Drill Calibration

1
Drill Calibration
2
What is Calibrating?

• Determining the amount of seed needed on a given
  area
• Measured in pounds per acre
• Seeding rates are figured in Pure Live Seeds
  (PLS) per acre but calibrations are made on bulk
  pounds per acre

3
Some Things to Think About Prior to Calibrating

• Do
• Know what your seeding equipment will seed
• Request seed samples
• Buy quality seed from a reputable vendor
• Have the appropriate calibration equipment
  available
• Most drills have instructions inside the box or
  in the owners manual

• Do Not
• Buy premixed seed unless you feel comfortable
  that the mix can be properly seeded
• Buy on a bulk weight
• Assume that customer knows how to mix seed

4
Two Main Calibration Methods

• Bulk weight method
• Seed is collected and weighed
• Must be wheel driven
• Seeds per row foot method
• Count the actual seeds being seeded
• SD Range Technical Note No. 4
• Perennial Vegetation Establishment Guide

5
Bulk Density Method

• Step 1
• Raise the drills drive wheel and measure its
  circumference in feet

6

• Step 2
• Measure the distance between seed spouts or disc
  openers (Usually 6 to 10 on most drills)

Disc opener spacing
Drive wheel
7
Use Table A to determine the number of
revolutions (R) to turn the drive wheel for the
row spacing and wheel circumference in feet (C)
of your drill
Table A
EXAMPLE 7 disc spacing and wheel circumference
of 6.8 ft 82/6.812 Revolutions Need to use 4
Spouts
8

• Step 3
• Place enough seed in the drill box to cover
  spouts (usually 1-4) from which you will be
  collecting seed
• Turn the drive wheel until all spouts are feeding
  and seed is falling

9

• Step 4
• Place containers under the correct number of seed
  spouts(4)(as determined from table A) and turn
  the drive wheel the number of revolutions
  previously determined (12 revolutions)

10

• Step 4 continued
• Weigh the total of all containers in grams
• Multiply this weight by 0.5
• The result is the pounds per acre at that drill
  setting
• Make adjustments in the drill setting and
  continue until desired seeding rate is obtained

11
Adjust setting on the drill to obtain the desired
rate
Slide lever system Grain or wheatgrass box
Gear sprocket and chain system Fluffy Box
12
Important Reminders

• The seeding rates as determined by this method
  are in bulk pounds per acre of seed (good seed
  plus junk)
• You will need to convert your seeding rate from
  pure live seed per acre to bulk seed per acre
  when using this method prior to calibrating
• Example 0.98 purity X 0.90 germination equals
  0.88 Pure Live Seed (PLS) or for every 1 pound of
  bulk seed, there is 0.88 PLS pounds of good seed
  (12 junk)
• 100 pounds PLS of this seed will equal 114
  pounds of bulk seed that you will need to use for
  calibration 100/.88114

13
Example
GIVEN Row Spacing7 inches Number of seed spouts
needed4 Circumference of drive wheel6.8
ft Revolutions of drive wheel (R)82/C R82/6.8
12 revolutions

• If we determined that we need a Bulk seeding
  rate of 15.1 lbs/ac
• Bulk LBSPLS LBS divided by purity and germ
• The drill would be properly set when the 4 seed
  spouts yield 30 grams of total seed after 12
  revolutions of the drive wheel
• 30 grams X 0.515 lbs/ac

14
Seeds Per Row Foot Method

• Count the number of seeds per foot of drill row
  while the equipment is in operation

15
Bulk Rate Pure Live Seed Rate Purity X
Germination

• First calculate the bulk seeding rate for each
  species in the mix
• 4.5 lbs PLS/ac of green needlegrass
• (80 purity and 70 germination)
• 4.5 lbs/.56 PLS 8 lbs bulk
• 4.0 lbs PLS/ac of western wheatgrass
• (92 purity and 85 germination)
• 4.0 lbs/.78 PLS 5.1 lbs bulk

16
Steps for Seed per Row Foot Method (Continued)

• Calculate the number of seeds per square foot
  (ft2) for each pound seeded
• seeds per pound/43,560 ft2/ac
• Green needlegrass 180,000 seeds/lb
• 180,000/43,560 ft2/ac
• 4.1 seeds green needlegrass per ft2
• Western wheatgrass 112 seeds/lb
• 112,000/43,560 ft2/ac
• 2.6 seeds western wheatgrass per ft2

17
Steps for Seed per Row Foot Method (Continued)

• Multiply the number of seeds per square foot for
  each pound seeded by the bulk seeding rate for
  each species
• Green needlegrass
• 8 lb/ac bulk X 4.1seeds/ft2/lb 32.8 seeds/ft2
• Western wheatgrass
• 5.1 lb/ac bulk X 2.6 seeds/ft2/lb 13.3 seeds
  /ft2
• The total seeds per square foot for the mix would
  be
• 32.8 13.3 46

18
What does this mean?

• You would physically be able to count 46 seeds in
  the drill row
• What distance would you count the seeds for?

19
46 seeds in a 7 inch row spacing would require a
distance of 1.7 feet (1ft2)

• Fill the drill with seed, make your drill setting
  and drive equipment over hard ground
• Count the number of seeds per foot of row and
  adjust your drill setting until proper seeding
  rate is attained
• Use Table B to determine the linear foot of row
  necessary to equal one square foot planted

Table B