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Post-harvest nutrient management in Alta.

Oct. 21, 2013, Stettler, AB - With the completion of harvest in many areas across Alberta, producers will already be thinking about the 2014 crop year. One aspect of next year's crop production that can be considered this fall is nutrient management.

"It is well recognized that proper nutrient management is required for producing crops with good yield and quality," says Mark Cutts, crop specialist with Alberta Agriculture and Rural Development. "The fall season allows two very important nutrient management activities to be carried out: soil fertility evaluation and fertilizer application."

Soil fertility evaluations: Soil testing in the fall is an excellent option for evaluating nutrient levels in the soil. Fall soil testing offers producers several advantages including:

  • having more time to collect the samples as compared to spring
  • allowing more time to plan fertilizer programs for the next cropping season
  • taking advantage of lower fertilizer prices that may occur
"Soil sample collection can occur once soil temperatures are below 7 C," says Cutts. "Waiting until soil temperatures are cooler will provide soil nutrient levels that should closely reflect spring nutrient levels."

It is important to ensure sample collection occurs in a consistent manner in representative areas of the field. For example, if there are small areas of poorly drained low spots in a field, these areas should not be included in the sample collection. The non-representative areas can be sampled separately to determine their fertility status. Sampling at the appropriate depths is also important to ensure meaningful nutrient information is obtained. Recommended sampling depths include: 0 to 15 cm, 15 to 30 cm and 30 to 60 cm. The 0 to 15 cm depth will capture crop available soil phosphorous and potassium. However, for mobile nutrients such as nitrate nitrogen and sulphate, sampling to a depth of 60 cm will provide a more reliable measure of the amount present in the soil profile.

Fall fertilizer application: Advantages of applying fertilizer in the fall include:
  • reducing the spring workload
  • an economic advantage that occurs when fall fertilizer products have a favourable price as compared to spring priced products
The most common approach for applying fall fertilizer is to band nitrogen either as urea (46-0-0) or anhydrous ammonia (82-0-0). Since nitrogen makes up the biggest volume of applied fertilizer, a fall application will enhance efficiencies during spring seeding.

"Fall nitrogen fertilizer applications can be made once soil temperatures are below 10 C," says Cutts. "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. For plant nutrients such as phosphorus and potassium, which are typically seed-placed, there is no real advantage to applying the fertilizer products in the fall."

By evaluating soil nutrient levels and applying nitrogen fertilizer in the fall, producers can gain efficiencies in time management and cost of production. For more information on post-harvest nutrient activities, call the Ag Info Centre toll-free at 310-FARM (3276).