The importance of soil formation, also termed 'pedogenesis', in shaping ecosystems, including human civilization, is hard to exaggerate. Soil formation determines the properties of soils, which determine the function and uses of this essential ecological and human resource. Numerous studies have shown that the availability of nutrients originating from soil limit the productivity of terrestrial ecosystems. Despite these facts, understanding soil formation impacts of the environment is not immediately obvious. In geological terms, soil is an extremely small part of the Earth's mass, varying from a few centimeters to a few meters in thickness, depending on the specific definition of 'soil' used. Unlike in the case of humanity, the bulk of beauty and function is literally skin-deep in relationship to the rest of the Earth. Vegetation growing in that thin layer of soil is responsible for turning sunlight into the chemical energy that drives terrestrial ecosystems, including human-manipulated agricultural systems that produce the bulk of human food and fiber. Soil has been termed 'the excited skin of the Earth', and the soil-forming processes are the ones that combine to create this dynamic, essential resource.
Past civilizations have risen based on the fertility of soil in producing an excess of food, allowing human effort to focus on government, industry, artistic, and military pursuits. Recent human experience has largely forgotten that essential human tie to the land, though it is just as important now as it was thousands of years ago. For instance, a recent survey of an Environmental Science class of about 700 students at the University of Washington showed only four students acknowledging their families had any direct role in producing food from land. These students are among a decreasing percentage (now less than 1%) of Americans living on farms.
If allowed, human consideration of distinct properties associated with soil formation starts at a very early age. Any child allowed to play with soil rapidly characterizes physical properties that determine how soil can be played with. Many of these characteristics are the same as evaluating soil for other uses. For instance, fine soil material can be packed and formed into shapes whereas coarser material cannot. Unfortunately, this education usually ends in childhood. Parents typically restrict their child's access to soil because of the tenacity with which it sticks to children and their clothing, but young children typically gravitate toward soil until forcibly taught otherwise. Civilization would probably avoid many of the problems we have with degradation of soil resources if that interest in soil were allowed to develop and continue throughout a human's lifetime. Instead, popular human culture actually teaches a loathing of soil. For instance, the terms 'dirty mind' and 'poor as dirt' are often used to reflect undesirable qualities in humans, and these putdowns are not lost in a world where humans act based largely on perceptions and peer pressure.
Thought not widely recognized, soil is a slowly renewable resource due to the processes of soil formation. Soil is continually changing and developing, otherwise, it is not soil by definition. Degraded soils and lands can improve and regain their original properties, though this usually takes decades or longer. A good example is the observation of Aldo Leopold in the classic book A Sand County Almanac (1949), where he develops the concept of land as an essential component of wildlife habitat in the Sand Hills region of Wisconsin. Leopold notes that degraded soils and wildlife habitat can be restored by natural processes over time provided that the problems causing the original degradation are not continued. Also, the processes of soil restoration can be accelerated by good management practices over what would occur naturally. The concepts of land husbandry formalized by Leopold are key in all aspects of modern conservation.
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