Cereals: Planting

Excerpt from Agronomy Guide for Field Crops (Chapter 6)

Order OMAFRA Publication 811: Agronomy Guide for Field Crops

Table of Contents

1. Depth of Seeding
   • Optimum Seeding Depth
2. Cereal Development
3. Planting Dates
   • Winter Cereals
   • Spring Cereals
4. Replanting
5. Determining Yield Potential for Various Plant Stand Counts - Table 6-6
6. Seeding Rates
   • Sample Calculations
7. Recommended Plant Populations for Cereal Crops - Table 6-7
8. Determining Seeding Rate - Table 6-8
9. Row Widths
10. Winter Wheat Row Widths - Table 6-9
11. Additional Management Opportunities
12. Updates on Cereals: Planting
13. Related links...

Depth of Seeding

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Figure 6-1. Days to Emergence at Various Seeding Depths

Still, 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.

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 press wheels trail double disc openers, or single coulters without parallel linkage are standard equipment.

Cereal crop yield is greatly affected by seeding depth variability and lack of accurate placement. Cereals are the most responsive crops to early, timely seeding (see the section Planting Dates). When cereals are not seeded at a uniform depth or are seeded too deep, delayed emergence of 1 week or more often occurs (see Figure 6-1. Days to Emergence at Various Seeding Depths). 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.

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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. Spring cereal yields will also increase using this strategy. Producers should strive to improve the seeding methodology to achieve the highest yields possible.

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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 the section Growing Degree Days. For cereal crops, use GDD base 0 calculations.

Generally, cereals require 80 GDDs for the seed to germinate. For emergence, 50 additional GDDs for each inch of planting depth are required.

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FIGURE 6-2. Cereal Growth Stages

At typical fall temperatures of 15°C days and 5°C nights, 8 days (15°C + 5°C = 20/2 = 10 GDD/day) 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.

Figure 6-2. Cereal Growth Stages, shows the breakdown of 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 when scouting for problems is essential to determining if control measures are warranted.

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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/ac/day) decrease in yield for each day that cereal planting is delayed beyond the optimum date.

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FIGURE 6-3. Provincial Winter Wheat Yield for 1981-2003

Provincial winter wheat yields from 1981 to 2000 are illustrated in Figure 6-3. Provincial Winter Wheat Yield for 1981-2003. Record yields in 1999 and 2000 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.

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 the section Winter Wheat Following Soybeans.

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Figure 6-4. Optimum Date to Seed Winter Wheat Across Ontario

Figure 6-4. 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, and actual results will vary slightly 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 much less winter hardiness than winter wheat.

Wheat can be seeded too early. Do not seed wheat more than 10 days before the optimum date to minimize Hessian fly and BYDV risk. BYDV is spread by aphids, which feed on wheat seedlings. Using insecticides to control aphids is not practical or economical. 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 the section Insects and Diseases.

As winter barley must be seeded early, select a variety with tolerance to BYDV.

Modern varieties of wheat do not produce excessive top growth if seeded early. While early seeded wheat may be more prone to snow mould, wheat seeded even 2 weeks before the optimum date has not had excessive top growth problems in at least 20 years.

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 to early 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 2,900 crop heat units, spring cereals are generally not recommended and should definitely not be grown if planting is delayed beyond April 20.

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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, without incurring a yield penalty. Assess the wheat crop during April and early May. The replant decision should be left as late as possible. Damaged plants will often recover under good weather conditions, while plants that are expected to recover may die if hot dry conditions exist. Table 6-6. 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.

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Source: Smid, Ridgetown College, University of Guelph, 1986-90.

¹Full stand.
²23 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.

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Seeding Rates

Historically, the seeding rates of cereal crops were recommended in bu/ac, with 2 bu/ac a standard that covered most cereal crops. Blanket statements of this nature are no longer acceptable. Seed size affects seeding rate. Optimum seeding rates should be set accordingly for each cereal crop. Table 6-7. Recommended Plant Populations for Cereal Crops, gives the recommended seeding rates for each crop.

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Table 6-8, 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.

The higher rates in Table 6-7 and Table 6-8, should be used:

1. where emergence and early seedling establishment are likely to be poor (for example, due to poor seedbed and aerial or broadcast seedings)
2. for late planting where tillering will be reduced.

The seeding rate can be determined using this formula:

Seeding rate (kg/ha) = (seeds/ha ÷ seeds/kg) X (100 ÷ % germination)

Seeding rate (lb/ac) = (seeds/ac ÷ seeds/lb) X (100 ÷ % germination)

Sample Calculation

Seeds/kg (seeds/lb) should be given on the seed tag or bag. For instance, if 3.7 million seeds/ha (1.5 million seeds/ac) is desired, with a germination rate of 95% and 26,500 seeds/kg (12,000 seeds/lb), the seeding rate should be 147 kg/ha (132 lb/ac).

Metric: (3,700,000 ÷ 26,500) X (100 ÷ 95) = 147 kg/ha

Imperial: (1,500,000 ÷ 12,000) X (100 ÷ 95) = 132 lb/ac

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Row Widths

Considerable research has been conducted on cereal row widths for maximum yield.

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Table 6-9. 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 in the table.

¹Source: Smid, Ridgetown College, University of Guelph, 1987-90.

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. Many of the new 25-cm (10-in.) row planters have more accurate seed placement than most 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 cereals, trials in Northern Ontario showed yield increases of more than 5% when row width was reduced from 18-10 cm (7-4 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.

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Additional Management Opportunities

Growers familiar with European cereal production are aware of the yield increases possible with the use of fungicides, growth regulators and increased fertility. Under Ontario conditions, it is more challenging to realize profits from incorporating these additional inputs within the production system. Experienced growers with high management capabilities in cereal production have developed the ability to use and profit from these strategies. Growers using this technology frequently benefit from increased yields associated with proper timing and use of these additional inputs. These growers are able to determine the best timing for application, if in fact application is warranted. Typically these growers achieve results well above average.

Foliar disease control is one of these management strategies. Further information on disease identification and control can be found in the section Diseases and in OMAFRA Publication 812, Field Crop Protection Guide. Thresholds for disease control vary, depending on the disease present in addition to the stage and condition of the crop. In general, it is important to scout the top two leaves of the cereal crop, at any stage of growth. If disease is moving onto one or both of these leaves, determine if the control threshold control has been reached and if control is warranted.

Growers who are proficient at cereal production realize yield increases well above the costs incurred by some of the newer fungicidal products on the market. A great deal of scouting and adjustment is necessary to optimize the return from using these more intense management tools.

Growth regulators are another management option to consider. Some cereal varieties have excellent yield potential but lodge prior to harvest, which reduces yield and quality. Growth regulators, when used at the proper application time and rate, can shorten and strengthen the straw and maintain standability until harvest of weaker strawed varieties. Stronger strawed varieties do not require this additional input. However, some growers feel that the increase in combine efficiency and speed of harvest of grain crops treated with a growth regulator justify treatment of all acres. Current research is continuing to determine if these benefits are real.

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Updates on Cereals: Planting

No updates available at this time.

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Related links...

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