Land cassification systems

One of the most influential land classification systems is that of the USDA. The system uses eight land capability classes as follows:

Class I: These are the best, most flexible soils and they can be used for almost any purpose, showing usually the most productivity for the least cost

Class II: These soils have some limits to how they should be used for but are generally very good soils

Class III: Soils in this class have severe limitations which reduce the choice of plants that should be grown or they require special conservation practices to prevent damage to land

Class IV: The soils in this class can be used for cultivation but there are severe limitations to the choice of crops and management practices

Class V: This land is unsuited to crop production for reasons such as short growing season, stony or rocky soils, flooding

Class VI: These soils suffer from extreme limitations such as steep slopes. Use is largely restricted to pasture, woodland and wildlife

Class VII: These soils have similar limitations to those of Class VI but with fewer opportunities for improvement. Access to them is very limited

Class VIII: Soils in this class should not or cannot be used for any commercial plant production. The land includes sand beaches and rock outcrops

Within the United Kingdom there have been several land capability systems introduced over the last 50 years. One of the most widely used ones has been the ALC which was produced for England and Wales. Aimed at identifying the areas of land of greatest potential for crop production, it was a post-World War II project seeking to identify those areas of the UK most able to produce high yields of crops and where there could be flexible cropping. As well as soil factors, climate and relief factors were integrated into the Classification. Land is placed in one of five grades: Grade I, with minor or no limitations; Grade II, land with minor limitations; Grade III, land of average quality; Grade IV, severely limited land; and Grade V, land of little agricultural value. Land Classification maps for the whole country were issued. In addition to advising government of potential of land for farming, they were also used to advise government and local government in cases of conflict between using land for farming and for other purposes such as building.

As more and more of the United Kingdom was covered by soil maps, so these became used as a base, together with relief and climate, for presenting soil surveys in a more applied way that could be used by farmers, planners, farm advisers and others. A Land Use Capability Classification was set up and maps showing the results of this Classification issued. Unlike in the ALC above, the scheme contained seven land use capability classes. A similar system, but modified to meet to the local conditions, has been issued for Scotland and Northern Ireland.