ASC Statsgo computed attribute definitions:

NAME:	Name of the soil mapping unit (usually an association of 2 or more soil series) 
AWC		Soil available water storage capacity ((cubic inches of water/inch of soil). Volume of water available to plants when the soil is at field capacity"
HSGA	Percent of the mapping unit area that is of Hydrologic Soil Group A 
HSGB	Percent of the mapping unit area that is of Hydrologic Soil Group B 
HSGC	Percent of the mapping unit area that is of Hydrologic Soil Group C 
HSGD	Percent of the mapping unit area that is of Hydrologic Soil Group D 

KFACT	K factor or soil erodibility factor.  It is a relative index of susceptibility of bare, cultivated soil to particle detachment and transport by rainfall.