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Zagazig University (2000)

Pedochemical studies on soils of some plains in Sinai

Abd Al-Aziz, Wafaa Hussein

Titre : Pedochemical studies on soils of some plains in Sinai

Auteur : Abd Al-Aziz, Wafaa Hussein

Etablissement de soutenance : Zagazig University

Grade : Doctor of Philosophy (PhD) 2000

he study concern the pedochemical characteristics of soil in El- Tina and EI-Qaa plain in the north western and south western parts of Sinai Peninsula. Twenty two soil profiles were taken to represent the different geomorphic units in the areas, and were morphologically described ; and their physical, chemical and mineralogical properties were measured. 1- Physical and chemical properties (I) Soils of EI- Tina plain geomorphic units : a-EI-Tina- plain. These soils have variable texture, sandy to clayey with increase of clay with depths. Content of CaC03 varies from 0.02 to 6.4 %, organic matter was less than 1.4 %. Soils are neutral to moderately alkaline (pH 7.0 to 8.3.) values ofEC of saturation extract =110 to 219 dSm-1 (extremely saline). Soluble ions Na+ >Ca++> Mg++>K+ ; CI> 804> HC03-(no cOtl. Gypsum : 0.3 to 9.9%. 20J b- The elevated sand dunes Soil textures mainly sands, with one sandy Ioam ; content of CaC03 = 1.8 and 6.6 % (no specific pattern with depth). Organic matter = 0.05 to 0.20/0. Soils are midly alkaline to moderately alkline (pH 7.6 to 8.3) ; E C = 0.4 to 1.4dSm-1• Soluble ions : Na+ »ca” > Mg++>K+ S04- > cr >HC03- in two profiles and cr > S04- > HC03- in the other two profiles. Gypsum = 0.13 — 0.280/0. (2) Soils of El- Qaa plain geomorphic units. a- The wadis. Soil txture varies from sand to silty clay ; CaC03 = 6.8 up to 39.2 %. The highest CaC03 is generally associated with the limestone parent material. Organic matter content< 0.40/0.soils are midly alkaline( pH 7.6
8.0). EC = 0.65 to 32.5 dSm-’ soluble ions : Na+ > Ca ++> Mg++ > K+ ; S04- »Cl’ >HC03 in two profiles, Cl> S04- > one profile. Gypsum content = 0.080/0to 5.5%. b- Soils of the alluvial fan. These soils have coarser texture ranges from sand to loamy sand ; Ca C03 = 1.7 and 10.3%. Organic matter < 0.04%. Soils are midly alkaline (pH 7.5 to 8.0), Ee = OJ to 0.7 dSm- 1 . Soluble ions c-Soil of the coastal plain. These soils have texture class varies from sand to sandy loam . CaC03 = 3.5 to 38.1 0,/0 no pattern with depth. Organic matter < 0.1 % Soils are mildly alkaline (pH 7.5 - 8.0). EC = 3.2 to 33.4 dSm Gypsum content =0.2 to 0.80/0. 2- Cation exchange capacity. Cation exchange capacity (CEC) = 16.5 - 53.2 me/IOOg EI-Tina  plain, with Mg++being the dominate followed by Ca++. CEC in elevated sand dunes = 2.7 - 6.8 me/IOOg. Ca >Mg++> Na+ >K. In EI-Qaa plain, CEC = 1.5 to 9.8 me/100g ; Ca >Na+ 3- The total amorphous inorganic materials In El-Tina plain content = 1.49-3.90/0ranged with the dominance of silica (0.9 _2.40/0)followed by iron oxides (0.14-1.2%) and alomina oxides(0.06-1.20/o). In the elevated sand dunes plain contents = 0.36- 1.43% ranged with dominant of silica ( 0.29-1.16°.10)followed by iron oxides (0.04 - 0.25%) and alumina oxides (0.004 - 0.03). In EI-Qaa plain content = 0.45-L51 with silica> iron oxides> alumina oxides. No specific depthwise distribution high contents El-Tina plain may be due to the long time of aqueous transportation prior to sedimantation and the low content in EI-Qaa is reflection of the arid conditions and the sandy nature dunes . 4-Total of Fe, Mo, Zn,and Cu. Total Fe = 1.5- 74.4 g kg” highest in EI-Tina plain and lowest in EI-Qaa plain. Total Mn = 10 to 1200 mg kg” g highest in EI-Tina ; lowest in El-Qaa. Cu = 2.0 -89.0 mg kg-l , highest in EI-Tina, lowest in EI-Qaa. Total Zn = 5.0to 85.3 mg kg”, highest in El-Tina plain, , lowest in El-Qaa plain. The vertical distribution of trace elements is discussed in light of the statistical parameters of weighted mean ”W”, trend ”T” and specific range ”R”. 5-Soil mineralogy. 5.1 Mineralogy of the sand fraction. Light minerals are almost entirely of Quartiz (> 92.49 %), associated minerals are feldspars of which orthclase and plagioclase are principal members while microcline is the least abundant. Heavy minerals are dominated by opaques ; the non-apques are dominate by proxenes, amphiboles and epidotes. Zircon, grant, rutile and tourmaline are in moderate amounts, the others are less or absent. Uniformity of soil parent materials A test of uniformity and development of soil profiles is conducted by based on evaluating the frequency distribution of resistant minerals and weathering ratios, soils are heterogeneous (either due to their multi-origin or to the subsequent variations during their sedImentation) being young pedologically. clay mineralogy. Mineralogical identification of 19 clay samples using x-ray diffraction showed smectite (montmorillonite) as the predominant minerals followed by Kaolinite then interstratified minerals, hydrous mica, vermiculite and chlorite. Accessory minerals are mostly quartiz followed by feldspars, with calcite and dolomite in traces. EI-Qaa plain> elevated sand dunes. 7- Cation exchange capacity of the clay fraction Values = 18.7 _ 52.2 me IIOOg., highest in EI-Tina plain, lowest in the elevated sand dunes ; since smectite was greater the former than the latter geomorphic unite than the soil samples of elevated sand dunes and EI-Qaa plain. 8-soil Taxonomy. Aridisols and Entisols. 1-Aridisols 1- Typic Aquisalids 2- Gypsic Aquisalds 3- Typic HaplosaUds 4- Gypsic Haplosalids 5- Typic Haplocakids 11- entisols 1- Typic Torri psamments. 2- Typic Torri orthents 9. Land evaluation ( 8 2 ) Good soils in part of the elevated sand dunes(El-Tina) and part of the coastal plain (El-Qaa) ( 8 3 ) Fair soils in El-Tina plain the elevated sand dunes, wadis (EI-Qaa) and alluvial fan (N) Non agricultural soils, in part of the elevated sand dunes (EITina)

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Page publiée le 27 janvier 2016, mise à jour le 5 février 2019