Spray insulation vs vapor barrier??

Out of curiosity I am wondering how much moisture spray foam insulation will barrier? Or in other words, if a home has had spray foam installed is there still a need for a vapor barrier on the soil area?

For starters, research the difference between open and closed cell foam:

Open Cell/Closed Cell - Understanding the different spray foam types | Icynene

Very good information, thanks for pointing me in the correct direction.