Conservation Buffers to Minimize Pesticide Losses

Conservation Buffers to Conservation Buffers to Minimize Pesticide LossesMinimize Pesticide Losses

One more reason to One more reason to promote buffers!promote buffers!

Buffer impacts...Buffer impacts... Trap sediment (and adsorbed and Trap sediment (and adsorbed and

absorbed pesticides)absorbed pesticides) Slow runoff (for sheet flow)Slow runoff (for sheet flow) Increase infiltrationIncrease infiltration Biological degradationBiological degradation Cuts down on drift and Cuts down on drift and

oversprayingoverspraying

Many studies...Many studies... Trapping efficiencies of 50% or Trapping efficiencies of 50% or

moremore Increasing water infiltration is the Increasing water infiltration is the

most important factor in trapping most important factor in trapping pesticidespesticides

Without buffers, edge of field losses Without buffers, edge of field losses can range from 1 to as much as can range from 1 to as much as 10%10%

““Conservation buffers are not a Conservation buffers are not a substitute for careful pesticide substitute for careful pesticide selection and use”selection and use”

““They are a tool to further improve They are a tool to further improve water quality…when used along water quality…when used along with other practices”with other practices”

……Not the total solutionNot the total solution

Types of buffers...Types of buffers... Grassed waterwaysGrassed waterways Contour buffer stripsContour buffer strips Vegetative barriersVegetative barriers Tile inlet buffersTile inlet buffers Field bordersField borders Filter strips and filter areasFilter strips and filter areas Riparian forest buffersRiparian forest buffers

Other specialty buffers...Other specialty buffers... Constructed wetlandsConstructed wetlands Windbreaks & shelterbeltsWindbreaks & shelterbelts Cross wind trap stripsCross wind trap strips Herbaceous wind barriersHerbaceous wind barriers Set-aside and special use areas (CRP Set-aside and special use areas (CRP

fields, wood lots, diversion fields, wood lots, diversion backslopes, ditchbanks, wildlife backslopes, ditchbanks, wildlife habitat plantings)habitat plantings)

Pesticide trapping...Pesticide trapping... Function of how tightly the pesticides Function of how tightly the pesticides

are adsorbed to soil particles (Kare adsorbed to soil particles (Kococ)) Pesticides with low KPesticides with low Kococ values values

(generally less than 500) tend to (generally less than 500) tend to move more in water that on sedimentmove more in water that on sediment

To trap low KTo trap low Koc oc pesticides effectively, pesticides effectively, buffers need to increase water buffers need to increase water infiltration and max. contact with soil infiltration and max. contact with soil and vegetation.and vegetation.

Some research results...Some research results...

Group Koc

Percentpesticidetrapped

PesticideHighlyadsorbedpesticides

1,1008,000

72-100%86-96%

LindaneTrifluralan

Low toModeratelyadsorbedpesticides

20100600

70%11-100%65%

2,4-DAtrazineNorflurazon

Designing buffers for Designing buffers for efficient pesticide efficient pesticide

trapping...trapping... location, location, locationlocation, location, location water must run through the system water must run through the system

by sheet flow, not concentrated flowby sheet flow, not concentrated flow grading may be necessarygrading may be necessary maintenance should be plannedmaintenance should be planned wider strips encourage sheetflow wider strips encourage sheetflow

and infiltrationand infiltration most effective at the top of the most effective at the top of the

watershed!watershed!

Considerations...Considerations... greatest volume of runoff enters the greatest volume of runoff enters the

watershed from the small streamswatershed from the small streams intermittent and 1st and 2nd order intermittent and 1st and 2nd order

streams require more buffer protectionstreams require more buffer protection relatively little “new” water enters 3rd relatively little “new” water enters 3rd

and 4th order streams over banksand 4th order streams over banks buffers along larger streams have many buffers along larger streams have many

other benefits but less for pesticide other benefits but less for pesticide interception and water qualityinterception and water quality

Dealing withDealing withconcentrated flow...concentrated flow...

level spreaderslevel spreaders gradinggrading waterbarswaterbars vegetated barriers perpendicular vegetated barriers perpendicular

to the flowto the flow remove the “natural” berms along remove the “natural” berms along

the field edgethe field edge

How wide?How wide? subject of considerable debatesubject of considerable debate factorsfactors

– soil type (drainage, permeability, zone of soil type (drainage, permeability, zone of seasonal saturation, % organic matter)seasonal saturation, % organic matter)

– antecendent moistureantecendent moisture– soil structure and compactionsoil structure and compaction– climate and storm eventsclimate and storm events– slopeslope– condition of vegetation, etc.condition of vegetation, etc.

