Land resource and land use classification concepts and methods

This report describes the concepts and methods used by A.I.D."s Comprehensive Resource Inventory and Evaluation System (CRIES) Project to classify and evaluate land in order to assist developing countries with agricultural planning and policy analysis. The CRIES land classification system develops geographic and soil data for three levels of policy planning: development of broad objectives and priorities; selection and general siting of programs; and designing and siting of projects to achieve program goals. CRIES is intended primarily for the higher levels of analysis, but can also delineate quite small geographic areas useful for unique, highly valuable agricultural production. CRIES uses two components - soil and climate - to delineate broad, relatively homogenous geographic areas, termed resource planning units (RPU"s), and to identify smaller and even more homogenous production potential areas (PPA"s) within an RPU. RPU"s provide overviews of a country"s physiographic regions. Agronomic analyses are made at the PPA level. A PPA is by definition sufficiently uniform with respect to plant adaptability and potential management requirements and productivity as to enable its development potential to be usefully interpreted for national and regional planners. CRIES interprets data on PPA"s and their distributional patterns (which can also affect agricultural potential) at two levels. General interpretations - based on such factors as soil potential, climate, and restrictive features - indicate the physical environment"s potential for supporting agricultural endeavors. More detailed interpretations denote where major crops or crop groups are adaptable and indicate yield potential. These crop recommendations are generalizations, best suited for initial screenings for national planning purposes. The report includes data on CRIES"s information sources, methods, mapping, and soil taxonomy and briefly describes CRIES"s methods for developing information on existing land use or cover (e.g., crops, forest, cities). Appendices provide sample descriptions of two RPU"s and their PPA"s and define some technical land classification terms.