This Mote of Earth farming guide will show you the place that I use for farming Mote of Earth. There were no major changes to Mote drop rates at Outland, so this guide can be used for Burning Crusade Classic (TBC) and Retail WoW.
Primal Earth comes from combining 10 Mote of Earth, so if you need Primal Earth, you have to farm Mote of Earth.
Mote of Earth
Shattered Rumblers in Nagrand is the best place to farm Mote of Earth. Just run in a straight line, then use your flying mount to fly back where you started.
If you kill the mobs too fast, you will usually have to wait 1-2 minutes before they start respawning.