Pesticides (n): a substance used for destroying insects or other organisms harmful to cultivated plants or to animals.
Whether you like it or not, we will all be exposed to pesticides within our lifetime—not just what’s sprayed on fields, but anything from rat bait to the flea and tick medicine used on your dog. They can be useful products when used properly and judiciously, but a few are notorious for their harmful effects on the environment.
The 1960s opened the public’s eyes to the adverse effects of pesticides in the environment, with the publication of Rachel Carson’s Silent Spring. This well-known piece of scientific literature explained how DDT, a popular pesticide of the time, was accumulating in the environment and consequently killing off wildlife. Ultimately, Carson’s book led to the U.S. banning DDT and forever changing the nation’s policy on pesticides.
Picture courtesy of Seney National History Association
Certain pesticides are persistent in nature (i.e., they last long periods of time before degrading). How rapidly a pesticide degrades is measured by half-life, the time it takes for 50% of the pesticide to break down. For example, DDT has a half-life of 15 to 17 years in the soil and up to 150 years in water.
Soil has the ability to hold tightly to certain particles. Some pesticides are easily adsorbed by soil particles, while others are not and run-off into nearby water sources quite easily. The amount of organic matter and the texture of the soil usually determine its ability to take up and hold onto pesticides. (source: http://extension.illinois.edu/soil/sq_info/pest.pdf)
The soil is an environment teeming with life, much of which current science knows little about. What is certain is that the microbiology (microscopic living portion) of the soil is instrumental to growing healthy crops and to the overall health of the environment. But pesticides kill much of the soil-dwelling life. With continuous use of pesticides, soil loses much of what makes it “soil” rather than “dirt”:
- It loses the ability to hold together, making the land prone to erosion.
- It has decreased amounts organic matter, which means less nutrition for plants.,
- It loses the ability to hold water for long periods of time, thus making the land less resilient during dry spells or drought.
- It becomes dependent on increasing amounts of chemicals to produce crops.
Simply put, the soil becomes devoid of life.
According the National Pesticide Information Center there are several things that affect how long pesticides remain in the soil:
- The ingredients/chemistry of the pesticide
- The weather conditions during and after when the pesticide has been applied
- The conditions in the soil (i.e. soil moisture, organic matter content, etc.)
A farmer is intimately tied the land and the soil they farm on. Reducing pesticides or eliminating them has huge benefits that include improving soil health, human health, and the health of the environment as a whole. Soil organisms may not be as majestic as bald eagles, but everything in nature is intimately tied together. If we lose life in our soils, what other consequences will we face in the near future?
Thankfully, organic farming is a solution. By eliminating the use of toxic, persistent pesticides, organic farmers are caring for not only the food that comes from the soil but also everything that calls the soil home.