Princeton University - Council of Science & Technology

POPE PRIZE

Essay 1
The Unknowns of the Tropical Forest
Jon W. Benner

Essay 2
A Few Words about Spin one Half
Thomas S. Jackson

Essay 3
How Do You Grow Organic?
Ben Jones

Essays 4, 5 & 6
Competing against the Body
Irrationally Rational
Beyond the Genome
Laura A. Shackelton

How do you grow organic?

Farming without the convenience of synthetic pesticides, herbicides, and fertilizers creates considerable challenges. How does an organic farmer do it? Ben Jones traveled to the Connecticut River Valley of Massachusetts to find out.

A slight breeze rattles the trees as birds chirp softly in the air. Only a handful of clouds hang in a background of blue sky, the sun shining brightly. The warm earth is moist with the previous night's rain. From this dirt sprout rows of plants, adding various shades of greens, yellows, and reds to the natural tapestry. Bees swarm among the plants as worms excavate their way through the spongy soil. Hungry bugs crawl along the ground, surveying the plants but moving on, not interested in the selection. Weeds poke up from the soil, but are not yet large enough to steal sunlight and nutrients from neighboring plants. Everywhere life is buzzing, humming, growing, prospering.

This ecosystem is not what you might expect. It is a commercial organic farm. And even though it is home to insects, native plants, and other organisms, the land still yields the produce that fills the organic section of the supermarket. Keeping the natural forces in check to be able to grow food, however, is much more difficult than this bucolic scene makes it appear.

Growing food organically - without the use of synthetic pesticides, herbicides, fungicides, and fertilizers, or genetically modified seeds - presents additional challenges to the rigors of conventional agriculture. Nonetheless, organic food products have been showing up in increasing numbers in supermarkets across the country. But what is really involved in bringing this food to the consumer? With fewer tools available to promote plant growth and to ward off pests and weeds, how does an organic farmer do it? To find the answer, one must look beyond the fruits and vegetables.

"The real heart of organic farming," says DeWitt Thomson, cofounder and owner of Full Bloom Market Gardens, an organic farm based in Western Massachusetts, "is in the process, the methodology, and the impact on the environment." And the results of this farming technique are becoming more and more popular. Over the past decade, nationwide sales of organic food products have increased 15 to 20 percent, five times larger than the growth of total food sales.

Thomson, a burly man with strong limbs and a mat of dark hair, has brought his farm from its roots as an experimental market garden project to a thriving full-scale business. From 1993 to present, Full Bloom has increased its acreage from 5 acres to 110 acres, its workforce from two to two dozen at the peak of the season, and its gross sales from $33,000 to almost $900,000. Sales grew by 40 percent this past year alone. Full Bloom now ships about 60,000 to 70,000 cases each year, which is enough produce to completely fill 20 tractor-trailers. That's a lot of vegetables.

"We caught the market at the right time," says Thomson. This timing is partly due to the fact that shoppers no longer have to go to the farmers' market to buy their organic produce. Full Bloom now sells most of its produce through the wholesale food cooperative Happy Valley Organics. This three-farm cooperative, co-owned by Thomson and his business partner Doug Coldwell, has contracts with Stop & Shop, Whole Foods, and Big Y, bringing Full Bloom's produce to supermarkets throughout New England.

Full Bloom contributes more than two dozen different types of vegetables, ranging from lettuce greens to squashes, peppers, and eggplant. These account for almost 65 percent of Happy Valley's gross sales. Such a diverse offering helps when negotiating contracts with large vendors but is also a key element to organic farming. While conventional farms can survive on huge monocultures - acres and acres of the same crop, planted year after year - as a result of heavy pesticide and herbicide use, this could be a disaster for an organic farm.

Crop diversity is a weapon in the constant battle against pests and weeds, helping to ensure revenue despite natural fluctuations that are beyond the farmer's control. If one crop suffers a major hit from a pest or withers in a dry spell, other crops that were not affected will hopefully make up for it. "I get nervous for my friend who just grows potatoes," says Thomson. "He's had some bad years where potatoes didn't do well. The leafhoppers just wiped them out." Leafhoppers are a common pest that attacks crops under drought stress, particularly potatoes and eggplant. Several successive seasons of leafhoppers could drive a financially stressed one-crop farm out of business.

