in the form of dead plants, dead animals and animal droppings. Natural soils are also home to a broad diversity of plant life that has evolved natural resistance to common diseases and pests. A naturally fertile soil is also rich with beneficial insects and microbial life that repel pests and cycle nutrients back into the earth.


Sustainable agriculture doesn't ask farmers to let their fields run wild, but to simply learn from nature's bag of tricks. For example, farmers can increase the organic matter content of their soils -- thereby improving soil texture and water-holding capacity -- by plowing in compost each fall. In a diverse and well-planned farm operation, the farm's own cows and horses can provide sufficient manure for composting. Farmers can also mimic nature by planting disease-resistant varieties of crops and using companion plants to attract beneficial insects that ward off invasive pests.

It is this goal of following natural processes that has fueled the organic farming movement, a subset of sustainable agriculture. In organic farming, no chemical fertilizers, herbicides or pesticides are applied to the soil or crops and animals are raised in more natural settings, often freely grazing on their natural diet rather than confined to pens and fattened with corn.

Some farmers and food activists believe the definition of sustainable agriculture should go even further. For them, the goal is not only to minimize environmental degradation, but to improve the land and the health of the broader ecosystem [source: Gerber].

On the next page, we'll outline a few of the main components of sustainable agriculture and what differentiates them from conventional or industrial farming.

Main Components of Sustainable Agriculture

The only real difference between sustainable and conventional farming lies in the methods used to grow crops.
The only real difference between sustainable and conventional farming lies in the methods used to grow crops.

The main components of both sustainable farming and conventional farming are exactly the same: soil management, crop management, water management, disease/pest management and waste management. It's the methods used that are often radically different. We'll discuss them in order, starting with soil management.

On a conventional farm, managing and maintaining soil fertility is as simple as running a soil test and applying the recommended doses of nitrogen, phosphorus, potassium and other nutrients to meet crop needs. In sustainable agriculture, soil fertility is maintained and improved through a careful rotation of crops and generous amounts of compost and green manure, which are cover crops that are plowed back into the soil to enrich organic matter.


Monoculture is the term for agriculture that only produces one crop, year after year. The danger of monoculture is that it requires more and more chemical fertilizer to replenish lost nutrients, and more and stronger chemical pesticides and fungicides to kill off the bugs and diseases that evolve alongside the same crop year after year. Sustainable agriculture employs a broad crop diversity and careful rotation, so that nutrients are replenished naturally and no single pest or disease is allowed to get out of control.

Unhealthy soils are easily eroded, and careless water management can allow chemical fertilizers, pesticides and fresh manure slurry to leach into rivers, streams and the drinking water supply [source: Sustainable Agriculture Initiative]. Sustainable water management views water as a precious resource, efficiently watering crops using drip irrigation, which cuts down on erosion and evaporation. Efficient water use is hugely important in arid climates, where sustainable farmers plant drought-resistant crops and limit animal grazing [source: Feenstra].

On a factory farm, the key to fighting infections and disease among confined animals is to treat them with prophylactic antibiotics. Conventional growers rid the soil of any potentially harmful diseases by spraying it with fungicides before planting, then bathing the growing plants in strong pesticides to kill off bugs. In sustainable farming, plants and animals are encouraged to use their natural resistance rather than chemical solutions. Animals that freely graze on a healthy diet are more resistant to infection and disease. Healthy plants grown in microbe- and nutrient-rich soil are more resistant to invading bugs and disease. When necessary, sustainable farmers will use natural solutions to pest and disease problems, including row covers and sprays made from natural ingredients.

Dairy farms, in particular, create an impressive amount of manure. In a sustainable waste management plan, the manure would be properly composted (which requires sufficient internal heat and turning of the compost piles) and applied to field or food crops. One promising new technology called an anaerobic digestor can convert animal waste into methane, which can provide a renewable on-farm source of electricity [source: SARE].

For lots more information on sustainable gardening and organic food, head to the links on the next page.

How Sustainable Agriculture Works: Author’s Note

This is a subject that's close to my heart. My wife and I have a small organic vegetable operation and sell our produce at a local farmer's market. Growing healthy, sustainably raised food is important to us, but I'll be the first to admit that it's much harder and more expensive than conventional farming. If we were trying to run a much larger farm, it would be very tempting to use packaged chemical fertilizers that are cheap and highly effective. Every time I lose a crop to a bug infestation or a fungal disease, I understand why chemical pesticides and fungicides are such a godsend for agriculture. But as a father of three young children, I'm also concerned about the unknown effects of chemicals in our food and water. I applaud research efforts and increased funding to make sustainable farming practices more effective and more profitable so that consumers don't have to pay extra for safer, healthier food.



  • Associated Press. "Corn boom could expand 'dead zone' in Gulf." December 17, 2007 (Accessed April 20, 2011.)
  • Bureau of Labor Statistics. "Food, clothing, and shelter see different historical spending patterns." August 31, 1999 (Accessed April 20, 2011.)
  • Feenstra, Gail. University of California Sustainable Agriculture Research and Education Program. "What is Sustainable Agriculture?" (Accessed April 20, 2011.)
  • Gerber, John M. University of Massachusetts Amherst. "Principles of Agricultural Sustainability." 1990. (Accessed April 21, 2011.)
  • Gold, Mary V. Alternative Farming Systems Information Center. "Tracing the Evolution of Organic/Sustainable Agriculture." May 2007 (Accessed April 20, 2011.)
  • McRae, Rod. McGill University. "Definition of the term 'Sustainable Agriculture'"(Accessed April 20, 2011.)
  • Sustainable Agriculture Initiative. "Principles & Practices for Sustainable Water Management in Agriculture At a Farm Level." 2010 (Accessed April 21, 2011.) %20for%20%20Sustainable%20Water%20Management%20_At%20a %20farm%20level.pdf
  • Sustainable Agriculture Research and Education. "Capture Fuel from Animal Manure and Plant Waste" (Accessed April 20, 2011.)
  • Walsh, Brian. Time Magazine. "Getting Real About The High Cost Of Cheap Food." August 21, 2009 (Accessed April 21, 2011.),8599,1917458-1,00.html

Sustainable Agriculture: Cheat Sheet

Stuff you need to know:

  • Sustainable agriculture is the name for a loose set of agricultural practices that conserve soil fertility, respect animal life, limit the use of potentially harmful chemicals, make efficient use of non-renewable resources and enhance the quality of life of farming communities and the larger society.
  • Sustainable agriculture employs natural processes to address issues like soil fertility, water management, crop management, energy management and waste management. While conventional farms might boost soil fertility with chemical fertilizers, a sustainable farm will rely on manure from on-farm animals and crop rotations. While a large conventional dairy will inoculate cows against bacterial infections with regular shots of antibiotics, a sustainable dairy will allow the cows to graze in more sanitary conditions, avoiding infections altogether.
  • Organic farming is a subset of sustainable agriculture in which no chemical fertilizers, pesticides or herbicides are applied to any crops or fed to any animals through non-organic feed sources.

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