Table 1.
Relative seed size, seeds per pound - spring wheat, oat, and barley.
|
Relative
Seed size
|
Crop
|
|
Spring wheat
|
Oat
|
Barley
|
|
|
seeds per pound
|
|
Small
|
16,000
|
17,000
|
14,000
|
|
|
15,000
|
16,000
|
|
|
Medium
|
14,000
|
15,000
|
13,000
|
|
|
13,000
|
14,000
|
|
|
Large
|
12,000
|
13,000
|
12,000
|
Note:
Seeds per pound decrease as seeds increase in size.
Table 2a. Recommended oat and barley spring seeding
rates per foot-of-row or per square-foot.
|
Conditions
at
seeding
|
Seeding method
|
|
Drill row spacing -
inches
|
Broadcast
|
|
6.0
|
6.5
|
7.0
|
7.5
|
8.0
|
|
|
seeds per foot-of-row*
|
seeds per square-foot *
|
|
Firm seedbed
|
14
|
15
|
16
|
18
|
19
|
28
|
|
Loose seedbed
|
16
|
17
|
19
|
20
|
21
|
32
|
|
Late seeding
|
18
|
19
|
20
|
22
|
23
|
35
|
|
|
|
|
|
|
|
|
|
|
*Assumes
100% pure-live-seed and 90% emergence, rounded to nearest whole number.
Table 2b.
Recommended hard red spring wheat seeding rates per foot-of-row or per
square-foot,
depending on the probability of using
preventative applications of fungicide for control
of Fuariium head blight (FHB) or
head scab.
|
Conditions
at
seeding
|
Probability of using preventative application of fungicides for FHB:
|
|
Low 1
|
High 2
|
|
Drill row spacing - inches
|
Drill row spacing - inches
|
|
6.0
|
6.5
|
7.0
|
7.5
|
8.0
|
6.0
|
6.5
|
7.0
|
7.5
|
8.0
|
|
|
seeds per foot-of-row*
|
seeds per foot-of-row*
|
|
Firm seedbed
|
14
|
15
|
16
|
18
|
19
|
21
|
23
|
24
|
27
|
29
|
|
Loose seedbed
|
16
|
17
|
19
|
20
|
21
|
24
|
26
|
29
|
30
|
32
|
|
Late seeding
|
18
|
19
|
20
|
22
|
23
|
27
|
29
|
30
|
33
|
35
|
|
|
|
|
|
|
|
|
|
|
|
|
1 Low- grower does not plan to spray for
FHB, or only sprays if disease is severe.
2 High– growers plans to spray for FHB; or if a seed grower, sprays to
protect yield and/or quality.
*Assumes 100% pure-live-seed and 90%
emergence, rounded to nearest whole number.
Table 3a.
Recommended spring wheat, oat, and barley seeding rates in pounds per
acre
according to seed size,
planting condition, and seeding rate.
|
Seed size
|
Planting conditions & Seeding rates (seeds per square foot)
|
|
Firm seedbed
(28)
|
Loose seedbed
(32 – 35)
|
Late seeding
(35)
|
|
seeds per pound
|
pounds of
pure-live-seed per acre*
|
|
17,000
|
72
|
82 - 90
|
90
|
|
16,000
|
76
|
87 - 95
|
95
|
|
15,000
|
81
|
93 - 102
|
102
|
|
14,000
|
87
|
100 - 109
|
109
|
|
13,000
|
94
|
107 - 117
|
117
|
|
12,000
|
102
|
116 - 127
|
127
|
|
|
|
|
|
|
* Assumes
100% pure-live-seed (PLS). PLS = percent
germination X percent purity.
NOTE: If seed containing 17,000 seeds per pound is
planted in a firm seedbed in April
a seeding
rate of 72 pounds per acre PLS is suggested. However, if the PLS is only 90%,
divide 100%
by 90% to obtain the conversion factor 1.11.
Next, multiply the initial 72 pounds
per acre by
the conversion factor 1.11 to obtain an adjusted seeding rate of 80 pounds per
acre
(72 X 1.11 = 80). This adjusted seeding rate of 80 pounds per
acre at 90% PLS will now
deliver the
desired 72 pounds of 100% PLS per acre.
Table 3b.
Recommended spring wheat seeding rates in pounds per acre if
preventative
applications of fungicide are planned to protect
the head (spike) against losses in
yield and quality as the result of Fusarium head blight (FHB) or head scab.
|
Seed size
|
Planting conditions & Seeding rates (seeds per square foot)
|
|
Firm seedbed
(42)
|
Loose seedbed
(48 – 53)
|
Late seeding
(53)
|
|
seeds per pound
|
pounds of
pure-live-seed per acre*
|
|
17,000
|
108
|
123 - 136
|
136
|
|
16,000
|
114
|
131 - 144
|
144
|
|
15,000
|
122
|
139 - 154
|
154
|
|
14,000
|
131
|
149 - 165
|
165
|
|
13,000
|
141
|
161 - 178
|
178
|
|
12,000
|
152
|
174 - 192
|
192
|
NOTE: Many growers practicing intensive
wheat management use higher seeding rates
than shown
in table 3a in order to obtain a shorter and more uniform flowering period. Uniform
flowering
period results from high seeding rates that produce more primary heads and
fewer
secondary heads
compared to low seeding rates. These primary
tillers head out and flower
earlier than the secondary tillers and heads. Consequently, high seeding rates make the
flowering period
shorter and more uniform in occurrence.
Thus, a greater percentage of heads
receive enough
of the fungicide at the proper growth stage to protect them against FHB.
Robert G. Hall, Extension Agronomist-Crops
SOUTH DAKOTA STATE UNIVERSITY – Plant Science Department,
Brookings, SD.