This document was made available on the Minnesota Department of Agriculture website, The Minnesota Department of Agriculture is

Transcription

1 This document was made available on the Minnesota Department of Agriculture website, The Minnesota Department of Agriculture is an equal opportunity employer and provider , TTY

2 TABLE OF CONTENTS 1. INTRODUCTION GIS METHODS AND DATABASE DEVELOPMENT Preparation of GIS Datasets and Field Survey Maps Development of Farm Survey Database FIELD SURVEY OF BEAUFORD DITCH AND MBWR WATERSHEDS Land Use Mapping Beauford Ditch Middle Branch of the Whitewater River Mapping Acetochlor Applications Acetochlor Application Practices Grower Use of MDA s Recommended BMPs for Acetochlor Suggested Refinements of Field Methods CONCLUSIONS FIGURE 1: Database Data Entry Form FIGURE 2: Land Use; Beauford Ditch, Minnesota FIGURE 3: Land Use; Middle Branch of the Whitewater River, Minnesota FIGURE 4: Acetochlor Usage; Beauford Ditch, Minnesota FIGURE 5: Acetochlor Usage; Middle Branch of the Whitewater River, Minnesota FIGURE 6: Structural Features; Beauford Ditch, Minnesota STONE ENVIRONMENTAL, INC. November 7, 2007 i

3 1. INTRODUCTION The Minnesota Department of Agriculture MDA) has statutory authority and responsibility within the State of Minnesota to develop and evaluate the effectiveness of voluntary Best Management Practices BMPs) intended to prevent or minimize the amount of crop protection chemicals entering groundwater of the state. The MDA conducts similar activities in response to surface water contamination. In 2004 MDA established voluntary BMPs to mitigate herbicide contamination of surface water and groundwater. These voluntary BMPs were established as a set of eight general practices for use with all agricultural herbicides and a set of five practices specific to acetochlor use. In early 2007, MDA approached the Acetochlor Registration Partnership ARP) for technical support of MDA s ongoing efforts to evaluate the effectiveness of the voluntary surface water BMPs for acetochlor. Stone Environmental personnel consultants to the ARP), with assistance from ARP and MDA personnel, conducted on-site evaluations to identify likely entry points for acetochlor into the surface waters of watersheds identified as vulnerable by the Minnesota Pollution Control Agency MPCA) and MDA. Two vulnerable watersheds were identified for this field effort; the Beauford Ditch and the Middle Branch of the Whitewater River MBWR). The investigation of these watersheds included interviewing growers and pesticide dealers, in addition to on-site observations in the fields. Land use within each watershed was mapped during the field effort and information on acetochlor use, use rates, and application practices, and the use of BMPs were collected from growers and professional applicators within the watersheds being evaluated. The field effort was supported by a geographic information system GIS) data compilation for the creation of field maps and cataloging information gathered on each grower and field, and a Microsoft Access database for evaluating and reporting the data. These watershed evaluations were a collaborative effort between the ARP, MDA, and Stone Environmental personnel. ARP personnel set-up interviews with dealers to determine where acetochlor was being applied and who was applying it, and Stone Environmental and MDA followed up by interviewing the growers to determine acetochlor application practices and BMP implementation. All three groups assisted in the windshield survey of crops in the fields. STONE ENVIRONMENTAL, INC. November 7,

4 2. GIS METHODS AND DATABASE DEVELOPMENT GIS datasets were collected and a database for managing and reporting farm field data was developed for use in the characterization of cropping practices and acetochlor use within the Beauford Ditch and Middle Branch of the Whitewater River MBWR) watersheds Preparation of GIS Datasets and Field Survey Maps The objective of the GIS data collection effort was to provide base maps for the field survey team to enable rapid characterization of cropping and management practice at the farm field level. The primary datasets required for the field survey were orthophotography, watershed boundaries and farm field boundaries. Watershed boundaries were delineated by hand in ArcGIS using US Geological Survey 1:24,000 scale topographic maps and Minnesota HUC14 boundaries. For portions of the Beauford Ditch and MBWR watershed boundaries that followed a pre-defined HUC14, the HUC14 boundary was adopted for the watershed. For portions of the watershed boundaries that were within the interior of a HUC14, the topographic map was used to define the boundary. The topographic maps were obtained in a digital raster graphics format from the USDA Geospatial Data Gateway and the HUC14 watershed boundaries were obtained from the GeoSTAC ) database. The locations of the monitoring points on Beauford Ditch and MBWR representing the outlets of the watersheds were obtained from MDA. Hydrography from the National Hydrography Dataset NHD) were obtained from the GeoSTAC database and was used for additional guidance during the delineation, as well as for display purposes. The total acreage for each delineated watershed was calculated by ArcGIS and is listed in Sections and below. The USDA Farm Service Agency s Common Land Unit CLU) dataset was obtained from the USDA Geospatial Data Gateway for the counties containing the Beauford Ditch and MBWR watersheds Olmstead and Blue Earth counties). The CLU dataset represents farm field boundaries that were identified and digitized from aerial photography. The aerial photography used to delineate the farm CLUs was 1:7,920 scale photography from The only attribute information distributed with the CLU dataset was the calculated field acreages. Stone Environmental created a unique Field_ID for each CLU feature to enable tracking and reporting of CLU characteristics gathered during the field survey. To supplement the CLU dataset, 2003 National Agricultural Imagery Program NAIP) orthophotos were obtained from the USDA Geospatial Data Gateway. This 1-meter resolution imagery is the highest resolution imagery publicly available in Minnesota. The main purpose of this dataset was to verify field boundaries from the CLU dataset and to serve as a backdrop for field survey maps. STONE ENVIRONMENTAL, INC. November 7,

