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USING ACTIVATED CHARCOAL

Herbicide residues can prevent establishment or re-establishment of some types of sensitive plants.

Activated charcoal can be used to remove the carryover problem and any delays in planting associatedwith the herbicide residue. The feasibility of using this material is generally limited to smaller areas orintensively managed soils such as turf grass. Activated charcoal is generally effective against mostorganic chemicals.

The rates of charcoal to be applied to deactivate the soil will depend on the amount of material present.This can be done with a chemical assay to quantitate the actual amount in the affected soil or, if in a smallarea, an estimation could be made. However, if this is the method to determine rates, there may be adelay due to an inadequate amount of charcoal applied. If a chemical assay is to be determined, thelaboratory will need to know which specific herbicide is to be analyzed.

The sampling procedures are very important and should be planned thoroughly to avoid any erraticresults. Soils should be sampled to the depth of incorporation. If the herbicide was applied to the surfacewithout incorporation, the sample should be taken in the top 1 - 2 inches. A representative sample shouldbe taken which means taking several cores from the affected area and compositing these into one sample.Excessive rainfall in combination with the coarse soil types may require a slightly deeper sample.

The results for the determination of the herbicide will be given in part per million. These will need to beconverted into pounds of active material per acre to determine the rate of charcoal needed. The followingequation is to be used:

(sampling depth (inches) x 0.30) x ppm of herbicide

Once the pounds of active material is determined, the following chart can be used for the rate of charcoal.

Pounds Active Pounds Active Pounds of Charcoal

Ingredient/Acre Ingredient/1000 sq. ft. Required/1000 sq. ft.up to 1.0 up to 0.02 2.0 - 3.5

1.0 - 2.0 0.02 - 0.04 4.5 - 7.02.0 - 3.0 0.04 - 0.06 7.0 - 10.53.0 - 5.0 0.06 - 0.11 11.5 - 17.05.0 - 10.0 0.11 - 0.22 23.0 - 35.0

10.0 - 20.0 0.22 - 0.45 45.0 - 65.0

If the rates of charcoal required are to be applied to a larger area, multiply the required rates on a poundsper 1000 square feet by 43.56 to obtain pounds per acre.

Once the rate is determined, the charcoal should be evenly applied and incorporated four to six inches.This will assure that the charcoal is mixed with the herbicide in the soil. After incorporation, the areashould be watered thoroughly for several days before planting. A test seeding should be used to checkthe rate of deactivation. If this fails, apply additional water and wait several more days. This delay willgenerally be enough for successful deactivation of the herbicide, however, an additional amount of theproduct may need to be applied.

To obtain activated charcoal, contact your chemical supplier or the agronomic staff at MidwestLaboratories Inc.