Go to a Stihl dealer and tell then what you need.

Their are tooth profiles that are more resistant to dulling from dirt.

They do not cut as well as the more common profile though.

Sounds like a job for a Maddox.....or possibly a stump grinder! The above poster is correct in the sense that there are blade profiles that will be slightly more forgiving when run into the dirt, but certainly not in the sense that you are talking.

There is a variation of a chainsaw that has a chainsaw motor with a reach arm and it is equiped with an abrasive type circular saw blade, called a "Demolishion saw". Demoslishion saws will cut through wood, light metal, concrete and masaonry walls.

They are commonly used by fire departments and rescue squads, but I have to warn you ahead of time,,,they are extremely expensive however you may be able to rent one at a local tool rental.

"but certainly not in the sense that you are talking."

They do not call them 'root cutting' blades for nothing.

Dirt itself is not the real problem, it is the small stones that get hit that case most of the damage.

Dirt is rarely as hard as wood.

For cutting roots in the ground I use a reciprocating saw, aka "sawzall", fitted with a long, aggressive cutting blade. I use it to cut roots when removing stumps....just pull the trigger and stab the blade into the ground. It works great and is a lot cheaper than new blades for the chain saw.

"fitted with a long, aggressive cutting blade."

Use a pruning blade.

Yesterday I cut the roots by chainsaw.The blades are made in carbide.