11 April 1997

Slopes affect spread pattern

A FERTILISER spreader may work perfectly on the flat but when spreading on a slope the picture can be very different, says Tim Baker, Greenland UKs technical manager.

The warning follows spread pattern testing on the gently rolling slopes of Lincolnshire by Spreader Calibration Specialists (SCS).

The company found that when operating on slopes most spreaders on the market will suffer a severe deterioration in spread pattern.

"Unless your fields resemble billiard tables there is every chance your fertiliser spreader will not be producing an even spread pattern," says Mr Baker.

"The point at which fertiliser contacts the disc is crucial to achieve the correct spread pattern and many spreaders on the market rely on dropping fertiliser on to the disc. When working on a slope, this point of contact is altered and the spread pattern can be disturbed."

Mr Baker points out that a correctly adjusted spreader will perform well on a flat field, with a coefficient of variation (C of V) as low as 6%, but even on a slight slope this can increase to 20%.

Greenland claims it has been able to avoid the hillside effect in the design of its own models by using a discharge chamber between the hopper and discs. These are designed to place fertiliser on the disc in exactly the same position, regardless of whether the machine is on the flat or on a slope.

"Spreading up a 12í slope, our machine produced a C of V of 8.32% over the full 24m working width. This compared to 32.3% for another spreader make on the same slope, which also suffered a reduced spread width of 19m," Mr Baker claims. &#42