The performance of fertilizer distributors and hence the evenness of the spread pattern depends to a large extent on the physical properties of the fertilizer. The influence of physical properties on the particle motion in the fertilizer distributor and through the air is discussed. Particle motion in the fertilizer distributor device is discussed for both spinning disc and reciprocating spout fertilizer distributors. The particle motion in the hopper and/or metering device is excluded from the discussion. Five important properties which affect particle motion are reviewed, namely particle size and particle size distribution, coefficient of friction, coefficient of restitution, aerodynamic resistance, and particle strength. The latter is indirectly related to particle motion. The coefficient of friction, the aerodynamic resistance, and the particle size and particle size distribution are most important because they influence the spread pattern to a large extent. The influence of the coefficient of restitution is not very clear and the particle strength is important in relation to quality requirements that fertilizers have to meet. Methods for determining the properties and the results of different tests are discussed; relevant data for the five properties reviewed are presented in tables or figures. © 1997 Elsevier Science Ltd. All rights reserved.