Crop rotation is also crucial. By varying the crop planted on a particular field, a farmer can help minimize bouts with pests and disease. A pest or disease that harms one crop is often harmless to another. Switching the composition of a field can throw off the development of these crop killers. Separating plant families is part of this effort, as the rotated crop must not be too closely related to its predecessor for the process to work. For instance, a farmer may grow broccoli, a member of the Brassica family, and then replace it the next year with a lettuce green, a Lactuca. If the farmer instead chooses cabbage as a replacement, the crop may struggle. Even though it is a different crop, cabbage is also a Brassica and is therefore vulnerable to the same cabbage loopers and diamondbacks that fed off of the broccoli. Leaving fields fallow can also help break these cycles.

Another important concern is to prevent the depletion of nutrients in the soil. In addition to sunlight and water, plants also need many nutrients to grow, just as humans need vitamins and minerals to round out a healthy diet. The most important of these are nitrogen and phosphorus. Since crops extract these nutrients from the soil, leaving a field unplanted every couple seasons gives the nutrient levels in the soil a chance to rebound.

During winter months and fallow periods, cover crops such as peas and rye can extract nitrogen from the air and turn it into a form useful to plants. Tilling down these crops helps replenish the nitrogen in the soil, ensuring its availability for the growth of the spring and summer months. But this rarely provides all of the nitrogen necessary for full growth.

Farmers, both organic and conventional, apply fertilizers rich in nitrogen and phosphorus to give the plants a boost. However, the type of fertilizer each uses has tremendous implications for the surrounding environment - how much remains in the soil and how much gets washed into nearby waterways. Algae are small, water-dwelling organisms that, like plants, grow better in the presence of these nutrients. Excess fertilizer in streams, rivers, and bays can cause explosions in algae populations, a process known as eutrophication. When this algae dies and sinks to the bottom, other microorganisms break it down, consuming the oxygen dissolved in the water. This lack of oxygen can lead to massive aquatic death. The Dead Zone, a section of the Gulf of Mexico so called because it is void of fish, results from excessive farm runoff into the Mississippi River.

Conventional nitrogen fertilizer is manufactured using the Haber process, which uses huge quantities of natural gas to convert nitrogen in the air to ammonia. While nitrogen gas is inert and useless to a plant, ammonia is water-soluble and available for plant uptake. Excessive crop fertilization as a result of this cheap synthetic fertilizer causes increased nitrogen runoff. Organic farmers use only naturally based fertilizers, those that originate not from a factory but from the land, plants, or animals. These include compost, seed meals such as soybean meal and linseed meal, rock powders, and slaughterhouse wastes such as blood meal and bone meal. These organic fertilizers are also more expensive than conventional ones, reducing the occurrence of overfertilization.

"It's really pre-World War II farming," explains Thomson. Many of the rock powders that he employs, such as rock phosphate for phosphorus, sulfate of potash for potassium, and gypsum for calcium, were used successfully in that time period, prior to the development of today's tools. Some conventional fertilizers still use these very same rock powders, but with alterations to hasten their breakdown in the soil. For instance, conventional rock phosphate often has a coating of sulfuric acid that makes the phosphorous available quickly, a boon when a farmer wants a fertilizer application to yield immediate results. This fast-acting fertilizer, however, leaks phosphorus into runoff water and has caused problems in areas like the Chesapeake Bay. Untreated organic fertilizers, on the other hand, break down much more slowly because they rely on weaker organic acids in the soil. Applying these fertilizers every year raises the soil nutrient level gradually, reducing runoff and the nutrient load on waterways.

Fertilizer is not all it takes to grow a good crop. Nutrients like nitrogen and phosphorus also help out pesky weeds. While conventional farmers can spray a range of artificial herbicides on their fields, organic farmers have no natural herbicide available. But the weeds cannot remain standing; they will soak up sunlight, water, and nutrients. So organic farmers must resort to mechanical means to rid their fields of these unwanted guests.

