# Presentation: 075997

## Drill Calibration

## 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

## 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

## 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

## Bulk Density Method

- _Step 1:_
- 	Raise the drill’s drive wheel and measure its circumference in feet

- _Step 2:_
- Measure the distance between seed spouts or disc openers (Usually 6” to 10” on most drills)

- Drive wheel

- Disc opener spacing

## 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

| Row Spacing  in inches | No. of Seed Spouts to Use | Turns of Drive Wheel | Row Spacing  in inches | No. of Seed Spouts to Use | Turns of Drive Wheel |
| --- | --- | --- | --- | --- | --- |
| 6 | 4 | 96/C=R | 24 | 1 | 96/C=R |
| 7 | 4 | 82/C=R | 30 | 1 | 77/C=R |
| 8 | 3 | 96/C=R | 36 | 1 | 64/C=R |
| 10 | 3 | 77/C=R | 42 | 1 | 55/C=R |
| 12 | 2 | 96/C=R | 48 | 1 | 48/C=R |

- Table A

- EXAMPLE:
- 7” disc spacing and wheel circumference of 6.8 ft
- 82/6.8=12 Revolutions
- Need to use 4 Spouts

## 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

- 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

## 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)

- 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)

## 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

- 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

## Adjust setting on the drill to obtain the desired rate

- Slide lever system
- Grain or wheatgrass box

- Gear sprocket and chain system
- Fluffy Box

## 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/.88=114

## Example

- 	If we determined that we need a Bulk seeding rate of 15.1 lbs/ac
- Bulk LBS=PLS 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 0.5=15 lbs/ac

_**GIVEN**_
- Row Spacing=7 inches
- Number of seed spouts needed=4
- Circumference of drive wheel=6.8 ft
- Revolutions of drive wheel (R)=82/C
- R=82/6.8 = 12 revolutions

## Seeds Per Row Foot Method

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

## 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

## 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

## 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

## 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?

## 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

| Row spacing   (in inches) | Linear foot of row (to equal 1 ft2) |
| --- | --- |
| 6 | 2.0  |
| 7 | 1.7 |
| 8 | 1.5 |
| 10 | 1.2 |
| 12 | 1.0 |

**Table B**