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Diammonium phosphate (DAP) fertilizers in fertilizer bag.

eKonomics News Team

Granular urea, monoammonium phosphate (MAP) and granular muriate of potash (MOP) are all products offered by Nutrien that can be applied alone or blended with other products. Even if your daily activities do not include handling, blending or field-applying fertilizers, this is important information for those that use fertilizers in their operations.

As site-specific management and precision technologies manifest themselves further into farming operations, it is anticipated that increasing demand for specific fertilizer blends will prevail. Consequently, it will be more important to understand established quality standards and procedures for producing quality dry bulk blended fertilizers.

Taking an example from the above mentioned fertilizers, there are several types of potash in the Nutrien granular MOP product line. Types are classified in different ways including granule size, shape and density. Different types of the same fertilizer exist because it is necessary to have all products in the blend be compatible in terms of size, shape and density. If products are not compatible, they will segregate (as seen in photo), making accurate and evenly dispersed field application virtually impossible.

Managing the quality and consistency of a dry blend should be a priority for all fertilizer manufacturers, retailers and farmers. There are negative agronomic consequences to improper management of product segregation (see accompanying table).

Agronomic consequences of segregated material:
  • Uneven nutrient spreading
  • Uneven nutrient distribution
  • Uneven crop growth (esp. w/nitrogen)
  • For impregnated materials, spread pattern is critical (esp. w/low rate chemicals)
  • Micronutrient uniformity may be significantly affected

Manufacturers and producers are initially responsible for supplying fertilizer that is properly sized and matched to nutrient content specifications. The Canadian Fertilizer Institute (CFI) has developed the Size Guide Number (SGN) concept to assist in the selection of compatible materials for blending by providing a common basis for size comparison. The Uniformity Index (UI) is an equally useful measure. Even within the same material, segregation does occur before blending. This makes it equally important for retailers to properly maintain blending equipment and follow best practices for determining the worthiness of a particular fertilizer in a blend. These procedures are necessary to maintain quality along the value chain.

How do products segregate?
  • During transportation, handling, storage, on the way to the field and in the field
  • Takes place within individual materials before blending
  • Takes place among different materials after blending
    • for example, micros, urea, DAP and MOP
What it is:
  • The calculated diameter of the average particle
  • Represents the particle size that divides the mass of all particles into two equal halves; one having all of the larger particles and the other having all of the smaller particles
How it is measured:
  • By mathematical calculation using screen sizes of material
  • By measuring devices using a series of screens
What it is:
  • A mathematical expression of the ratio of the small particles to large particles
Why it is important:
  • Acceptable assured by using both the SGN and UI to set limits on variation
  • If a particle in a blend is within 10 percent of the average screen analysis of all materials in the blend, it will remain mixed when handled and applied properly