5 All the CLUs intersecting the Beauford Ditch and MBWR watersheds were extracted, labeled, and displayed on 50 x 42 1:7,000 scale maps. These maps also included watershed boundaries and the NAIP imagery. The maps were printed for use in the field survey effort, which is described in Section Development of Farm Survey Database A Microsoft Access database was developed to store all farm survey data. The CLUs extracted from the GIS analysis were imported into the Access database. Additional data fields were added to identify the Owner of the field and the 2007 Crop Type. All survey questions from the survey conducted in the Beauford Ditch and MBWR watersheds were entered into a separate table. Responses to the surveys were entered into a data entry form by field personnel as shown in Figure 1 on page 16. STONE ENVIRONMENTAL, INC. November 7,

6 3. FIELD SURVEY OF BEAUFORD DITCH AND MBWR WATERSHEDS Representatives of the Acetochlor Registration Partnership ARP) and Minnesota Department of Agriculture MDA) interviewed growers and pesticide dealers and investigated fields in the Beauford Ditch and Middle Branch of the Whitewater River MBWR) watersheds during the week of June 11, 2007 to obtain current information on grower practices and acetochlor use. Participants in this field survey were Ron Struss, Joe Zachmann, and Gregg Regimbal of MDA; Dave Gustafson of Monsanto; Marvin Schultz of Dow AgroSciences; and Dave Braun of Stone Environmental Inc. consultant to the ARP). The following subsections describe the methods and results of the field survey Land Use Mapping Land use in the Beauford Ditch and MBWR watersheds was surveyed from the roadway during the week of June 11, Crop type and non-cultivated land uses were noted on field maps orthophotos of each watershed overlayed with USDA Farm Service Agency s Common Land Unit CLU) field boundaries and field IDs. In some instances the CLU delineated field boundaries were not consistent with the observed field boundaries for example, a CLU field polygon may be planted as two fields with different crops in 2007); however, overall the match between the observed field boundaries and the CLU boundaries was good. Where the field boundaries needed to be corrected, they were redrawn as accurately as possible directly on the field map. The most problematic aspect of the land use mapping was accurately representing strip cropping, which is common in the MBWR watershed. Notations on the field maps were ultimately used to produce a digital 2007 land use datalayer for each watershed Figures 2 and 3). The land use data were transcribed to a land use field in a GIS attribute table and the CLU field boundaries were adjusted where necessary Beauford Ditch The Beauford Ditch watershed is relatively small 5,353 acres), flat, and open. These characteristics enabled comprehensive mapping of land use in the watershed from the roadway. Approximately 100 percent of the watershed was mapped during the week of June 11, Nearly all cropped land in the watershed was in corn or soybean production in June STONE ENVIRONMENTAL, INC. November 7,

