By: Janine Paly
Nitrogen fertility is a crucial piece of winter wheat production to help ensure producers realize the 10 to 40 per cent yield advantage as compared to spring wheat. Producers should match their fertility rate to yield goals. Fertility management can be one of the most challenging factors for producers planning winter wheat. The choices can seem overwhelming. The 4R Nutrient Stewardship approach: Right Source @ Right Rate, Right Time, Right Place can be helpful in assessing the merits of various nutrient management options. By adopting the 4R Nutrient Stewardship approach producers maximize the productive capacity within their operation without adversely affecting the other pillars of sustainability: environment and social.
The 4Rs of Nutrient Stewardship
Selecting the right source will help ensure your soil has a balanced supply of essential plant nutrients. Performing annual soil tests and applying nutrients to meet crop requirements will assist in deciding the right rate. Applying nutrients at the right time will ensure nutrient uptake when the demand is high. Lastly, the right place helps minimize the risk of loss while increasing the availability of nutrients to the crop.
4R Nutrient Stewardship is a site-specific, integrated approach that considers source, rate, time, and place decisions for the
cropping system. These decisions work towards the economic, social, and environmental sustainability goals for the farm.
To learn more about 4R practices and programs in Canada, visit Farming4RFuture.ca.
Nitrogen Fertilizer Options
There are several advantages to applying all of the nitrogen required by the winter wheat crop during the seeding operation. Typically, the price of N is more cost-effective in the fall than in the spring. A fall application ensures that there are nutrients available to the crop early in the spring, a critical time in establishing yield potential. Possible disadvantages of N application at seeding time are the risk of seedling damage and risk of significant N losses. If the decision is to place N in the seed row, safe rates up to 30 lbs/ac can be applied, but this may vary with moisture conditions, soil type, type of opener, and row width. A slow release N product can be incorporated into the fertilizer blend, which can create more options for producers wishing to place higher rates at seeding time.
If a producer is considering a split/spring application of nitrogen the key to successfully manage a top-dress application is to apply early when the soil conditions are still cool and soil moisture is dry enough to safely drive upon without creating ruts. Cereals will use 70 per cent of their N by late tillering, and late applications of N will only hinder the yield potential of winter wheat.
Liquid UAN (28-0-0) and ammonium sulfate are less susceptible to volatilization losses compared to urea (46-0-0), but under ideal conditions (cool soils and/or before a significant precipitation event) all three of these products perform well. However, if warm and humid conditions persist for a period of time, some N losses will likely occur. To reduce losses, the use of a commercial urease inhibitor can be considered.
For those producers who have excessive soil moisture due to an abundance of spring moisture, a split application may be a better option as there will be less chance of leaching and denitrification to take place in the fall.
Winter wheat nitrogen management is different compared to spring wheat; therefore, when considering how to adopt the 4Rs into your farm operation, it may involve different choices than a spring-sown crop. For example, choosing the right source/lowest risk product (i.e. a urease inhibitor) based on best management practices may help reduce risks associated with broadcasting if this is the best choice to achieve the desired nutrients to the crop at the right time and right rate.
Winter wheat requires very similar levels of macro and micronutrients as spring wheat varieties, specifically phosphorus, potassium, sulfur, and copper. It is important to pay attention to phosphorus requirements as this nutrient will aid in winter survival by increasing the health of the roots (including the crown region). The general recommendation is to apply 20 to 25 lbs/ac of actual phosphate with the seed. By managing these nutrients appropriately, it will help aid in developing a well-established winter wheat crop in the fall.
Regardless of application method chosen for nitrogen fertilizer, the most frequent error new winter wheat growers make is not meeting the needs of the crop. This often leads to disappointment in not realizing the expected yield advantage versus spring wheat. Using appropriate tools, such as a soil test, a tissue test, and the assistance of qualified agronomists, can help determine proper rates and application methods.