الفهرس 
ACKNOWLEDGEMENTSOnly 14 pages are availabe for public view
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Abstract
The area under investigation is a part of wadi Abu Shih that lies in the eastern desert plateau, east of Elbadary district, Assiut Governorate. It is located about 45 Km south of Assiut city. It represents the western preface of the eastern desert plateau and lies between latitudes 26o 51/ and 26o 55/ N and longitudes 31o 33/ and 33o 40/ E. It is considered one of the most promising wadies for agricultural expansion in upper Egypt. The total area understudy covers about 2,000 feddans.
The current investigation aims to give some information about soil origin, morphology, mineralogy and some physical and chemical properties of plaeonile sediment soils of wadi Abu- Shih.
Fifty one soil profiles were selected to cover the whole study area. Each profile was dug to 1.5 m in depth. After the morphological description of each profile, soil samples were taken from each layer for physical, chemical and mineralogical analyses (175 samples).
A general discussion of the different soil data obtained from the present study could be outlined in the following:
A. Soil Physical and chemical properties:
Wide variations in the physical and chemical properties were found in these soils. They can be summarized in the following:
1. Gravel content ranges from nil to 31.37 %; the highest amount of gravels lies in the subsurface layers of most soil profiles. Soil texture is mostly coarse (mainly sand, loamy sand and sandy loam). Finer soil texture i.e. silty loam, and sandy clay loam is not frequently present. In most cases, the soil texture becomes finer with depth.
2. Bulk density varies from 1.41 to 1.96 Mg/m3. A slight increase in the bulk density was observed with depth. This may be related to the decrease in the organic matter with depth.
3. Organic matter content of the soil samples ranges between 0.12 to 0.45%. In most soil sites, organic matter decreases with depth. This reflects the effect of the scanty rainfall during winter and the prevailing dry climate. However, few occasional torrents may occur and are responsible for growing natural annual plants that add their residues to the soil.
4. Total carbonates vary from 14.0 to 71.4% in these plaeonile sediment soils. All of soil samples have more than 10% of total carbonates. Therefore, these soils were considered calcareous. The high content of CaCO3 in these soils is mainly attributed to the Eocene limestone of the eastern plateau that surrounds the area understudy.
5. Soil pH values range between 7.59 and 9.20. Most of soil samples are strong alkaline. No relationships between the pH value and the profile location were observed. Such behavior is due to the young nature, weak development and the heterogeneity of the parent materials at various locations and within each profile of these soils.
6. Salinity values (ECe) of the studied samples differ from 0.27 to 67.70 dS/m. Most soil samples are non saline, but sometimes they increase in the surface and the subsurface layers. This could be attributed to the barren nature of the soil and, also, to the ineffective role of leaching due to the scanty rainfall received.
7. Soluble cations are dominated by sodium (0.17 to 76.60 mmol/kg) followed by calcium (0.08 to 13.01 mmol/kg), magnesium (0.02 to 4.28 mmol/kg) and then, potassium (0.04 to 3.12 mmol/kg). Soluble anions are dominated by chlorides (0.21 to 99.02 mmol/kg) followed by sulphates (0.01 to 5.52 mmol/kg) and bicarbonates (0.12 to 1.05 mmol/kg). Irregular distribution patterns of soluble cations and anions were noticed with depth and among soil profiles. However, certain profiles showed a decrease in soluble cations and anions with depth.
8. Gypsum content is low in all soil layers of the investigated profiles, as it ranges from 0.07 to 0.32%. This indicates that the soils were developed from parent sediments that were poor in gypsum.
B. Mineralogy of the very fine sand fraction:
Eleven soil samples representing the area understudy were chosen for light and heavy mineral identification.
1. Light minerals.
The percentages of the light minerals (90.35 to 97.05 %) in the very fine sand fraction were much higher than those of heavy minerals. Quartz (66.40 to 80.77%) dominates in the light fraction of the very fine sand. Calcite is found in moderate amounts (15.36 to 29.02%), while feldspars are present in lower amounts with a maximum percentage of 6.67 %. The main prevalent feldspars are plagioclase, while orthoclase and microcline occur in low amounts.
