Scientific Order of Mixing Spray Chemicals – The WALES Formula
During agricultural spraying, multiple products such as insecticides, fungicides, water-soluble fertilizers, micronutrients, bio-fertilizers, biostimulants and spray adjuvants are often mixed together. Using the correct dosage alone is not sufficient; following the correct mixing order is equally important.
If chemicals are mixed in the wrong order, problems such as solution breakdown, sediment formation, chemical inactivation or reduced spray effectiveness may occur. Therefore, preparing the spray solution scientifically is essential.
What is the WALES Formula ?
The WALES formula is an internationally accepted guideline that defines the correct sequence for mixing spray chemicals in the tank.
Meaning of WALES :
W = Water-soluble fertilizers and wettable powders (WP, WDG)
A = Agitation must be continuous until complete dissolution
L = Liquid formulations (SL, SC)
E = Emulsifiable concentrates, oil-based products (EC)
S = Surfactants, stickers or spray adjuvants
How to Prepare Spray Solution Using WALES Formula ?
First, fill the spray tank with half the required water.
Then add water-soluble fertilizers, wettable powders or granules.
Once fully dissolved, add liquid formulations.
After that, mix emulsifiable or oil-based products.
Finally, add spray adjuvants, stickers or spreaders.
Why This Order is Important ?
Adding heavier and soluble products first prevents sediment formation. Liquid products mix uniformly when added later. Adjuvants added at the end enhance spreading, adhesion and absorption on plant surfaces. Reversing this order may cause separation or chemical reactions.
Conclusion
Successful spraying depends not only on quality chemicals but also on the correct preparation of the spray solution. Following the WALES formula improves chemical efficiency, reduces wastage and ensures better crop response.
