Ask your Agronomist: Understanding blend and compound fertilisers

A proud farmer inspects his healthy maize crops. Compound fertilisers give 20 times more nutrient to the crop and has high spread in the soil compared to blends hence increasing yield by up to 10 per cent. FILE PHOTO | NATION MEDIA GROUP

What you need to know:

  • In blend fertilisers, all nutrients are present but as separate granules.
  • Each plant has a lesser chance of getting the right mix of nutrients for optimum growth, leading to crop striping due to under or over application of one or more nutrients.
  • A compound fertiliser has all the nutrients contained in each and every granule.
  • For crop specific fertiliser recommendations, please consult Yara agronomists in your area.

Q: I recently bought an NPK fertiliser from an agrovet in my area and upon opening the bag, the particles were of three different colours and sizes.

I was told the fertiliser was a blend. Please tell me what is the difference between blend and non-blend fertilisers?

Ambrose

Most farmers are unaware of the differences between these two kinds of fertilisers. What you are calling particles are actually granules for a blend fertiliser.

On the other hand, non-blend refers to a compound fertiliser. The two are similar in that both blend and compound fertilisers contain essential nutrients for successful crop production.

The biggest question is, however, how do you choose between the two as a farmer.

Blend fertilisers

In blend fertilisers, all nutrients are present but as separate granules. This is usually a mixture of three different fertilisers, nitrogen, phosphates, potash and sulphur, among others.

Blends might be cheaper but their performance in most cases is inconsistent.

This is because individual granules vary in weight and size. Segregation can, therefore, happen during transportation, or on the farm where heavier granules will move to the bottom and lighter ones at the top.

Blends again land on the soil at different trajectories due to difference in dimensions, weight, and size resulting in uneven distribution of nutrients and variable number of landing sites.

Each plant has a lesser chance of getting the right mix of nutrients for optimum growth, leading to crop striping due to under or over application of one or more nutrients.

Compound fertilisers

A compound fertiliser has all the nutrients contained in each and every granule. Therefore, every granule in each bag contains the same nutrient analysis.

The flow is equal, and there is zero chance of segregation during transportation. Either manual or mechanised application is efficient since the granules land on the farm at the same time.

Typically, compound fertilisers give 20 times more nutrient to the crop and has high spread in the soil compared to blends increasing yield by up to 10 per cent.

In turn, a farmer realises a greater return on investment due to compound fertilisers.

For crop specific fertiliser recommendations, please consult the following agronomists in your area:

Western and Nyanza, Daniel Mui, 0702466343.

Rift Valley, Dennis Nyandaya, 0702466372.

Central, Robert Ngatia, 0702466318.

Peter Wekesa, Senior Agronomist, Yara