Here's what I think is the main reason agriculture is so much more a part of the Georgia economy than the Alabama economy.  Check out the soil difference below.

Alabama Soil   (Click HERE to go to GEORGIA SOIL)

Alabama Soil

Georgia Soil     (Click HERE to go to ALABAMA SOIL)

Georgia Soil

source: http://www.nrcs.usda.gov/wps/portal/nrcs/site/soils/home/