ABSTRACT
Soil is an interesting medium for growing microorganisms. Engineering courses dealing with soils are concerned more with the physical characteristics of soils than with their chemical characteristics. Precipitation is one of the main forces helping to create and change soil. The soil environment determines the specific microbes that can grow and their numbers. Moisture, nutrients and particulate surfaces are essential for the growth of microorganisms in the soil. The gaseous atmosphere in the void spaces is also important in microbial growth. Plowing the soil surface can mix large organic particles into the soil and create an environment for microbial growth to the depth of the plow. Temperature exerts a major influence on the rate of microbial metabolism in soil. The lack of mixing of microbes, water, nutrients, oxygen, and alkalinity in soil limits the rates of metabolism. At the other extreme, warm, wet conditions allows the surface metabolism to proceed at a rapid rate.
