Some fertilizers consistently spread further and more accurately than others, so what are the properties to look for in a fertilizer if spreading accurately over wide bout widths is important to you.
A heavier fertilizer granule will spread further and more evenly
Essentially a heavier and larger granule will spread further because the fertilizer spreader can put more energy into it but the granule also needs to be strong enough to withstand this without shattering. So these are three properties of fertilizer that influence how far it can be spread : weight, size and hardness; or in other words bulk density, particle size and crush strength.
Bulk density is weight of a given volume of fertilizer and measures how heavy a fertilizer is. This is determined by the manufacturing process and the chemical nature of the fertilizer – urea is always lighter than ammonium nitrate. YaraBela Extran has a bulk density of 1.0 kg/litre, compared to Granular urea which only has a bulk density of only 0.7 kg/litre.
Particle size is the measure of how large the individual particles are. This is influenced by the physical structure of the particles and depends mainly on the manufacturing process so will vary from factory to factory. The YaraBela range of ammonium nitrate based fertilizers are all granular products with particle sizes ranging from 3.4 to 3.6mm average whereas ammonium nitrate prills will typically have an average particle size of only 2.4mm. Particle size distribution is also important as it affects both the evenness of spreading and the maximum spreading width.
Crush strength or particle hardness depends on the chemical composition of the fertilizer and on the manufacturing process. If a particle is not hard enough it will shatter when it is hit by the spreader vanes and the harder they can hit it the further it will go. A cloud of dust following a fertilizer spreader is a sure sign the spread pattern will not be very accurate. YaraBela Extran has a particle strength of 9.2 kg which is more than double that of most prills or urea.
Read more on the physical properties of fertilizer
So much for the theory, what about in practice?
At a recent demonstration YaraBela Extran and Axan were both spread accurately to over 40m and indeed some spreader manufacturers give recommended settings for YaraBela Extran up to 54m.
When spreading over these wider bout widths it is important to maintain accuracy which requires a uniform fertilizer. A heavier and larger granule will be less affected by wind so will spread more accurately in marginal conditions.
Just as important the fertilizer spreader must be well maintained and accurately calibrated. This can only be checked by conducting a tray test in the field. Spreader manufacturers settings are a good starting point but these must always be checked in the field with each fertilizer, this is especially important for wider bout widths of 36m and more.
Recommended Yara Fertilizers
These fertilizers all have higher bulk densities and particle sizes and as they are all solid granules also have high crush strengths so are ideally suited to spreading over wider bout widths.