7 Middle Branch of the Whitewater River The MBWR watershed is 16,236 acres, three times larger than the Beauford Ditch watershed. The land is rolling and the view from the road is blocked in many areas by hills and trees. Every public road in the watershed was traveled to obtain the best possible views of land use. Approximately 95% percent of the watershed was mapped during the week of June 11, 2007; crop type could not be determined in the remaining 5% percent either because the view from the roadway was obstructed or because the sight distance was too great. The predominant crops in the watershed were corn and soybeans, followed by forage crops which, for the purposes of this report, includes grass, pasture, oats, and alfalfa), peas, sweet corn, and wheat. There are many dairy farms and animals on pasture in the watershed Mapping Acetochlor Applications In advance of the field survey, Dave Gustafson of Monsanto and Marvin Schultz of Dow AgroSciences worked with company sales representatives to identify pesticide dealerships serving growers in the Beauford Ditch and MBWR watersheds. To protect dealership anonymity within this report each dealership was assigned an identification number comprised of an abbreviation for the watershed name and a sequential number e.g., Dealership BD3). Meetings were arranged with these dealerships to obtain information about acetochlor sales and custom applications in each watershed. Interviews with 13 dealerships revealed that eight of the dealerships had neither performed custom applications of acetochlor in the watershed nor sold acetochlor products to growers whom they believed applied acetochlor in the watersheds in It was a busy time of year for the dealerships and we were unable to obtain information from four of the nine identified dealerships that possibly serve growers in the MBWR watershed. Information obtained from the dealer meetings included the location of acetochlor treated fields, the product applied, the type and timing of application, the rate applied, and the grower s name. Two dealers provided copies of pesticide application records. Based on information provided by the pesticide dealerships, growers were contacted. Growers provided additional information about acetochlor applications, in a couple cases contradicting certain information provided by the dealers. Where memories conflicted, the information from the grower was used unless the dealer had written documentation of the information. The results of the dealer interviews are presented in Tables 1 and 2. STONE ENVIRONMENTAL, INC. November 7,

8 Table 1. Summary of Dealership contacts in the Beauford Ditch Watershed Number of Dealerships Results of Interview with Dealership Personnel 5 No custom applications of acetochlor or sales of acetochlor products for use in the watershed in A dealer that formerly managed a now closed dealership. Dealership BD3 has retained customers in the watershed. They sold acetochlor to one grower who treated fields in the watershed. 1 Dealership BD7 identified two growers using acetochlor and five treated fields in the watershed in Dealers identified only three growers that used acetochlor products in the Beauford Ditch watershed in 2007, all of which were contacted for interviews. Dealership BD7 performed custom Harness 1 applications in the watershed for two growers. Dealership BD3 sold Surpass EC 1 to one customer in the watershed. There is an inconsistency between application information provided by this dealership and information from his customer: the dealer recalled Surpass EC being applied preplant and incorporated, whereas the grower in question recalled applying the product over the row after planting. Additionally, this customer identified a fourth acetochlor user in the watershed in 2007, his brother. This grower applied Keystone 1, the only use of this product confirmed in either watershed. Table 2. Summary of Dealership contacts in the MBWR Watershed Number of Results of Interview with Dealership Personnel Dealerships 1 The local distributor indicated they were not permitted to release sales information, and referred us to an out-of-state contact who did not respond to telephone inquiries from Stone personnel. 3 No custom applications of acetochlor or sales of acetochlor products for use in the watershed in The dealer identified one grower for whom his dealership performed custom application of Harness and a second grower to whom they sold Harness 20G. The dealer also mentioned that his dealership had performed a custom application of Harness on 400 acres in the watershed for a grower who requested anonymity. 3 No information obtained. 1 The dealer identified three growers using acetochlor products in the watershed in Harness, Harness Xtra, and Harness 20G, products are registered trademarks of Monsanto Technologies LLC. Surpass EC and Keystone are registered trademarks of Dow AgroSciences LLC. The mention of trade names is for informational purposes only and does not constitute endorsement by study participants. STONE ENVIRONMENTAL, INC. November 7,

9 Dealership MBWR7 and Dealership MBWR4 were the only dealerships with known acetochlor applications and sales in the MBWR watershed in Dealership MBWR7 performed post-plant, pre-emergent applications of Harness in the watershed for two growers, and sold 400 lb of Harness 20G, a granular product, to a grower in the watershed who practices ridge till. All three customers were contacted for interviews. Dealership MBWR4 performed custom pre-plant, incorporated applications of Harness for two growers and sold Harness Xtra to one grower who treated 80 acres at 1.1 qt./a 1.18 lbs a.i./a). Only one grower receiving the custom application was interviewed; the grower who purchased the Harness Xtra could not be reached despite numerous attempts. Between the two watersheds, a total of ten growers using acetochlor in 2007 were identified, and eight of these growers were interviewed. Figures 4 and 5 display known acetochlor use within each watershed Acetochlor Application Practices The rapid adoption of herbicide tolerant corn varieties has led to changes in acetochlor application practices. Adoption of herbicide resistant corn varieties has allowed growers to reduce pre-emergent herbicide rates because they have options for post-emergent weed control i.e., glyphosate, glufosinate) they would not have with conventional corn; they are not entirely dependent on the preplant or pre-emergent herbicide application to protect the crop through the growing season. Several acetochlor users interviewed favor an herbicide program in which acetochlor is applied at a reduced rate with nitrogen and incorporated prior to planting, followed by a post-emergent, non-selective herbicide application. Monsanto, Dow AgroSciences, and the University of Minnesota Extension are promoting pre-plant use of reduced rate acetochlor as a foundation treatment, to minimize risk of herbicide resistant weed development. Application rates associated with reduced rate acetochlor programs range from 1.0 to 1.5 lbs. per acre active ingredient a.i.), compared to recommended label rates of 1.75 to 3.0 lbs. per acre a.i. Incorporation of acetochlor at reduced rates prior to planting was a common practice among the growers interviewed. The growers applying and incorporating acetochlor at reduced rates prior to planting tended to farm larger areas than the growers applying acetochlor over the row after planting. They cited several benefits of this practice, including: Cost savings as compared to use of acetochlor products at the full labeled rate Improved efficacy of incorporated product compared to surface application Reduced potential for development of herbicide resistant weeds, as compared with use of post-emergent herbicides only Fewer trips over the field due to combining nitrogen and herbicide application, resulting in cost savings and less soil compaction. Dealership BD7 and Dealership MBWR4 indicated that pre-plant, incorporated application of Harness was their typical acetochlor application method. Dealership BD7 applies Harness in a tank mix with 32% nitrogen, whereas Dealership MBWR4 impregnates Harness into urea, a STONE ENVIRONMENTAL, INC. November 7,

