The Land Capability Classification is explained in section (622.02) of the National Soil Survey Handbook and in Agricultural Handbook 210, Land Capability Classification, 1973, USDA, SCS. Agricultural Handbook 210 is out of print but an electronic copy can be obtained from Gary Muckel at the National Soil Survey Center. (gary.muckel@nssc.nrcs.usda.gov)
The National Soil Survey Handbook is available at the following web site:
http://www.statlab.iastate.edu/soils/nssh/
Agricultural Handbook 210, Land Capability Classification, 1973, USDA, SCS.