“... the Latin name for man, homo, derived from humus, the stuff of life in the soil.”
Dr. Daniel Hillel

Weathering is a crucial part of the rock cycle as we saw in the rock cycle figure in the section The Great Rock Cycle. As rocks are exposed at the Earth’s surface, weathering is inevitable. When solid rock is subjected to air, moisture, and organic matter, it breaks down, and regolith is formed. The part of the regolith that can support rooted plants is the soil. More definitively, soils are regolith weathered from solid rock combined with water, air, and organic material called humus. Knowing this, we can see that soils are a result of the interactions among the lithosphere, hydrosphere, atmosphere, and biosphere. The lithosphere provides the parent material of solid rock. The hydrosphere plays a role with rain, snow, ice, the flow of streams and rivers to break down this rock, as well as transport rock material, so that sedimentation can occur. Gases from the atmosphere chemically react with water to further break down rock. The actions of organisms within the soil and the decaying of plant matter are contributions from the biosphere for the formation of soils.

Soil is one of our most important renewable resources. However, in many areas within the United States and around the world, human activities are contributing to the loss and/or reduction of the value of soil. Unless those practices are changed, there is apt to be seriously negative consequences that negatively impact human health as well as finance. Many of the major current famines, such as those in the Sahal region of Africa, which contribute to the political unrest in that area, are the result of poor soil management. In the United States, more than three billion tons of soil are lost from croplands each year via water and wind erosion. Also the minerals in much of the soil that do remain are being depleted at a more rapid rate than they are being restored. To reverse those conditions, sustainable development practices need to be adopted. Sustainable development involves using natural resources over the long-term without degrading the environment or compromising the ability of future generations to meet their own needs which depend on those resources. If the future voters and decision makers have a better understanding of and appreciation for soil, it increases the likelihood that more sustainable practices will be adopted.

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