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Summary: OrganicChemicalsin the Environment
Mineralization of Norflurazon in a CranberryBog Soil: LaboratoryEvaluations
of ManagementPractices
Mary C. Savin* and Jos6 A. Amador
ABSTRACT
Norflurazon(4-cldoro-5-(methylamino)-2-(~,~,~-trifluoro-m-tolyl-
3(2H)-pyridazinone) is a pre-emergent herbicide used in cranberry
(VacciniummacrocarponAir.) cultivation to control annual grasses,
sedges, and broadleaf weeds. Cranberries are an economically impor-
tant crop in NewEngland,Wisconsin, andother parts of the northern
USA.Thebiodegradation of norflurazon in the high organic matter,
acidic soil characteristic of cranberrybogs has beenshownto proceed
slowly (Savin and Amador,1998). Thepotential effects of cranberry
cultivation practices--soil moisturecontrol, fertilization, sandaddi-
tion, andherbicide application rate--on mineralization of norflurazon
in a bog soil wereevaluatedin a laboratory study. Optimalsoil mois-
ture for norflurazonmineralization wasbetween80 and90%of water-
holding capacity (WHC)in soil fromthe Oi andA horizons. Saturating
the soil reducedthe rate of nodlurazonmineralization significantly.
By contrast, soil respiration was maximal at 25%of WHCin both
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