10 crystalline solid form of nitrogen 46% N). Nitrogen must be incorporated to minimize volatilization and the efficacy of acetochlor is higher when incorporated. The one grower interviewed who reported using Harness at the full rate was a dairy farmer in the MBWR watershed growing feed for his stock. Tables 3 and 4 summarize information regarding known acetochlor application in the Beauford Ditch and MBWR watersheds in In the Beauford Ditch watershed, information on acetochlor use was obtained from every known dealership in the area. It is not possible to determine conclusively whether the acetochlor use data are complete, but we have no reason to suspect otherwise. In the MBWR watershed, information is lacking from four of the nine dealerships contacted; therefore there is a greater likelihood that undocumented acetochlor applications occurred in Table 3. Known Acetochlor Use in the Beauford Ditch Watershed Total Acreage 5,353 Corn Acreage 2,735 Corn acreage with known 2007 acetochlor 530 application Percent of corn acreage with known acetochlor 19% application Acetochlor treated acreage breakdown percent): Reduced Rate ~Full Rate Incorporated %) 0 Not Incorp %) 0 Total known acetochlor use lb ai) 584 Table 4. Known Acetochlor Use in the Middle Branch Whitewater River Watershed 1 Total Acreage 16,236 Corn Acreage 7,002 Corn acreage with known 2007 acetochlor 1,090 1 application Percent of corn acreage with known acetochlor 16% application Acetochlor treated acreage breakdown percent): Reduced Rate ~Full Rate Incorporated %) 2 Not Incorp %) %) Total known acetochlor use lb ai) Total Acetochlor use and acreage treated includes 400 incorporated acres reportedly treated with Harness at 1.1 pt/a 0.96 lbs a.i./a)somewhere in the watershed for a grower who requested anonymity. 2. A 2006 MDA survey of 29 farmers in the Middle Branch of the Whitewater River Watershed found acetochlor was applied to 2,062 acres of the 6,693 acres of corn grown in 2005, or 31%. Of these 2,062 acres treated with acetochlor, 547 acres, or 27%, incorporated the product after application. Reasons for the difference between these numbers and the results of this study are discussed on page 10. STONE ENVIRONMENTAL, INC. November 7,

11 3.4. Grower Use of MDA s Recommended Best Management Practices for Acetochlor To reduce the risk of herbicide movement to surface water and groundwater, MDA has established a list of recommended best management practices: Water Quality Best Management Practices for All Agricultural Herbicides. To address concerns regarding acetochlor, MDA has promoted additional voluntary management practices specifically for acetochlor: Water Quality Best Management Practices for Acetochlor. Growers using acetochlor were asked about each recommended practice to obtain information on adoption rates and barriers to implementation. The grower interviews provided valuable insights into barriers to BMP implementation. MDA is reportedly planning to revise the acetochlor specific BMPs to improve their effectiveness. The BMPs applying to all herbicides and those specific to acetochlor are listed below, together with a brief discussion of findings during the field survey. MDA s pesticide BMPs specifically focused on groundwater protection were not considered in the grower interviews. Water Quality Best Management Practices for All Agricultural Herbicides 1. Scout fields for weeds and match the management approach to the weed problem. None of the eight growers interviewed scouted fields in planning acetochlor use. Apparently, growers feel scouting is of little use in guiding use of pre-emergent herbicides. Scouting is frequently performed to gauge the timing and rate of post-emergent herbicide application. One grower also expressed that as more acreage is custom applied scouting is less commonly used in planning herbicide programs. 2. Evaluate reduced or split herbicide application rates. All ten growers including the anonymous grower) with known acetochlor applications in the Beauford Ditch and MBWR watersheds applied acetochlor at reduced rates. Eight of the growers used acetochlor products at half or less than half of their maximum labeled rate. Of the two remaining growers, one treated several small fields with Harness at the rate of 2.0 pt/a 1.75 lbs a.i./a) and the other grower treated several fields with Harness at 2.0 pt/a 1.75 lbs a.i./a) and one field at 2.75 pt/a 2.41 lbs a.i./a). Refer to Tables 3 and 4 for a summary of corn acreage treated at reduced application rates. Only one grower is known to have applied acetochlor using a banding technique. This grower practiced ridge till on continuous corn. Banded pre-emergence application of acetochlor over the row is appropriate in ridge tillage systems because row centers are cultivated; however, ridge till is not a common practice in either watershed. None of the growers interviewed thought that split applications of acetochlor were appropriate in their weed management program. STONE ENVIRONMENTAL, INC. November 7,

