How to use the granular size box correctly?

Step 2: Close the cover and shake the box in such a way that the fertiliser will separate and go through the grids until no further separation is possible. It is important to shake long enough to get the final correct result! By adding up the result of the different compartments, you should always end up with 100%.

Repeat the operation several times (at least 3 times) and take the fertiliser from different locations in the big bag, hopper or silo, to get an average fractionation. Loose fertiliser can separate into different granular sizes more easily than in bags. In this case, do not take samples from the surface, but try to find a representative place more inside the fertiliser.