4.2 Land Suitability, agricultural land was to evaluate for each economic crop (rice,
sugarcane, cassava, mango, rubber). The FAO Land Evaluation (FAO, 1983) was employed in
this study. For each crop, land units resulting from the overlay process of the selected factor
layers were established. Factors used in land suitability were collected based on affecting
growth and yield of each crop as Table 1. Each factor is a thematic layer in the GIS. The
evaluation process comprised 6 steps which include:
1) Suitability based on climate, the factor used to evaluate was only the average
annual rainfall.
2) Suitability base on soil, the factor used to evaluated comprised of 7 factors
which include (1)Drainage capacity (DRN, it is a layer name) (2)Soil depth (DPT) (3)Soil
texture (TXT) (4)Cation exchange capacity(CEC) (5)Base saturation(BS) (6)Available