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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 field 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 significantly 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 field 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 find the actual percentage loss.
Grain loss calculation examples
Example 1
When harvesting barley with a 360 cm wide cut in a field 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 field 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 field 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
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, 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 field 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
