Slide Presentation
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Water Quality and Herbicides
AUTHOR
Eric P. Prostko
Professor and Extension Weed Specialist
University of Georgia
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TABLE OF CONTENTS
Water Quality and Herbicides
A common question?
Important Water Qualities
Turbidity
Water pH
Alkaline Hydrolysis
Water Hardness
Ammonium Sulfate and Hard Water
Water Conditioners
In the absence of hard water, is AMS really needed?
In the absence of hard water, is AMS really needed?
Sample Water Quality Report
Water pH and major cation concentrations of South Georgia Wells
Check Labels
Water Testing Labs
Questions?
SLIDE CONTENTS
Water Quality and Herbicides Eric P. Prostko Professor and Extension Weed Specialist Department of Crop & Soil Sciences
A common question? Should I use AMS with that?
Important Water Qualities turbidity pH hardness
Turbidity Suspended solids, soil, and OM Can affect herbicides with high Koc values Paraquat Glyphosate Don’t use muddy water!
Water pH Measurement of acidity/alkalinity <7.0 = acidic >7.0 = alkaline 7.0 = neutral 4.0 to 7.0 is fine Alkaline hydrolysis above 7
Alkaline Hydrolysis Valor (flumioxazin) Soil-Water Half-Life pH 5.0 = 3.4 to 5.1 days pH 7.0 = 21.4 to 24.6 hours pH 9.0 = 12.6 to 22.0 minutes
Water Hardness Measure of cations (+) in solution Ca, Mg, Fe, K, Na Can influence the performance of weak acids glyphosate glufosinate
Ammonium Sulfate and Hard Water (NH4)2SO3 Overcomes antagonistic effects of cations How? Lowers pH NH4+ binds with herbicide SO4- binds with cations 8.5-17 lbs/100 gals (dry) 2.5-5.0 gals/100 gals (liquid)
Water Conditioners CPS Non-AMS water conditioner 0.25% to 0.50% v/v ~$34/gal $0.85-$1.70/A – 10 GPA Helena Non-AMS water conditioner 0.25%-0.50% v/v ~$24/gal $0.60-$1.20/A – 10 GPA
In the absence of hard water, is AMS really needed? AMAPA 19 DAT CN-10-13 AMS Xtra @ 2.5% v/v RUP = Roundup ATZ = Atrazine LBY = Liberty CAP = Capreno SFQ = Steadfast Q
In the absence of hard water, is AMS really needed? Cadre 70DG 1.44 oz/A COC @ 1% v/v CASOB PE-08-04 AMS 100 DF @ 3 lb/A
Sample Water Quality Report pH = 4.28 Hardness = 88 ppm CaCO3 Moderately hard (USGS) Using NDSU-AMS equation 0.3 lbs AMS/100 gals
Check Labels
Water Testing Labs UGA $20/sample Waters Agricultural Lab $38/sample
Questions? eprostko@uga.edu www.gaweed.com