(Please read the notice at the bottom of the page.)
The registration of acetochlor brings a new level of stewardship to the Agrochemical industry. As part of the registration, the Acetochlor Registration Partnership (ARP) manages and stewards all acetochlor-containing products with a unique program, which includes:
Several factors can affect the movement of a herbicide through the soil profile. These include soil texture, organic matter, location of water table, and herbicide characteristics such as solubility, persistence (half-life) and the herbicides ability to adsorb or bind to soil.
Most herbicides have the potential to move in soil or water, although for acetochlor the potential is small due to rapid degradation by soil micro-organisms. However, the potential has been virtually eliminated by additional voluntary restrictions included in all acetochlor product labels.
Acetochlor should not be mixed within 50 ft. of any wells (including abandoned wells and drainage wells), sink holes, intermittent streams and rivers, and natural impounded lakes and reservoirs. This does not apply to properly capped wells or properly diked mixing/loading areas. Acetochlor should not be applied to frozen or snow covered soils or highly compacted soil, because of greater potential for runoff.
Additionally, acetochlor should not be applied to soils classified as:
In each case acetochlor can be applied unless all three of the criteria for restriction are present: soil texture, organic matter level and depth to ground water. For instance, acetochlor can be applied to loamy sand soil when ground water is within 30 feet of the surface provided there is more than 2% organic matter.
To determine the location of soils potentially meeting the restrictions contained on all acetochlor product labels, the ARP has initiated extensive soil mapping of all major corn-growing areas in the United States. An example of this detailed mapping is shown for Dundy County, Nebraska. Over 300 similar resolution maps have now been produced for key corn-growing counties and are provided to dealers and distributors to ensure that acetochlor-containing products are not applied to especially vulnerable areas.
The approach taken to identify soils meeting the restricted criteria involves the use of four levels of mapping as described below.
Level 1: Three individual maps are produced for each state which show soils that potentially contain the following combinations of soil texture and organic matter:
Level 2: One map for each state is produced that overlays all three of the Level 1 maps for that state. The resultant map indicates where soils in the state potentially exist that meet any of the three soil texture and organic matter combinations.
Level 1 and Level 2 mapping has been completed for all corn growing states.
Using the Level 2 state map and corn intensity data available on a county basis, a county map is produced which indicates where soils in the county potentially exist that meet any of the three soil texture and organic matter combinations (Level 3 map).
Level 3 maps are only produced for counties where significant corn intensity exists and a high potential for one or all three soil texture and organic matter combinations exists.
Level 4: Using the Level 3 county map, copyrighted maps are produced using proprietary technology. The resultant map indicates, with a 90% probability, exact locations of each of the three soil texture and organic matter combinations. Overlays of both major roads/towns and soil survey air photo grids are included in order to better identify specific locations.
Level 4 county maps have been completed to date in the following states and are available for viewing.
As detailed above, the acetochlor label prohibits application to certain coarse textured soils, with low organic matter, when ground water is less than 30 feet from the soil surface. The location of soils fulfilling these basic textural and organic matter criteria have been mapped for over 300 counties and are provided on this web site and highlight the areas where a consideration of the depth to ground water is also required prior to product applications. It should be remembered that acetochlor use is permitted on these soils when the depth to ground water is greater than 30 feet.
Most landowners have wells on their properties and know their depth to ground water. However, in some circumstances it may be necessary to make additional inquiries prior to making applications to soils fulfilling the "3,2,1" criteria. In cases where there are no wells located near the fields in question, it is advisable to consult local well drillers who have experience of installing wells in the area. Their knowledge of the local ground water, its utility, and the individual State codes for well construction is extensive and the drillers should therefore be able to guide users of acetochlor-containing products on the probable depth to ground water in their area.
An extensive user-training program has been implemented by both Monsanto and Dow AgroSciences, to ensure the safe handling, use, and disposal of acetochlor-containing products. In addition to the information provided here, please view the American Crop Protection Association web site under "outreach" and "liquid bulk handling information" for dealer site self assessment materials. The ARP has also published an informative brochure on many of these topics which may be downloaded as a pdf file.
Personal protective equipment reduces the chances for
pesticide absorption. At any dealership, the following
safety equipment should be available:
All of these cleaning requirements apply to acetochlor.
The bulk handling manuals for acetochlor provide additional information.
Several factors need to be considered when mixing and loading
agrochemicals.
Follow all restrictions on the EPA registered label, and observe the following:
Surface water contamination with herbicides, fertilizer or manure can occur following application of the materials and after rainfall events. This often occurs in the spring of the year.
Factors that affect the amount of surface water contamination include:
Amount of precipitation: Most soil-applied herbicides need at least half an inch of precipitation for acceptable weed control. However, too much rainfall may cause the herbicide to move on soil particles into surface water or move directly into the surface waters.
Erodability of land: Soils with high erosion potential may move into surface waters. Herbicides attached to these soil particles may be found in surface water. Using soil erosion control practices such as reduced tillage, terraces, filter strips, contour planting and waterways helps reduce the amount of erosion and subsequent herbicide movement into surface water.
Location of surface waters: Areas with a great deal of surface water and agriculture are most susceptible to contamination. Along with rivers, streams, and wetlands, farmland that has sinkholes or karst formations (underground passages in limestone areas) are also susceptible to surface and ground water contamination. Avoiding herbicide and fertilizer application near these bodies of water and following good land management practices will help in preventing contamination of these areas.
Tillage system used: Tillage systems that leave crop residue on the soil surface reduce the amount of soil erosion, which in turn reduces the amount of fertilizer, herbicide or manure moving into surface waters. Erosion reduction generally is greatest with no-till, followed by mulch tillage and ridge tillage. Most conservation compliance plans have detailed information on the influence of tillage systems on the amount of erosion.
