How to calibrate the Agrowdrill AD140

Correct calibration of your seed drill will improve metering and result in more cost-efficient sowing

There are four steps for calibrating your AD140 or AD130 seed drill. Note that these steps are only for the main boxes. For help calibrating your small seeds box, refer to page 34 of the Agrowdrill Operators Manual. 

  1. Set the gates and restrictors
  2. Set the sowing rate
  3. Calculate the actual sowing rate
  4. Adjust the sowing rate to suit your desired output

TIP: There are a number of factors that influence sowing rates. These tables are offered as a guide; your machine may need slightly different settings.

We recommend you calibrate your machine according to the following instructions and re-check the results after a hectare to ensure consistency and accuracy. 

1. Set the gates and restrictors

  • Check the restrictor and gate settings recommended for your seed and/or fertiliser in the recommended restrictor and gate settings table.
  • Fit restrictors to your seed rollers as described in the table. 
  • Adjust the roller gates according to the recommended rate. 

The roller gate adjustment levers are located on the right-hand side of the machine. They can be adjusted by rotating the handle anticlockwise to loosen the handle, then sliding the lever to the desired setting. Once in place, rotate the handle clockwise to lock it in place. 

NOTE: The gate setting levers allow broad calibration changes, usually based on seed type and size. Do not adjust gate settings to increase the application rate. This can be adjusted using the rate adjustment levers, which allow for much more precise changes. 

The fluted seed rollers have a fine and a coarse side. This design allows both small and large seeds to be accurately metered. Apply restrictors by positioning them sideways above the seed roller and twisting them into place in the adjustable stoppers. There should be an audible click as they are positioned. 

For more information on restrictor positioning for different seed and fertilisers, see how to reposition seed roller restrictors

Recommended restrictor and gate settings


Gate setting

Restrictors fitted

Lupins 1 None
Barley 0.6 2 of 4
Oats 0.8 None
Wheat 0.6 2 of 4
Sorghum 0.6 2 of 4
Canola 0.2 3 of 4 (leave fine tooth exposed)
Sub clover 0.2 3 of 4 (leave fine tooth exposed)
Lucerne 0.2 3 of 4 (leave fine tooth exposed)
Ryegrass 0.2 2 of 4
Single super 0.8 None or 2 of 4
DAP 0.6 None or 2 of 4
Urea 0.6 2 of 4

restrictor setting

2. Set the sowing rate

  • Set the rate adjustment lever to the desired application rate (measured in Kg/Ha) as described in the calibration chart

The rate adjustment levers can be found on the left-hand side of the machine. Adjust the front and rear hoppers with the levers closest to the front and the rear of the machine. To adjust the rates, rotate the handle anticlockwise to loosen and slide the lever up and down to the desired setting. Once in place, rotate the handle clockwise to lock it in place. 

Calibration Chart

Artboard 1

NOTE: This chart is a guide only. Seed sizes can vary between varieties, from season to season, and crop to crop. Oaten and barley varieties, in particular, can also be affected by the cleanliness of the sample. Always check the application rate prior to sowing. 


3. Calculate the actual sowing rate

Once the sowing rate has been set, you need to measure the actual volume of product being passed through the seed rollers in order to adjust the sowing rate to your target output.

  • Add the seed or fertiliser being calibrated to the seed box. You need enough to completely cover the outlets being calibrated. The outlets being calibrated are the ones that feed into the calibration tray. 
  • Remove the spacer tray and replace it with the calibration tray. 
  • Prime the seed rollers by inserting the calibration handle and rotating anti-clockwise until product appears in the calibration tray. 
  • Empty the trays and replace the calibration tray under the seed rollers. 
  • Turn the seed rollers the number of turns specified in the 'crank handle turns' section of the calibration table. 
  • Weigh the resulting product and calculate the application rate (in Kg/Ha) according to the following formula. Use the calibration table to find the correct calibration factor. 

Calibration Formula

Calibration weight to collect (grams) = target amount (Kg) ÷ calibration factor

Calibration Table

AD140 Model

10 rows

12 rows

16 rows

20 rows

Sowing rows 10 x 150mm 12 x 150mm 16 x 150mm 20 x 150mm
Sowing width 1.5m 1.8m 2.4m 3.0m
FarmScan pulse metres 1.303 1.303 1.303 1.31
Collect from no. of hoses 5 5 5 5
Crank handle turns 51 43 64 51
Calibration factor 0.200 0.240 0.160 0.200

NB: Calibration figures are also applicable to the AD130

4. Adjust the sowing rate to suit your desired output

  • Use the rate adjustment levers to make minor adjustments to the sowing rate. 
  • Repeat step 3 and recalculate the sowing rate until the target output is achieved. 
  • Remove the calibration tray and replace it with the spacer tray. 
  • Place a known amount of seed in the hopper and calculate the expected area to be covered with this quantity of grain. Review the application rate by sowing that area and confirming the correct amount of seed has been sown.