FT TRUCK MT
10
FERTILIZER CALIBRATION
General Factors That Affect Spread Patterns:
Fertilizer Size and Density
The particle size will also determine the maximum spread pattern width. The spread pattern can
vary anywhere from 25 ft for powder type materials such as lime or up to 60 ft for fertilizer
pellets.
Large, dense particles will be thrown further than finer materials with lower density. Even after
un-sized fertilizer has been thoroughly blended, segregation will occur during the spreading.
Size is more important than density in determining the distance a particle is thrown. For
example, granular urea is less dense than potash or phosphate materials, but it has a larger
particle. In most cases when spreading a blend, a higher percentage of urea will be found on the
outer edge of the spread pattern.
Driving at an interval to obtain a 100% overlap will minimize the effect of segregation (See
Diagram A
).
Application Rate and Ground Speed
These two factors combine to produce a flow rate. Drivers should avoid situations where both
factors are high. As application rate is increased, ground speed should be lowered accordingly.
When both ground speed and application rates are high, too much material is delivered to the
spinner. When this happens the material will dribble off the spinners instead of being thrown,
causing a heavy swath directly behind the spreader.
Generally, the best spread patterns are obtained when a spreader is operated at 5-10 mph.
Spinner RPM
Spinner speed is adjustable from approximately 400 to 900 RPM. However, spinners should be
operated at approximately 550-650 rpm. As spinner speed is increased within the recommended
range, the spread width will widen. This is a function of the hydraulic spinner system, which can
be controlled by the priority valve.
ADJUSTMENTS
Diagram A