![]() Predicted Pesticide Concentrations in StreamsĪssessment and management of pesticides require far more information than we can afford to directly measure for all the places, times, and pesticides of interest. Watershed Regressions for Pesticides (WARP) - Atrazine, 2012 The reliability of estimates, however, generally decreases with scale and these maps are not intended for detailed evaluations, such as within or between specific individual counties. These pesticide use estimates are suitable for evaluating national and regional patterns and trends of annual pesticide use. A graph accompanies each map, which shows annual national use by major crop for the mapped pesticide for each year during the period. Maps were created by allocating county-level use estimates to agricultural land within each county. The pesticide-use maps provided on Pesticide National Synthesis Project website show the geographic distribution of estimated pesticide use on agricultural land in the conterminous United States for numerous pesticides. Pesticide concentrations in streams vary widely across the United States and are influenced by many factors, such as the amount and timing of pesticide applications and the soils, climate, and hydrology where they are applied ( Gilliom and others, 2006). Pesticides applied to crops and soil, however, can be transported to surface water and groundwater, where they can degrade water quality. This is because while weeds will allways grow and always be a problem for famers, insects will only attack an unhealthy plant.Pesticides are important to crop management because they contribute to increased crop yields and improve the quality of crops. You can see that herbicides are used in the highest quantities. This is a graph of agricultural pesticide use in the United States in 1992. 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. The problem is that some insects will always survive so that the farmer will have to continue to add more chemicals. This forces farmers to use more and different kinds of pesticides, so they can kill all of the insects that might destroy their crop. Pesticide, not all of the insects will die, and the ones that remain will produce offspring that will also be tolerant to the spray. One of the reasons that they feel differently is because of something called pesticide resistance and resurgence. 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. Many people, including farmers, question what kind of impact chemicals have on our ecosystem. Photo from Cunningham, W.P., Understanding our Environment, 1994 Dead grass in a soybean field that has been sprayed with herbicides. Herbicides are also made up of strong chemicals. To get rid of the weeds without killing the crop many farmers spray their fields with herbicides. When weeds grow in farmland they can damage the crops and decrease the crop yeild of the farm. One of the biggest concerns for farmers is weed control.Insectisides are strong chemicals that will kill the insects that will harm the crop without killing the actual crop. To keep this from happening many farmers will spray their crops with insecticides. Insects such as worms and beetles can infest a crop and destroy it. Because insects make up 3/4 of all species on earth, they can be a big problem on a farm.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. To put more of these nutrients back into the soil many farmers will add fertilizers. Unfortunately, nutrients that the plants also need such as nitrogen, phosphorus and potassium can run out. Nutrients such as carbon, oxygen and hydrogen are always available to the plants. Plants need nutrients in order to grow on a farm.Farmers that make the decision not to use any chemicals are called organic farmers. All three of these pesticides are used to kill different kinds of pests that can be found on a farm. There are three different kinds of pesticides herbicides, insecticides and fungicides. Many farmers choose to use chemicals to keep weeds and pests from destroying their crops and to add more nutrients to the soil. Chemicals Chemicals in the Farm Ecosystem Chemical Sprayer
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