Chapter 2 - Concepts and definitions
The purpose of zoning, as carried out for rural land-use planning, is to separate areas with similar sets of potentials and constraints for development. Specific programmes can then be formulated to provide the most effective support to each zone..
Agro-ecalogical zoning (AEZ), as applied in FAO studies, defines zones on the basis of combinations of soil, landform and climatic characteristics. The particu- lar parameters used in the definition focus attention on the climatic and edaphic requirements of crops and on the management systems under which the crops are grown. Each zone has a similar combination of constraints and potentials for land use, and serves as a focus for the targeting of recommendations designed to improve the existing land-use situation, either through increasing production or by limiting land degradation.
When combined with an inventory of land use, expressed as land utilization types and their specific ecological requirements, zoning can then be used as the basis of a methodology for land resource appraisal. The addition of further layers of information, on such factors as land tenure, land availability, nutritional requirements of human and livestock populations, infrastructure and costs and prices, has enabled the development of more advanced applications in natural resource analysis and land-use planning.
AEZ can be regarded as a set of core applications, leading to an assessment of land suitability and potential productivity, and a further set of advanced or peripheral applications, which can be built on the inventories and results of the core AEZ studies (Figure 1). Outputs of core applications include maps showing agro-ecological zones and land suitability, and quantitative estimates on potential crop areas, yields and production. Such information provides the basis for advanced applications such as land degradation assessment, livestock productivity modelling, population support capacity assessment and land-use optimization modelling.
Before applying the procedures of AEZ, the potential user should have a good appreciation of the underlying concepts, so that the potential uses and limita- tions of the methodology are understood. The essential elements of the core applications of AEZ comprise: