Much of the current success with direct seeding can be attributed to the learning experiences producers had with no-till winter wheat during the 1980's. In Saskatchewan, during the 1980's, the acreage of direct seeded winter wheat was greater than the total combined direct seeded acreage of all other annual commercial crops. Winter cereals are "systems" crops that have an excellent fit in direct seeding and zero tillage production systems. As more producers in Western Canada adopt these systems, the opportunity to successfully produce winter cereals will grow. However, to achieve this success producers must become familiar with the agronomic management practices that have been developed specifically for these crops. They must also evaluate their cropping rotation and determine how to include a winter cereal in their plans.
Some producers have been reluctant to include a winter cereal in their rotation. The reasons commonly cited include concerns about winter injury, additional labour and equipment requirements at seeding time, the time conflict associated with seeding a winter cereal during the harvest of spring crops, and grain handling and storage concerns. While those concerns are important the most often cited reason for not seeding winter cereals is not having available stubble during the prime fall seeding window. All of these factors are management related and can be overcome with good planning and with a "systems" approach to including winter cereals in rotation. Producers who have learned to adapt their cropping systems to include winter cereals have noted the following benefits:
Increased economic returns through higher crop yields and lower input costs
More efficient use of spring soil moisture and precipitation
Protection against seeding delays in spring due to excessively wet conditions
Farm work load and labour requirements are spread more evenly throughout the year
More efficient use of capital investments (equipment, etc.)
Improved weed control and the opportunity for reduced pesticide use
Numerous potential end uses (grazing, green feed, silage, and grain for human and animal consumption) that help to diversify risk and provide greater flexibility
Soil, water and wildlife habitat conservation
Other agronomic advantages offered by these crops have also contributed to the renewed interest in winter cereal production. The earlier development and maturity of winter crops tends to reduce the risk of certain insect and disease infestations such as Orange wheat blossom midge and Fusarium head blight (scab). In the spring, the competitive advantage winter cereals have over weeds often provides an opportunity for producers to eliminate the use of grassy weed herbicides. This makes winter cereals an excellent tool for managing herbicide rotations and reducing the risk of weed resistance.
Interest in winter cereal production, particularly winter wheat, is on the rise again in Western Canada as farmers reacquaint themselves with the agronomic, economic and environmental benefits that fall seeded crops have to offer. Over the past five years we have witnessed a slow but steady increase in winter wheat acres, accompanied by an encouraging increase in average yields. However, surveys have shown that farmers have great difficulty incorporating winter wheat into their cropping rotations, and this has become the key factor that is limiting the growth of winter wheat acreage. There are a number of issues that need to be addressed in order to adapt to a cropping sequence that includes winter cereals.
Shifting the "Spring Crop Paradigm"
The mind is a powerful thing! Our entire agricultural industry including the equipment, crop input, grain handling, transportation and marketing sectors is predicated on a spring crop paradigm - crops are sown in the spring and harvested in the fall. As a result, producers, agronomists, extension specialists and people in the farm service industry tend to focus only on those issues that are relevant to spring crop production. For example, when was the last time your local equipment dealer had a special on zero-till seed openers in August, or your fertilizer agronomist contacted you to discuss the importance of seed-placed phosphorus for winter wheat? Unfortunately, most of our research dollars are also allocated to spring crops, and it has been very frustrating for advocates of winter cereals to obtain support for winter cereal plant breeding, variety testing and agronomic research.
Growing winter cereals requires a "shift" in thinking - not away from spring crops, but to a new way of thinking that includes both winter and spring crops. Many producers are "opportunistic" growers of winter wheat. Their decision to grow winter wheat is made in the fall just prior to seeding, because they happen to have a field ready, rather than as part of a long-term crop rotation strategy. Experience, and a survey of producers, has shown that this approach to winter cereal production can be an exercise in frustration. Equipment, seed and fertilizer are hastily prepared, and often times some compromise is made in terms of agronomic management (i.e. the optimal seeding date window is missed) and the crop does not meet expectations. The resulting frustration is not likely to encourage future production of winter cereals! If you are committed to growing winter cereals, you have to commit the resources needed to grow the crop successfully, and devote the same level of planning and preparation as for all other crops in your rotation.
What is the best stubble to seed winter cereals into?
