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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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slide1

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
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.

our mission
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
slide4

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

further consideration
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.

slide11

Microbial Biomass C vs. Atrazine Degradation in Soils

Correlation Coefficient = 0.58

p = 0.015

slide12

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

objectives phase i
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.
slide14

(ATR)

(DEA)

(HA)

(DIA)

(DEHA)

(DIHA)

measured enzymatic activities
Measured Enzymatic Activities
  • Fluorescein Diacetate Hydrolytic (FDA) Activity (proteases, lipases, and esterases)
  • Dehydrogenase Activity (dehalogenation, biological oxidation)
  • b-Glucosidase Activity (carbon utilization efficiency)
slide16

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

slide17

Control

E1, E2: summit

E3: shoulder slope

E4: back slope

E5: foot slope

E6: toe slope

Grass Buffer

Agroforestry

slide18

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

slide19

Dehydrogenase Activity (mmole g-1 h-1)

E1, E2: summit

E3: shoulder slope

E4: back slope

E5: foot slope

E6: toe slope

slide20

b-Glucosidase Activity (mmole g-1 h-1)

E1, E2: summit

E3: shoulder slope

E4: back slope

E5: foot slope

E6: toe slope

microbial mineralization rates of atrazine vs microbial enzymatic activity
Microbial Mineralization Rates of Atrazine vs. Microbial Enzymatic Activity

* correlation coefficient

slide25

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.
glyphosate and its metabolite
Glyphosate and Its Metabolite

Glyphosate

Aminomethylphosphonic acid (AMPA)

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