Presume that the amount of fertiliser to apply is 250 kg of 2:3:2 (30) per hectare. From the previous calculations it is known that with the 900 mm-row spacing, there will be 111 rows in one hectare of 100 meters each. If the supply needs to be 250 kg of fertiliser per hectare, this means that it can deliver 2.25 kg of fertiliser per row. (250 kg/ha divided by 111 rows = 2.25 kg of fertiliser per row) Some maize planters are driven from the PTO shaft on the tractor, but most conventional planters are driven from a drive wheel with spikes on the ground.
For example:
Fertiliser application
The following factors will be unknown:
1. How many times does the ground wheel turn over 100 meters?
2. How much fertiliser the supplier must release in 10 meters?
The following equipment is needed:
1. A small gram scale (kitchen scale)
2. Calculator
3. Measuring tape
4. Pen and notebook
5. Spanners or tools for adjustment
6. Bucket or bag to sample fertiliser
Calculation method:
- Measure the diameter of the ground wheel. Presume it is 2 meters in total.
- Diameter of the ground wheel = 2 meters
- This means that over a distance of 10 meters the wheel will turn 5 times. (10 meter distance divided by 2 meters diameter = 5 turns in 10 meters)
Method:
Hook the planter on the tractor and lift it high above the ground so that the ground wheel can turn freely. Put some fertiliser in one bucket at a time. Put an empty bucket or plastic bag underneath the supplier pipe and turn the wheel now 5 times by hand to simulate a distance of 10 meters. Some fertilisers will be released by the supplier in the bucket or bag. Take the scale and weigh this amount of fertiliser simulated to be placed over 10 meters. It is known from the previous calculations that 2.25 kg of fertiliser is required over 100 meters. This means that in 10 meters an amount of 0, 23 kg or 230 grams must be released. (2,25 kg divided by 10 meters = 230 grams.) Adjust the supplier and keep on measuring the fertiliser released after 5 turns of the wheel until it delivers the 230 grams of fertiliser from each of the supplier buckets.