No-Till: How Farmers Are Saving the Soil by Parking Their Plows
sciam.com
John Aeschliman turns over a shovelful of topsoil on his 4,000-acre farm in the Palouse region of eastern Washington State. The black earth crumbles easily, revealing a porous structure and an abundance of organic matter that facilitate root growth. Loads of earthworms are visible, too—another healthy sign.
Thirty-four years ago only a few earthworms, if any, could be found in a spadeful of his soil. Back then, Aeschliman would plow the fields before each planting, burying the residues from the previous crop and readying the ground for the next one. The hilly Palouse region had been farmed that way for decades. But the tillage was taking a toll on the Palouse, and its famously fertile soil was eroding at an alarming rate. Convinced that there had to be a better way to work the land, Aeschliman decided to experiment in 1974 with an emerging method known as no-till farming.
Most farmers worldwide plow their land in preparation for sowing crops. The practice of turning the soil before planting buries crop residues, animal manure and troublesome weeds and also aerates and warms the soil. But clearing and disturbing the soil in this way can also leave it vulnerable to erosion by wind and water. Tillage is a root cause of agricultural land degradation—one of the most serious environmental problems worldwide—which poses a threat to food production and rural livelihoods, particularly in poor and densely populated areas of the developing world. By the late 1970s in the Palouse, soil erosion had removed 100 percent of the topsoil from 10 percent of the cropland, along with another 25 to 75 percent of the topsoil from another 60 percent of that land. Furthermore, tillage can promote the runoff of sediment, fertilizers and pesticides into rivers, lakes and oceans. No-till farming, in contrast, seeks to minimize soil disruption. Practitioners leave crop residue on the fields after harvest, where it acts as a mulch to protect the soil from erosion and fosters soil productivity. To sow the seeds, farmers use specially designed seeders that penetrate through the residue to the undisturbed soil below, where the seeds can germinate and surface as the new crop.
In its efforts to feed a growing world population, agriculture has expanded, resulting in a greater impact on the environment, human health and biodiversity. But given our current knowledge of the planet’s capacity, we now realize that producing enough food is not enough—it must also be done sustainably. Farmers need to generate adequate crop yields of high quality, conserve natural resources for future generations, make enough money to live on, and be socially just to their workers and community [see “Sustainable Agriculture,” by John P. Reganold, Robert I. Papendick and James F. Parr; Scientific American, June 1990]. No-till farming is one system that has the potential to help realize this vision of a more sustainable agriculture. As with any new system, there are challenges and trade-offs with no-till. Nevertheless, growers in some parts of the world are increasingly abandoning their plows... |
