The soil beneath our feet is a critical resource we often take for granted. But I have heard that there are many threats to soil. What are they and how do we make things right?
—J. Lyons, Andover, MA
Even among the ecology-minded, soil falls well below the radar of important causes. But the relationship between soil quality and both environmental and human health is intricately entwined. From the food we eat and the clothes we wear, to the air we breathe and water we need to drink, we depend upon the dirt beneath our feet. Soil nurtures and feeds all life on Earth, while it under girds our cities, forests, waterways and crucial agricultural activities. Further, healthy soil and the plant matter it holds steady act as important “carbon sinks” that lock vast amounts of carbon up that would otherwise contribute to global warming.
Throughout history, great civilizations prospered where soils were fertile and fell when soils could no longer sustain rough treatment. In Mesopotamia, poor land management caused soils to become degraded, leading to loss of agricultural productivity, migrations—and ultimately, civilization collapse. Ancient Greece suffered a similar fate. Many experts also blame the fall of the great Mayan civilization on soil exhaustion and erosion, resulting from agricultural practices and clear-cutting of forests.
Today, we face many of the same issues: forest loss, over-consumption, overpopulation and over-worked soils nearing collapse. While factors such as logging, construction, off-road vehicles, floods and droughts threaten soil, high use of agricultural pesticides, fertilizers and other chemicals, as well as livestock grazing and the “factory farming” of food animals, are primary culprits.
Chief among threats to soils is damage to or loss of fertile topsoil. According to the American Society of Agricultural and Biological Engineers (ASABE), topsoil erosion today reduces productivity on 29 percent of U.S. cropland and negatively affects 39 percent of rangeland. In West Africa, fertilizer overuse is causing already acidic soils to become even more so, making the farming of even native crops difficult. In Sub-Saharan Africa, declining soil fertility from intensive farming is a main cause of poverty and hunger.
Urban erosion is equally significant and is becoming more serious as population growth fuels urban development. Housing and building projects gouge the soil and strip its vegetation. Rain then washes the soil away into sewers and then waterways. This leads not only to water pollution, but the glut of nutrients the soil carries with it causes “algae blooms” that use up oxygen and choke out the aquatic life.
Educating farmers in the U.S. and abroad about the damaging effects of intensive agriculture and over-application of synthetic fertilizers and pesticides is a good place to start to try to make things right. Converting more farming over to organic methods that eschew chemicals altogether is an even better solution. Supporting local farms also promotes better land stewardship, as mega farms make heavy use of synthetic fertilizers, and factory animal farms generate huge amounts of animal waste, which pollutes surrounding land and soil. And cities and towns can do their part by supporting low-impact development and mandating greener design standards.