Controlled release fertilizer coating

The effective use of fertilizers is essential for healthy and rapid plant growth. Efficient nutrient uptake directly impacts plant health and crop yield which in turn depends on the composition and dosage of the fertilizer applied. Most fertilizer granules have excellent water solubility. This is important to ensure that the plant can take up sufficient nutrients and flourish. Unfortunately, this water solubility can decrease overall efficiency. If irrigation is too heavy or during heavy rainfall, nutrients can prematurely dissolve and be released into the soil resulting in runoff into neighboring water bodies making them no longer fully available to the plant. Similarly, the premature conversion and emission of important active substances such as ammonia from the soil into the atmosphere reduces the supply of nutrients to the plant leading as well to significant environmental pollution in the long term. This inefficient use of fertilizer can lead to higher labor and material costs as re-fertilization is required at regular intervals to ensure a continuous supply of nutrients to the plant. 

To overcome these issues, slow release and controlled release fertilizers have been developed. Both types have coatings which retard dissolution in water with the rate at which nutrients are made available depending on a variety of factors. Slow release fertilizers release nutrients slower than untreated fertilizer, though the release is still dependent on many uncontrolled factors. Controlled release fertilizers (CRF) have well controlled factors to tailor the pattern and duration of nutrient release. This ensures longer term availability with minimal nutrient wastage thereby significantly increasing the efficiency of the applied fertilizer while minimizing collateral environmental damage.

ASK Chemicals has developed ASKOCOAT™, a proprietary controlled release technology where water penetrates a protective coating in a very controlled manner. This dissolves the nutrients and transports them into the soil where they can be absorbed by the plant. While weather impacts release rate, it is primarily the composition and thickness of the coating that determines the rate of release of the nutrients. Both can be optimally adjusted to ensure the desired rate of supply to the plant during the growth phase; controlling desired nutrient availability in a highly controllable manner improves efficiency and also protects the environment to a decisive degree. 

The patented ASKOCOATTM technology is a 2K polyurethane system where the polyol formulation contains over 60% renewable raw materials. Both components are solvent-free and contain only reactive ingredients, preventing leaching of the coating components into the soil. The catalyst used for curing can be introduced into the process in a variety of ways, allowing fast and complete curing without subsequent sticking of the coated granules.  

The advantages of ASKOCOATTM technology at a glance: 

•    2K polyurethane coating 
•    Renewable raw materials (>60%) 
•    100% reactive components (solvent-free) 
•    Applicable to all types of fertilizer granules 
•    Nutrient release adjustable from 2 to 16 months 
•    Prevents salt stress 
•    Improves fracture strength, i.e. improved crush resistance (less dusting)

More information