Steps to calibrate to seeding rate to pounds/acre:
1. Figure out how much area one rotation of the drive wheel covers. This will = length of rotation * seeding width
a. Length of rotation: pi * D = drive wheel’s circumference. Our diameter = 28”. 28 * 3.14= 88 inches per rotation
b. Seeding width: Our planter = 10’, with 20 seed openings, thus each opening does 6”. We calibrated using just 4 openings, so 24” of length.
c. Area per rotation: rotation length * seeding width / 144 (sq inches/sq foot) = area in feet squared covered by each rotation.
For us 88*24 / 144 = 14.6 ft2 covered per rotation.
2. Figure out how many rotations of the drive wheel it takes to empty one pound of seed from the seed openings you are using.
a. Evenly space one pound of seed over your openings. (We used four openings =24”)
b. Put a tarp under where the seed come out.
c. Mark the drive tire (or use the valve) for a starting point.
d. Spin the drive wheel, while counting rotations until the seeder is empty. (Try to keep the seed even over all the openings you are using)
3. Pounds per acre = 43, 560ft2 (sq feet in an acre) / (number of rotation * area per rotation).
For us we were planting a wheat, barley, oat mix, shooting for 100lb/acre.
Setting 5 took 40 rotations to empty a pound of seed. 40 rotations * 14.6 ft2 = 584ft2/ pound of seed, or 43,560/584 = 74.5 pounds per acre. Too light!
Setting 9 took 31 rotations which is 31 * 14.6 = 452.6ft2 /pound of seed or 43,560 ft2/ acre ÷ 452.6ft2 /pound = 96 lb/acre. Almost right.
Setting 10 took 28 rotations, which is 28 * 14.6 = 408.8ft2/ lb or 43,560/408.8 = 106.5 lb/acre. We'll probably go a little high, and use setting 10.
4. Adjust your settings to get desired lb/acre
Keywords: double run, double-run, grain drill, seeder, International Harvester, McCormick Deering, John Deere, barley, oats, wheat, grass, sudan, corn, beans, dog, Sadie, farmer, farm