Calibration Calculations

For correct application rates every time, use the following calibration methods.

Meter calibration

Information needed:

1. Effective fertiliser width of the machine.
   
2. Speed of operation.
   
   This can be calculated by measuring any distance in the field to be worked, then selecting the engine revs, gear and operating depth of implement you plan to use, recording the time taken to cover the measured distance.
   
   Formula: speed = distance divided by time = meters/second x3.6 = km/hr
   
3. Rate of nitrogen to be applied. (To covert lbs/acre to kg/ha multiply lbs/acre by 1.12).
   
   Choose the correct formula:
   - low volume metermatic A6001 (factor 0.223)
   Width (meters) x speed (km/hr) x rate (kg/ha) x 0.223 = meter setting
   
   - standard volume metermatic A6000 (factor 0.086)
   Width (meters) x speed (km/hr) x rate (kg/ha) x 0.086 = meter setting
   
   - high volume metermatic A6500 (factor 0.268)
   Width (meters) x speed (km/hr) x rate (kg/ha) x 0.268 = meter setting

Testing for accuracy

To test the metermatic flow rate for accuracy, the following information is needed:

1. Tank capacity in kilograms

Tank capacity is stamped on the compliance plate. Capacity in kilograms is given in the chart below:

NH3 applicator and nurse tank sizes

 Nominal capacity (US gallons; kilolitres)
 Nominal capacity (litres)
 Kilograms of N at 85% capacity
 
1100 USG
 4179
 1799
 
1000 USG
 3786
 1625
 
2.5 kl
 2460
 1057
 
2.5 kl
 2228
   959
 
583 USG
 2207
   948
 
550 USG
 2082
   895
 
500 USG
 1893
   812
 
250 USG
   946
   406
 
150 USG
   568
   243
 
100 USG
   379
   162
  

2. Time to empty tank.

Formula:

Tank capacity

The meter setting x the flow rate of the meter 

Metermatic flow rate

A6001 low volume                     
Set on 1     0.454 kg N/hr
 
A6000 standard volume
Set on 1     1.172 kg N/hr
 
A6500 high volume 
Set on 1     0.377 kg N/hr

3. Percentage per hour being used.

Formula: 85% divided by the time to empty the tank.

From this information, your metermatic setting can be regularly checked by observing the percentage volume gauge.

For example, using 40% per hour, you will use 20% in 30 minutes. If you check your gauge after 30 minutes you should have 85% - 20% or 65% left in your tank.