1. BACKGROUND
Agricultural land use planning requires spatial information on the land suitability for avariety of
economic crops within agricultural areas. Currently, the FAO guidelines for land evaluation are widely accepted (FAO, 1983). The FAO land evaluation system is based on an integration of various land qualities as they relate to individual crop requirements. A similar system, developed by Sys et al. (1991), provides the crop requirements based on the experimental studies and results over land in the tropics. To formulate effective land use planning, the evaluation has to provide alternative plans with more or less marketing risk. To lower marketing risk, the combination of various economic crops within the area should be considered and evaluated. Rice, sugar-cane, cassava and rubber trees are important export crops and products from Thailand. Their combined crop area is extensive and covers over 70% of the total cultivated land in Northeast Thailand. In Thailand, land classifications have been conducted over the past three decades. The classification system includes land capability classes for field crops and land suitability classes for rice (Land Development Department (LDD), 1996). To date, the land suitability maps are defined as the inherent capacity of a soil to grow crops. The overall mapping process still considers the inherent capacity of soils in defining the suitability of the land unit. Recently, these land suitability maps were digitally encoded in a geographic information systems (GIS) database. Furthermore, a number of pilot projects have been undertaken to test the land evaluation method using GIS. There still remains the need to establish an integration method for the relevant land qualities in the modeling of land suitability.
1. BACKGROUND
Agricultural land use planning requires spatial information on the land suitability for avariety of
economic crops within agricultural areas. Currently, the FAO guidelines for land evaluation are widely accepted (FAO, 1983). The FAO land evaluation system is based on an integration of various land qualities as they relate to individual crop requirements. A similar system, developed by Sys et al. (1991), provides the crop requirements based on the experimental studies and results over land in the tropics. To formulate effective land use planning, the evaluation has to provide alternative plans with more or less marketing risk. To lower marketing risk, the combination of various economic crops within the area should be considered and evaluated. Rice, sugar-cane, cassava and rubber trees are important export crops and products from Thailand. Their combined crop area is extensive and covers over 70% of the total cultivated land in Northeast Thailand. In Thailand, land classifications have been conducted over the past three decades. The classification system includes land capability classes for field crops and land suitability classes for rice (Land Development Department (LDD), 1996). To date, the land suitability maps are defined as the inherent capacity of a soil to grow crops. The overall mapping process still considers the inherent capacity of soils in defining the suitability of the land unit. Recently, these land suitability maps were digitally encoded in a geographic information systems (GIS) database. Furthermore, a number of pilot projects have been undertaken to test the land evaluation method using GIS. There still remains the need to establish an integration method for the relevant land qualities in the modeling of land suitability.
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