Cereals: Planting and Crop Development
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Pub 811:
Agronomy Guide> Cereal
> Planting and Crop Development
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811: Agronomy Guide for Field Crops
Table of Contents
Depth of Seeding
Seeding depth can have a significant impact on plant development
Figure 4-1, Days to Emergence at Various Seeding
Depths, but soil conditions at the time of planting must always dictate
seeding depth. Do not plant shallow into dry soil in anticipation of rain
for germination. Plant into moisture to ensure quick and uniform emergence,
even if deep planting is required. However, when soil conditions are too
wet, consider shallow planting or making an additional tillage pass in
an attempt to dry the soil.
Figure 4-1,
Days to Emergence at Various Seeding Depths
Text Explantion
for Figure 4-1, Days to Emergence at Various Seeding Depths
Cereals are lagging far behind corn and soybeans in the
development and adoption of technology to accurately control seeding depth.
With current drills, seed depth can vary from 1.25-7.5 cm (1/2-3 in.)
in the same row, depending on soil conditions.
Growers can attempt to minimize this variation in depth
by using seed firmers, which hold the seed at the bottom of the trench.
Level fields and slower planting speeds will help reduce variability.
Seeding depth accuracy in cereals will not match corn as long as depth
gauge wheels (press wheels) trail double disc openers, or single coulters
without parallel linkage are standard equipment.
Cereals are the most responsive crops to early, timely seeding
see Planting Dates. When cereals are seeded too deep,
delayed emergence of 1 week or more may occur Figure
4-1. Delayed emergence is equivalent to an equal delay in seeding
date, resulting in an equal reduction in yield. It is evident that the
accuracy of seeding equipment requires improvement.
At typical fall temperatures of 15°C days and 5°C
nights (15°C + 5°C = 20/2 = 10 GDD/day), 8 days would be required
for germination and an additional 5 days for each inch of planting depth
to reach emergence. Cooler temperatures will slow this process.
Optimum Seeding Depth
Cereals should be planted uniformly at a depth of 2.5 cm (1 in.). This
encourages early emergence and rapid development of an extensive secondary
root system. Moisture availability is an overriding factor, and seed must
be placed into moisture. A 2.5-cm (1-in.) planting depth is of little
value if moisture is not available at this depth.
Growers that do an accurate job of seeding winter wheat will experience
better winter survival and higher yields.
Cereal Development
The development of the cereal seedling can be determined by following
growing degree day (GDD) accumulations. GDD calculations are discussed
in greater detail in Growing
Degree Days. For cereal crops, use GDD base 0 calculations.
Generally, cereals require 80 GDDs for the seed to germinate and 50 additional
GDDs for emergence, for each inch of planting depth.
For more detailed information and identification of cereal growth stages,
see the Cereal Staging Guide
at Bayer CropScience website (under Tools
and Guides).
Figure 4-2, Cereal Growth Stages, shows the
cereal crop development according to the "Zadok's Scale" ("Feekes"
is another cereal development scale not shown here). These stages are
critical in many management decisions that growers make. Nitrogen and
herbicide applications must be completed during the tillering stage; disease
control is most critical in the stem extension and heading stage. Knowing
the growth stage of the crop is essential to accurately schedule management
inputs and control measures.
Figure 4-2. Cereal Growth Stages
Text Explantion for Figure
4-2, Cereal Growth Stages
Planting Dates
Cereal crops are even more responsive to planting date than corn. Ontario
research shows a 0.07 t/ha/day (1.1 bu/acre/day) decrease in yield for
each day that cereal planting is delayed beyond the optimum date.
Provincial winter wheat yields from 1981 to 2008 are illustrated in Figure
4-3, Provincial Winter Wheat Yield for 1981-2008. Record yields in
2006 and 2008 were primarily due to early planting the previous fall,
while low yields in 1993 were the result of late seeding in the fall of
1992. The low yield of 1996 was caused by a severe fusarium infection.
Figure 4-3. Provincial Winter Wheat
Yield for 1981-2008
Text Explantion for Figure
4-3. Provincial Winter Wheat Yield for 1981-2008
Early Planting
Winter cereals can be seeded too early. Seeding more than 10 days before
the optimum date introduces risk from Hessian fly, snow mould, and barley
yellow dwarf virus (BYDV) infection. BYDV is spread by aphids, which feed
on wheat seedlings. Seed-applied insecticides can minimize the risk of
spread of BYDV but will not eliminate the risk. Check varietal response
to BYDV in the performance trials at www.gocereals.ca.
Aphids are very susceptible to low temperatures. Aphid numbers and related
concerns drop off as cool fall temperatures arrive. (For more information
on Hessian fly, cereal aphids or BYDV, see Chapter
13, Insects and Pests of Field Crops, and Chapter
14, Diseases of Field Crops).