Research findings...Research findings... 10 to 650 feet10 to 650 feet under most conditions at least 50 feetunder most conditions at least 50 feet NRCS draft standardNRCS draft standard

– min. 30 ft. for trapping sediment and min. 30 ft. for trapping sediment and adsorbed pesticidesadsorbed pesticides

wider is not always better, depends on wider is not always better, depends on soils, climate, vegetation, & pesticide!soils, climate, vegetation, & pesticide!

Relatively narrow buffers can still have Relatively narrow buffers can still have big impacts (narrow is better than none)big impacts (narrow is better than none)

Check this web site...Check this web site... www.ftw.nrcs.usda.gov/tpham/www.ftw.nrcs.usda.gov/tpham/

buffer/akey.htmbuffer/akey.htm offers assistance in selection and offers assistance in selection and

sizing of bufferssizing of buffers NRCS standards & specifications:NRCS standards & specifications:

www.ftw.nrcs.usda.gov/nhcp_2.htmlwww.ftw.nrcs.usda.gov/nhcp_2.html

Vegetation…Vegetation… many optionsmany options zonation considerationszonation considerations 3 zone riparian buffer3 zone riparian buffer

– Zone 1 undisturbed forest (closest to Zone 1 undisturbed forest (closest to stream)stream)

– Zone 2 management forestZone 2 management forest– Zone 3 vegetative filter for runoff controlZone 3 vegetative filter for runoff control

maintenance considerationsmaintenance considerations

Economics...Economics... ““giving up land”giving up land” incentive paymentsincentive payments tax exemptionstax exemptions cost of installation and maintenancecost of installation and maintenance some limited income potentialsome limited income potential environmental and good neighbor environmental and good neighbor

benefitsbenefits may be a “compliance” requirementmay be a “compliance” requirement

Maintenance matters...Maintenance matters... periodic sediment removalperiodic sediment removal mowing (at proper height)mowing (at proper height) harvest to remove accumulated harvest to remove accumulated

nutrientsnutrients potential reseedingpotential reseeding avoid oversprayingavoid overspraying avoid use as turning areas and avoid use as turning areas and

drivewaysdriveways weed & insect controlweed & insect control

Integrating buffersIntegrating bufferswith other BMPs with other BMPs

IPMIPM pesticide selectionpesticide selection pesticide timingpesticide timing banded applicationsbanded applications soil incorporation (?)soil incorporation (?) conservation tillageconservation tillage nutrient nutrient

managementmanagement subsurface drainagesubsurface drainage

contour farmingcontour farming stripcroppingstripcropping crop rotationcrop rotation terracesterraces detention pondsdetention ponds irrigation timingirrigation timing irrigation water irrigation water

managementmanagement compaction compaction

reductionreduction

Many references availableMany references available NRCS/SWCD officesNRCS/SWCD offices Banks and Buffers,Banks and Buffers, A Guide to A Guide to

Selecting Native Plants for Selecting Native Plants for Streambanks and Shorelines.Streambanks and Shorelines. Tennessee Valley Authority. CD-ROM. Tennessee Valley Authority. CD-ROM. Call 423-751-7338 Call 423-751-7338

Watch for: Watch for: Conservation Buffers to Conservation Buffers to Reduce Pesticide LossesReduce Pesticide Losses (NRCS) (NRCS)

www.nhq.nrcs.usda.gov/CCS/www.nhq.nrcs.usda.gov/CCS/Buffers.htmlBuffers.html

For an Electronic Copy: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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