Product incompatibilities cause problems for both groundspreaders and aerial top-dressing operators. For groundspreaders the difficulties are largely to do with operational issues, as spinners become clogged with wet, lumpy material.
For aerial top-dressing pilots, the consequences of product incompatibility are more extreme, so product stability is of even greater importance. This is influenced by:
All of these factors are also influenced by the temperature, moisture content and chemical composition of the products to be used.
Some products present specific issues for aerial top-dressing. These are listed in the following table.
Product | Precaution |
Nitrogen-containing blends, e.g. DAP sulphur super, some pasturemag products, urea and superphosphate blends | Risk of blend setting up in hopper. Even if product does not set up there is a strong possibility of striping from uneven spreading of product |
Calmag | Magnesium oxide reacts with ammonium salts and releases ammonia gas, which is flammable and harmful if inhaled |
Salt | Salt can cause pinpoint corrosion in metalllic sections of the hopper. In time this can result in equipment failure |
Durasul | Where a component of a blend, Durasul needs to be kept at or below 23% of the total mix. Failure to do this can result in a sulphur cloud forming during sowing, and this can ignite with the heat thrown off the plane |
Dicalcics | Any dicalcic product to be spread must be well cured and fully reverted before being despatched from a store. Failure to do this carries a risk of product setting up in the hopper and/or striping from uneven spreading of product. |
