The effect of granulometric structure and moisture of fertilizer on its static strength

During the load of vertical static force the strength limit of individual fertilizer particles was studied in relation to the fertilizer moisture content and granulometric composition. The experiment was conducted for the fertilizer damage at the different level of fertilizer moisture content and particle size groups. The result of the first part indicates the need to point out the differences of static strength between prilled and granular fertilizers. Both types of prilled fertilizers reached from 3 to 8 times lower values of static strength than standard granular fertilizers. The theses above point out the need for more caution during manipulation, storage and application of prilled fertilizers, the quality of which may be affected at some point by the greater extent of static load. The second part of the study was focused on the effect of moisture and granulometric fraction of fertilizer on static strength of fertilizer. For all tested fertilizers the statistical difference was observed for both of variation factors. Their mutual ratio of the effect is however different for each individual fertilizer. This fact may be interpreted as the dependence of the quantity of water that the individual fertilizers are able to absorb. This amount was influenced by very different types of fertilizers' hygroscopicity. The interaction of both factors at the same time was not confirmed for any fertilizer tested.