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Leading the way... For Precision Seed Placement

Chances are, if you have questions, others have similar thoughts and questions about the planting and establishment of native grasses and wildflowers. Therefore we have developed a list of some of the most common questions we hear, our responses, and additional material and resources you may want to research. The owner’s manual that is included with each Truax Drill provides a great deal of information about the set up, adjustment and calibration of Truax equipment. In addition, the Resource Directory section of our web site lists many experienced, and knowledgeable professionals in the field that can answer many of your questions. We will add to the list on a regular bases and if you have a question you want answered please send an e-mail.


Seed placement is the primary concern of a person involved in the planting of native and cool season grasses. Most species require shallow placement in the soil. Even species that is surface seeded require soil to seed contact. Truax provides several diameter depth bands, 9-1/2", 11-1/2", 12", and 12-1/2" to allow the installation contractor the flexibility to adjust his Drill to meet the site conditions and individual species needs. The standard size is 12" and works well under most condition; however, site conditions such as seed bed firmness, no-till litter and wear on disc blades can also affect seed placement. This important subject is discussed in a USDA-NRCS publication titled: Five Keys to successful Grass Seeding, published in 2003. Copies can be obtained by contacting the NRCS-PMC in Bismarck, North Dakota. Phone: (701) 250-4330.


The operator has several options to adjust the seed box output of the Drill. Seed flow from the small seed box and cool season/grain box is set by moving the shift levers located on the seed boxes. Moving these levers opens and closes the exposed metering flutes in the seed cup. When closing the exposed flute to reduce seed flow, do not close the flutes so tight that they damage the seed as they turn. Output from the fluffy box is set using the derailleur (roller chain on double set of 5 sprockets).

When the seeding rate needs further reduction several approaches can be used. Newer Drills can be equipped with an Output Reduction Kit to slow output by 50% from all seed boxes. Seed gaskets and retainer plates provided with the Drill can be placed over the picker wheels in the fluffy box. Various sprockets can be changed to adjust output up or down. The attached chart lists the available options and the approximate change in seed output.

After mechanical changes have been made to the Drill additives or fillers that can be mixed with the seed. This allows you to meter smaller amounts of seed for distribution over a large area. One method to do this is to put the amount of seed to be used on one acre in a five-gallon bucket and add enough extenders to fill the pail. Determine the weight of the seed and extender mix and calibrate the Drill to apply this amount of material over one acre of area. Some materials that have been used successfully as extenders include horticulture grade vermiculite; clean, dry pine sawdust; cotton seed hulls; rice hulls; or on smaller jobs a food grade puffed rice, puffed wheat, or oatmeal.

In all cases after adjustments are made to the Drill set up use the calibration process to determine the Drill output for the seed lot or material being seeded. This procedure is described on the decal found on the seed box lid and in the Operator Manual.


After making mechanical adjustments as outlined above there are a few other things that can be done to further fine tune the Drill’s calibration. In the fluffy seed box renew the seed gaskets in the fluffy box. Normal usage may have created a wider gap around the picker wheel. Adding duct tape under the retainer plates to restrict the slot opening can further reduce the open slot around the picker wheel. The trailing end of the picker wheel slot can be restricted by cutting a piece of pop can metal and adding it under the gasket.

Plugging one or more seed tubes can also reduce the seeding rate from the Drill. This has the affect of reducing the overall seeding rate for the field. Note however that this method will result in non-uniform distribution of species over the fields.


Location Sprocket # # of Sprocket Teeth Sprocket Style Approximate % Reduction
Leg Drive Shaft to Clutch 1045A 18 Single Standard
Output Reduction Kit 710532 18/36 Double 50% on all seed boxes
Small Seed Box 1055 20 Single Standard
  1054A 30 Single 35% on small seed box
Fluffy Seed Box
Seed Gaskets/Retainer Plates 1005/1006 None Gasket/Retainer 20-30% on fluffy seed box
Picker Wheel Drive Sprocket 1055A1 30 Single
Picker Wheel Drive Sprocket 1055A2 36 Single 30% on fluffy seed box
Picker Wheel Drive Sprocket 1055A212 42 Single 35% on fluffy seed box
Cool Season/Grain Seed Box 3095X 30/20 Double Standard

42/20 Double 35% on cool season seed box
1044 30 Single Standard
Note: 54 & 60 Tooth sprockets can not 1144E 48 Single 40% on all seed boxes
be used with Output Reduction Kit 1144A 54 Single 45% on all seed boxes
  1144B 60 Single 50% on all seed boxes
Note: Actual seed box output reduction achieved with any change will vary depending on seed quality. See Operators Manual #5999, "Seeding Rate Variables" on Page 30-3 for factors that will affect seeding rate. Always recheck calibration after any change is made.

Truax Company, Inc. | 4300 Quebec Avenue North | New Hope, MN 55428 | Phone (763) 537-6639 | Fax (763) 537-8353 | Email:
Truax Seeding Equipment Applications