There are two considerations. Firstly, from an agronomic perspective, the general guidelines for rotation planning apply to winter cereals just as with spring crops. Whenever possible, a "good" crop rotation should alternate between cereal, oilseed and pulse crops, and a crop should not be planted back into its own stubble type or the stubble of a similar crop type (i.e. winter wheat on spring wheat stubble). Alternating crop types helps to minimize the risk of weed, insect and disease problems, and provides for optimal use of moisture and nutrients due to the different rooting habits and nutrient requirements of different crops. Secondly, since winter cereals, particularly winter wheat and winter triticale, require a protective blanket of snow cover through the winter period, the snow trapping potential of the spring crop stubble must be taken into consideration. Dr. Brian Fowler from the University of Saskatchewan Crop Development Centre has devised a simple method of estimating the snow trapping potential of any standing stubble prior to seeding winter cereals. The snow trapping potential (STP) index is determined as follows:
STP = Stubble height (cm) x Stubble stems per metre2
100
Dr. Fowler's research has determined that the risk of winter injury to winter wheat and winter triticale is significantly reduced in stubble fields with a post-seeding STP index of 20 or greater. Taking stubble disturbance at seeding time into consideration, pre-seeding STP targets should be 40 or higher to ensure adequate stubble density (Figure 1). As a general guideline, cereal crops such as wheat, oats and barley often have pre-seeding STP's of 90 or higher, while oilseed crops such as canola, mustard and flax are often in the 35 - 40 range.
Figure 1. Snow Trapping Potential (STP)
Farmer experience has determined that the preferred stubble type for winter cereals is canola, followed by barley and oats. Flax is also a good option, but is rarely harvested in time to allow winter cereal seeding at the optimal time in early September. What about peas and other low residue crops? Seeding into pea stubble is a matter of risk. Rarely do peas provide enough snow trapping potential to reduce the risk of winter injury to acceptable levels. The stubble tends to be short, thin and susceptible to knock down at seeding time. While some producers are willing to take the additional risk of sowing into pea stubble, those that do should expect increased levels of winter kill particularly in winters with low snowfall and or high winds.
Where do winter cereals fit in my rotation sequence?
Unfortunately, this issue is still unresolved. There has not been sufficient research to qualify and quantify the agronomic and economic rotation benefits of winter cereals. Anecdotal information from experienced growers suggests that the yield performance of winter wheat tends to be highest when the crop is sown on canola stubble, provided that adequate STP's are maintained. Many growers report that field peas or lentils are their crop of choice after winter wheat, presumably due to the reduction in weed pressure that typically follows winter cereal production, and differences in the rooting habits and crop water use between cereal and pulse crops.
Winter Cereals Canada, in co-operation with Ducks Unlimited Canada and other agencies, is in the process of implementing a research study into the "whole farm" economics of winter cereal production. Crop planning guides such as those published annually by Saskatchewan Agriculture and Food only provide a partial budget snapshot of the economics of growing a crop on a particular field in a particular year. Experienced winter cereal growers report that including winter cereals in their crop rotation offers economic and risk management benefits to all the other crops they grow. Examples often cited include:
More timely spring seeding operations, leading to earlier harvest and reduced risk of frost and weathering losses at harvest time for spring-sown crops.
Reduction in equipment investment cost per acre by spreading harvest and seeding operations.
Time management and the ability to spread workload or farm more acres.
Reduction in pesticide costs in the year of winter cereal production and in the subsequent year due to the competitive nature of winter cereals and their winter annual life cycle.
Reduction in overall herbicide use and more opportunity to manage herbicide rotations to minimize the risk of weed resistance.
Many of these benefits are difficult to quantify and cannot be accurately reflected in simple annual cropping budgets. However, experienced growers state that they are significant factors in the decision to include winter cereals in their rotation.
How do I get winter cereals seeded on time?
The most difficult adjustment for new winter cereal growers has been the need to have a standing stubble field available early enough to allow their winter cereal crop to be seeded by early September. This requires a major change in management philosophy. To assist producers with this challenge, the Crop Development Centre, with support from Ducks Unlimited Canada, has initiated a project to develop an interactive planning tool that can be used to determine seeding dates for spring crops so winter cereals can successfully be integrated into the production system. The tool is comprised of a database of historic daily temperature records, combined with data pertaining to the growing degree-days (GDD), or heat unit, requirements of commonly grown spring crops. Based on any given spring seeding date, the tool calculates the probability of the spring crop reaching maturity prior to the desired seeding date for the winter cereal.