12 3. For Surface Water protection: Soil incorporate herbicides. The grower interviews indicated that incorporation is a common practice. Four of the ten growers using acetochlor incorporated the product in the soil. Three of the four incorporated applications were made with a nitrogen fertilizer. The technique of remaining incorporation application is unknown because the grower requested anonymity. Two of the six growers using acetochlor in the MBWR watershed incorporated. Acetochlor was incorporated on 53% and 73% of the known treated area in 2007 in the Beauford Ditch and MBWR watersheds, respectively. The figures for the MBWR watershed include the 400 acre application by Dealership MBWR4 for a grower requesting anonymity. A 2006 MDA survey of 29 farmers in the MBWR watershed found that 31% of corn acres were treated with acetochlor in Of the acres treated with acetochlor, 27% had the product incorporated. It is unclear whether the percentage of incorporation on acres treated with acetochlor has increased since 2005 or whether our results simply reflect practices among a smaller subset of growers known acetochlor users in 2007), which may not be representative of the larger population of growers MDA interviewed. 4. For Surface Water protection: Evaluate surface drainage patterns in your field and install filter strips and establish buffer zones for streams, sinkholes and tile inlets. The topography of the Beauford Ditch watershed is generally flat, while the MBWR watershed is rolling. Accordingly, the Beauford Ditch watershed is extensively ditch and tile drained while the MBWR is not. Although not investigated in detail, the geology of the watersheds is also quite different. The MBWR watershed lies in the karst region of southeastern Minnesota. While no growers were aware of any sinkholes in the watershed, exposed limestone formations are apparent in many places. Conditions in the Beauford Ditch watershed A drainage map of the Beauford Ditch watershed, provided by Dr. Scott Matteson at Minnesota State University at Mankato, reveals that most fields are underlain with drainage tile, and that the extent of drainage tile increased dramatically between 1993 and All the growers interviewed indicated that their fields had tile drainage. These tile lines discharge to the Beauford Ditch. Standpipes and other surface drains conveying flow directly to the tile lines have been installed throughout the watershed to eliminate water ponding in low areas in and near fields. All surface inlets visible from the roadway were mapped during the field survey, using either a GPS unit or by approximating their position on the field maps Figure 6). STONE ENVIRONMENTAL, INC. November 7,

13 With the exception of standpipes located in swales adjacent to roadways, no vegetated buffers were observed around tile inlets. Grassed waterways are present in the Beauford Ditch watershed, although not as prevalent as in the MBWR watershed. Road ditches are generally thickly vegetated. In all locations where Beauford Ditch was accessed, the channel banks were uniformly graded and vegetated. Erosion problems in Beauford Ditch appear confined to the slope under and around pipe outfalls. At the top of the channel bank along both sides of Beauford Ditch there is a vegetated buffer which varied in width from several feet to over one hundred feet. Bordering the channel in most areas is a slight levee. In multiple locations culverts were installed at field edges bordering Beauford Ditch to convey field runoff through this levee to Beauford Ditch. Runoff pour points were also evident at low points in the levee. Conditions in the Middle Branch Whitewater River watershed The MBWR watershed is not as extensively tile drained as the Beauford Ditch watershed. Three growers interviewed had some drainage tile, generally installed at the base of slopes beneath grass waterways. Only three standpipes were observed in the watershed. Despite the karst geology, none of the growers interviewed reported having sinkholes in their fields and none were observed by Stone personnel. Grassed waterways are very common throughout the MBWR watershed. Partly due to the prevalence of grassed waterways, few examples of severe erosion were observed in the MBWR watershed. In reconnaissance in the MBWR watershed the most obvious cause of erosion and surface water impairment was livestock grazing and watering in the stream. Forested and herbaceous stream buffers are common in the MBWR watershed. Based on review of orthophotographs, the majority of the stream length in the watershed is protected by a buffer of some type and extent. A thorough assessment of stream buffers was not performed due to time constraints and the need for landowner permission. In one location acetochlor treated corn was planted within 10 feet of a stream and possible herbicide injury was observed on weeds within five feet of flowing waters. Assessment of Buffers and Applications Setback BMPs Well maintained grassed waterways are common throughout the MBWR watershed and also occur in the Beauford Ditch watershed. In the MBWR watershed, grassed waterways were typically feet in width. While grassed waterways are not specifically mentioned by MDA as a voluntary BMP to protect surface water, they undoubtedly reduce runoff of sediments and agricultural chemicals to receiving waters, as compared with bare ditches. Adding grassed waterways to MDA s list of voluntary BMPs could encourage growers to maintain and extend grassed waterways. STONE ENVIRONMENTAL, INC. November 7,

