الفهرس | Only 14 pages are availabe for public view |
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). 17 ===============:====Su””,uuy===== 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. |