Presentation on theme: "Conservation Buffers to Minimize Pesticide Losses One more reason to promote buffers!"— Presentation transcript:
Conservation Buffers to Minimize Pesticide Losses One more reason to promote buffers!
Buffer impacts... n Trap sediment (and adsorbed and absorbed pesticides) n Slow runoff (for sheet flow) n Increase infiltration n Biological degradation n Cuts down on drift and overspraying
Many studies... n Trapping efficiencies of 50% or more n Increasing water infiltration is the most important factor in trapping pesticides n Without buffers, edge of field losses can range from 1 to as much as 10%
n “Conservation buffers are not a substitute for careful pesticide selection and use” n “They are a tool to further improve water quality…when used along with other practices” …Not the total solution
Types of buffers... n Grassed waterways n Contour buffer strips n Vegetative barriers n Tile inlet buffers n Field borders n Filter strips and filter areas n Riparian forest buffers
Other specialty buffers... n Constructed wetlands n Windbreaks & shelterbelts n Cross wind trap strips n Herbaceous wind barriers n Set-aside and special use areas (CRP fields, wood lots, diversion backslopes, ditchbanks, wildlife habitat plantings)
Pesticide trapping... n Function of how tightly the pesticides are adsorbed to soil particles (K oc ) n Pesticides with low K oc values (generally less than 500) tend to move more in water that on sediment n To trap low K oc pesticides effectively, buffers need to increase water infiltration and max. contact with soil and vegetation.
Some research results...
Designing buffers for efficient pesticide trapping... n location, location, location n water must run through the system by sheet flow, not concentrated flow n grading may be necessary n maintenance should be planned n wider strips encourage sheetflow and infiltration n most effective at the top of the watershed!
Considerations... n greatest volume of runoff enters the watershed from the small streams n intermittent and 1st and 2nd order streams require more buffer protection n relatively little “new” water enters 3rd and 4th order streams over banks n buffers along larger streams have many other benefits but less for pesticide interception and water quality
Dealing with concentrated flow... n level spreaders n grading n waterbars n vegetated barriers perpendicular to the flow n remove the “natural” berms along the field edge
How wide? n subject of considerable debate n 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.
Research findings... n 10 to 650 feet n under most conditions at least 50 feet n NRCS draft standard –min. 30 ft. for trapping sediment and adsorbed pesticides n wider is not always better, depends on soils, climate, vegetation, & pesticide! n Relatively narrow buffers can still have big impacts (narrow is better than none)
Check this web site... n buffer/akey.htm n offers assistance in selection and sizing of buffers n NRCS standards & specifications:
Vegetation… n many options n zonation considerations n 3 zone riparian buffer –Zone 1 undisturbed forest (closest to stream) –Zone 2 management forest –Zone 3 vegetative filter for runoff control n maintenance considerations
Economics... n “giving up land” n incentive payments n tax exemptions n cost of installation and maintenance n some limited income potential n environmental and good neighbor benefits n may be a “compliance” requirement
Maintenance matters... n periodic sediment removal n mowing (at proper height) n harvest to remove accumulated nutrients n potential reseeding n avoid overspraying n avoid use as turning areas and driveways n weed & insect control
Integrating buffers with other BMPs n IPM n pesticide selection n pesticide timing n banded applications n soil incorporation (?) n conservation tillage n nutrient management n subsurface drainage n contour farming n stripcropping n crop rotation n terraces n detention ponds n irrigation timing n irrigation water management n compaction reduction
Many references available n NRCS/SWCD offices n Banks and Buffers, A Guide to Selecting Native Plants for Streambanks and Shorelines. Tennessee Valley Authority. CD-ROM. Call n Watch for: Conservation Buffers to Reduce Pesticide Losses (NRCS) n Buffers.html
For an Electronic Copy: Conservation Buffers to Reduce Pesticide Losses NRCS National Water and Climate Center’s website: go to: /water/quality/common/pestmgt/files/newconbuf.pdf
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