14 Two growers remarked that requiring vegetated buffers around standpipes would remove valuable land from production. No growers endorsed buffers around standpipes as a feasible BMP. One grower felt it would be feasible to turn off a spray boom when passing standpipes, then return with a different herbicide to clean up the area around each standpipe, but also speculated that requiring a setback of 66 feet the atrazine setback for standpipes in terraced fields) would effectively end use of acetochlor products. An application setback requirement would not be practical for growers incorporating acetochlor with nitrogen because the crop in the vicinity of each standpipe would be deficient in nitrogen. The culverts draining field runoff directly to Beauford Ditch present similar concerns regarding buffer zones and application setbacks. Growers did not express reservations about stream buffers beyond the obvious concern that these take land out of production. Stream buffer zones in both watersheds appear as a patchwork based on topography, land ownership, and land use. The minimum stream buffer widths observed in both watersheds <10 feet) may not be protective. Alternately, there were also extensive stream buffers >100 feet) in both watersheds, which should mitigate sediment and pesticide runoff in these areas and provide valuable habitat. 5. For Ground Water protection: Determine the depth to groundwater in your fields and consider protective practices in vulnerable areas. Not considered. 6. Rotate herbicide modes of action chemistry). Growers in general appeared aware of the issue of resistance management. Some growers considered herbicide resistance in selection of corn variety and associated post-emergent herbicides. All growers rotated chloracetamide herbicides as a function of crop rotation, but none specifically rotated use of acetochlor or other chloracetamide compounds in corn on corn rotations. 7. Consider precision application of herbicides. [Precision application of herbicides spot spraying or use of variable rate technologies) is based on weed scouting and variation in soil properties soil organic matter and texture). Adjust application rates according to weed pressures and soils information.] None of the eight growers interviewed scouted fields in planning acetochlor use; however all used reduced rates see answers to BMP # 1 and 2 above). Apparently, growers feel the reduced acetochlor rates, when combined with herbicide tolerant corn, are sufficient for weed control. 8. For Ground Water protection: Develop an Irrigation Water Management Plan. Not considered. STONE ENVIRONMENTAL, INC. November 7,

15 Additional) Water Quality Best Management Practices for Acetochlor 1. Adopt the core BMPs for All Agricultural Herbicides when applying acetochlor. See BMPs #1-8 above. 2. Evaluate surface drainage patterns in your field, then identify points where surface runoff leaves the field and consider protective practices in vulnerable areas, including tile inlets. Redundant. See information under BMP #4 above. 3. Determine your soil s texture and organic matter content, then limit acetochlor application rates to the indicated label recommendation. As described above and in Tables 3 and 4, eight of the ten growers with known acetochlor applications in the Beauford Ditch or the MBWR watershed used substantially reduced application rates. Seven of the growers used rates equal to or below the minimum recommended rate for the acetochlor product on any type of soil. An eighth grower used Harness at a rate 1.4 pt/a or1.23 lbs a.i./a) near the low end of the range for coarse soils with low organic matter. The remaining two growers used Harness at 2.0 pt/a 1.75 lbs a.i./a), which is the high point in the rate range for coarse textured soil but below the rate range on medium and fine textured soils, on all but one field. This last field was treated at 2.75 pt/a 2.41 lbs a.i./a), the maximum rate for a fine textured soil with 3 percent or more organic matter. Based on these results, it is not generally relevant whether growers considered soil texture or organic matter content in selecting an appropriate application rate. 4. Adopt conservation tillage practices appropriate for your farm s topography and in SE Minnesota karst areas. The impression among growers and dealers interviewed was that no-till was viable for soybeans but not generally appropriate for corn production in the watersheds. A dealer serving growers in the MBWR watershed estimated that a maximum of 5-10 percent of the corn acreage is no-till in his sales area. A dealer serving growers in the Beauford Ditch watershed said there was no no-till in that area. None of the corn acreage treated with acetochlor was no-till. Chisel till is the dominant tillage practice in both watersheds. However, some growers and dealers commented that increasing corn yields and adoption of corn varieties with insect resistance traits were creating more crop residues. Greater amounts of crop residue are reportedly causing some growers to begin using a moldboard plow after years of disuse. Cropping corn on the contour and strip cropping are common practices in the MBWR watershed. Strip cropping and contour planting were not apparent in the Beauford Ditch watershed due to its generally flat topography. STONE ENVIRONMENTAL, INC. November 7,

