We’re running out of dirt. So says geologist David R. Montgomery in Charles Mann’s article about the perils affecting the world’s soil, including soil compaction in industrialized nations, drought in Africa, and erosion in China.1 Not that progress isn’t being made. Some of the farm land in Burkina Faso has been recovered by local farming techniques.
He assembled the farmers in his area, and by 1981 they were experimenting together with techniques to restore the soil, some of them traditions that Ouédraogo had heard about in school. One of them was cordons pierreux: long lines of stones, each perhaps the size of a big fist. Snagged by the cordon, rains washing over crusty Sahelian soil pause long enough to percolate. Suspended silt falls to the bottom, along with seeds that sprout in this slightly richer environment. The line of stones becomes a line of plants that slows the water further. More seeds sprout at the upstream edge. Grasses are replaced by shrubs and trees, which enrich the soil with falling leaves. In a few years a simple line of rocks can restore an entire field.
For a time Ouédraogo worked with a farmer named Yacouba Sawadogo. Innovative and independent-minded, he wanted to stay on his farm with his three wives and 31 children. “From my grandfather’s grandfather’s grandfather, we were always here,” he says. Sawadogo, too, laid cordons pierreux across his fields. But during the dry season he also hacked thousands of foot-deep holes in his fields-za”i, as they are called, a technique he had heard about from his parents. Sawadogo salted each pit with manure, which attracted termites. The termites digested the organic matter, making its nutrients more readily available to plants. Equally important, the insects dug channels in the soil. When the rains came, water trickled through the termite holes into the ground. In each hole Sawadogo planted trees. “Without trees, no soil,” he says. The trees thrived in the looser, wetter soil in each zai. Stone by stone, hole by hole, Sawadogo turned 50 acres of wasteland into the biggest private forest for hundreds of miles.
Sawadogo’s method turned out to be a little too successful. Burkina’s government allows cities to annex nearby land and Sawadogo’s forest was recently snatched up by a nearby town. Don’t forget to check out the accompanying photos…this is National Geographic after all.
 Mann is the author of 1491, one of the most interesting books I’ve read in the past few years. ↩
At PopTech a few weeks ago, Lester Brown, who has been a leading advocate of environmentally sustainable development for almost 30 years, spoke about the impact of the increasing production of ethanol. As more corn gets used for making automotive fuel, that reduces the amount of grain available for food production. As demand rises, so will the price…no matter what people are using the corn for, be it fuel or food. The countries that will really suffer in this scenario are those that import lots of grain for food.
When Brown said this, I immediately thought of Mexico. When you consider the food culture of Mexico, one of the first things to mind is corn. Corn (maize) was likely first domesticated in Mexico and remains the cornerstone of Mexican cuisine; in short, corn is far more Mexican than apple pie is American. In 1491, his excellent book on the pre-Columbian Americas, Charles Mann tells us that despite corn’s high status, Mexico is increasingly importing corn from the United States because it’s cheaper than local corn:
Modern hybrids are so productive that despite the distances involved US corporations can sell maize for less in Oaxaca than can [local farmer] Diaz Castellano. Landrace maize, he said, tastes better, but it is hard to find a way to make the quality pay off.
Those great tortillas you had at some local place while on vacation in Mexico? There’s an increasing chance they’re made from US corn. Mmm, globalizious! Of course, Mexican farmers are getting out of the farming business because they can’t compete with the heavily subsidized US corn and Mexico is losing control over one of their strongest cultural customs. Now that ethanol is changing the rules, there’s a bidding war brewing between Americans who want to fill their gas tanks and Mexicans who want to feed their children. Odds are the tanks stay fuller than the stomachs.
For reference, here’s what increasing ethanol production has done to the price of corn over the past three months:
And that’s despite a fantastic US corn harvest. The graph is from this article in the WSJ, which contains a quick overview of the effects that the growing ethanol industry might have.
Short positive review of 1491: New Revelations of the Americas Before Columbus (@ Amazon). Thumbed through it at the bookstore yesterday and it did look good…but I’ve got too many books in my queue already.
I was somewhat disappointed in the 2003 edition of this collection, especially after enjoying so much the last three editions. Perhaps Oliver Sacks and I disagree on what makes science writing good. The two best articles were 1491 by Charles Mann about what the Americas were like before Columbus landed and the effect of the European arrival:
In North America, Indian torches had their biggest impact on the Midwestern prairie, much or most of which was created and maintained by fire. Millennia of exuberant burning shaped the plains into vast buffalo farms. When Indian societies disintegrated, forest invaded savannah in Wisconsin, Illinois, Kansas, Nebraska, and the Texas Hill Country. Is it possible that the Indians changed the Americas more than the invading Europeans did? “The answer is probably yes for most regions for the next 250 years or so” after Columbus, William Denevan wrote, “and for some regions right up to the present time.”
and Atul Gawande’s The Learning Curve, an article on how doctors need to learn on the job (while potentially making costly mistakes) in order to become more effective overall:
In medicine, there has long been a conflict betwenn the imperative to give patients the best possible care and the need to provide novices with expericne. Residencies attempt to mitigate potential harm through supervision and graduated responsibility. And there is reason to think that patients actually benefit from teaching. But there is no avoiding those first few unsteady times a young physician tries to put in a central line, removes a breast cancer, or sew together two segments of colon. No matter how many protections are in place, on average these cases go less well with the novice than with someone experienced.