Issue. One of the main factors in influencing both fertiliser spreading, uniformity and accuracy is the physical characteristics of the product being spread. Solution. Testing your fertiliser products prior to spreading with a fertiliser test kit is the easiest way of determining these physical features. 1; A fertiliser sieve box from 2 – 5mm will show the operator what size particles and the distribution they are dealing with. Aim for fertiliser to be in the 2 – 4mm size range i.e. the 2 middle sections of the sieve box. 2; Fertiliser density is the mass of fertiliser to the volume ratio of granules. Density will have the biggest impact on spreading widths. Denser particles such as CAN 27% will be easier to spread over wider widths than less dense products such as Urea. 3; Granule hardness is the force that can be applied to a single fertiliser granule before it breaks. This can be measured using a crush tester with a scale of 1 to 10 (1 being the weakest and 10 being the strongest). Granule hardness will dictate the disc speed and the bout width.