Photo credit: Agvise Labs
4R Nutrient Stewardship is an internationally recognized program that advocates for responsible and effective management of nutrient resources. The 4Rs stand for the right source of fertilizer used at the right rate, at the right time and in the right place. 4R best management practices are economically, socially and environmentally beneficial.
Many growers unknowingly follow 4R practices because of the inherent benefits associated with proper nutrient management. The 4R Nutrient Stewardship program is a formal way for growers to participate and implement the 4Rs on their farm and be recognized for doing so. By working with a 4R designated agronomist to develop and execute a 4R plan, the designated agronomist will submit 4R acres on a grower’s behalf, which allows for these best management practices to be accounted for and recognized. More information on the 4R Nutrient Stewardship program including a list of 4R designated agri-retailers can be found through Fertilizer Canada.
The 4R planning process allows for agile decision making to maximize resources. The 4Rs are highly intertwined in these plans and account for the challenges of growing crops such as canola, i.e., when one practice may not be an option, there are ways to compensate by looking at the 4Rs collectively. There is rarely one simple answer when it comes to fertilizer management, but a 4R plan can help with finding an adequate solution that responsibly maintains productivity.
Canada’s canola industry has a goal to see 4R practices utilized on 90 per cent of canola acres by 2025. This is part of an overall strategy to profitably increase yield of canola while improving environmental sustainability to meet growing global market demand. Following the 4Rs will lead to improved nutrient use efficiency, which is good for both farm productivity and our environment. For further details, read about the Keep it Coming 2025 strategic plan.
To see results from canola nutrient management research projects, visit the Canola Research Hub.
What do the 4Rs mean for canola nutrient management?
For canola nutrient management, the Right rate means using the right amount of fertilizer to achieve your desired yield target. Once an appropriate yield target has been selected based on your field’s productivity, soil testing will give you the most accurate estimate of what nutrients are available in the soil.
Soil testing is a relatively easy practice that doesn’t require a large investment. For more information on soil testing, visit the Identifying Nutrient Requirements entry in the Canola Encyclopedia. Using the soil analysis results along with your canola field’s nutrient requirements to meet the yield goal will give you the amount of additional fertilizer nutrients required to meet the needs of your canola crop.
Each individual field should be treated independently of other fields when determining the Right rate, and while it may not be feasible to use a fertilizer blend specific to each field, using a common blend for all canola fields on a farm operation, and varying the application rate based on productivity levels in the field, is one way to tailor the fertilizer application to each field. Variable rate nutrient management is a more advanced way of managing the variability within fields by applying the amount of nutrients required for the differing production zones within the field.
The Right source of fertilizer is influenced not only by the other Rs, but also by environmental conditions. There are many fertilizer products and formulations available for growers to choose from, and the timing and placement of the fertilizer can impact which source is the most acceptable. When it comes to following 4R Nutrient Stewardship principles, an example of the right source is using products such as urea (46-0-0) or anhydrous ammonia (82-0-0) in fall banding applications, rather than products such as urea ammonium nitrate (28-0-0), which is more prone to losses based on its nitrate content. If spring banding is chosen as the application method, then all forms of nitrogen become viable options.
Enhanced efficiency fertilizers are sources of fertilizer that have slow-release properties from product coatings that slow the release of less stable nitrogen forms or additives that slow the conversion of nitrogen fertilizers to forms that are more easily lost. To learn more about the nitrogen cycle and potential mechanisms that cause losses, visit the Nitrogen cycling entry in the Canola Encyclopedia.
The Right time for fertilizer application is generally as close to the time of crop uptake as possible. For canola, this would mean spring and early summer applications which reduce the amount of time between fertilizer application and when the crop needs the added nutrients. Due to logistical constraints, this may not always be feasible and other acceptable application timings include fall banding and in-crop top-dress applications. Even within a more logistically feasible application timing such as top-dressing, precipitation is required to move nutrients like nitrogen or sulphur into the root zone, and therefore the best timing for this application could be just prior to an adequate rainfall.
Not all nutrients will have the same flexibility of application timings, so planning fertilizer applications early in season, at seeding for example, is one of the more common practices. One application time to avoid regardless of the fertilizer source you choose is when the ground is snow covered and frozen. Winter applications are prone to high losses, therefore will not maximize the economic return of input expenses and are less environmentally responsible.
Subsurface fertilizer applications have multiple benefits. First, they are placed in the root zone, where plants can utilize the nutrients. Second, fertilizer that is in the soil is much less prone to losses than if it were sitting on the soil surface. For these reasons we generally consider banded in the soil the Right place for fertilizer.
One exception is elemental sulphur which needs to oxidize on the soil surface to become a plant available form. Also, while there are logistical advantages to growers broadcasting nutrients such as nitrogen as their method of placement, the risks of losses are higher. If broadcasting is the chosen method, then using enhanced efficiency fertilizers as the right source is the best option. This reinforces that fact that the 4Rs are influenced by one another, and a proper plan will look at both the tradeoffs and complements each R has on its counterparts.
For canola nutrient questions and inquiries related to 4R Nutrient Stewardship practices, contact Warren Ward, agronomy specialist and canola nutrient management lead with the Canola Council of Canada.