16 5. Rotate use of acetochlor and alachlor, metolachlor and other chloracetamide herbicides) with herbicides from a different chemical class. Redundant. See information under BMP #6 above Suggested Refinements of Field Methods Based on both the successes and the difficulties of the field survey and grower interviews, the following changes to the methods are suggested: 1. Review additional data sources in advance of spatial analysis and field efforts: a. Collaborate with Dr. Scott Matteson at Minnesota State University in Mankato regarding data collection efforts on the Beauford Ditch watershed. b. Review recent MDA grower survey data for the Middle Branch Whitewater River. 2. Send letters to dealers several weeks in advance asking for their assistance. For reference, include maps with the watershed boundaries, Public Land Survey Grid, and major roads. Prior to field survey, follow-up with dealers to get contact information for growers using acetochlor products in the watershed. We can then follow up with growers directly to locate the specific fields receiving acetochlor. 3. Use a random method of selecting growers for interviews. Using pesticide dealers to generate dealer contacts has the potential of skewing the selection process to growers who have had custom product application or are known for running good operations. 4. Overlay the Public Land Survey Grid on the field maps. This grid will make it easier for growers to orient themselves when looking at large orthophoto maps. 5. Obtain plat books for counties in the studied watersheds. 6. Prepare grower interview questions in cooperation with MDA in advance of the field survey. The interview questions should not simply restate MDA s current voluntary BMPs but rather should elicit the best information from growers. This is consistent with MDA s interest in developing improved BMP recommendations. 7. Better define the data to be collected on each acetochlor treated field, assuming the grower has granted permission to enter. 8. Bring binoculars for enhanced scouting of fields. 9. Provide advance letters to landowners in the study watersheds. Strangers driving road with maps and clipboards can raise concern in rural communities. It would be best to give residents advance notice of what is being planned. STONE ENVIRONMENTAL, INC. November 7,

17 4. CONCLUSIONS The field effort was largely successful in fulfilling its goals. In the Beauford Ditch watershed approximately 100% of the cropped land was mapped and all known acetochlor applications were identified and characterized. In the Middle Branch of the Whitewater River MBWR) watershed 95% of the cropped land was mapped, however it is clear that not all of the acetochlor applications that occurred within the watershed were mapped and characterized. There were several pesticide dealers that could not be interviewed due to time constraints and one grower whose fields could not be mapped because he chose not to be identified. BMP implementation by the eight acetochlor users interviewed was documented, providing insight into barriers to BMP adoption. Within the Beauford Ditch watershed the main issue with regard to acetochlor entering the waterway appears to be the lack of protections for tile inlets, tile outlets, and culverts. Runoff water in this watershed is unbuffered as it drains to low spots in fields, into tile systems and then directly into the Beauford Ditch. Runoff water also enters the ditch through unbuffered culverts that go directly through the protective levee bordering the ditch. Overall, growers felt that providing a substantial application setback from tile inlets such as the 66 foot setback required for stand pipes in terraced fields for atrazine products) would be impractical and remove a significant amount of crop land from production. Perhaps future BMP recommendations could include smaller buffers around tile inlets and ditch culverts. Within the MBWR watershed known applications of acetochlor were largely incorporated; fields generally had protective measures in place to prevent or mitigate acetochlor entry into the waterway, and there were only three tile inlets encountered. We did not observe obvious problems to account for acetochlor detections found by the Minnesota Department of Agriculture MDA) surface water sampling program. All of the known acetochlor applications occurred in the upper reaches of the watershed, far away from the MDA sampling location. Unfortunately, to more fully understand the dynamics of this watershed and make worthwhile conclusions we need to know the location of the 400 acre acetochlor treatment of the grower who requested anonymity and be certain that there are no other users of acetochlor within the watershed; and we need to better understand the geology of this watershed to determine if karst topography could be responsible for conveying acetochlor into the waterway. Due to a reduction in application rates and an apparent increase in acetochlor incorporation, acetochlor detections in the Beauford Ditch and MBWR watersheds could possibly decline in the future. The frequency and magnitude of acetochlor detections in the MDA surface water sampling program over the next several years will determine if this is the case. Any future efforts in the collaboration between MDA and the Acetochlor Registration Partnership ARP) should include continued work with MDA to refine voluntary BMPs to improve their effectiveness and acceptability. STONE ENVIRONMENTAL, INC. November 7,

