Conservation Buffers to Minimize Pesticide Losses

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Conservation Buffers to Minimize Pesticide Losses

• One more reason to promote buffers!

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Buffer impacts...

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

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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

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Not the total solution

• Conservation buffers are not a substitute for
  careful pesticide selection and use
• They are a tool to further improve water
  qualitywhen used along with other practices

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Types of buffers...

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

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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)

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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.

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Some research results...
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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!

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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

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Dealing withconcentrated flow...

• level spreaders
• grading
• waterbars
• vegetated barriers perpendicular to the flow
• remove the natural berms along the field edge

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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.

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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)

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Check this web site...

• www.ftw.nrcs.usda.gov/tpham/buffer/akey.htm
• offers assistance in selection and sizing of
  buffers
• NRCS standards specificationswww.ftw.nrcs.usda
  .gov/nhcp_2.html

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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

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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

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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

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Integrating bufferswith other BMPs

• contour farming
• stripcropping
• crop rotation
• terraces
• detention ponds
• irrigation timing
• irrigation water management
• compaction reduction

• IPM
• pesticide selection
• pesticide timing
• banded applications
• soil incorporation (?)
• conservation tillage
• nutrient management
• subsurface drainage

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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

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