While seeding of winter cereals can be too early, the risk of not planting
in a timely fashion carries great yield risk for growers on heavy, poorly
drained clay soils. In these situations, plant if the soil conditions
are fit. When seeding more than 10 days prior to the optimum date, decrease
the seeding rate by 25%. Using lower seeding rates in this situation reduces
the risk of snow mould and lodging potential. Yields often increase with
lower seeding rates at these early planting dates.
As winter barley must be seeded early, select a variety with tolerance
to BYDV, or utilize seed-applied insecticides that control aphids. See
Publication 812, Field Crop
Protection Guide.
Spring Cereals
It is virtually impossible to seed spring cereals too early, unless soil
conditions are excessively wet. This tremendous response to early seeding
is convincing some producers to consider frost seeding. Cool, moist spring
conditions promote tillering and production of large heads. The flowering
dates of the crop are also advanced, avoiding the hot, dry conditions
that often exist in late June and July.
The target date for planting spring cereals is April 10 for Southwestern
Ontario, April 15 for Central and Eastern Ontario and May 10 for Northern
Ontario. In areas of greater than 3,100 CHUs, spring cereals are generally
not recommended and should definitely not be grown if planting is delayed
beyond April 20.
Figure 4-4. Optimum Date to
Seed Winter Wheat Across Ontario
Winter Cereals
The seeding date for winter wheat is often determined by the date soybeans
are harvested. This can delay optimal planting dates for winter wheat,
resulting in reduced yields. Wheat grown after soybeans is easily facilitated
by following the simple guidelines outlined in Winter
Wheat Following Soybeans.
Figure 4-4, Optimum Date to Seed Winter Wheat Across
Ontario, shows the optimum seeding dates for winter wheat. The isolines
on the map are based on average weather conditions; actual results will
vary from year to year. Seed winter barley 7-10 days prior to the optimum
dates for winter wheat to improve winter survival. Winter barley has less
winter hardiness than winter wheat.
Replanting
Winter cereals are one of the few crops that provide a second opportunity
to assess the crop in spring and replant to another crop if winter survival
was not acceptable. Assess the wheat crop during April and early May.
Leave the replant decision as late as possible to accurately determine
plant stand and plant health.
Table 4-8. Determining Yield Potential
for Various Plant Stand Counts
|
Number of Plants
|
% Yield
Potential |
Planting Date |
| per metre of
row |
per foot of row |
Yield t/ha (bu/acre) |
| Oct. 5 |
Oct. 15 |
|
66
|
201
|
100
|
5.34 (80)
|
4.84 (72)
|
|
33
|
10
|
95
|
5.11 (76)
|
4.57 (68)
|
|
23
|
7
|
902
|
4.84 (72)
|
4.37 (65)
|
|
20
|
6
|
85
|
4.57 (68)
|
4.10 (61)
|
|
16
|
5
|
80
|
4.30 (64)
|
3.90 (58)
|
Source: Smid, Ridgetown College, University of Guelph, 1986-90.
1 Full stand.
2 23 plants/m (7 plants/ft) of row, healthy and evenly distributed,
will still achieve 90% of yield potential and does not require replanting.
A field with an average of 23 plants/m (7 plants/ft) of row without relatively
uniform distribution, or with plants severely damaged by heaving and other
injury factors, will not yield satisfactorily. Consider replanting in
this case.
Damaged plants will often recover under good weather conditions, while
plants that are expected to recover may die if hot dry conditions exist.
Table 4-8, Determining Yield Potential for Various
Plant Stand Counts, indicates yield potential for various plant stand
counts. The planting date will have an impact on the replant decision.
Seeding Rates
Historically, the seeding rates of cereal crops were recommended in bu/acre,
with 2 bu/acre a standard that covered most cereal crops.
Blanket statements of this nature are no longer acceptable. Seed size
affects seeding rate. Set optimum seeding rates for each cereal crop.
Table 4-9, Recommended Plant Populations for Cereal
Crops, gives the recommended seeding rates for each crop. Table
4-10, Determining Seeding Rate, indicates the seeds per metre of row
and kilograms of seed per hectare required to achieve various desired
plant populations.
In terms of seeding rates and desired plant populations, a variety with
fewer seeds/kg will be at a disadvantage to a variety with more seeds/kg.
To achieve the recommended rate for most soils, a higher seeding rate
(kg/ha) will be required for varieties with few seeds/kg.
