Conservation Buffers to Minimize Pesticide Losses

1. Conservation Buffers to Minimize Pesticide Losses One more reason to promote buffers!

2. Buffer impacts... • Trap sediment (and adsorbed and absorbed pesticides) • Slow runoff (for sheet flow) • Increase infiltration • Biological degradation • Cuts down on drift and overspraying

3. Many studies... • Trapping efficiencies of 50% or more • Increasing water infiltration is the most important factor in trapping pesticides • Without buffers, edge of field losses can range from 1 to as much as 10%

4. …Not the total solution • “Conservation buffers are not a substitute for careful pesticide selection and use” • “They are a tool to further improve water quality…when used along with other practices”

5. Types of buffers... • Grassed waterways • Contour buffer strips • Vegetative barriers • Tile inlet buffers • Field borders • Filter strips and filter areas • Riparian forest buffers

6. Other specialty buffers... • Constructed wetlands • Windbreaks & shelterbelts • Cross wind trap strips • Herbaceous wind barriers • Set-aside and special use areas (CRP fields, wood lots, diversion backslopes, ditchbanks, wildlife habitat plantings)

7. Pesticide trapping... • Function of how tightly the pesticides are adsorbed to soil particles (Koc) • Pesticides with low Koc values (generally less than 500) tend to move more in water that on sediment • To trap low Koc pesticides effectively, buffers need to increase water infiltration and max. contact with soil and vegetation.

8. Some research results...

9. Designing buffers for efficient pesticide trapping... • location, location, location • water must run through the system by sheet flow, not concentrated flow • grading may be necessary • maintenance should be planned • wider strips encourage sheetflow and infiltration • most effective at the top of the watershed!

10. Considerations... • greatest volume of runoff enters the watershed from the small streams • intermittent and 1st and 2nd order streams require more buffer protection • relatively little “new” water enters 3rd and 4th order streams over banks • buffers along larger streams have many other benefits but less for pesticide interception and water quality

11. Dealing withconcentrated flow... • level spreaders • grading • waterbars • vegetated barriers perpendicular to the flow • remove the “natural” berms along the field edge

12. How wide? • subject of considerable debate • factors • soil type (drainage, permeability, zone of seasonal saturation, % organic matter) • antecendent moisture • soil structure and compaction • climate and storm events • slope • condition of vegetation, etc.

13. Research findings... • 10 to 650 feet • under most conditions at least 50 feet • NRCS draft standard • min. 30 ft. for trapping sediment and adsorbed pesticides • wider is not always better, depends on soils, climate, vegetation, & pesticide! • Relatively narrow buffers can still have big impacts (narrow is better than none)

14. Check this web site... • www.ftw.nrcs.usda.gov/tpham/buffer/akey.htm • offers assistance in selection and sizing of buffers • NRCS standards & specifications:www.ftw.nrcs.usda.gov/nhcp_2.html

15. Vegetation… • many options • zonation considerations • 3 zone riparian buffer • Zone 1 undisturbed forest (closest to stream) • Zone 2 management forest • Zone 3 vegetative filter for runoff control • maintenance considerations

16. Economics... • “giving up land” • incentive payments • tax exemptions • cost of installation and maintenance • some limited income potential • environmental and good neighbor benefits • may be a “compliance” requirement

17. Maintenance matters... • periodic sediment removal • mowing (at proper height) • harvest to remove accumulated nutrients • potential reseeding • avoid overspraying • avoid use as turning areas and driveways • weed & insect control

18. IPM pesticide selection pesticide timing banded applications soil incorporation (?) conservation tillage nutrient management subsurface drainage contour farming stripcropping crop rotation terraces detention ponds irrigation timing irrigation water management compaction reduction Integrating bufferswith other BMPs

19. Many references available • NRCS/SWCD offices • Banks and Buffers,A Guide to Selecting Native Plants for Streambanks and Shorelines.Tennessee Valley Authority. CD-ROM. Call 423-751-7338 • Watch for: Conservation Buffers to Reduce Pesticide Losses (NRCS) • www.nhq.nrcs.usda.gov/CCS/Buffers.html

20. For an Electronic Copy: Conservation Buffers to Reduce Pesticide Losses NRCS National Water and Climate Center’s website: http://www.wcc.nrcs.usda.gov go to: /water/quality/common/pestmgt/files/newconbuf.pdf

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