MODIFIED LAND SUITABILITY EVALUATION MODEL FOR IRRIGATED AGRICULTURE

Abstract

The proposed modification of soil rating was performed to study the comparison between different methods of land evaluation for the irrigated arid and semi-arid regions. Therefore, twenty-two soil profiles were chosen to represent some soils of the main geomorphic units within the Nile Delta and its desert fringes in Egypt. These soil profiles were assessed to identify the suitability classes by using the parametric soil rating of Storie and Sys systems as well as the descriptive FAO and USBR schemes. Data revealed the major differences in suitability classes with respect to their either descriptive or parametric system. The modified soil rating model depends mainly on soil characteristics itself. The principle of land classification in arid and semi-arid regions, the concepts of FAO Framework, Storie and Sys methods, as well as the guidelines for soil profile description and the criteria of soil taxonomic units, were all take into consideration. The soil rating chart includes the more stable characteristics (factor a), the relatively less stable characteristics (factor b); surface characteristics (factor c), and the miscellaneous (factor x) with respect to Suitability index values of (Si) is calculated as: Si = Factor (a) x factor (b) / 100 x factor (c) / 100 x factor (x) /100 However; S1 (Si ≥ 80) Highly Suitable S4 (20 – 39) Marginally Suitable S2 (60 - 79) Suitable SC (10 – 19) Conditionally Suitable S3 (40 - 59) Moderately Suitable N (Si < 10) Unsuitable By using the modified rating, the obtained results would become more reliable application and qualitative evaluation of either current or potential suitability classes pertinent the preproject, reconnaissance and even detailed phase of soil survey.