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Why We Need Biodiversity in Our Crops

Today’s agricultural industry bears little resemblance to farms of yore that grew a wide variety of crops. But romantic nostalgia isn’t the only reason we should reconsider the technological advances that have shaped modern farming practices.

| 3 min read

Today’s agricultural industry bears little resemblance to farms of yore that grew a wide variety of crops. But romantic nostalgia isn’t the only reason we should reconsider the technological advances that have shaped modern farming practices.

We’re used to warnings about the massive loss of biodiversity in rainforests and coral reefs, but few people understand the risks that extinction pose to our food supply. The diversity of crops we eat has dramatically fallen in the past century as a result of changing agricultural practices. Our ancestors subsisted on a much wider variety of crop species, but in the past century we’ve narrowed this group down by about 75 percent. Today, most of our plant food comes from only 15 plants. Over 60 percent of the calories consumed by the world population come from wheat, rice, and maize (corn).

Over thousands of years of breeding and selection, farmers developed a tremendous variety of types and species, called “landraces,” that were well adapted to local conditions. Farmers used to grow multiple landraces on smaller plots of land. After each harvest, they gathered and saved the seeds to be replanted the following year, or stored away as insurance against disaster. They switched things up by cycling plots through different crops each year, to give the soil a chance to replenish its nutrients. Most importantly, if a single crop species was attacked by disease, farmers could simply rely on the other varieties for sustenance.

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Nowadays, the name of the game is monoculture. Like everything else, growing food has become a strictly regulated industry that, while efficient, puts the world at risk of a food crisis. Modern farms devote vast fields to a single variety of a single species, chosen for its high yield in order to be commercially competitive. Supporting that high yield requires mechanized application of fertilizer and pesticides, intense irrigation systems, and tilling procedures that disrupt the integrity of the soil and the local ecosystem.

Although farmers can still choose which seed cultivars to purchase and plant, it only makes sense to pick the ones that have been altered and proven to be the most productive, resistant to pesticides and drought, and longest-lasting — even if local varieties are better adapted to their specific environmental conditions. As a result, farms struggle to eke out a profitable yield of soybeans to meet the staggering global demand for these top crops, instead of growing amaranth or sorghum to which their land might be better suited.

Fresh vegetables: eggplant, tomato, carrots, radishes, string beans, zucchini, potatoes

Not only do they taste better, but they’re crucial for global food security. Photo credit: dumbonyc/Flickr in (CC BY-SA 2.0)

One consequence of this genetic uniformity is that our diets have become similarly monotonous. It’s estimated that in the past century, the United States has lost 90 percent of the historic cultivars that once provided a medley of interesting flavors. We will never know how the 7,000 apple breeds grown in the 1800s tasted, as only about a hundred remain today. The recent “foodie” movement that prizes local heirloom strains has made a greater variety of food plants available to those lucky enough to live near independent farms and afford such luxury produce. But for the most part, we’re stuck with types chosen for their hardiness and yield rather than flavor or texture — the only possible explanation for the ubiquity of Red Delicious apples, a specimen almost universally loathed for its insipid taste and mealy texture.

On a more serious note, the loss of genetic diversity amongst our crops is like putting all our eggs in a glass-spun basket. The genetic uniformity of crops makes them vulnerable to diseases, which constantly evolve and can at any time conquer the resistance we’ve bred into our most highly favored species. Once a new strain of disease arises and infects a single plant, it will obliterate the entire field and can easily spread to other farms.

To stay on top of these menaces, agricultural scientists need access to the genetic variations hidden in landraces, where they might find a gene that can restore the plant’s immunity. In addition to rapidly morphing diseases, climate change can also threaten crops that thrive at current temperatures and weather conditions. But as we continue to rely on a mere handful of plants for our global food supply, the pond of genetic variation in which we can fish for useful genes is drying up.

There’s still time to turn around the monoculture trend. The aforementioned independent farmers have helped popularize eating locally for improved nutrition and flavor. If we can convince the population to accept a wider variety of plants into their diet, we can change the demands that dictate what farmers choose to plant. Changes in agricultural policy can also promote farmers to save seeds and generate banks of genetically diverse breeds. But it’s clear that if we don’t act soon to preserve the genetic diversity of crops, we will face huge risks to our food security.

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