Granules of 3 fertilizer types (superphosphate, NPKS and NCaMg) were divided into 7 size fractions (1–6 mm) by using a sieve analyzer and then the force destroying the granules of each fraction of fertilizers tested was detd. by using a head with a variable pressure. Two-parameter Weibull distribution was used to analyze the results to det. the probability of destruction of each granule fraction as a function of the force acting on it.