I have no real experience in this sort of thing but I know that smells like colored dyes are subject to destruction by oxidation. Hydrogen peroxide is a strong oxidizing agent and it decays into oxygen and water so it would not leave any poisonous residues. It also is a good bacteriocide so it should kill anything generating odors. It might be worth a try.

You might try baking soda as it has a lot of smell asborbing properties.

You might try baking soda as it has a lot of smell asborbing properties.

Have you tried charcoal? I would use standard charcoal (not self-lighting; quick-burning might work) smashed into a powder or at least gravel sized. I don't know what it will do for the ground, though.

You could also try sod or topsoil, perhaps spiked with earthworms. This would probably replenish the ground as well, encouraging natural organisms to do away with the remnants.

A fairly tricky process called alkaline hydrolysis involves using sodium or potassium hydroxide (caustic soda or potash, respectively) and pressurized steam.

Napalm--yes, gelled gasoline--might help to burn away any remnants.

Some more ideas you can find here. Most likely you'll need the advice of an animal control agent or a veteran handyman at your hardware store.

Try a product callef Fabreeze. A little bit removes the smell of cigarette smoke in an entire room. Also, check with your local morague and funeral homes. They have to deal with the odors of dead bodies all the time.