The primary weeding technique is by tractor. Driving back and forth across the fields, the farmer drags a cultivator behind or underneath the tractor, disturbing the soil in between each row. Weeds between the individual plants often need more attention. "No matter what you do to try to manage the weeds mechanically," Thomson explains, "you're going to send a crew in there and you're going to have to pay the labor to get the fields weeded properly." They do not pick out every single weed as if this were a backyard vegetable garden, but sometimes they do resort to hand weeding. Otherwise, hoeing is the method of choice. At Full Bloom, workers hoe an acre of lettuce per week. Conventional farmers have quite a luxury with respect to weeds. "It's labor in a bottle," says Thomson. "Dump it on and you can have huge fields of conventional carrots that you never see anyone in. Just one application at the right time."

To minimize this labor-intensive process, organic farmers try to kill the weeds before planting. The farmer makes a raised bed of soil, an extra half inch of dirt above ground level, and lets the weeds grow. Similar to skimming the fat off the top of a pot of gravy, the farmer then knocks down the weeds with a cultivator. This shallow, horizontal weed elimination tries to prevent stirring of the soil, which would bring up new weed seeds. The farmer then plants the crop, giving it a jump start on the next batch of weeds.

When it comes to pests, organic farmers have a few natural pesticide options. These pesticides are naturally occurring chemicals that are used at designated times throughout the growing season to target crop-specific pests. Conventional pesticides, on the other hand, are artificial, human-made substances that decimate a wide range of insect populations, even those that help build healthy soil or that feast on other pests. These pesticides are also often toxic to those who spray the fields.

The primary organic pesticide comes from Bacillus thuringiensis, or Bt, a soil organism whose toxin kills various crop pests. Several strains of Bt exist that work on different families of organisms. Bt pesticides control cabbage pests such as the cabbage looper and diamondbacks, as well as the Colorado potato beetle, which attacks potatoes, eggplant, and sometimes tomatoes and peppers. A strain of non-organic, genetically modified corn grown by some conventional farmers also incorporates the Bt gene into its genetic makeup. This may threaten the effectiveness of Bt on organic farms (see "How conventional farming threatens organic farming").

One of the other major plights that can destroy a farmer's harvest is fungi. Fungi attack all crops, responding in particular to cycles of moist and dry conditions. Conventional farmers spray fungicides that penetrate the produce and remain with it until human consumption. Organic farmers have only one fungicide that is not even effective enough to warrant its use. This fungicide is a spray of copper sulfate. It coats the plant, providing a physical barrier so a fungus cannot infect the plant. This barrier washes off, however, and every rainfall requires another spraying. Fungicides also increase the storage and shelf life of produce. Organic farmers have no fungicides to prolong the life of their harvests.

"There are definitely times when you wish you had something you could use in a pinch," admits Thomson. "In the end, it tends to work out." To avoid a complete annihilation by a fungus, Thomson staggers his plantings, seeding several smaller groups of crops every couple weeks instead of seeding a huge crop all at once. Although this may result in reduced yields on each individual crop, it ensures that a fungus will not wipe out an entire season's worth of produce. Fine-tuning the details of when and how much to plant is largely experiential. "We've lost certain crops over the years. You have to take it as a learning process."

Organic tomatoes, for instance, are difficult to grow outside because of fungal problems. Inside a greenhouse the tomato leaves remain dry, greatly reducing the incidence of fungi. But greenhouses are more costly than open fields. Thomson has approximately three-quarters of an acre spread among his various greenhouses but he uses this primarily for starting seedlings that he later transplants into the field. There is not much space left for tomatoes, which are a big hit at the local Amherst Farmers' Market. "I still grow some field tomatoes," says Thomson, "but every year I'm impressed by how many we lose."

