Variables Affecting Caking on Granular Phosphorous Containing Fertilizers

Granular fertilizers are not usually produced near the regions where they are applied. They have to be stored and transported after their production for long periods before being actually applied on the fields. During this time, most fertilizers, including those containing phosphorous, can agglomerate, or cake, making their manipulation and application more difficult or even impossible. Caking is the result of various physical and chemical processes that may occur simultaneously, which are more or less affected by external and internal variables during their production, storage and transportation process. In this paper, a study of the impact of different variables such as time, temperature, moisture and pressure on the caking tendency of different fertilizers containing phosphorous is presented. The principal variables affecting the caking process are discussed, based on results from mechanical tests and chemical analytical measurements such as scanning electron microscopy and x-ray fluorescence. Solutions to decrease the caking of granular fertilizers, notably by the use of bio-sourced protecting coatings and their characteristics, are also discussed.