NC State Extension Publications

Steps at a Glance

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  1. Preventative maintenance
  2. Gather supplies
    1. Seed
    2. Accurate scale
    3. Calculator
    4. Wire flags
    5. Tape measure
    6. Collection containers (Ziplock bags or small cups)
    7. Wire ties and/or duct tape
    8. Tools to fit your drill
  3. Setting up the drill
    1. Determine the target seeding rate
    2. Fill drill with seed, set the seed gate, and turn the drive wheel so that seed is flowing
    3. Disengage the seed tubes and attach collection containers
    4. Set the drill to the recommended seeding depth
  4. Setting up the course:
    1. Place a flag at the beginning of the course
    2. Measure 100 feet and place a flag at the end of the course
    3. OR measure the circumference of the drive wheel
  5. Driving the test run
    1. Get the tractor to the correct speed and gear prior to entering the course
    2. Drop the drill into the ground and drive the course
    3. Disengage after passing the end flag
    4. OR turn the drive wheel an appropriate number of times
  6. Calibrating
    1. Make sure the seed is planted at the correct depth
    2. Remove the seed collection containers and note whether they all appear to have similar amounts in each
    3. Pour the seed onto the tared scale container and weigh
    4. If too little or too much, reset the seed gate and retest
Seeding machine

Brian Maddy, UGA Extension


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Calibrating a seed drill before planting is an important task that can help to maximize the success of your forage stand. Economically speaking, if the equipment is not properly calibrated, you risk losing money by planting either too much or too little seed. Planting lower than the recommended seeding rate may compromise your bottom line by allowing for weed competition within the stand. This leads to both lower yielding and lower quality forage. Meanwhile, planting more seed than required is an unnecessary means of increasing establishment costs.

Table 1. Recommended seeding rates and seeding depths of common forage crops.
Forage Crop Seeding rate, lb/A Seeding depth, inches
Alfalfa 12 - 25 14 - 12
Arrowleaf clover 5 - 10 0 - 12
Ball clover 2 - 3 0 - 14
Bermudagrass, common 5 - 10 0 - 12
Cowpea 100 - 200 1 - 3
Crimson clover 20 - 30 14 - 12
Oats 90 - 120 1 - 2
Orchardgrass 15 - 20 14 - 12
Pearl millet 25 - 30 12 - 112
Red clover 12 - 15 14 - 12
Rye 90 - 120 1 - 2
Ryegrass, annual 20 - 30 0 - 12
Sorghum, forage 15 - 20 1 - 2
Soybean 60 - 100 1 - 3
Tall fescue 15 - 20 14 - 12
Wheat 90 - 120 1 - 2
White clover 2 - 3 0 - 14
Adopted from Forage Crop Pocket Guide by D.M. Ball, C.S. Hoveland, and G.D. Lacefield.

Preventative Maintenance

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Preventative maintenance is often overlooked and can lead to equipment failures, malfunctions, and increased depreciation. It is good practice to spend a little extra time caring for you machinery to ensure its proper function and to help increase its lifespan. The first step to equipment maintenance is always to read the operators manual. The manual gives both safety information and instructions on how to properly maintain the drill. A few key maintenance objectives should be to check the tire pressure on all wheels, grease all fittings, and oil the drive chains. The next step is to check the function of some of the key working parts of the drill such as the feed slides, the no-till coulters, the double disc openers and the press wheels. If there is any wear on the double disk openers, it is recommended that those be replaced. Finally, maintenance of the seed box and seed tubes is of critical importance for proper establishment. A shop vacuum or air hose can be used to clean out old seed or debris. It is also not uncommon for insects such as spiders and mud daubers to build nests in the seed tubes which can ultimately block seed flow and prevent proper seeding densities.

Calibration Procedures

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In order to correctly calibrate a drill and determine the appropriate seeding rate, the area covered in the test run and the amount of seed used must be known. The following equation can be used to calculate seeding rate:

Seeding Rate (lbs ÷ A) = (Amount of Seed (lbs) ÷ Area Covered (Acres))

1. Determining Seeding Area

The best way to determine the area covered in the test run is to first measure the seeding width of the machine to be used. Often, this information can be found in the operator’s manual. Otherwise, the seeding with can be determined with a measuring tape. It is then recommended that you pull the machine, or turn the drive wheel or sprocket, at least 100 feet to get an accurate seeding estimate. Thus, area covered in square feet is calculated by width of drill x length of test run. If turning the drive wheel is a more viable method, the circumference or distance around the drivel wheel will need to be measured. Once the circumference is known, the number of turns required to obtain a distance of 100 feet can be calculated. For example, if a drive wheel is 63 inches, or 5.25 feet in circumference, it will take 19 turns of that drive wheel to equal a distance of 100 feet (100 feet / 5.25 feet = 19 turns). The formula for calculating the seeding area to be covered in the test run is provided below:

Area Covered (Acres) = [(Area Covered in Test Run (square feet)) ÷ (43,560 (square feet in 1 acre))]

2. Determining Seeding Amount

The first step in determining the seeding amount is to set the seed gate to the recommended setting for the particular seed you are planting. Most drill manufacturers provide a meter setting chart. Although this chart can be helpful and is a good place to start, drill wear and condition can often times make it inaccurate. Once the seed gate has been set, pull the drill or turn the drive wheel so that the seed flows freely though the machine. Next, detach the seed tubes at the top or bottom and place a collection device such as a cup or ziplock bag to the drill (Figure 1 and 2). A common practice is to catch 40% of the row openers. However, if the drill has uneven wear and you know some rows may plant heavier than others, catching all of the seed from all of the row openers is recommended to ensure a more accurate calibration.

Once the seed gate has been set and the collection devices are in place, it is time to drive the machine (or turn the drive wheel) the appropriate distance. For best results, travel at a speed that will be replicated during the actual planting.

Before weighing the seed, tare the collection container on the scale. Carefully remove the seed collection bags or cups and note whether they all appear to have similar amounts of seed in them. This can be helpful in determining whether there is a blockage or if the drill needs an alignment. Next, pour all collection cups or bags into the tared collection container and weigh. Once a collective seed measurement has been made, the seeding rate can be calculated using the equation below:

Seeding Rate (lbs ÷ A) = [(Amount of Seed (lbs) ÷ (Area Covered (Acres)]

If the calculated seeding rate is more than or less than the recommended rate, adjust the seed gates and retest. Ensuring that a drill is properly calibrated is a quick and easy means of promoting the success of a forage stand.

Example Calculation

A grain drill has a seeding width of 10 feet. After running the grain drill for 100 feet and collecting the oat seed, you found that you collected 2.89 lbs of oat seed. What is the seeding rate?

1. Determining seeding area:

Area Covered (Acres) = [(Area Covered in Test Run (square feet)) ÷ (43,560 (square feet in 1 acre))]

Area covered (square feet) = width of the drill X length of test run

10 feet x 100 feet = 1,000 square feet in the test run

1,000 ft2 ÷ 43,560 ft2 = 0.0229 acres

2. Determining seeding rate:

Seeding Rate (lbs ÷ A) = [(Amount of Seed (lbs) ÷ (Area Covered (Acres)]

2.89 lbs of seed ÷ 0.0229 acres = 126.20 lbs/acre

Figure 1. Collection bags attached at the bottom of the seed tub

Figure 1. Collection bags attached at the bottom of the seed tubes.

Figure 2. Collection cups attached to the drill at the row opene

Figure 2. Collection cups attached to the drill at the row openers.


Extension Livestock Specialist, Animal Science
Animal Science
Extension Forage Agronomist
University of Georgia

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Publication date: Feb. 15, 2018

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