To illustrate the potential uses of the tool, let's look at the implications of a May 15th seeding date in two areas of Saskatchewan with very different growing seasons and cropping options, Gravelbourg in southern Saskatchewan and Prince Albert in the northern parklands (Table 1). A longer growing season at Gravelbourg means that producers have a full range of spring cropping options if they are targeting an early September seeding date for their winter cereal. However, in the Prince Albert area, barley, polish canola and oats are the best choices. Spring wheat, flax and Argentine canola would have to be seeded earlier to be an option most years.
Table 1. Probability (%) of selected spring crops reaching physiological maturity* by
August 25th when seeded on May 15th.
| Site |
Barley |
Polish canola |
Oat |
Argentine canola |
Hard red spring wheat |
Flax |
| Morden, MB |
100 |
100 |
100 |
100 |
90 |
90 |
| Gravelbourg |
100 |
100 |
100 |
96 |
80 |
74 |
| Wynyard |
100 |
100 |
97 |
88 |
35 |
29 |
| Nipawin |
100 |
100 |
95 |
88 |
33 |
17 |
| Prince Albert |
100 |
100 |
91 |
72 |
21 |
14 |
* Physiological maturity is when seed moisture content is below 30% and the crop is ready
to be swathed. An additional 7 to 14 days is normally needed to complete harvest.
At present, the spring crop planning tool has only been developed for selected sites in Western Canada. The plan is to expand the database to include all 179 sites that have at least 30 consecutive years of climate records. Tables, risk maps and fact sheets will be developed that will allow producers to determine acceptable seeding dates based on local or regional data. If there is sufficient interest, the spring crop planning tool may be incorporated into an interactive Internet site and/or CD-ROM so producers can evaluate "what if" scenarios based on seeding dates for various spring crop choices.
In Saskatchewan, the acreage sown to winter wheat declined sharply through the late 1980's and early 1990's due to the negative experiences many growers had with rust, lodging and winter injury problems. However, in the past five years winter wheat acreage has almost tripled, and average yields are almost 20% higher than for spring wheat. What has happened to bring about the renewed success with winter wheat? Most farmers would suggest that the varieties we grow now are much better than Norstar, the variety grown in the 1980's. It's true; over the past decade several new varieties have been registered, offering improvements in yield, straw strength, rust resistance and other agronomic traits. However, to the surprise of most farmers, the new varieties are NOT more winter hardy than Norstar! How can this be, given that over the last five years, we have lost less than 2% of our crop to winter injury annually? The answer is that over the past decade a great deal has been learned about winter wheat agronomy, particularly the importance of seeding practices. The losses experienced in the 1980's had as much to do with management practices as they did with the shortcomings of the varieties that were grown.
Dr. Brian Fowler has devoted considerable time and effort into understanding and promoting the "best management practices" for winter cereal production in western Canada. His research and observations have been compiled into the Winter Wheat Production Manual, a comprehensive how-to guide for winter cereal growers. If you are considering the addition of a winter cereal to your crop rotation, you can manage your risk by following the proven agronomic guidelines that Dr. Fowler has developed:
Plan Ahead - Successful winter cereal growers all have one thing in common; they know that winter cereal production begins with the spring crop they intend to seed their winter cereal into in the fall. Think about the fields you intend to seed, how the spring crop residues will be managed, and what weed control practices will be needed. Make sure your seeding equipment is ready, and that seed and fertilizer needs have been arranged well before seeding. Consider how you will manage your equipment and labour needs, given that you will be seeding at the same time as spring crops are being harvested. By planning ahead you can reduce the time conflicts (and the stress) and increase the probability of getting your winter cereal crop seeded on time with optimal agronomic practices.
Seed Shallow - Winter cereals should never be seeded more than one inch (2.5 cm) deep, even when the soil is dry. Deeper seeding delays emergence and results in weak, spindly plants that are more susceptible to winter injury. Research indicates that improper seed placement usually results in later maturity and reduced yield potential.
