Dirt may seem simple, but the substance Tamsyn Jones calls 'the skin of our planet' in E Magazine is surprisingly complex and absolutely essential to our survival. Soil provides the foundations for human life, from air to food to clothing. What's more, it's key to carbon recycling: Because dirt absorbs some of the elements from decomposing plants and animals, it holds twice as much carbon as the atmosphere and triple the amount in the Earth's vegetation.

According to Jones, since the start of agriculture, great civilizations throughout history have risen and fallen with the quality of the soil. Erosion and soil depletion caused by overuse, too much irrigation, and clear-cutting led to struggles over resources, land, and power, which eventually ended in collapse. Today, says Jones, the same issues confront Americans as a result of wide-scale, unsustainable farming practices that have eroded, exhausted, and compacted soil. Urban erosion, caused by construction, is another culprit.

The soil problems we face today aren't limited to land. Erosion has caused aquatic pollution, as dirt and the pesticides, nitrogen, and other excess nutrients it contains run into waterways and eventually oceans. In the Gulf of Mexico, excess nutrients have enabled toxic algae to flourish and choke off indigenous aquatic life. 'Aquatic ecosystems have probably suffered the most so far,' according to the World Resources Institute, an environmental think tank.

Other bad habits are catching up with us as well, writes Jones. In desert regions of the United States, massive irrigation has turned the soil salty, disrupting its natural balance. Nationwide, the incessant construction of big-box stores makes for increased acreage of urban erosion. And a general lack of interest in the soil problem means less funding for research and conservation.