European Fertiliser Blenders Association
Granule hardness, or crush strength as it is more commonly referred to, is a measurement of the pressure or weight a granule can withstand before fracturing. The granule hardness is measured in kilogrammes or newtons.
Fertiliser granules must be strong enough to withstand handling at all stages through the blending, bagging and handling process.
Breakdown of granules due to low hardness will lead to an increase in fines or dust which can increase the risk of caking and affect the flow rate of the product.
Granules also have to be sufficiently strong to withstand the point of impact with high-speed steel vanes (throwing shovel) on fertiliser spreaders.
With farmers increasingly looking to spread fertiliser to wider widths, crush strength is an important physical characteristic that needs to be taken into account when considering product quality.
| Raw Materials (% in Blend) | Blend Made in Accordance with EFBA Handbook | Raw Materials (% in Blend) | Blend Not Made in Accordance with EFBA Handbook |
|---|---|---|---|
| Granular CAN (59.58%) | 8.44 | Prilled AN (46.62%) | 1.89 |
| DAP (21.75%) | 8.67 | DAP (21.75%) | 8.67 |
| MOP (16.67%) | 8.50 | MOP (16.67%) | 8.50 |
| Limestone Grit (2.00%) | 9.20 | Limestone Grit (14.96%) | 9.20 |
| Average Within Blend | 8.51 | Average Within Blend | 5.56 |
| Range Within Blend | 8.44 – 9.20 | Range Within Blend | 1.89 – 9.20 |
A crush strength of 3-5kg and above indicates granules will be sufficiently strong to maintain their integrity through the blending and spreading processes.
The low crush strength of the prilled AN used in the blend not made in accordance with EFBA handbook would create an uneven spread of nitrogen and nutrient segregation across the spread width.
