Soil is called the skin of the earth. It is a mixture of minerals,organic matter, gases, liquids, and countless organisms that together support life on Earth. Soil is a natural body called the pedosphere (the sphere on which we walk) and has important functions: it is a medium for plant growth; it is a means of water storage, supply and purification; it is a modifier of the atmosphere; it is a habitat for organisms. It is a recycling system for nutrients and wastes. It is a major component of the ecosystem because it is one of the world’s best providers for ecosystem services. In terms of ecosystem relationships, without soil there would no land plants, less oxygen production, less food, no crops or livestock. Following the atmosphere, the soil is the next largest carbon reservoir on Earth, and it is potentially one of the most reactive to human disturbance.
Soil formation is related to five basic factors in any specific environment: parent material, climate, organisms, topography and time. It takes a long time for soil to develop. In arid regions soil formation takes much longer than in temperate regions. For example, once rock is exposed in a warm, humid climate, it may take a hundred years for mosses and lichens to take hold. They trap dust and organic matter and break down the rock. Within a few hundred years, grasses and shrubs become established. Roots begin to penetrate the rocks and accelerate physical and chemical weathering. Over thousands of years, climate, organisms and topography influence how parent materials are turned into soils.
Land degradation refers to a human-induced or natural processes which impairs the capacity of land to function. Soil degradation involves the acidification, contamination, desertification, erosion or salination. The Dust Bowl is an example of land degradation. With insufficient understanding of the ecology of the plains, farmers had conducted extensive deep plowing of the virgin topsoil of the Great Plains during the previous decade; this had displaced the native, deep-rooted grasses that normally trapped soil and moisture even during periods of drought and high winds. The rapid mechanization of farm equipment, especially small gasoline tractors, and widespread use of the combine harvestor contributed to farmers' decisions to convert arid grassland to cultivated cropland.The drought and erosion of the Dust Bowl affected 100,000,000 acres and, in many regions, more than 75% of the topsoil was blown away by the end of the 1930s. Land degradation varied widely. Aside from the short-term economic consequences caused by erosion, there were severe long-term economic consequences caused by the Dust Bowl. Mass migration and food shortages persisted for over a decade.
Soil can be degraded and the community of organisms living in the soil can be damaged by the misuse or over use of pesticides. Soils that are teaming with life produce more vegetables and fruits, and more lush lawns and green spaces than sterile soils. Fungi can develop symbiotic relationships with plants that enhance plant growth; other organisms convert plant waste and aerate the soil. When you maintain healthy soil, you can reduce the need for fertilizer and pesticides.
Over use or misuse of pesticides not only degrades and damages soil, it enters and moves through the food chain affecting many organisms. And all the time there is more evidence surfacing that human exposure to pesticides is linked to health problems. Pesticides have been linked to a wide range of human health hazards, ranging from short-term impacts such as headaches and nausea to chronic impacts like cancer, reproductive harm, and endocrine disruption. Studies by the National Cancer Institute found that American farmers, who in most respects are healthier than the population at large, had startling incidences of many forms of cancer. Chronic health effects may occur years after even minimal exposure to pesticides in the environment, or result from the pesticide residues which we ingest through our food and water. A July 2007 study conducted by researchers at the Public Health Institute, the California Department of Health Services, and the UC Berkeley School of Public Health found a six-fold increase in risk factor for autism spectrum disorders (ASD) for children of women who were exposed to organochlorine pesticides. In May 2010, scientists from the University of Montreal and Harvard University released a study that found that exposure to pesticide residues on vegetables and fruit may double a child’s risk of attention deficit hyperactivity disorder. Because of the effect of some pesticides on the endocrine system, fertility issues associated with developed nations are associated with pesticide use.
Soil can be replenished by compost and manure and also by letting the soil do its thing. Cultivated soil should be left fallow every seven years so natural processes can restore soil health. “Everything comes from the soil and returns to the soil. Food comes from the soil, water is held by the soil. The soil is a metaphor for the entire natural system. If we take care of the soil, the soil will take care of us. Though the soil, we are all related and interconnected.” (Satish Kumar from Soil, Soul, Society: A New Trinity for our Time). Soil is life.
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