Chelation is a means of bonding a small amount of inorganic nutrient on to a stable but lengthy organic molecule so protecting the nutrient from interacting with unwelcome external factors.

 

In theory this bonding gives chelates agrochemical compatibility and stability within the soil so avoiding leaching and colloidal interactions. There is no doubt that when liquid chelates were introduced they proved popular, primarily because the only alternative was mixing manganese sulphate. They did have excellent compatibility due to the chelation effect but also because not much Manganese was being added to the sprayer. There has, however, always been a question mark over their ability to cure severe deficiency at economic rates of application and hence their overall cost effectiveness.

 

Chelated liquids and powders - Pros and Cons

  • With the exception of Iron, chelates have not been successful in controlling deficiency when applied to the soil despite the theoretical chemical arguments.

  • Liquid chelate formulations do not contain any adjuvants. They are just dissolved in water.

  • The chelate molecule itself is so large that it cannot be absorbed by the leaf stomata of the plant.

  • Therefore, the nutrient and the chelate molecule have to split before the nutrient can enter. This has to occur under particular conditions and so can lead to a delay in availability.

  • Chelates are costly to produce and have been superseded by more effective formulations.

  • There is no difference in performance between liquid and powder chelates.

  • Powders are just the dried and hence more concentrated form of the liquid.