Table 4-9. Recommended Plant Populations
for Cereal Crops
| |
Target Plant Population
|
|
Crop
|
Plants/m2
(plants/ft2) |
Seeds/ha
(x1,000) |
Seeds/acre
(x1,000) |
| Barley |
250-350 (23-33)
|
2,500-3,500
|
1,000-1,400
|
| Oat |
200-300 (19-28)
|
2,000-3,000
|
800-1,200
|
| Mixed grain |
200-350 (19-33)
|
2,000-3,500
|
800-1,400
|
| Spring wheat |
300-400 (28-37)
|
3,000-4,000
|
1,200-1,600
|
| Winter wheat |
350-450 (33-42)
|
3,500-4,500
|
1,400-1,800
|
Use the higher rates in Table 4-9 and Table
4-10:
- where emergence and early seedling establishment are likely to be
poor (for example, due to poor seedbed and aerial or broadcast seedings)
- for late planting where tillering will be reduced
- on very heavy clay soils
The seeding rate can be determined using this formula:
Seeding rate (kg/ha) = (seeds/ha ÷ seeds/kg) x (100 ÷ %
germination)
Seeding rate (lb/acre) = (seeds/acre ÷ seeds/lb) x (100 ÷
% germination)
Sample Calculation
Seeds/kg (seeds/lb) should be stated on the seed tag or bag. For instance,
if 3.7 million seeds/ha (1.5 million seeds/acre) is desired, with a germination
rate of 95% and 26,500 seeds/kg (12,000 seeds/lb), the seeding rate would
be 147 kg/ha (132 lb/acre).
Metric = (3,700,000 ÷2 6,500) x (100 ÷ 95) = 147 kg/ha
Imperial = (1,500,000 ÷ 12,000) x (100 ÷ 95) = 132 lb/acre
Table 4-10. Determining Seeding Rate
| |
Desired Plant Population
seeds/ha x 1,000 (seeds/acre x 1,000) |
| |
2,000 (809) |
2,500 (1,012) |
3,000 (1,213) |
3,500 (1,416) |
4,000 (1,619) |
4,500 (1,661) |
|
Row Width
|
Seeds per Metre of Row (seeds
per foot of row) |
| 25 cm 10 in. |
49 (15)
|
62 (19)
|
75 (23)
|
89 (27)
|
102 (31)
|
112 (34)
|
| 20 cm 8 in. |
39 (12)
|
49 (15)
|
62 (19)
|
69 (21)
|
82 (25)
|
92 (28)
|
| 19 cm 7.5 in. |
38 (12)
|
46 (14)
|
56 (17)
|
66 (20)
|
75 (23)
|
85 (26)
|
| 18 cm 7 in. |
36 (11)
|
43 (13)
|
52 (16)
|
62 (19)
|
69 (21)
|
79 (24)
|
| 15 cm 6 in. |
30 (9)
|
39 (12)
|
46 (14)
|
52 (16)
|
59 (18)
|
69 (21)
|
| 10 cm 4 in. |
20 (6)
|
26 (8)
|
30 (9)
|
36 (11)
|
39 (12)
|
46 (14)
|
|
Seeds/kg (seeds/lb)
|
Kilograms of Seed per Hectare
(lb of seed per acre) |
| 22,100 (10,000) |
90 (80)
|
112 (100)
|
134 (120)
|
157 (140)
|
179 (160)
|
202 (180)
|
| 24,300 (11,000) |
82 (73)
|
102 (91)
|
122 (109)
|
142 (127)
|
162 (145)
|
184 (164)
|
| 26,500 (12,000) |
75 (67)
|
93 (83)
|
112 (100)
|
131 (117)
|
149 (133)
|
168 (150)
|
| 28,700 (13,000) |
69 (62)
|
86 (77)
|
103 (92)
|
121 (108)
|
138 (123)
|
155 (138)
|
| 30,900 (14,000) |
64 (55)
|
80 (71)
|
96 (86)
|
112 (100)
|
128 (114)
|
144 (128)
|
| 33,200 (15,000) |
59 (53)
|
75 (67)
|
90 (80)
|
104 (93)
|
120 (107)
|
134 (120)
|
| 35,400 (16,000) |
56 (50)
|
71 (63)
|
84 (75)
|
99 (88)
|
112 (100)
|
127 (113)
|
| 37,600 (17,000) |
53 (47)
|
66 (59)
|
80 (71)
|
92 (82)
|
105 (94)
|
119 (106)
|
| 39,800 (18,000) |
49 (44)
|
62 (55)
|
75 (67)
|
87 (78)
|
100 (89)
|
112 (100)
|
| 42,000 (19,000) |
47 (42)
|
59 (53)
|
71 (63)
|
83 (74)
|
94 (84)
|
106 (95)
|
| 44,200 (20,000) |
45 (40)
|
56 (50)
|
67 (60)
|
78 (70)
|
90 (80)
|
101 (90)
|
Table 4-11. Winter Wheat Row Widths
| |
|
Winter Wheat Row Spacing |
| |
10 cm (4 in.) |
18 cm (7-7.5 in.) |
25 cm (10 in.) |
36 cm (14-15 in.) |
51 cm (20 in.) |
| Location |
Yield t/ha (bu/acre) |
|
U.S
|
Wisconsin
1985-87 |
6.32
(94)
|
6.32
(94)
|
5.44
(81)
|
-
|
-
|
| Ohio |
-
|
4.10
(61)
|
4.03
(60)
|
3.97
(59)
|
3.56
(53)
|
|
Canada
|
| Ontario1 |
5.38
(80)
|
5.38
(80)
|
-
|
-
|
-
|
| Ontario2 |
|
88.8
|
-
|
81.4
|
-
|
|
On-Farm Trials
|
Essex
County |
-
|
5.12
(76)
|
4.97
(74)
|
-
|
-
|
Middlesex
County |
-
|
5.98
(89)
|
5.91
(88)
