Document Type : Original Article
Authors
Pedology Dept., Water Resources and Desert Land Division, Desert Research Center, Egypt.
Abstract
Desert development is the key role of enhancing agricultural production in Egypt. The northwestern coast
is one of the most attractive desert regions for sustainable agrarian development due to its abundant qualifications which have not sufficiently used yet. This investigation was carried out in El-Qasr - Um El-Rakham area as a model for rainfed pattern at the northwestern coast, to assess both of types and capability of the soils representing dominant land forms in the area. Studied area extends over about 159603 feddan including 12 drainage basins.
The extent of landforms was spatially identified using geological and topographic maps in integration with DEM. The area represented by 6 main land forms; (1) Coastal plain (17.8%) which include: Alluvial fans (9.1%), Lagoonal depression and salt marsh (3.5%), Oolitic longitudinal sand dunes (2.2%) and Oolitic sand beach (2.8%) – (2) Alluvial terraces and Interfluves wadis (9.7%) – (3) Wadi course (2.7%) – (4) Escarpment (4.3%) – (5) Piedmont plain (13.6%) – (6) Plateau (52.1%) which include: Lower plateau (18.6%) and Higher Libyan plateau (33.5%).
Soils of the area were surveyed through 261 soil profiles which spatially distributed upon ETM+ LANDSAT 7 image classification to represent achieved landforms. Twenty four representative soil profiles were
selected in this study. A digital vector database was created using GIS, consequently, soil and evaluation maps were generated. Results indicated that ten soil mapping units were differentiated according to differences in profile depth, texture and topography properties in the area under study. Further, data emphasized that 13.6% and 19.6% of the total area, respectively have deep and moderately deep profile depth. Coarse to moderately coarse texture classes dominated whole soils. Almost flat topography to gently undulated conquered the area over 69.3%.
Based on field check and laboratory analysis, soils were classified into 10 family classes, while at sub great
group level seven classes were differentiated. These are Typic Torrifluvents (24259 F – 15.2%), Typic
Torripsamments (28728 F – 18.0%), Lithic Torripsamments (36070 F – 22.6%), Lithic Torriorthents (56978 F – 35.7%),oolitic Torripsamments (7980 F - 5.0%), Typic Aquisalids (5586 F - 3.5%), and Typic Haplosalids (260 F -0.15%).
Soils of oolitic sand beach were classified as Oolitic Torripsamments, while soils of the lagoon depressions and
salt marsh were classified as Typic Aquisalids. Soils of alluvial fans were classified as Typic Torrifluvents. As well, soils of the alluvial terraces and interfluves wadis, piedmont plain and wadi courses are generally belong to the subgroups Typic and lithic Torripsamments and Torriorthents, except small areas in the alluvial terraces and interfluves wadis and the lower portions of wadi courses were classified as Typic Torrifluvents and Typic Haplosalids. Generally, soils of plateau are classified as lithic Torriorthents.
The study concluded that, soil potentiality classified as "Good" over 13.6% of the area, including soils of alluvial fans, partially alluvial terraces and down streams of wadi courses landforms, where the potentiality index varied between 60.9 and 68.1%. Meanwhile, the potentiality was classified as "Fair" on 19.6% of the area, representing some soils of alluvial fans, alluvial terraces, wadi middle streams and piedmont plain landforms, where the potentiality index ranged from 42.5 to 57.0%. "Poor" potentiality unit extend over 22.6% of the area occupying some soils of alluvial terraces, wadi upper streams and piedmont plain landforms, as the potentiality index ranged from 30.5 to 36.8%. Potentiality indices ranged between
1.2-11.5% indicating "Very poor" and "Non agricultural" units over the rest of the area, which may be relevant to other land utilization types. Low soil potentiality associated with limitations related to; limited soil profile depth, poor drainage, coarse texture, low clay content, high salinity, high lime content and low fertility status.
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