Chemicals in the Farm Ecosystem

Chemical Sprayer Photo From Farm Journal, Feb. 1994

Many farmers choose to use chemicals to keep weeds and pests from destroying their crops and to add more nutrients to the soil. There are three different kinds of pesticides; herbicides, insecticides and fungicides. All three of these pesticides are used to kill different kinds of pests that can be found on a farm. Farmers that make the decision not to use any chemicals are called organic farmers.

• Plants need nutrients in order to grow on a farm. Nutrients such as carbon, oxygen and hydrogen are always available to the plants. Unfortunately, nutrients that the plants also need such as nitrogen, phosphorus and potassium can run out. To put more of these nutrients back into the soil many farmers will add fertilizers. Replacing these nutrients back into the soil with fertilizers can help the growth of the plant, which then increases the crop yield on the farm.

• Because insects make up 3/4 of all species on earth, they can be a big problem on a farm. Insects such as worms and beetles can infest a crop and destroy it. To keep this from happening many farmers will spray their crops with insecticides. Insectisides are strong chemicals that will kill the insects that will harm the crop without killing the actual crop.

• One of the biggest concerns for farmers is weed control . When weeds grow in farmland they can damage the crops and decrease the crop yeild of the farm. To get rid of the weeds without killing the crop many farmers spray their fields with herbicides. Herbicides are also made up of strong chemicals.

Many people, including farmers, question what kind of impact chemicals have on our ecosystem. Many farmers believe that if they are very careful to control where they spray chemicals, and how much they spray, pesticides and fertilizers can be helpful and safe in farming.

Some farmers disagree. One of the reasons that they feel differently is because of something called pesticide resistance and resurgence. When a field is sprayed with a pesticide, not all of the insects will die, and the ones that remain will produce offspring that will also be tolerant to the spray. This forces farmers to use more and different kinds of pesticides, so they can kill all of the insects that might destroy their crop. The problem is that some insects will always survive so that the farmer will have to continue to add more chemicals. Another reason some farmers do not like to use chemicals is because if the chemicals are not controlled very carefully they can get carried away by run-off and eventually end up in a water source.

This is a graph of agricultural pesticide use in the United States in 1992. You can see that herbicides are used in the highest quantities. This is because while weeds will allways grow and always be a problem for famers, insects will only attack an unhealthy plant.

Click HERE to see a table of common farm chemicals!