الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
Under arid and sem- arid conditions, as in Egypt, soil profile is
characterized by certain 1ayers as a result of the prevailing soil forming factors
which are well known as diagnostic horizons.
from the previous studies it was found that the most abundant
diagnostic horizons in the soils of Egypt are calcic, gypsic and salic horizons.
Therefore the study of these prevailing horizons is very important for compre
hensive und~Tstanding of the factors influencing individual soil qualities and
consequently thcrr effecc on plant growth and the suitability of certain crops.
Accordingly. eleven profiles have been selected as follows:
1- Soils with calcic horizon profiles ( No. 3,4,5,6, and 7) from EI-Fayoum
Governorate and Weszern Desert.
2- Soils with gypsic horizon, profiles ( No.1, 2 and 10) from EI- Manzala
and El - Kattamia regions.
3- Soils with salic norizon, profiles ( No. 8 and 9) from EI Sirw area, EI
Manzala,
4- Soils without diagnostic horizons profile (No. 11) from E1 Qanater, south
of the Delta
To study the impact of the specific characteristics of the previously
sampled diagnostic horizons on plant growth, a pot experiment in greenhouse
was conducted using sorghum ( sorghum bicolar munch ) and sunflower
(Helain- thus annuus ) as an indictors.
According to the data of laboratory analysis as well as field
observations, the following samples were selected for the pot experiment:
Profile No.3 (30 - 70 an), profile No.6 (60 - 120 em)
Profile No.1 ( 0 - 30 em ), profile No.8 ( 60 - 90 em )
profile No.9 (0 - 30 em) and profile No. 11 (0 - 15 em).
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from the obtained results, the folloVlirUconclusions could be outlined:
Soils with calcic horizon :
Morphological observations and the analytical data revealed that the
depth of calcic horizon differs from one profile to another. Regarding the form
of carbonates in the calcic horizon, it is obviously clear that fine grains and
powdery matrix are prevailing in profiles No.3 and 4. However large and small
concretions are abundant in the other profiles.
Calcium carbaiu.re percentage in the studied calcic horizons varied from
16.50 to 40.85. Formation of calcic horizon can be associated with gypsum
precipitation. Data o~~r-H,~J.leN5o. 3,4 and 7 indicated the presence of gypsum
( 1.26 - 7.98 % ), and ’his content does not satisfy the requirement of gypsic
horizon.
According to th~’ morphological description in the field and the
analytical data. these profiles are classified as Typic Calciorthids.
Soils with gypsic horizon:
Three profiles have been selected for the study of gypsic horizon from
two locations: El-kattania (profile No.1 and 2) and EI Manzala (profile No.
10).
Gypsum cantent ranges between 5.12 to 7.63 allover profile NO.1 and
from 3.56 to 5.17% in profile NO.2. These amounts of gypsum satisfy the
requirement of typical gypsic horizon according to the definition of Keys to
Soil Taxonomy ( 1992 ). Gypsum was identified in the field as single white
crystals, needles and po\Vday forms. Profile No.2, has surface calcic horizon.