The Use of Inverse Distance Weighted and Fuzzy Logic to Estimate Land Suitability by Geographic Information System in South of Iraq

As soils considered an open system, adjacent of them are common in some characteristic. The use of inverse distance weighted (IDW) technology in geographic information systems (GIS) is one of the best ways of soil  characteristic interpolation depending on the Inverse distance  where there is a negative relationship between characteristic and the of the IDW, such as soil salinity and other characteristic. The main objective of this study is to estimate land suitability depending on fuzzy logic. The studied area are located in Thi-Qar province, Iraq in coordinate of 643949.033m  X, 3441469.288m Y, 643949.033m X, 3417061.751m Y, 689849.773m X, 3417061.751 Y, 689849.7733m X, 3441469.288 Y, respectively. The results indicated that most of the studied area lands were influenced by salinity, the lowest value of soil salinity was 8.45 ds/m while the highest was 152.56 ds/m. Soil textures are tending to be in the range of silt clay loam, silt clay, silt loam and loam, the dominant drainage class was poorly to moderate, while there were some classes in well and imperfect drainage classes. Gypsum content was less than 2.94%, while lime content  ranged from 24.40%  to 38.19%. The studied area was classified into five classes, the first was non suitable (red color), second class was few suitable (yellow color), third class was moderate suitable( brown color), fourth class was suitable (green color) and very suitable (chartreuse color) for grain crops. Soil classified two order Entisols and Aridisols in two sub order fluvents and salids great groups in three great group Torrifluvents,  Aquisalids  and Haplosalids  in five subgreat group of typic Torrifluvents, Aquic torrifluvent, typic Haplosalids, typic Aquisalids and calcids Aquisalids.