One common mistake made by inexperienced growers is "seeding to moisture". In most stubble fields, soil moisture is often depleted, leaving a dry seedbed for winter cereals. Moisture conditions do not improve dramatically with depth, so there is no advantage to seeding deeper than the minimum depth required to provide good seed-to-soil contact. Moisture in the fall comes from above, in the form of rain. Shallow seeding allows the seeds to take advantage of small rainfall events. As little as 1/3 inch of rain is enough to successfully establish a winter cereal since they exhibit very little seed dormancy and are ready to germinate immediately after seeding.
Seed on Time - In order for winter cereals to achieve maximum cold tolerance, healthy, vigorous plants must be established before freeze-up. A plant that has three or four true leaves and is starting to develop its first tiller would be ideal. By this stage, crown tissue has developed just below the soil surface. It is the crown tissue that survives the winter and regenerates roots and leaves in the spring when favourable growing conditions return. Fall soil temperatures influence optimal seeding dates. As a result, the optimal timing for seeding differs in each production region of Western Canada. Research has demonstrated that seeding during the period from late August to early September (approx. August 25th to September 5th) consistently produces the best crops in terms of both yield and quality. It is always better to seed early as late seeding often results in reduced winter hardiness.
The stage of plant development prior to winter freeze-up also impacts the agronomic performance of the crop during the following growing season. Seeding too early often results in yield reduction and smaller seed size. Late seeding results in significant yield reduction, delayed heading, later maturity, lower bushel weights and increased problems
with weeds and other crop pests such as insects and disease organisms. All this being said, there are several uncontrollable factors that impact the crop's potential. This includes soil temperature, soil moisture and weather conditions the following growing season. Responses to seeding date cannot always be determined simply by looking at a calendar!
There are many other factors to consider, but these are the key "risk management" variables that can determine your success or failure as a winter cereal grower.
Concerns about the risk of winter injury continue to be one of the reasons cited for not growing winter cereals. As stated earlier, winter injury has not been a significant factor in recent years, and can largely be mitigated by proper agronomic practices. Producers who have successfully integrated winter cereals into their cropping rotation are much less likely to encounter winter injury problems than occasional "opportunistic" growers.
The mechanisms that influence cold tolerance and winter survival are very complex genetic processes. Winter cereals over-winter as seedlings. In order to survive winter conditions, they must acclimate or acquire cold tolerance during the fall growth period. Soil temperatures at the depth of the crown tissue regulate the genetic system that induces cold acclimation (Figure 2). The crown of the plant contains the tissues that are necessary for plant survival and regeneration of roots and leaves. Cold acclimation begins in the fall once soil temperatures drop below +9o C and full cold acclimation is normally achieved by late November. Once this process starts, the degree of cold hardiness, and the maintenance of low temperature tolerance, are directly related to the sequence of temperature changes that the crown tissue is exposed to during the fall and winter. In other words, cold acclimation can be stopped, reversed or restarted by changes in temperature!
Figure 2. Schematic of a winter cereal plant showing the development of
the over-wintering crown tissue
Four to eight weeks at crown temperatures below +9o C are usually required to fully acclimate plants. Once fully acclimated, winter cereals are very tolerant to the cold as long as soil temperature remains below freezing, and there is adequate snow cover to buffer the soil against the effects of air temperature changes. Winter hardiness gradually decreases over the winter in order to allow the plants to "deharden" and resume growth in the spring. This process is also governed by temperature. Producers are often too hasty in deciding that slow growth in the spring indicates that the crop has suffered winter injury. In most instances, provided that proper agronomic practices were used, the crop has survived and the crown tissue just needs a few days of warm weather to increase soil temperatures to levels where growth will resume.
One of the challenges of winter cereal production is dealing with dry seedbed conditions at seeding time and the implications of poor fall establishment. To achieve maximum cold tolerance and yield potential, winter cereal crops should reach the 3 to 4 leaf stage prior to freeze-up. Unfortunately, the fall of 2001 was extremely dry in most regions of Western Canada, and there were numerous reports of poor germination and establishment, with plant development in individual fields ranging from ungerminated seed to plants in the 2 or 3 leaf stage. With the variable establishment this fall, many producers are wondering if their crops will survive the winter and what type of stand they can expect in the spring of 2002. The stage of development in the fall influences not only winter survival and yield potential, but also crop competitiveness, maturity and the risk of infection with diseases such as rust and fusarium head blight (Table 2).
