Awareness of Harvest Losses in Corn and Soybean
 Some mechanical damage is expected at harvest.
 Grain loss behind the combine should be measured to determine the need for combine adjustments.
 Careful operation and adjustment of combines can reduce harvest losses to an acceptable level.
Corn kernels and soybean seeds left behind when the
field is combined represent a loss of profits. Harvest
losses cannot be completely eliminated, but can be
reduced to 1 to 2 bu/ acre by checking the performance
of your combine.
Table 1. Length of row (feet) for 1/100 acre for measuring
ear losses.
Row Width
Number of Rows Being Harvested
Inches
2
4
6
8
CORN: How to Measure Harvest Loss
20
131
66
44
33
Determine total ear loss by counting the number of fullsize ears, or the equivalent, in a 1/100 acre area (Table 1).
Each full-size ear represents about 1 bu/acre loss.4
28
94
47
31
23
30
87
44
29
22
36
73
36
38
69
35
To measure kernel loss, count the loose kernels on the
ground and those still attached to threshed cobs in a 10
square foot area for each row behind the combine. The
area should have width equal to the planted row width
(Table 2). Two kernels per square foot equals a 1 bu/acre
loss.4
Reduce Corn Harvest Loss
Proper combine settings can help maximize income by
reducing harvest loss and reduce volunteer corn issues
for the next growing season. Mechanical losses may be
due to ear drop, stalk lodging, and kernel loss from
threshing and cleaning. Mechanical losses are expected,
but keeping them to a minimum of 1% for ear loss, 0.3%
threshing loss, and 0.5% loose kernel loss should be the
goal.1 Altogether, a 1.8% mechanical loss from a 150 bu/
acre corn yield would be 2.7 bu/acre or an average of 5.4
kernels/ square foot.
Ear loss can be minimized by setting snapping rolls to fit
stalk width, and running snapping rolls at the same speed
as ground speed. Cylinder or rotor speed can be adjusted
to minimize threshing losses and kernel damage. Loose
kernel losses can be affected by fan and shoe settings,
and combines should be adjusted where stressed plants
produced lighter kernels. Follow manufacturer’s settings
to minimize losses.
AsgrowandDEKALB.com
Source: Shay, C., Ellis, L.V., and Hires, W. 1993. Measuring and reducing corn
harvesting losses. University of Missouri Extension. G1290.
Table 2. Row length (inches) for 10 square foot frame.
Row Width
Row Length
Inches
Inches
20
*see footnote
28
51.5
30
48
36
40
38
38
40
36
Source: Shay, C., Ellis, L.V., and Hires, W. 1993. Measuring and reducing corn harvesting
losses. University of Missouri Extension. G1290.
*Use same frame as for 40-inch rows, but place frame over two rows at a time.
Asgrow and the A Design® and DEKALB and Design® are registered trademarks of Monsanto Technology LLC.
Awareness of Harvest Losses in Corn and Soybean
SOYBEANS: How to Measure Harvest Loss
Losses are determined by counting the number of
soybeans on the ground in a 10 square foot area (Table
3).4 The number of soybeans lost per square foot can be
determined by counting soybeans in this area and
dividing by ten. Approximately four soybeans/square foot
equals 1 bu/acre loss.2,3 Therefore, dividing the number of
soybeans/square foot by four will give the loss result in
bu/acre. Make loss determinations at several locations
and calculate an average.
Reduce Soybean Harvest Loss
Soybean combine losses can be as much as 15%.
Careful maintenance and operation can help keep
soybean harvest losses to 3%, which would be 1.35 bu/
acre in a 45 bu/acre crop (or 5.4 soybeans/square foot).
Most of soybean harvesting losses occur at the gathering
unit of the combine between the header and standing
soybean plants.2 Loss at the gathering unit is often from
shattering.
Table 3. Dimensions for a measuring soybean loss with a
rectangular 10 square foot plot.
Swath Width (feet)
Inches Along Row to Enclose 10
Square Feet
10
12.0
12
10.0
14
8.6
16
7.5
18
6.7
20
6.0
Source: Beasley, E.O. Reduce soybean harvest losses. North Carolina State University.
http://ipm.ncsu.edu.
Shattering loss can be reduced by harvesting soybeans
as quickly as possible when soybean moisture reaches
15%.3 Ground speed should be reduced to 3 miles/ hour
or less, and reels should operate about 25% faster than
ground speed. The best guide for correct combine
settings and adjustments is your operator’s manual.
Summary
Each harvest season producers have the opportunity to
save yield potential through combine adjustments and
careful machinery operation. While some grain loss is
expected during harvest, mechanical losses should be
kept to a minimum. Measurement of grain left behind the
combine is the key to making adjustments to combines
and proper combine operation.
Figure 1. Most soybean harvest losses occur at the gathering unit, often from
shattering.
Sources:
1
McNeill, S. and Montross, M. Corn harvesting, handling, drying, and storage.
www.ca.uky.edu
Beasley, E.O. Reduce soybean harvest losses. North Carolina State University.
http://ipm.ncsu.edu
3
Staton, M. and Harrigan, T. 2011. Reducing soybean harvest losses. Michigan State
University Extension. http://michigansoybean.org
4
Shay, C., Ellis, L.V., and Hires, W. 1993. Measuring and reducing corn harvesting losses.
University of Missouri Extension. G1290.
Web sources verified 09/08/2015
2
For additional agronomic information, please contact your local seed representative.
Individual results may vary, and performance may vary from location to location and from
year to year. This result may not be an indicator of results you may obtain as local growing,
soil and weather conditions may vary. Growers should evaluate data from multiple locations
and years whenever possible. ALWAYS READ AND FOLLOW PESTICIDE LABEL
DIRECTIONS. All other trademarks are the property of their respective owners. ©2015
Monsanto Company. 130808060309 071514JMG