Fall-applied fertilizers

Alberta Agriculture and Rural Development

With fall harvest upon us, there is an opportunity for producers to begin to plan for next year’s crop.

Mark Cutts, crop specialist at Alberta Agriculture and Rural Development (ARD), said that one aspect of crop production that can be considered is the fall application of fertilizers. “The advantages of applying fertilizer in the fall include reducing the spring workload as well as taking advantage of the lower prices of fertilizer products in the fall as compared to in the spring.”


In order to benefit from these advantages there are several factors that should be considered to ensure the application of fall fertilizers will be effective.

Fertilizer products

 The most common fertilizer nutrient that is fall applied is nitrogen (N). Since nitrogen makes up the biggest volume of applied fertilizer, a fall application will enhance efficiencies during spring seeding. The most common approach for applying fall nitrogen fertilizer is to band either urea (46-0-0) or anhydrous ammonia (82-0-0). It is preferable to band urea as compared to broadcasting because the banded fertilizer is less susceptible to over-winter losses. Another product that can be beneficial to apply in the fall is elemental sulphur (eg. 0-0-0-90). Although it is not a major component of most nutrient plans, a fall broadcast application will aid in making it more effective. Elemental sulphur needs to physically degrade and exposure to freeze/thaw cycles in the fall will aid the degradation. In the spring the sulphur product can be incorporated and converted to plant available sulphate sulphur by soil microbes. For plant nutrients such as phosphorus and potassium, which are typically seed-placed, there is no real advantage to applying these fertilizer products in the fall.

Timing of application

For nitrogen applications in the fall, the decision to apply fertilizer is based on soil temperature. Fall nitrogen fertilizer applications can be made once soil temperatures are below 10 degrees Celsius. Applying urea or anhydrous ammonia fertilizer at cooler soil temperatures will help maintain nitrogen in the ammonium (NH4+) form. The ammonium form of nitrogen is preferred as it will be protected from losses that can occur as a result of denitrification or leaching that can occur in the spring. If nitrogen fertilizers are applied to warm soils in the fall, fertilizer nitrogen can be converted to a nitrate (NO3-) form and this pool of plant available nitrogen will be susceptible to losses in the early spring.

Amounts to be applied

If a producer has collected soil samples and is certain of their cropping plans applying all of their required nitrogen in the fall is an option. If producers want to be more conservative due to concerns about potential over-winter nitrogen losses or spring soil moisture conditions they could consider applying less than the full rate of nitrogen. For example, a producer could apply two thirds of their required nitrogen in the fall and then apply additional nitrogen in the spring during seeding.Fall applications of fertilizers can provide an economic benefit and make spring seeding more efficient. In order to gain from these benefits, producers need to consider the type of fertilizer product being applied, timing of the application and amounts to be applied.

Please contact the Ag-Info Centre (310-FARM) for more information on fall applied fertilizers.