There are certain crops for which the cost of growing organically may outweigh the price they carry. One of these is sweet corn. To grow organic sweet corn free of worms, the farmer must hand treat every single ear of corn in the field. As the tassels are poking their way out of the tip of the ear, the farmer must squirt a mixture of mineral oil and Bt to prevent the worm from crawling inside. Not surprisingly, Thomson gave up trying to grow sweet corn.

Overall, Full Bloom's organic procedures have helped to lighten the impact agriculture has in the Valley. But does this organic farming hurt the environment in any way? Actually, yes. The diesel fuel that powers farm vehicles releases carbon dioxide, a greenhouse gas that most scientists believe is warming the planet. It also produces several harmful pollutants such as soot, particulates, nitrogen oxides, and sulfur oxides, which have damaging impacts on human health and the natural environment. Full Bloom's vehicles are no exception. With its 110 acres spread out over 10 miles, transportation of two dozen people and 60,000 to 70,000 cases of produce, as well as its use of several tractors, Full Bloom's monthly diesel bill often reaches $1,200 to $1,500 at peak. Thomson acknowledges this fuel use and wants to take his environmental stewardship one step further by replacing the diesel fuel with biodiesel, a vegetable oil-based alternative that is non-toxic and biodegradable. Biodiesel, which costs almost twice as much per gallon, releases fewer pollutants and results in almost no net gain in carbon dioxide emissions. Thomson sees this as purely an environmental maneuver. "We wouldn't really reduce our costs much," he admits, "but we'd reduce our emissions for sure."

Conventional farms can also switch to biodiesel but this would eliminate only a portion of the environmental damage that their labor-saving techniques cause. So the next time you are in a supermarket deciding whether to buy those organic carrots that cost twenty cents more per pound, consider the added labor and time that went into growing them as well as the environmental benefits that come from this organic process. Oh, and that they taste better too.

- Many thanks to DeWitt Thomson for his numerous contributions to this article.

How conventional farming threatens organic farming

Conventional farming is not only easier than organic farming, but the very practices themselves may actually threaten the effectiveness and prosperity of the organic process.

Bt Corn

This genetically modified corn variety grown by some conventional farmers includes the gene that makes the natural Bt toxin. Every part of the plant makes the toxin at all times of the year, killing any caterpillar that nibbles on its leaves. This is roughly the equivalent of spraying Bt on the cornfields every day. Such a massive exposure may increase overall pest resistance to this strain of Bt, rendering one of an organic farmer's few available pesticides ineffective.

GM Soybeans

The new US Department of Agriculture National Organic Program replaces a long-standing list maintained by the Organic Materials Review Institute (OMRI) based out of Oregon. Every independent organic certifier across the country accepted this document, which listed all the materials that were and were not allowed. It was the standard. The National Organic Program incorporates much of the old OMRI list. It states that organic food may not be produced by the use of pesticides, synthetic fertilizers, genetic modification, hormones, or antibiotics. This is nothing new.

One dilemma that has arisen is that the National Organic Program no longer allows the use of genetically modified (GM) soybean fertilizer for organic crops. Although this may seem logical, it has many organic farmers at a temporary loss because the overwhelming majority of US soybean production is genetically modified. Monsanto's Roundup Ready soybean includes a gene that makes it resistant to Monsanto's herbicide product Roundup. A conventional farmer can therefore spray Roundup to successfully kill every single weed in a field without harming the soybeans.

Soybean meal is an important natural fertilizer for organic farms. Considerable pressure from organic farmers may lead to an increase in the supply of the more expensive non-GM soybeans in the years to come. At least the farmers hope so.

Land Transition

If farming the land were not enough of challenge, just acquiring it can be a struggle for an organic farmer. Once a farmer purchases or rents new land that was not previously certified organic, the land must sit for three years before any crops grown on it can bear an organic tag. This transition period allows for any residues of conventional farming to subside before the first organic seeds hit the dirt. But for three years, an organic farmer must pay mortgage or rent without a single crop. In the Connecticut River Valley of Massachusetts, organic farming is still relatively new and any good farmland along the river that one may find for sale will have had conventional crops on it.