The importance of quality for the foliar spraying of SOP
It is very important that growers wishing to apply foliar sprays of SOP use a product that is compatible with the application methods and equipment that is used for foliar spraying.
In fertigation systems, regular water-soluble fertigation grade products are dissolved in large tanks with continuous stirring. Once a homogeneous solution has been formed, it is introduced into the irrigation system. These systems are widely used in modern greenhouses and in open field drip irrigation at technically advanced farms.
In contrast, for foliar application in field crops, modern tractor sprayers are now used in many parts of the world. In such systems, the product is introduced directly into the spray tank - often by means of suction (via an induction bowl) - and dissolution takes place by means of circulation of water and agitation in the sprayer tank rather than by mechanical stirring.
These differences can have a profound effect on the performance of a soluble SOP product in the two systems. A trial carried out with a foliar sprayer in France highlighted the potential constraints when not using SOP that has been specifically developed and formulated for foliar application:
A typical foliar sprayer
Regular water-soluble SOP is introduced into the 'bowl' for transfer into the spray tank by means of suction
Results from an 8% solution after spraying – much of the product did not dissolve and remained in the tank
Results from a 4% solution after spraying – the results were better but some of the product remained undissolved
The test shown above clearly demonstrates that regular fertigation grade SOP is unfortunately far from ideal as a foliar product for modern sprayers. Farmers cannot accept such performance as firstly the product may be 'wasted' if it remains in the tank and, secondly, they have the additional work of cleaning the tank after spraying.
There is also the serious risk that an undissolved product could actually block the sprayer nozzles and damage the equipment. It is for these reasons that growers wishing to make foliar applications of SOP should only use a product market for this specific application, such as K-Leaf®.
Download our K-Leaf brochure here.