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Soil Microbiological Activities in Vegetative Buffer Strips and Their Association with Herbicide Degradation

Soil Microbiological Activities in Vegetative Buffer Strips and Their Association with Herbicide Degradation. By C.H. Lin, R.N. Lerch, R.J. Kremer, H.E. Garrett, U. Ranjith and M.F. George . Recent Studies Regarding Herbicides and Health, Ecological and Social & Economic Impacts.

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Soil Microbiological Activities in Vegetative Buffer Strips and Their Association with Herbicide Degradation

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  1. Soil Microbiological Activities in Vegetative Buffer Strips and Their Association with Herbicide Degradation By C.H. Lin, R.N. Lerch, R.J. Kremer, H.E. Garrett, U. Ranjith and M.F. George

  2. RecentStudies Regarding Herbicides and Health, Ecological and Social & Economic Impacts • Public Heath Impact The men living in the Mid Missouri, as compared to other U.S. urban areas, tend to have poorer sperm quality and lower sperm counts. (Dr. Swan et al. 2003) The lower sperm quality and counts strongly associated with the higher herbicides residue levels (alachlor, atrazine) in their urine samples. (Dr. Swan et al. 2003; Center for Disease Control and Prevention 2003) (None of the men in the study worked at or lived next to farms) • Ecological Impact Frogs exposed to atrazine in the reservoir near Midwest states developed reproductive deformity (hemaphroditic; mixtures of ovaries and testes) (Dr. Hayes et al. 2003). • Social & Economic Impact To comply drink water regulation, St. Louis County estimated the costs of compliance for their five drinking water treatment plants by the installation of granular activated carbon at a capital cost of $164 million, with operation and maintenance costs of $7 million per year.

  3. Our Mission • To optimize the riparian buffer designs in agroforestry systems to reduce the herbicide transport from nearby agricultural lands before they reach the reservoirs or drinking water sources • To develop the recommendations (species selection and biodegradation agents) and cost-effective management plans to enhanced the degradation of trapped herbicides within buffers

  4. Effectiveness of Grass Buffer Designs in Reducing Herbicides Transport in Surface Runoff (University of Missouri Bradford Research Center)

  5. Atrazine Transport in Surface Runoff

  6. Metolachlor Transport in Surface Runoff

  7. Glyphosate Transport in Surface Runoff

  8. Further Consideration A robust buffer design needs to rapidly degrade the deposited & intercepted herbicides before they have a chance to be released to surface and subsurface flow.

  9. Site of Lysimeter Project at University of Missouri

  10. Microbial Biomass C vs. Atrazine Degradation in Soils Correlation Coefficient = 0.58 p = 0.015

  11. Contour Buffers Watershed Project Control-traditional corn-soybean rotation Grass Contour Buffer-redtop, brome grass and birdfoot trefoil Agroforestry Contour Buffer- pin oak, white oak, bur oak and same mixture of grasses

  12. Objectives (Phase I) • *To evaluate the effect of vegetation buffers and topographic factors on soil enzymatic activities and their association with herbicides degradation • To evaluate the effects of the contour buffers on herbicides transport and transformations in sub-surface flow.

  13. (ATR) (DEA) (HA) (DIA) (DEHA) (DIHA)

  14. Measured Enzymatic Activities • Fluorescein Diacetate Hydrolytic (FDA) Activity (proteases, lipases, and esterases) • Dehydrogenase Activity (dehalogenation, biological oxidation) • b-Glucosidase Activity (carbon utilization efficiency)

  15. Contour Buffers Watershed Project Control-traditional corn-soybean rotation E1, E2: summit E3: shoulder slope E4: back slope E5: foot slope E6: toe slope Grass Contour Buffer-redtop, brome grass and birdfoot trefoil Agroforestry Contour Buffer- pin oak, white oak, bur oak and same mixture of grasses

  16. Control E1, E2: summit E3: shoulder slope E4: back slope E5: foot slope E6: toe slope Grass Buffer Agroforestry

  17. Microbial Enzymatic Potential for Herbicides Degradation [Fluorescein Diacetate HydrolyticActivity (FDA; mmole g-1 h-1)] E1, E2: summit E3: shoulder slope E4: back slope E5: foot slope E6: toe slope

  18. Dehydrogenase Activity (mmole g-1 h-1) E1, E2: summit E3: shoulder slope E4: back slope E5: foot slope E6: toe slope

  19. b-Glucosidase Activity (mmole g-1 h-1) E1, E2: summit E3: shoulder slope E4: back slope E5: foot slope E6: toe slope

  20. 14CO2 Trap

  21. HPLC-FSA

  22. Microbial Mineralization Rates of Atrazine vs. Microbial Enzymatic Activity * correlation coefficient

  23. Conclusions • Contour vegetative buffer across the landscape showed significantly increased soil enzyme activities compared to cropped control treatment. • Soils collected from grass buffers showed the highest microbial enzymatic activities and herbicide degradation potential. • Topographic positions did not significantly affect soil microbial enzymes activities in this study. • The preliminary results from growth chamber study suggested dehydrogenase and b-Glucosidase activities showed promise as useful tools for evaluating the overall herbicide bioremediation potential of various vetetative buffer designs.

  24. Current Efforts

  25. Glyphosate and Its Metabolite Glyphosate Aminomethylphosphonic acid (AMPA)

  26. Turbo-Ion Spray LC-MS/MS

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