|
-
|
-
|
1 Source: Smid, Ridgetown College, University of Guelph, 1987-90.
2 Johnson, 2006/2007 Cord report.
Row Widths
Considerable research has been conducted on cereal row widths for maximum
yield. Table 4-11, Winter Wheat Row Widths, summarizes
some winter wheat row width research from across Ontario and the northern
U.S. On-farm results from Ontario are included. There is no evidence to
support narrowing row widths below the standard 18-19 cm (7-7.5 in.) spacing
for winter crops.
There appears to be a yield penalty with wider rows. The most recent
Ontario row-width research shows an 8% decrease in yield when moving to
38 cm (15 in.) rows from 19 cm (7.5 in.). In some cases, this yield loss
may be offset by reduced equipment costs and result in more profit if
less equipment investment is required. Many of the new 25-cm (10-in.)
row planters have more accurate seed placement than 19-cm (7.5-in.) drills.
With the importance of seeding depth, this improved accuracy may partially
overcome the row width impact, as indicated by the Essex, Middlesex and
Ohio data, where accurate planting equipment was used for the 25-cm (10-in.)
row widths.
For spring cereal crops, trials in Northern Ontario have shown yield
increases of more than 5% when row width was reduced from 18-cm to 10-cm
(7-in. to 4-in.) spacing. Moving to 10-cm (4-in.) rows in this production
area may prove beneficial. However, it is difficult to achieve these narrow
row widths in a no-till system.
Table 4-12. Management Considerations
for Wheat Following Various Crops in Rotation
|
Following:
|
Comments |
|
Beans (soybeans or dry edible beans)
|
- Excellent rotation
- When soybean harvest is delayed, wheat planted later will have
lower yield potential.
- On sandy soils, European chafer populations can reduce plant
stands.
|
|
Canola
|
- Excellent rotation
- Best option for timely planting
- Response to starter P may be greater
|
|
Corn
(silage or grain)
|
- Highest risk of fusarium
- Timely planting is possible.
- For wheat after corn, plant a variety that is MR for fusarium
(see www.gocereals.ca) and plan to apply a fungicide to prevent
fusarium.
|
|
Alfalfa
(pure stands)
|
- Timely planting is possible.
- Insect damage is a concern.
Nitrogen credit is not fully utilized because of timing of N release
relative to crop requirements. Up to half the N is released after
crop uptake is complete.
|
|
Grass hay
|
- Poor rotation
- Primary risk is take-all, a root disease that infects the crop
in the fall with a potential yield loss of over 50%, and other
root diseases.
- Later planting combined with seed-placed potash fertilizer provides
some take-all suppression.
|
|
Oat
|
- Reasonable rotation. Few diseases cross over between wheat and
oat.
|
|
Barley
|
- Not a desired rotation
- Many of the root diseases cross over between barley and wheat.
- Later planting combined with seed-placed potash fertilizer provides
some take-all suppression.
|
|
Wheat
|
- Worst rotation choice (not a rotation)
- Leaf disease and root disease pressure will be at its maximum.
- Take-all, eyespot and cephalosporium stripe are at high risk
with little or no management options.
- Expect a minimum 10% yield loss.
|
Crop Rotation for Winter Wheat
Crop rotation is an integral part of any production system. The greatest
benefit to a good crop rotation is increased yields. A well-planned crop
rotation will help with insect and disease control and aid in maintaining
or improving soil structure and organic matter levels. In addition to
increasing yields, using a variety of crops can reduce weed pressures,
spread the workload, protect against soil erosion and reduce risk. Table
4-12, Management Considerations for Wheat Following Various Crops in Rotation,
shows some of the risks associated with, and management options for, wheat
following other crops.
