Assiut university researches
PEDOLOGICAL STUDIES ON SOME
PALEO-NILE SEDIMENT DERIVED SOILS
IN WADI-ABU SHIH, ASSIUT, EGYPT
‫درا سات ب يدول وج ية ع لى ب عض االرا ضى ال نا ش ئة من‬
‫–ال تر س ي بات ال ن ي ل ية ال قدي مة ف ى وادى اب و ش يح‬
‫م صر –أ س يوط‬
YASSER ABD EL-AAL SAYED
‫ي ا سر ع بدال عال س يد‬
Mohamed A. El-Desoky, Mohamed El-Ameen A. Faragallah,
Mahmoud A. Essa
‫ محمود ع ي سى‬،‫ محمد األم ين ف رج هللا‬،‫محمد ال د سوق ى‬
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 nonopaque 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, micasmectite 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-citratebicarbonate (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.