Ramil -

"There was an oil spill, but the land was cleaned up" (and I'd always add the "up". I think. ):
Four guys with spades and buckets turned up, dug out the black bits (and emptied the buckets on the neighbour's land ). There. Clean.

"There was an oil spill, but the land/ground was cleansed":
A special firm turned up with a truck and diggers, removed the upper layer of soil, took it to the cleansing plant where the soil was washed with detergents and rinsed, then put it back.

"There was an oil spill, but the soil was purified" (although I must say I don't like this construction very much. Maybe it's just me, but I'd probably only use the word "purify" for liquids ):
A special firm turned up with a truck, diggers, and men in white suits and masks; they removed the upper layer of soil, took it to the cleansing/purification plant where the soil was washed with detergents, rinsed, treated with chemicals, sterilized (etc, add your own! ). Then they put it back.




Sort of......


All this being said, in everyday use, you'd probably just use "cleaned up".