Contamination of surface waters can be minimized by overall good land stewardship. Reducing soil erosion, properly timed applications, and using common sense in selecting the site of application helps protect the safety of our water.
The ARP supports and promotes the use of Best Management Practices (BMP's) for the protection of ground and surface water, such as the voluntary BMP's established by the state of Minnesota. Here is a direct link to the Minnesota BMP's.
If acetochlor is detected in ground water or in drinking water at levels above Federal standards, the ARP Stewardship Team responds immediately by launching an investigation into the incident. During these investigations, the ARP usually takes follow-up samples to confirm the detection, prior to prescribing any corrective action. These investigations may take several months and require additional site investigations and environmental samples to fully determine the cause of the detections. All results of these investigations are reported at both a State and Federal level.
Occasionally, such investigations may involve additional field sampling work. As shown in the photos below, this can include the installation of an additional well to determine whether residues observed in a nearby well are the result of an isolated incident near the original well-head or reflect a field-wide leaching event. In the case shown below (IL24-2 from the ARP State Ground Water Monitoring Program), the newly installed well has remained free of residues, demonstrating that no field-wide movement into ground water had taken place at the IL24 site.
The Acetochlor Registration Partnership (ARP) is committed to make sure that any crop protection product containing the active ingredient acetochlor meets or exceeds government standards designed to protect water quality.
The ARP has designed a Well Assistance Program (WAP) to help ensure rural drinking water quality. The program provides assistance to owners of rural domestic drinking water wells in which herbicides containing acetochlor are detected and verified at levels above 1 part per billion (1 ppb).
The Well Assistance Program is available in rural areas to owners of wells used to supply their own drinking water for domestic consumption and also to owners of community drinking water supply wells.
For the purpose of this program, "rural areas" are defined as those areas where products containing the active ingredient acetochlor are used in the growing of corn.
All products sold in the United States that contain the active ingredient acetochlor are included in this program. These products include: Harness, Harness Xtra, Harness 20-G, Degree, Degree Xtra, Field Master, Surpass EC, Surpass 20-G, Surpass 100, TopNotch, DoublePlay, and FulTime.
Assistance provided by the ARP as part of this program may
include:
In support of the acetochlor registration, the ARP conducted a ground and surface water monitoring program of unprecedented scale. The program contained the following elements:
The ARP Ground Water Monitoring Program involved the creation of a unique network of 175 ground water monitoring wells of great relevance to U.S. agriculture because they represent the range of corn agronomy and soils in each of seven key Midwest states (Illinois, Indiana, Iowa, Kansas, Minnesota, Nebraska, and Wisconsin) and were positioned directly next to treated corn fields. The program is providing valuable scientific data on the agricultural behavior of a number of corn herbicides; this information is being shared with relevant scientists in the States and with Federal EPA. Monthly data were collected at all 175 sites through late 1999, and more than 150 of the original 175 sites continued to be sampled quarterly through December 2001.
The ARP Surface Water Monitoring Program initially included 175 community water systems (CWS's) with watersheds in corn-producing areas of Illinois, Indiana, Iowa, Kansas, Minnesota, Nebraska, Wisconsin, Ohio, Missouri, Pennsylvania, Maryland, and Delaware. The CWS's in this program used only surface water, or could discretely sample surface water from the public supply and each system was sampled every two weeks during the spring and summer months and then quarterly during the Fall and Winter. More than 150 of the original 175 sites continued to be sampled through December 2001.
In December 1999, the U.S. Environmental Protection Agency (EPA) requested that the ARP analyze water samples collected during 1999 in the State Ground Water and State Surface Water monitoring programs for two soil degradates of acetochlor. The EPA also requested that such sampling continue through December 2001, thereby providing three years of monitoring data for these materials. The monitoring is now complete, which suggests the degradates are detected somewhat more frequently than parent acetochlor. However, a detailed discussion of these results is available, demonstrating that the presence of these trace concentrations in surface and ground water poses no significant risk to public health or the environment.
The ARP Prospective Ground Water (PGW) monitoring program is designed to investigate the potential for acetochlor transport to shallow ground water under managed test conditions resulting from the labeled use of herbicides which have acetochlor as the active ingredient. The ARP is conducting a total of eight studies within this program. These highly instrumented sites are distributed across a wide range of soil textures and geographical locations, representative of corn agriculture in the U.S.
Acetochlor is the most active acetanilide herbicide and provides annual grass and small seeded broadleaf weed control at lower rates (active ingredient) than most competitive products. Acetochlor requires less rainfall (moisture) for activation than other pre-emergence corn herbicides. These benefits have been realized by many growers, applicators, and dealers in the U.S. As a result, the use of competitive products has declined significantly since the introduction of acetochlor in 1994.
In agreeing to the registration conditions for acetochlor, the ARP agreed to ensure that there would be a net cumulative usage reduction of the six mentioned corn herbicide products equal to 66.3 million pounds -- a one-third decrease from baseline levels -- five years after registration of acetochlor. Interim use reductions targets are 4 million pounds after 18 months and 22.6 million pounds after three years.
Use reduction is monitored by an independent market research firm selected by the ARP and accepted by EPA. According to EPA, all target net cumulative reduction figures have now been achieved, including the final 5-year target. Further information from EPA on acetochlor is available on the EPA OPP Acetochlor Page.
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NOTICE:
Copyright © 1995-2007 Acetochlor Registration Partnership. All rights reserved. Retransmission, reproduction or distribution without express written permission of the Acetochlor Registration Partnership is prohibited.
This page was last updated on 23-Aug-07.
Please direct Web site questions and comments to:
Dave Gustafson
Monsanto Company
800 N. Lindbergh Blvd
St. Louis, MO 63167