You should have collected more soil than is needed for testing, so a sub-sample is taken. The sub-sample has to represent all the soil collected so you must mix the entire sample together, taking care to break up all the cores.  Then take the amount you require from several places in the fully mixed sample. Sieving all the collected soil through a garden sieve and carefully mixing it before taking the sub-sample helps ensure your tested soil is truly representative (Figures 12 and 13).

Soil samples that are going to be analysed for N should be kept chilled and sent to the lab as soon as possible. They need to arrive at the lab at <4°C (fridge temperature) but should not be frozen. Carry a chilly bag or bin with ice packs, particularly on hot sunny days, so samples can be chilled immediately.

If soil samples warm above 4°C, microbes will mineralise nitrogen and the lab may measure more available N in the sample than is in the paddock. This could lead to a falsely low fertiliser recommendation.