18 FIGURE 1: Database Data Entry Form STONE ENVIRONMENTAL, INC. November 7,

19 O:\Proj-07\1921-F Ace Minnesota\Data\MapDocuments\BeaufordCrop_11x17_v3.mxd; Aug 2nd 2007; NEF Streams MDA Sample Locations Sources: Streetmap USA, NRCS, USDA Geospatial Data Gateway, ARP, SEI Beauford Ditch, Minnesota MDA - ARP Watershed Evaluation Project Figure 2 - Land Use. Watersheds Forage 88 ac.) Fallow 249 ac.) Soybeans 1615 ac.) Crop Types Corn 2,735 ac.) Legend ². 22 CORD 10 CORD CORD 28 S CORD 174 CORD 176 CORD 16 1 Miles

20 CORD 152 CORD 7 CORD 107 CORD 107 CORD 9 CORD 9 CORD 136 CORD th St SE O:\Proj-07\1921-F Ace Minnesota\Data\MapDocuments\WhitewaterCrop_11x17_v3.mxd; Aug 2nd 2007; NEF CORD 7 CORD 10 CORD 136 W 5th St CORD 7 W 7th St Park St CORD 142 Legend Crop Types Corn 7,002 ac.) Carolann St W 2nd St E 2nd St Soybeans 2,075 ac.) Forage 1,748 ac.) Pasture 548 ac.) Fallow 317 ac.) Peas 228 ac.) Sweet Corn 148 ac.) Wheat 3 ac.) Watersheds MDA Sample Locations Streams MDA - ARP Watershed Evaluation Project Figure 3 - Land Use Middle Branch of the White Water River, Minnesota Sources: Streetmap USA, NRCS, USDA Geospatial Data Gateway, Monsanto, SEI Miles

21 O:\Proj-07\1921-F Ace Minnesota\Data\MapDocuments\BeaufordAcetochlor_11x17_v4.mxd; Aug 2nd 2007; NEF CORD 28 S CORD 174 CORD 176 CORD 16 CORD 175 CORD 10 ² Legend Acetochlor Incorporated 281 ac.) Acetochlor Product Applied Harness 281 ac.) Keystone 75 ac.) Surpass 175 ac.) Watersheds. MDA Sample Locations Streams MDA - ARP Watershed Evaluation Project Figure 4 - Acetochlor Usage Beauford Ditch, Minnesota Sources: Streetmap USA, NRCS, USDA Geospatial Data Gateway, ARP, SEI Miles

22 O:\Proj-07\1921-F Ace Minnesota\Data\MapDocuments\WhitewaterAcetochlor_11x17_v4.mxd; Aug 2nd 2007; NEF 42 Ca rol an ns t CORD 7 Streams CORD th St SE Sources: Streetmap USA, NRCS, USDA Geospatial Data Gateway, ARP, SEI Note: Acreage totals for Acetochlor Incorporated and Harness include a 400 acre application in an unknown location. Middle Branch of the Whitewater River, Minnesota MDA - ARP Watershed Evaluation Project Figure 5 - Acetochlor Usage. MDA Sample Locations Watersheds Acetochlor Product Applied E 2 nd St Harness 942 ac.) W 5th St Harness 20G 76 ac.) W 7th St Harness Xtra 73 ac.) W 2n d St Acetochlor Incorporated 797 ac.) Legend CORD 9 Silver Creek Rd NE CORD 7 CORD 136 CORD 136 ² CORD t u CORD 9 South St Center St CORD 10 CORD CORD 152 St 6th St W W 6th 2 Miles W 1st St CORD 22 TWHY 9 Elba CORD 107 CORD 7

23 O:\Proj-07\1921-F Ace Minnesota\Data\MapDocuments\BeaufordGPS_11x17_v1.mxd; Aug 2nd 2007; NEF Watersheds Streams MDA Sample Locations. 22 Sources: Streetmap USA, NRCS, USDA Geospatial Data Gateway, ARP, SEI Beauford Ditch, Minnesota MDA - ARP Watershed Evaluation Project Figure 6 - Structural Features by GPS and field location). Feature Standpipe ile Outlet Cul ert Cul ert Outlet ield Draina e Pour Point Le ee Road rate Water ay Legend ² 10 CORD CORD 16 CORD 175 CORD CORD 28 S CORD Miles