ABSTRACT
A common bumper sticker used to be one that asked the question, “Have you thanked a green plant today?” This is an obvious reference to plants whose photosynthesis produces the food that we and most other animals depend on for our existence. An even more fundamental question is whether we have thanked the soil—the clods of dirt—upon which green plants depend for their existence. For humans and other land-dwelling organisms, soil is literally Earth’s lifeline. Good, productive soil in the geosphere combined with a suitable climate and adequate water is the most valuable asset that a nation can have. Vast areas of the world lack this fundamental asset, and the people living in areas with poor soil often suffer poverty and malnutrition as a result. Furthermore, areas that once had adequate soil have seen it abused and degraded to the extent that it is no longer productive. Earth’s layer of life-giving soil is very thin and fragile. If Earth were the size of a geography class globe, the average thickness of productive soil on its surface would be less than that of a human cell! One of the central challenges to environmental chemistry is to retain and enhance the productive qualities of soil. The remainder of this chapter addresses soil and those aspects of agriculture related specifically to soil.