Table 2. Potential Impacts of Fall Growth Stage on Winter Wheat Production Factors
|
Growth Stage |
Date of Germination |
Yield Factor |
Competition Factor* |
FSI** |
Rust Risk*** |
Relative Maturity |
|
3 Leaf + Tiller |
5-Sep |
100% |
5 |
514 |
1 |
0 days |
|
1 - 2 Leaf |
15-Sep |
90 - 100% |
4 |
510 |
2 |
+ 4 |
|
Sprouted (not emerged) |
1-Oct |
80 - 100% |
2 |
476 |
4 |
+ 8 |
|
Not Germinated (imbibed) |
15-Oct |
60 - 100% |
1 |
499 |
5 |
+ 10 |
* Competition Factor: 5 = Most competitive, 1 = Least competitive
** FSI: Field Survival Index; a measure of cold tolerance (514 is maximum for winter wheat)
*** Rust Risk: 1 = Lowest risk; 5 = Highest risk
Well-developed plants will have the highest yield potential and winter survival ratings, will be more competitive and less likely to be impacted by rust and other disease organisms. The 1 to 2 leaf stage plants will have retained most of their yield potential and their winter survival ratings will only be slightly lower. Competitiveness with early spring annual weeds will be slightly less so more attention must be paid to early germinating weeds. Maturity will be slightly delayed and the crop will be more susceptible to rust, assuming there is no varietal resistance.
Seeds that have sprouted and not yet emerged have lost slightly more yield potential and will be much less competitive with early weeds. Wild oats and early broadleaf weeds will have to be eliminated early to avoid further yield losses. Maturity will be extended, creating higher risk of rust infection. The greatest risk for sprouted seeds is their lower level of winter hardiness. Most of the energy reserves in the seed were utilized to initiate germination and no additional energy was assimilated through photosynthesis. Germinated seeds that have not emerged require adequate snow cover to ensure survival through prolonged cold spells.
Seeds that have not sprouted will have the lowest yield potential and will be the most susceptible to early weed competition. Their winter hardiness is better than sprouted seeds due to the energy reserves remaining in the seed. Relative maturity is extended and harvest dates may only be a week earlier than spring cereals. Rust, and other plant diseases, are more likely to be a concern due to the delay in maturity.
Winter wheat crops that did not germinate and establish uniformly in the fall are at a disadvantage, but with timely management in the spring and some co-operation from Mother Nature, excellent crops are still possible. Winter wheat has an unmatched ability to compensate by producing tillers, and it is often the most ragged looking crops that produce the best yields! Don't be too hasty to write off a poor looking stand in the spring. Wait until at least mid-May to give the crop an opportunity to recover. You'll still have time to reseed if necessary.
One of the unique characteristics of winter cereals is the diversity of potential end uses they offer. Fall rye, winter wheat and winter triticale are not only grown for traditional grain production, but are being used increasingly for green feed, silage and grazing, either alone or as a component of an inter-cropping program that includes spring and winter cereals. This creates unprecedented rotation planning opportunities and provides grain and livestock producers with a tool to manage economic and environmental risks.
Research is also being conducted into the potential for using winter cereals in relay and double cropping programs in areas of Western Canada that have enough late-season heat and water resources to support legume cover crops.
There is no perfect rotation that will work for every situation and every farm. The challenge is to develop a cropping sequence that will maintain a high level of soil productivity, keep pests at manageable levels, provide adequate economic returns and be flexible enough to deal with problems and opportunities as they arise. Producers who grow winter cereals on at least 15% of their cropped acreage each year frequently report that having a winter cereal in their rotation lowers the production risks for their spring crops. Spring cropping operations such as seeding, spraying and harvesting occur on a more timely basis, resulting in lower losses due to pests and less risk of weathering losses at harvest time. This is a significant advantage when you consider the economic consequences of grade losses in crops such as malt barley, durum wheat and pulse crops. More and more producers are catching on to the benefits of winter cereals - are you?
Fowler, D.B., L.J. Boychuk, B. L. Duggan and L.R. Moats. 2001. Crop Rotation for Successful Winter Wheat Production. p. 170-176. In Soils and Crops Workshop Proceedings 2001. Extension Division, University of Saskatchewan, Saskatoon, SK.
Saskatchewan Agriculture and Food. 1997. Principles and Practices of Crop Rotation.
Fowler, D. B. 1995. Winter Wheat Production Manual. Ducks Unlimited Canada, Yorkton, SK.