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Use Management Practices to Protect Ground Water from Agricultural Pesticides 1
O. Norman Nesheim2This document describes workable, tested practices that help protect our ground water.
Summary
Cleaning ground water contaminated with one or more pesticides is complicated, time-consuming, expensive and usually not feasible. The best solution is prevention. The following management practices will help to retain pesticides in target areas and keep them out of ground-water resources.Consider the Vulnerability of the Site
Determine the susceptibility of the soil to leaching. Soil texture, organic matter content, soil moisture and permeability affect pesticide movement. Some pesticides readily move through soils that are well-drained, sandy, or low in organic matter. Determine, to the extent possible, the depth of the water table and the relative permeability of the geologic layers between the soil surface and the ground water. If sinkholes are present, surface water runoff can quickly reach ground water with little natural soil filtering.Evaluate the Pesticide
Select pesticides that are less likely to leach. Pesticides that have the greatest potential to leach to ground water are highly water soluble, relatively persistent and do not adsorb to soil. The Cooperative Extension Service and the Natural Resources Conservation Service can assist you in selecting the appropriate pesticide.Evaluate Location of Water Sources
Pesticide contamination of ground water frequently is associated with pesticide handling practices in the vicinity of wells. Pesticide spills near wells can move directly and quickly into ground water. Wells should be properly cased, capped, and grouted.Unprotected wells act as conduits for surface contaminants to the aquifer. Open wells near mixing-loading sites are particularly vulnerable to contamination. Slope the grade around the wellhead to direct runoff away from the well. Close abandoned wells and never dispose of wastes in unused wells. Avoid mixing, storing, or disposing of pesticides within 100 feet of a well. Some pesticide labels may recommend greater distances.
Read and Follow the Label
Read the label before you purchase, use or dispose of a pesticide. Check for ground water advisories or other water protection guidelines. You are required by law to follow label directions. Be aware of how your pesticide handling and application practices can impact ground water.Use Integrated Pest Management (IPM)
IPM combines chemical, cultural, and biological control practices into one program to manage pest populations. Scout fields to identify pests, their population levels, and extent of damage. Make pesticide applications only when necessary, using the lowest rate required for adequate control. Reduction in the amount of pesticide use lowers potential movement through soil to ground water, protects the environment and reduces costs. For more information on IPM programs and practices contact your IFAS Cooperative Extension Service county office.Consider Weather and Irrigation
Delay the pesticide applications if heavy or sustained rain is anticipated. Pesticide runoff and leaching are favored by rainfall soon after application. Do not apply pesticides before scheduled irrigations, unless the product must activated by moisture. Control the quantity of irrigation water to minimize leaching and runoff.Measure Pesticides Carefully
Accurately calculate the amount of pesticide needed to treat the site to assure you are staying with in the label rate. Careful calculations help eliminate disposal problems associated with excess spray mix.Calibrate Sprayer
Calibrate application equipment frequently to assure the desired amount of pesticide is being applied. Check the equipment for leaks and malfunctions.Mix and Load Carefully
Repeated pesticide spills at mixing and loading sites may exceed the capacity of the soil to adsorb or degrade the chemical and increase the likelihood of ground water contamination. If spills occur, follow containment and cleanup procedures. Consult the label or the County Extension office for cleanup procedures.If possible, mix and load on a permanent or portable containment pad to avoid saturating the soil with pesticide. If the water source (well, canal or pond) used for filling a spray tank is not protected by a concrete pad, berm or wall to prevent runoff into the source, fill the spray tank as far as possible from the water source or fill the tank in the field from a nurse tank. Nurse tanks are used to transport clean water for mixing and loading. Add the pesticide concentrate to the sprayer in the field.
Use a check valve (anti-siphon device) or a 1-2 inch air gap between the end of the water supply hose and the highest water level in the spray tank to prevent back-siphoning from the spray tank into the water supply. Anti-siphon devices are required for chemigation equipment in Florida. Do not leave the spray tank unattended when filling. Do not allow tanks to drain at mixing and loading sites. Close the tank opening to prevent spills when transporting the sprayer to the field.
Store Pesticides Safely
Store pesticides in a facility with restricted access and away from all water resources. Use a facility with a concrete floor that has been sealed to facilitate clean-up in the event of a spill or leak. Inspect containers regularly for leaks and corrosion. Bulk pesticide storage tanks should be placed on concrete pads with dikes built around them to prevent movement of pesticide should a spill or leak.Dispose of Wastes Carefully
Follow the label when disposing of pesticides. Triple or pressure rinse empty pesticide containers and add the rinse to the spray tank. Apply excess spray mix and rinse water from equipment cleaning to crops or sites listed on the label. Don't drain it on the ground. Mount a tank of fresh water on the sprayer to rinse the tank and sprayer. Where practical, excess spray mix or rinses can be held in a tank for use in a later spray mix.Take empty, rinsed plastic pesticide containers to pesticide container recycling facilities or to sanitary landfills. Excess pesticide concentrates can be given to another qualified user, safely stored for hazardous waste collection days, or disposed of by a firm licensed to dispose of hazardous waste.
Use Buffer Zones Around Sensitive Areas
Use a buffer zone between sensitive areas and pesticide application or handling sites by leaving untreated borders or establishing grass or other vegetative borders. Sensitive areas include wells, ground water recharge areas, sinkholes, and surface waters, such as springs, streams, ponds, and wetlands.Ground water provides water for use in agriculture, homes, and industry. The aquifers providing this supply will remain a high quality source for future needs only if they are protected now. Consider how your activities, including the handling and use of pesticides, can impact ground water. Seek assistance if you have questions or problems.
References
Some of the information in this Fact Sheet was adapted from the following sources:The Fate of Pesticides in the Environment and Groundwater Protection, Agrochemical Fact Sheet 8, College of Agriculture, Cooperative Extension, Pennsylvania State Univ. 1989.
Farm Chemicals--A Blueprint for Protecting Groundwater , Meister Publishing Co., Willoughby, OH. Special Issue: Summer, 1989.
Footnotes
1. This document is PI1, one of a series of the [] Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date June 1993. Revised April 1984. Reviewed April 2003. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.2. O. Norman Nesheim, Ph.D., professor and pesticide information coordinator, Food Science and Human Nutrition Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611-0710.<h3>
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.
U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.
Copyright Information
This document is copyrighted by the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) for the people of the State of Florida. UF/IFAS retains all rights under all conventions, but permits free reproduction by all agents and offices of the Cooperative Extension Service and the people of the State of Florida. Permission is granted to others to use these materials in part or in full for educational purposes, provided that full credit is given to the UF/IFAS, citing the publication, its source, and date of publication.