Place a minimum of 250 ml (one US cup) of water into a clean, resealable container. Fill the container fully to avoid air.

Remove organic matter (leaf litter, sticks, etc) from the surface of the location to be sampled, then dig to the desired depth (typically top 15 cm/6 in) with a clean trowel or shovel. Place 500 mL (two US cups) into a clean ziplock bag and seal the bag. Then place this bag into another bag for transport.