By JR on Saturday, July 23, 2011
Their farts have been forgiven apparently
In reports of rising CO2 levels, it's easy to get the impression that the carbon-and-oxygen molecule is a kind of toxin, some alien vapor coughed up by a century-plus of heedless industrialism now coming back to haunt us. But on closer inspection, it seems that the problem isn't the carbon itself—it's that there's too much in the air and not enough in the ground.
When we consider our CO2 predicament, we tend to fault our love affair with the car and the fruits of industry. But the greater culprit has been agriculture: since about 1850, twice as much atmospheric CO2 has derived from farming practices as from the burning of fossil fuels (the roles crossed around 1970). Over the past 150 years, between 50 and 80 percent of organic carbon in the topsoil has vanished into the air, and seven tons of carbon-banking topsoil have been lost for every ton of grain produced.
So, how do we get that carbon out of the air and back into the soil? Some suggest placing calcium carbonate or charcoal (aka "biochar") directly into agricultural soil (see "Black Is the New Green," Conservation, Summer 2010). But a growing number of soil and agricultural scientists are also discussing a low-tech, counterintuitive approach to the problem that depends on a group of unlikely heroes: cows. The catalyst for reducing CO2 and restoring soil function and fertility, they say, is bringing back the roving, grazing animals who used to wander the world's grasslands. The natural processes that take place in the digestive system and under the hooves of ruminants might be the key to turning deserts back into grasslands and reversing climate change. In other words, a climate-friendly future might look less like a geo-engineered landscape and more like, well, "Home on the Range."
Perhaps the most steadfast advocate of this future is Allan Savory. A 76-year-old native of Zimbabwe, Savory has the relaxed, weathered look of a lifelong outdoorsman more attuned to the etiquette of the bush than that of the boardroom. In the 1960s, as a young wildlife biologist in what was then called Southern Rhodesia, he noticed that, when livestock were removed from land set aside for future national parks, "almost immediately, these wonderful areas suffered severe loss of both plant and animal species." Cattle, he began to realize, could play—if properly managed—the crucial role in grassland ecology that used to be occupied by herds of wild herbivores. They could help prevent and even reverse land degradation and the desertification of grasslands, combating in the process both human poverty and the disappearance of wildlife. Over the course of several eventful decades—during which he was elected to the parliament, served as an opposition leader against Rhodesia's white-minority government, and spent four years in political exile—Savory developed a program to put these ideas into action.
Savory's singular insight is that grasslands and herbivores evolved in lockstep with one another. This means that to be healthy, grasses need to be grazed. Animals eat plants and stimulate their growth; they cycle dead plants back to the surface, which allows sunlight to reach the low-growing parts; their waste provides fertilizer. When a predator—say, a lion—comes into this bucolic scene, the animals bunch together and flee as a herd, their hooves breaking up and aerating the soil. Then, on a new patch of land, the process starts again. This way all plants get nibbled, but none are overgrazed. And none are overrested, which leads to accumulated dead plant material that blocks sunlight and hinders new growth.
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