The latex calk is rich earth and charcoal, both by Selleys. Fine grit mixes into the wet grey calk, and that goes on first. I used to premix, but that makes getting the mini in harder. Now I surface-sprinkle.
Earth calk goes on then while everything is still wet (dab on more water as needed) embed the minis.
Use a edging brush to work the calk or grit-mix onto the bases thoroughly, you should ideally barely glimpse the base.
In this particular case I'm drifting flock on immediately, using a basic summer mix from Warlord Games.
Once everything is dry I can add in brush and grass tufts.