Pesticides whether natural or synthetic, organic or inorganic, must be released into the environment if they are to do their job of controlling pests. Once released, many processes come to bear to determine the ultimate fate of the chemicals. These processes affect whether the are neutralized or if they persist and cause other problems.

• Adsorption and absorption. Adsorption with a "d" happens when a chemical bonds to the surface of a soil particle similar to the way iron filings cling to a magnet. Absorption occurs when pesticides "soak into" the soil or plant debris.
  
  

• Volatilization. Some chemicals turn into a gases after being applied. These gases can drift onto non-target plants or animals. Pesticides known to volatilize often need to be incorporated into the soil at application.
  
  

• Run-off and leaching. Pesticides mixed with water or tied to the soil may be moved to other locations as water runs over the surface of the land. In sandy soils, pesticides mixed with water may move down into the groundwater by leaching.
  
  

• Crop removal. A certain, small amount of the pesticide may be left on the crop. It is moved to new locations when the crop is harvested. On most crops, this residue is removed or degraded during washing and processing.
  
  

• Microbial degradation. Certain bacteria and fungi in the soil and on plants will break pesticides down to inert materials. They use certain pesticides as a food source.
  
  

• Chemical degradation. Chemical reactions in the soil due to pH, temperature and moisture interactions can decompose some pesticides.
  
  

• Photodegradation. Many pesticides are formulated to breakdown when exposed to sunlight. This minimizes the time they are active in the environment. It also limits the length of time they will be effective as pesticides on the crop.

These processes apply not only to pesticides but also to fertilizers, used engine oils, household cleaners, gasoline, paint thinners and all the other chemicals used around the home or farm. Care should be taken with all of these materials to prevent them from moving to unwanted locations in our environment.