2. Heavy minerals.
The content of the heavy minerals in the very fine sand fraction of most studied soil samples are relatively low (2.95 to 9.65%). The index figure values are also relatively low (3.04 to 10.68%) in most soil profiles. These minerals have, generally, irregular distribution with depth in most of the studied soil profiles. Opaque minerals are the most predominant constituents in all samples. They range from 35.65 to 59.34% of the heavy fraction, without any systematic vertical distribution. The non-opaque minerals were found in the order of pyroxenes (10.61 to 31.12%), epidotes (5.03 to 10.62%), rutile (4.32 to 14.66%), amphiboles (2.19 to 8.68%), zircon (1.06 to 5.94%), sphene (0.85 to 4.03%), garnet (0.51 to 4.01%), tourmaline (0.00 to 3.40%) and other minerals (1.12 to 2.90%). Abundance of pyroxenes, epidotes and amphiboles in the studied soils emphasizes that these soils are pedologically young and the role of chemical weathering processes are relatively very weak.
3. Soil Uniformity and Weathering.
Resistant minerals such as zircon, tourmaline and rutile are used as indicators of the origin and uniformity of soil parent material. The obtained results reveal that the distribution of such resistant minerals with depth or among soil profiles does not follow any specific pattern. Values of uniformity ratios, also, reflect the non-uniformity of the parent materials and emphasize the multi-depositional regime that occurred in these soils and caused the heterogeneous nature of the parent materials. The computed weathering ratios show that these soils are weakly developed, pedogenically young and formed from different parent materials.
C. Mineralogy of the clay fraction:
Eleven soil samples that were taken from three soil profiles were selected for clay analysis including X-ray diffraction, cation exchange capacity and free iron oxides. These samples were chosen from those that were selected for the identification of light and heavy minerals.
1. Clay Minerals.
X-ray diffractograms indicate that kaolinite is the most predominant mineral in the clay fraction followed by smectites, mica-vermiculite interstratified minerals, vermiculite, chlorite, palygorskite, sepiolite, micas, mica-smectite interstratified minerals and pyrophyllite. Accessory minerals, such as quartz, k-feldspars, plagioclase and calcite represent minor proportions in this fraction. There are no specific distribution patterns of these minerals with depth. These results indicate that the studied soils are mainly formed from material derived from the eastern plateau and are still young with no clear signs of profile development.
2. Free Iron Oxides.
Free iron oxides were removed from the clay fraction of some soil samples using the dithionite-citrate-bicarbonate (DCB) method. The contents of free iron oxides (calculated as Fe2O3 %) in the clay fraction of the studied samples are relatively low and range between 2.95 and 4.32%. In most cases, values of free iron oxides are lower in the surface layer than in the subsurface one of the studied soils. However, in some cases, they are higher in the surface layer than in the subsurface one of the studied soils. These variations may be due to differences in the iron oxides of the original soil parent material suggesting a slight weathering effect at the surface of most soil profiles.
3. Cation Exchange Capacity (CEC).
Values of CEC for the clay fraction vary from 31.32 to 41.21cmol (+)/kg. These moderate CEC values are due to the dominance of both kaolinite and smectite minerals in the studied samples. Results of the CEC coincide well with the clay mineral suits of these soil samples.
D. Soil Classification:
Soil classification of the area understudy was based on field observations and laboratory data. They have an aridic (torric) soil moisture regime and hyperthermic temperature regime; these characteristics make the soils to be classified in the orders of Entisols and Aridisols. According to the Soil Taxonomy (2010), Subgroups of Typic Torripsamments, Typic Torriorthents and Typic Haplocalcids were recognized in the soils understudy.
E. Land Capability:
The studied soils were differentiated into three suitability classes of almost unsuitable (IV), unsuitable (V) and completely unsuitable (VI).
In conclusion, the Paleo-Nile sediment soils of wadi Abu Shih mostly have a coarse texture. They are considered calcareous and, in most cases, are non saline and strong alkaline.
They are weakly developed, show pedologically young nature where the chemical weathering processes are almost nil. They were formed from different parent materials. They are classified as Typic Torripsamments, Typic Torriorthents and Typic Haplocalcids.