Our lives all depend on a layer just a few dozen centimeters thick: the topsoil that covers our planet and enables us to farm. This shallow layer is disappearing as it is stripped of its nutrients. Fertile land is being transformed into barren plains, arid terrain, and desert.
Today almost 40% of the Earth’s arable land has been degraded in one way or another. The causes are numerous, including deforestation, overgrazing, and ìunsuitableî farming practices, often associated with intensive methods or poorly regulated irrigation systems which increase the soilís salinity. Once damaged, the land is eroded by wind and rainwater until the shallow fertile layer disappears altogether. In a few short years, humans have destroyed soil which has often taken millennia to form through the slow fragmentation of rocks blended with humus, providing a fertile base for plants to grow in.
Over the centuries, agricultural productivity has risen by extending the surface area utilized. But today, most of our arable land-or the best-quality land, at least-has already been used. There is nowhere left to go. We must therefore not only preserve the land we have, but also farm it differently.
Countries such as China, Haiti, Mali, and Algeria, which are suffering from soil erosion and desertification, are already engaged in this task. Experts have identified numerous ways to prevent erosion such as tree planting and terracing, minimal plowing, and combating deforestation. A newer technique, terra preta (“black earth“ in Portuguese) involves mixing charcoal obtained from organic waste matter into the soil. This porous material creates a soil base in which micro-organisms can thrive, and nutrients necessary for plant growth can accumulate. The soilís productivity thus increases two—or threefold.
As this example illustrates, changing agriculture is within our reach. It need not require state-of-the-art technology or heavy financial investment.