الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 259 |  |  |
| | | from | 259 | | |
Abstract
The study area occupies a portion of the North western coastal
belt of the Mediterranean sea which is considered among the accessible
areas attaining the most promising lands for agricultural expansion
beyond the Nile valley and Delta. It extends from Alexandria
on the east to Ras El-Dabba on the west, between latitudes 30° 40
and 31° 10 N and longitudes 28° 20 and 29° 50 E.
The physiographic features of the area are presented with particular
emphasis to the major features of the environments pertaining
to the land use, namely; climate, geology, geomorphology, ground water
conditions and vegetation.
The aim of the current work is to demonstrate the applicability
of qualitative and quantitative systems for assessing land capability
on basis of most soil properties relevant to pedogenetic classification.
To fulfil the aim of the study, 29 soil profiles stretching
along the study area are chosen to cover the major soil mapping units
encountered in the area in regard to geomorphologic aspects. These
profiles are morphologically described and 85 soil samples were
collected to represent the morphological variations within the entire
depths of profiles. These samples were evaluated for their
relevant physical, chemical and mineralogical properties.
Besides, field infiltration tests were conducted adjacent to
the most representative soil profiles. The obtained data reveal
that though the studied soils have interrelated origin, yet their
profiles display a wide range of variability in their properties,
depending on locality, lithology, landforms and depositional environments.
The most prominent feature is that particle size distribution
and textural classes vary considerably from one profile to another
and even in the subsequent layers of some profiles. Consequently,
the soil mapping units are distinguished on basis of gemorphology
(landforms) and textural variations.
Briefly, the obtained results are summarized as follows.
1- Texture varies widely from sand to clay. The soils are non
saline to extremely saline with an apparent dominance of Na+ and C1-
in the soil extract. Soil reaction is neutral to alkaline. Cation
exchange capacity varies widely from about 3 to 23 me/l00g with a
dominance of Ca on the exchange complex. Organic matter content is
very low, not exceeding 1.4%. The macronutrients(NPK) levels are
seemingly low, indicating inadequacy of N and,to some extent,P while
K level lies within the sufficient range.
2- Rating of morphological properties was figured out using
the relative horizon distinctness and horizon index. Modifications of
the morphological rating systems was provided through the inclusion
of missing data concerning CaC03 and salinity which have significant
importance in the studied soils. Their results indicate apparent
discontinuity and stratification of profile layers as shown by the
variations in RHO and horizon indexes.
3- CaC03 content ranges widely from 17.77 to 94.48% with
apparent increase of carbonate in the finer soil fractions except
for the oolitic dunes.
4- Amorphous inorganic materials content ranges from 1.1 to
4.6, 0.05 to 0.5, and 0.4 to 4.6%for 5i02, A1203 and Fe203, respectively.
The vertical distribution of these components does not
follow any specific pattern pertaining to lithology, locality or
landform. The regional distribution indicates an increase of silica
due west in contrast to alumina while both components increases from
the sea shore southwards. Amorphous iron have a common pattern
characterized by a pronounced increase with the fineness of textural
classes and also in the deepest layers of profiles.
5. Chemically extractable micronutrients vary widely from 0.36
to 2.31, 0.05 to 1.82,0.5 to 3.9, 0.5 to 14.8 and 0.05 to 9.04 ppm
for hws-8, EOTA-extractable Cu, Zn, Mn and Fe, respectively. These
levels indicate that the coarser the texture the lower is hws-B and
vice versa. Conversely, higher EOTA-extractable Cu and Zn is associated
with finer texture. A regional distribution of these elements
indicates that the weighted means of hws-B and EDTA-extractable Cu
tend to decrease westwards to El-Hammam then become almost constant
while they increase southwards from the sea shore inland. For Zn
and Mn, the maximum weighted means correspond to the soils of Burg
El-Arab and decrease progressively due East and West while weighted
mean of Fe displays a steady decrease on passing from Maryut soils
westwards. The similarity of weighted means in some profiles representing
different geomorphic units may indicate an interrelated
origin of the studied soils. The relationship between micronutrients
and soil variables was also evaluated through statistical analysis.
6- Mineralogy of the sand fraction reveals that the light fraction
is generally dominated by quartz with less pronounced amounts of
feldspars (orthoclase, plagioclase and microcline). The heavy residue
is composed essentially of opaques followed by pyroboles, epidote,
ubibuitus and parametamorphic minerals in different frequencies.
The vertical distribution of these minerals verifies the multi-depositional
regime of the non uniform parent material already established
through rating of morphological properties.
7~ Mineralogy of the clay fraction shows that palygorskite dominates
the mineralogical composition of clays irrespective of location,
mode of formation or depositional environments. The relation of clay
minerals to lithology, landform and depositional environments were
also correlated with soil origin and genesis.
8- Moisture characteristics coincide very well with textural
variations among soil profiles and layers.
9- Infiltration studies of the representative profiles indicate
a rapid to moderately slow infiltration class depending on
textural variations and succession of layers throughout profile
depth. The effect of soil variables on infiltration parameters
was evaluated statistically.
10- Soil classification was carried out following the most
recent American system ”Soil Taxonomy, 1975” down to the family
level. Briefly, the soils are placed as Typic and Lithic Torripsamments.
Typic and Lithic Torriorthents, Typic Calciorthids and
Typic Salorthids. On basis of particle size class within the
profile control section,mineralogy, soil moisture and temperature
regimes, soils belonging to the former taxonomic units are differentiated
into five families.
11- Based on the foregoing soil characteristics and recognized
agricultural limitations, qualitative land capability classification
was performed using the USDA system (1973), Parson’s system (1962)
and FAD framework of land suitability classification (1976). According
to these systems thesoils are placed under classes III to VII,
II to V and S1 ’ S2 ’ S3 ,N1 and N2 ’ respectively.
Quantitative land capability classification is also worked
out following both the modified Storie index (1933) and Sys and
,
Verheye system (1978). Accordin9 to these systems the soils of the
study area are grouped into classes C, D and E and 51’ 52’ 53’
N1 and N2, respectively. Each of these systems of land capability
classification is critically criticised and its applicability
on the study area is discussed. Moreover, modifications
for the quantitative systems to suit the highly clacareous conditions
of the arid and semi-arid lands are suggested.