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Sentry 6510 Capacity Monitor
Calculation of grain loss
This table indicates the number of lost seeds per metre of straw behind the combine harvester when the loss is 1% and the eld yields
4000 kg/ha.
Width of cut Barley Oats Wheat Rye
Centimetre Foot 25 seeds=1 g 28 seeds=1 g 21 seeds=1 g 25 seeds=1 g
100 100 112 84 100
180 6 180 201 161 180
240 8 240 268 201 240
265 8½ 265 296 222 265
300 10 300 336 252 300
360 12 360 403 302 360
420 14 420 470 352 420
450 15 450 504 378 450
510 17 510 571 428 510
570 18 570 638 478 570
If the yield is signicantly different from 4000 kg/ha, calculate the percentage loss by hand.
1. Place a piece of canvas under the sieves to collect lost seeds.
2. Harvest exactly one metre.
3. Count the lost seeds collected on the canvas. Disregard any seeds lying in the eld before beginning to harvest.
4. Divide the actual number of seeds lost by the expected number of seeds lost from the table above.
5. Divide 4000 kg/ha by the actual yield in kilograms per hectare.
6. Multiply the results of these two operations to nd the actual percentage loss.
Grain loss calculation examples
Example 1
When harvesting barley with a 360 cm wide cut in a eld yielding 4000 kg/ha, and 220 lost seeds are collected:
Loss = 220/350 = 0.6%
Example 2
When harvesting barley with a 360 cm wide cut in a eld yielding 4800 kg/ha, and 220 lost seeds are collected:
Loss = 220/360 x 4000/4800 = 0.5%
Example 3
When harvesting wheat with an 265 cm wide cut in a eld yielding 5000 kg/ha, and 200 lost seeds are collected:
Loss = 200/222 x 4000/5000 = 0.7%
Rule of thumb
From the grain loss table above it can be concluded that for every centimetre of cut width, about one seed will be lost per metre driven.
Since lost seeds usually land in a track about one metre wide, the number of lost seeds listed in the table covers about one square metre.
Since the human hand is on average about 1/100 m
2
, acceptable loss is about 1/100 of the loss indicated in the grain loss table.
Rule of thumb example
A combine harvester with a 510 cm cut width is harvesting barley in a eld yielding 4000 kg/ha.
The grain loss table indicates an acceptable 1% loss in 510 seeds per metre.
When holding the hand over the lost seeds, an acceptable number of seeds under the hand would be:
510/100 = 5.1 seeds
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