Page 204 - Nutrient Management Planning Guide

198

Calibrating Manure Application Equipment

Figure 4.6.6 Using ‘Reference’ Application Rate to Determine Appropriate Application Speed.

The equation will determine the manure ‘reference’ application rate that must be looked up, along the vertical axis of the calibration graph. A straight line can be drawn horizontally from this ‘reference’ application rate to the calibration line, for a given setting (Figure 4.6.6). From this identified point on the calibration line a vertical line can be drawn down identifying the travel speed, which will be required to achieve the desired application rate for the different density material.

For example, if the calibration curve was developed for manure with a density of 0.9 t/m 3 and the manure to be applied had a density of 0.45 t/m 3 , the application rate of the new manure would have to be doubled in order to put on an equivalent amount of material. To double the application rate the application speed will have to be cut in half or settings adjusted. The calibration line can be used to determine the application speed needed to apply the desired rate of the lighter material.

Correcting Application Rate for New Manure Density in Order to Use an Existing Calibration Graph

A calibration graph for a solid manure spreader was based on cattle manure with a density of 0.72 t/m 3

(Figure 4.6.6). Sheep manure with a density of 0.56 t/m 3 is to be applied at a rate of 16 t/ha using the same spreader.

The ‘reference’ application rate needed to determine the appropriate speed using the existing calibration graph is calculated by:

‘Reference’ application rate (t/ha)

= 16 t/ha × (0.72 t/m 3 ÷ 0.56 t/m 3 ) = 16 t/ha x (1.2857)

= 20.6 t/ha is the ‘reference’ application rate

The ‘reference’ application rate of 20.6 t/ha would be used on the vertical axis of the existing calibration graph to determine the appropriate speed for this particular applicator to apply the lighter sheep manure at a rate of 16 t/ha (Figure 4.6.6). This means that for this applicator to apply the lower density sheep manure, at a rate of 16 t/ha, this applicator would travel at the slower application speed needed as if it was applying 20.6 t/ha of the heavier cattle manure.

Application rate (low speed)

20

Application rate (high speed)

Calibration curve (setting A)

30

0

10

5

40

10 0

Application speed (km)