Agricultural Pesticides
Chemical Use in Agriculture
In 1948, an entomologist named Paul Mueller received the Nobel Prize for his discovery of a chemical named DDT. DDT was a miracle, a potent pesticide that allowed humans not only to win the war on crop destroying pests, but also prevent disease. It seemed to be the answer to every farmer's prayers. Mueller, however, was not the first human to venture into the world of chemicals to combat pests. In fact, humans have been looking for ways to protect their crops for hundreds of years. The Development of Chemical Use
The first pesticides used by mankind were plant derived. Sulfur was believed to have been used as an insecticide long before 500 BC. In the 1400s people applied formulations of lead, arsenic and mercury to their crops. The popular choice for crop protection during the 1600s was nicotine compounds, derived from tobacco leaves and sprinkled onto crops.
Modern times brought about pesticides that were not derived from plants, but rather formulated in the laboratory. After Mueller's discovery of DDT, a major industry was created. Chemical pesticides had become big business. On top of the use of pesticides, today's farmer also commonly uses chemical fertilizers. With such products, farmers are able to increase crop yield, improve crop quality, and reduce their costs. Chemicals are undeniably a major component of modern agriculture.
Types of Chemicals Used
Chemical fertilizers are normally manufactured or refined from rock, animal, or petroleum products. Examples of these include ammonium sulfate, ammonium phosphate and potassium sulfate. The nutrients in these fertilizers are heavily concentrated in order to make them more readily available to plants.
The term pesticide is really a blanket term for the variety of chemicals used to prevent pests in crop production. A pesticide is any substance or mixture of substances that is intended to prevent, destroy, or repel any pest. Pests include insects, mice and other animals, weeds, fungi or microorganisms such as bacteria. Commonly used pesticides and their functions include the following:
- Herbicides: used to kill plants, mainly weeds
- Insecticides: used to kill insects
- Fungicides: used to kill fungus and molds
- Nematocides: used to kill nematodes, or worms
- Rodenticides: used to kill rodents
- Miticides: used to kill mites
Benefits of Chemical Use
Chemicals are used in agriculture to improve both the yield and the quality of crops. For example, chemical fertilizers are immediately available for the plant to utilize. A natural fertilizer, such as manure, releases its nutrients much more slowly. These fertilizers have to go through the natural biological and chemical processes that break them down in order to make their nutrients available to the plant. Also, natural fertilizers release a lower concentration of nutrients relative to chemical fertilizers. The end result of a chemical fertilizer is richer, more fertile soil in a shorter amount of time.
Pests are a major problem that farmers are faced with. Crop yield and quality can and will drop drastically if pests are not managed. What this means for the consumer is less produce at a higher price. It is here that chemical pesticides provide the greatest benefit. These pesticides are readily available, highly affective and relatively inexpensive. The use of such chemicals insures a good crop yield. For example, weeds are one of the most pervasive pests. According to the Department of Agriculture, the share of all pesticide-acre treatments (number of acres treated times the number of pesticide treatments) aimed at controlling weeds was nearly 100 percent for soybeans, 90 percent for wheat and 83 percent for corn. Without chemical herbicides, large portions of these crops would be lost to weeds.
A comparison of crop yields in the United States illustrates just how great an impact chemical pesticide and fertilizers have had on crop yields. In the 1930s, U.S crop yields were comparable to those of India and Argentina. Since the 1950s, after the development and use of many chemicals, crop yields in the U.S have skyrocketed, making us largest farming economy in the world.
Other benefits of pesticides include the rate at which they work. Chemical pesticides undoubtedly work faster and more effectively than other pest eliminating alternatives, such as pest-eating insects. Newer pesticides also do the job at lower application rates than the older products. Mueller's pesticide, DDT, has been a lifesaver to millions. This chemical prevented the contraction of such diseases as malaria, bubonic plague, and typhus.
The Risks of Chemical Use
Unfortunately, all of the benefits of chemical use have come to us at a price. Chemicals used have undoubtedly affected the environment, altering both soil and water quality. Perhaps more frightening is the immediate health risks that chemical use present to us, the consumer.
Despite the zeal with which the United States previously used DDT, it is now outlawed in the United States. Problems with the pesticide first appeared in the forties, when some insects begin to show a resistance to it. Also, DDT proved highly toxic to fish. The major problem, however, is that DDT is not rapidly metabolized by mammals. Instead it is deposited and stored in the fat tissues. Over time, with ingestion continuing at a steady rate, levels of DDT in the body build up. The pesticide became outlawed in 1973.
As with DDT, many insects develop resistance to the chemicals used as pesticides. For example, the Colorado Potato Beetle has built up a tolerance to the pesticide used to combat it. A greater application of pesticide is now required to keep this pest under control. In fact, pesticide use has increased more than 33 fold in the last fifty years. Meanwhile, it is estimated that around 37 percent of the food supply today are lost to pests, while in the 1940s around 31 percent were lost. Another problem that insecticides present is that they are not selective, and often kill off the beneficial insects. These include bees, which are necessary to the pollination of crops.
In terms of the environment, chemical use is quite costly. The Environmental Protection Agency has detected pesticides and nitrates from fertilizers in the groundwater of most states. This groundwater is the source of drinking water for about 50 percent of the nation. The nitrates and phosphorous from fertilizers also run-off into the ocean and cause large algal blooms. These blooms use up oxygen and then die, creating a scummy surface on the ocean. This in turn causes the fish to die, creating large areas of "dead zones." Continuous use of pesticides can cause the soil to harden and decrease its water- holding ability. Pesticides sprayed in fields can wash into streams and rivers polluting them and killing fish. Birds and other animal eating these fish are in turn affected. These are just a few among many of the environmental concerns created by chemical use.
Chemicals used in agriculture have also been proven harmful to humans. The health concerns primarily addressed when discussing pesticides are that they can act as acute poisons and the effects of long term exposure to pesticides. If a high dosage of a pesticide is ingested dizziness, nausea, headaches, diarrhea, numbness, and visual disturbances will occur. It has also been known for quite some time that long term exposure can cause health problems such as cancer, birth defects, genetic damage, respiratory problems, liver and kidney damage, neurological disorders and reproductive problems. Organophosphates, such as malathion and diazanon, are some of the known compounds that cause these problems. Organophosphates make up about 40 percent of the pesticides commonly used today.
More recently, a new health concern has come up regarding the use of pesticides. According to the World Resources Institute, recent studies have shown that common pesticides can suppress responses of the human immune system, making us more susceptible to disease agents. The pesticides tested include organochlorine, organophosphate, and metal-based pesticides. All of these are routinely used. The EPA recently banned a commonly used pesticide sold under the trade names Dursban and Lorsban. It was found to lead to brain damage in fetal rats. The fear that such a chemical might pose a threat to developing human fetuses led to the banning of Dursban.
Chemical use has allowed agriculture to grow by leaps and bounds. Thanks to the fertilizers that make the soil rich and the pesticides that protect crops, farmers are now able to yield far more out of an acre than ever before. Chemicals have allowed the worlds food supply to grow, providing more for the ever increasing population. The other side of this coin is the risks that seem to be growing along with the use of chemicals to harvest our food. As we look into the future, we need to weigh the benefits and costs of the chemicals used and explore alternatives that will eradicate the problems created by the chemicals used in agriculture.
