Why gardening/agriculture fights depression

Here is yet another reason why I've argued that being isolated from gardening and agriculture increases mood disorders and other depression related problems.

http://www.sciencedaily.com/releases/2007/04/070402102001.htm

The article demonstrates that components of the earth are beneficial to human well being. Not surprising - only surprising how people have forgotten this. People are humans, not robots in sterile environments. Now if only people could get back to the earth but have sterile hospitals, that would be nice.