Spreading Segregation of Blended Fertilizers: Influence of the Particles Properties

The blending of solid granular fertilizers produces an almost infinite range of compounds with some raw materials. These can be specifically matched to a farmer's needs at a reasonable cost. The main problem is that the blended fertilizers are exposed to the risk of segregation. With granular materials, the differences in physical properties can lead to the segregation of the particles. This study aims at analyzing and quantifying the particles influence on segregation during spreading of blended fertilizers. The experiment consisted of mixing two raw materials that differed by one characteristic: the size, the density, or the shape. The physical properties of each raw material were carefully measured. Twenty-six blends were spread on the field with a centrifugal spreader and samples were collected in order to measure segregation. The proportion of each component was calculated with the chemical content of the raw materials and blended samples. Two coefficients of segregation were determined. Great segregation in some cases was observed. The original proportion of 50% for each component can become 30/70 on the field. The analysis of the influence of each parameter shows that major effects occur with a difference of size and density. The influence of shape is minimal. A relationship was proposed between the differences of physical properties of the blend components and the spreading segregation.