How Oil Decays in Soils

Higher Soil pH

• In a study reported in the International Journal of Environment and Pollution and Science Daily, researchers at China's Wuhan University noted that chicken waste raises soil pH -- the measurement of a soil's acidity or alkalinity -- to a range between 6.3 and 7.4. A measurement of 7 designates a neutral balance of acidity and alkalinity with numbers lower than 7 indicating acidity. The researchers discovered that this increase in pH encourages the growth of oil-metabolizing bacteria.

Oil Munchers

• The Wuhan University researchers identified 12 bacteria in the chicken excrement that consume and break down crude oil. They determined that the most successful bacteria are Bacillus species and Pseudomonas aeruginosa. The oil-munching microbes they discovered also included Proteus, Enterobacter, and Micrococcus bacteria. The researchers theorize that other livestock manures may also contain chemicals and microbes that break down crude oil.

Effects of Fertilizer

• The nitrogen and phosphorus in the excrement feed bacterial growth. Shoreline bioremediation of oil following Alaska's Exxon-Valdez spill in 1989 showed that application of these fertilizers plus iron caused the oil to decay up to five times faster than if it were left alone. However, the use of fertilizers on such a large scale can be expensive. In China, the use of chicken manure to bioremediate oil contamination may also help minimize another pollution problem -- how to dispose of increasing livestock wastes.

Oil Pollution in Garden Soil

• Soil in home gardens can become contaminated with petrochemicals if homeowners have dumped old motor oil in the yard. Nearby gas stations can also cause oil pollution. One way that pollutants travel from one property to another is by groundwater. The University of Louisville website recommends collecting samples of soil from parts of a yard where the homeowner plans to grow edible plants. This reveals any problems with oil or other pollutants and indicates which parts of the yard to avoid for growing foods.

  If there are no usable areas, the university suggests a number of remediation techniques of varying cost. Building raised beds fitted with impermeable liners and clean soil is one relatively inexpensive solution. Another is microbial bioremediation. If petrochemical pollution exists, adding plenty of well-rotted chicken manure may be part of the solution.