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Effects of long term irrigation with reclaimed wastewater on the efficacy and fate of ALS inhibiting herbicides PowerPoint PPT Presentation


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Effects of long term irrigation with reclaimed wastewater on the efficacy and fate of ALS inhibiting herbicides. Gal Dvorkin, M Manor, M Sibony, B Chefetz and B Rubin The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University in Jerusalem, Rehovot, Israel .

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Effects of long term irrigation with reclaimed wastewater on the efficacy and fate of ALS inhibiting herbicides

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Effects of long term irrigation with reclaimed wastewater on the efficacy and fate of ALS inhibiting herbicides

Gal Dvorkin, M Manor, M Sibony, B Chefetz and B Rubin

The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University in Jerusalem, Rehovot, Israel


Na’an- double cropping irrigated with pivot - 2.8.2006

The field is irrigated with reclaimed wastewater (RWW) for the last 40 years

introduction


Applied herbicides at Na’ad cotton field 2006

  • 28.4.06 – Glyphosate 0.84 kg ae/ha

  • 30.4.06 – Prometryn 1.5 kg/ha

  • 21.5.06– Trifloxysulfuron 11.25 g/ha

  • 11.6.06 – Fluometuron 1.25 kg/ha

  • 26.6.06 – Prometryn 1.4 kg/ha

  • 14.7.06 – Trifloxysulfuron 11.25 g/ha

introduction


The main problems in Na’an field

  • The trifloxysulfuron that was applied twice in the highest recommended dose, was not able to control the Amaranthus palmeri.

  • Wheat that followed the cotton 4 months after the trifloxysulfuron application, was not damaged by residues that were supposed to remain in the soil.

introduction


Hypothesis

  • The long term irrigation with RWW have caused changes in the soil (OM and microorganisms), thus decreasing the persistence of ALS herbicides.

  • The Amaranthus palmeri populationdeveloped resistance to trifloxysulfuron

hypothesis


Research Objective

  • To elucidate the effect of a long term irrigation with RWW on the behavior of ALS inhibiting herbicide trifloxysulfuron in the soil


Materials and Methods

  • Field experiments were conducted at the problematic field, in 2007,2008 and 2009.

  • Dose response curves to trifloxysulfuron in RWW irrigated soil and in fresh water (FW) irrigated soil

  • Develop chemical analysis method to extract and estimate trifloxysulfuron residues from the soil.


The field experiments

  • Herbicides were sprayed with a “backpack sprayer”, each plot 2 m wide and 12 m long

  • Every 2 weeks soil samples were taken using soil driller

  • Herbicide content in the soil samples was examined using Sorghum bicolor as test plant, and harvested 3 weeks later.

Materials and methods


Results of field experiments


Results field experiment 2008

Pelmer amaranth on the day of post-em application -16.6.08

Results


Trifloxysulfuron 11.25 g ha-1 -15.7.08

Results


150 mm

14 day

Trifloxy 11.25

Control

460 mm

54

40

178 mm

Control

Trifloxy 11.25

Control

Trifloxy 11.25

27

Bioassay of soil samples

70 mm

0

Trifloxy 11.25

Control

Control

Trifloxy 11.25

Results


A

A

A

A

A

AB

B

Results bioassay 0-15 cm depth

Results


Lab experiments


Comparing the effect of trifloxysulfuron in RWW soil and FW irrigated soil

  • RWW irrigated soil was collected from Na’an field, and FW irrigated soil was collected from near by field.

  • Both soils were air dried, sieved (5 mm), and were put in 7*7*7 (cm) plastic pots.

  • The pots were planted with wheat, and sprayed with trifloxysulfuron and irrigated with FW.

  • After 3 weeks in the screen house, Plant harvested and shoot fresh wt was recorded

Materials and methods


Soil properties


Results

RWW soil- Trifloxysulfuron

control

1.9 g ai/ha

3.8 g ai/ha

30 g ai/ha

7.5 g ai/ha

15 g ai/ha

FW soil- Trifloxysulfuron

1.9 g ai/ha

3.8 g ai/ha

30 g ai/ha

7.5 g ai/ha

15 g ai/ha

control


Results


RWW soil-trifloxysulfuron

30 g ai/ha

1.9 g ai/ha

3.8 g ai/ha

7.5 g ai/ha

15 g ai/ha

control

Fresh water soil- trifloxysulfuron

Results


Results


Chemical analysis of Trifloxysulfuron in the soil

  • Soil samples were collected from the field experiment in Na’an.

  • The samples were extracted and filtered.

  • Extracts were injected to LC/MS and a method for identifying trifloxysulfuron residues in the soil was developed.


Preliminary results

Results


Conclusions

  • Trifloxysulfuron dissipates faster in RWW soil compare to FW soil.

  • Enhanced dissipation of trifloxysulfuron under field conditions is evident.

  • More experiments are required in order to determine the factors involved in the faster dissipation of trifloxysulfuron in the soil


Acknowledgments

  • Prof. Tom Mueller, University of Tennessee.

  • Weed lab group: Coby Goldwasser, Hadas Rozenberg, Or Levy, Maor Mazraffi, Ella Cohen Alon Vallch and Tal Naamat.

  • Soil & Water lab- Michal Shechter, Ziva Hochman, Daniela Harush, Yaniv Olshansky and Shay Eldad.


Thank you very much for listening


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