The International Fertilizer Development Center (IFDC) has prepared a manual outlining methods for the determination of physical properties of fertilizer, which includes procedures used by IFDC to evaluate the physical quality of commercial and experimental fertilizer products and raw materials. Many of the procedures included in the manual were adopted from the Tennessee Valley Authority (TVA)/National Fer­tilizer Development Center (NFDC)and other organizations involved in the meassure­ment of physical properties. IFDC does not endorse these methods as being standards.
The physical properties of fertilizer that are included in the manual are critical relative humidity, moisture absorption-penetration characteristics, flowability, chemi­cal compatibility in blends, caking tendency, size analysis, physical compatibility in blends, angle of repose, bulk density, apparent density, true density of solids and li­quids, viscosity, granule crushing strength, abrasion resistance, impact resistance, handling strength, sphericity, conditioner adherence, dustiness, surface area, disin­tegration rate, and porosity.