Fecal Soil Analysis

Human and animal feces contain many bacteria. Animal feces are used as fertilizer for some plants and vegetables. The microbial diversity that feces contribute to soil is generally a good thing. It promotes the breakdown of various nutrients and several of these bacteria live symbiotically with plants. Testing soil for fecal contamination revolves around this increase of microbes.

Coliform Test

• A coliform test is in fact a test for the presence of bacteria from the family Enterobacteriaceae. E. coli, commonly found in feces, is a member of this family. A high count of E. coli, such as 200 organisms per 100 milliliter of dissolved soil, is taken as evidence of fecal contamination in the soil.

"Let It Rot"

• A cheaper, easier but more time consuming test is the "let it rot" test. Soil contaminated by feces contains microbes that will decompose materials like paper, cloth and wood. You can determine if the soil is contaminated by comparing the time it takes for a piece of paper to be degraded by sterile soil to the time it takes paper to be degraded by an equal amount of the questionable soil.

Respiration Rate

• When soil releases excess carbon dioxide, it said to have a high respiration rate. This can indicate there are extra microbes present. However, moisture and temperature also affect respiration. Therefore, high respiration is indicative but not definitive of fecal soil contamination.