Monday, October 15, 2012

Methods of Soil Creation

All around the world, the material that lies beneath us is crucial to what can grow and what can be built in a given area. Especially important to the farming community is the general makeup of the soil to be planted on. Its presence is often taken for granted and its origin often overlooked. From varying compositions of parent material (the original rock that gets broken down), soils of many types and mineral contents are formed. Soil forms by three non-mutually exclusive methods:

1). Physical/Mechanical: methods that involve a mechanical breaking or grinding of the parent material. Ex. - rainfall, glacial movement, wind exposure, water freezing (seen below), etc.

2). Chemical: methods that involve the alteration of parent rock by the effects of the presence of chemicals on the rock surface. Ex. - acid rain, pollutant spills, runoff, etc.
3). Biological: methods that involve biota effecting the rate of the breaking down of the parent rock. Ex. - root growth into rock, growth on the rock surface altering the level of exposure, biproducts of life processes causing deterioration of rock surface, etc. These can also be considered physical or chemical, but since they are due to an organisms life processes, they are categorized as biological methods.
The balance between soil formation and soil erosion has been both positively and negatively impacted by the presence of human activity. The urbanization of many areas has slowed the progress of the natural cycle of soil production and erosion by placing a barrier (a building, parking lot, etc.)between the soil and the environment. Also, the over-farming of areas has sped up the process of soil erosion and nutrient-leaching. With over-farming, the root growth also breaks up the soil faster than what occurs under natural conditions. Despite these negative impacts, the presence of humans has led to the preservation of many areas of natural soil production and erosion by the implementation of legislation defining nature preserves and state/national parks.
One of the most heavily affected areas of negative human impact on soil production and erosion is on the island nation of Haiti.  Here, the lumber trade has cut down a large majority of the nation's trees, leaving the ground underneath without a support structure that was originally supplied by the complex tree root system. Because of the lack of support, the soil is washing down hill, carrying sewage, trash, and more importantly homes. Fresh water is then heavily silted and polluted and unsuitable for human use. The washing away of soil has also left the agricultural community without a place to plant their crops.
Soil, both in Haiti, and also elsewhere in the world is important to preserve because of the geologic timescale in which it is formed. When we destroy the quality of soil now, we neglect the time required to replenish a suitable soil composition for our uses. It takes tens of thousands of years for parent rock to develop into soil through the three processes discussed above. It only takes a matter of years for us to decimate an entire nation's soil supply and utilization, but it will take an untold amount of time to recover.
- Evan A.

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