DICKEY-john Corporation | Agricultural, Analytical, & Public Works Electronics

Granular Fertilizer Spreading Tips

For a V-Box spreader with adjustable gate and spread width, it's a good idea to calibrate the spreader each year with the material that will be applied in the field.
If a ground speed controller is not being used, the spreader can be calibrated based on the gate height and set position of the hydraulic flow valve as follows:

  • Set the gate height.
  • Set the position of the hydraulic spreader control valve.
  • Start up the truck and engage the hydraulics.
  • Catch the material discharged from the spreader for 1 minute and weigh.
  • Use the following formula, which allows for various truck speeds and spread widths:
    • 60-foot spread width formula: 60/mph x material lbs discharged in 1 minute/7.27
    • 50-foot spread width formula: 60/mph x material lbs discharged in 1 minute/6.06
    • 40-foot spread width formula: 60/mph x material lbs discharged in 1 minute/4.85

Note: As the density of the material (lbs/ft3) being applied and ground speed varies so will the accuracy of the application rate per acre being applied.

Use a ground speed control system for the application of granular fertilizer spreader.
Control systems maintain a desired target application rate as ground speed of the vehicle changes. When these systems have been set up and calibrated properly they will maintain a 2% accuracy of application per acre. The graph below demonstrates the inaccuracy of application when a ground speed control is not utilized, with the only variable being changes in vehicle speed.

dickey-john nh3 granular fertilizer spreader control versus no control chart

The maximum amount of material that can be discharged from a V-Box spreader is limited by the gate height, conveyor width, hydraulic motor, and gallons per minute of hydraulic oil the hydraulic pump can deliver.
Use our CCS LM Calculators to assist in determining the correct size hydraulic motor and control valve to install to meet the rpm requirements of the conveyor belt for maximum application rates desired.

When it comes to spreading granular fertilizer, DICKEY-john offers a number of products to help reduce costs: