When we promote the benefits of winter cereals, we often talk about things such as spreading out the spring and fall workload, maximizing use of spring soil moisture and precipitation, and reducing pesticide use. These are important factors, but perhaps the greatest benefit to including a winter cereal in your annual crop rotation is risk management. Farming is all about risk management, whether it is financial, environmental or production risk.
On the financial risk side of the equation, winter cereals, especially winter wheat, have "penciled out" very well in cropping budgets due to their higher yield potential, and the reduced need for herbicides and insecticides relative to spring wheat. At today's commodity prices, net returns for winter wheat look very favourable. Plus, winter cereals can often be moved into the market right off the combine, reducing storage costs and generating cash flow early in the harvest season.
The spring of 1999 was a sober reminder of the need to manage environmental and production risk by diversifying crop rotations. Producers in south eastern Saskatchewan and south western Manitoba who seeded winter cereals in the fall of 1998 looked like geniuses the next spring when it was too wet to seed spring crops. Despite some flooding, winter cereals enjoyed the cool, wet spring season, and yields were significantly better than spring cereals. In contrast, the 2000/2001 growing season may not be a banner year for winter cereals. The crop established well in the fall, and winter injury was minimal. However, the lack of rainfall many areas have experienced this spring and summer has limited the yield potential of winter crops, and the recent rains will be more beneficial for spring crops. This underscores the importance of growing a diversity of crops and not having "all your eggs in one basket."
Risk management starts with rotation planning and includes pricing and marketing strategies as well as thorough knowledge of the cost of production for each crop to be grown. While there is no perfect rotation that fits on every farm, a "good" rotation should include cereals, oilseeds and pulse crops whenever possible. The cereal component should be split between spring and winter types. With the advent of fall seeded canola, farmers can diversify their risk even further by including both spring and fall sown canola. By altering crop types and seeding seasons, it is possible to effectively minimize the risk of losses due to weeds, insects, diseases and adverse weather conditions such as frost, drought, heat stress or excessive moisture.
If you are considering the addition of a winter cereal to your crop rotation, you can manage your risk by following these proven agronomic guidelines:
Plan Ahead - Successful winter cereal growers all have one thing in common - they plan ahead! Many of the winter wheat failures of the past two decades can be attributed to poor management practices that resulted from poor planning and decision making. 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 likely 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 seeding on time and with optimal agronomic practices.
Direct seed (zero till) into standing stubble - Winter cereals, particularly winter wheat and winter triticale, need snow cover to insulate the plants through the winter. You can decide if your fields are suitable by calculating the snow trapping potential (STP) of your stubble prior to and after seeding. Post-seeding STP's greater than 20 are acceptable for winter wheat and winter triticale seeding. Lower STP's are acceptable for fall rye. Based on the stubble disturbance of your seeding equipment, you may need to set pre-seed STP targets of 40 or more. For reference, cereal stubble typically has pre-seed STP's of 80 or better, while canola and flax are normally in the range of 30 to 50.
STP = Stubble height (cm) x Stubble stems per metre of row x Stubble rows per metre
100
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 stubblefields, soil moisture is often depleted, leaving a dry seedbed for winter cereals. Moisture conditions do not improve dramatically with depth. Seed at the minimum depth required providing 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.
Schematic of a winter cereal plant showing the development of the over-wintering crown tissue
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 rather than late as late seeding often results in reduced winter hardiness (Figure 1).
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!
Crop nutrition must also be taken into consideration at the time of seeding. As with all other crops, the fertility requirements for winter cereals should be based on a reliable soil test, used in conjunction with knowledge of past management practices and local cropping conditions. It must be noted that winter cereals have the potential to out-yield their spring counterparts by 20 to 25%. To achieve the higher yield potential, winter cereals require higher rates of fertilizer than spring cereals, particularly nitrogen. It has been suggested that insufficient nitrogen fertilization is the leading cause of lower than expected yields of winter cereals relative to spring types.
The traditional method of applying nitrogen for winter cereals has been to broadcast 34-0-0 early in the spring. However, with the development of new direct seeding implements and openers, producers are looking at a number of alternatives for nitrogen. Sidebanding all the nitrogen requirements at seeding is becoming more popular with the development of double shoot sidebanding openers. Producers should be aware that the risk of fall leaching losses is high under this scenario. Conversion of applied nitrogen to nitrate is a factor due to the warm soil temperatures that prevail in late August and early September. If sufficient conversion takes place the nitrate will be subject to leaching.
Research data shows that the most consistent response in terms of both yield and quality is from spring broadcasting of 34-0-0. Urea (46-0-0) and urea ammonium nitrate (28-0-0) are subject to losses in the spring through volatilization, reducing the efficiency of application by as much as 10 - 20% depending on soil moisture and rainfall. In the next issue of the Prairie Steward, spring applied nitrogen will be discussed further.
Phosphorous, Potassium and Sulphur are essential for successful winter cereal production. Phosphorus enhances winter survival by promoting early plant development as well as vigorous root and shoot growth. The phosphate requirements should be seed placed or sidebanded at seeding time. Research indicates that phosphorus deficiencies have an impact on winter hardiness (Figure 2). Winter wheat seeded into soils with low residual phosphate levels that do not receive sufficient seed placed phosphorus can be subject to significant reductions in winter hardiness. The risk of winter injury increases, and adequate insulation from snow cover becomes more critical.
Figure 2. Impact of seed placed phosphorus on winter hardiness
Potassium chloride (KCl) helps plants tolerate moisture stress conditions and improves lodging resistance. The chloride component has been linked to lower incidence of certain foliar and root diseases. Sulphur is often required on winter cereals, particularly in incidences where the crop is sown on canola stubble. Sulphur helps to increase the efficiency of nitrogen and phosphorus applications and plays an important role in end use parameters such as flour yield and loaf volume. Application rates for phosphorus, potassium and sulphur should be based on soil test recommendations.
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. More detailed information can be obtained from the "Winter Wheat Production Manual", the comprehensive how-to guide for winter cereal growers developed by Dr. Brian Fowler, the winter wheat breeder at the Crop Development Centre in Saskatoon. The manual, and other winter cereal information, is available from Winter Cereals Canada at (306) 782-8188.