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Third Presentation Structure Index


Clayey Soil degradation is detected via a recent method (introduced by Monier, 1994, in France) for the calculation of a Structure Index using three fluids

Clayey Soil degradation is detected via a recent method (introduced by Monier, 1994, in France) for the calculation of a Structure Index using three fluids

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  • 1. Presentation by Prof. Dr. Mohamed Fahmy Hussein The 4 th Conference on Recent Technologies in Agriculture Challenges of Agricultural Modernization Faculty of Agriculture, Cairo University Tuesday, 4 November, 2009
  • 2. Mohamed Fahmy Hussein * , , Salah El-AMIR * and Essam RAMADAN ** Application of Structure-Index Technique to Detect Soil Degradation فحص تقنية دليل بناء لرصد تدهور الأراضى * Cairo Univ., Fac. of Agric., Soil & Water Dept., Egypt ** Ministry of Agriculture, Cairo, Egypt
  • 3. Location Map, Nile-Delta Apex, Bagour, Monofyah, Egypt
  • 4. Some Experimentral Data ESP = Exchangeable Sodium% ECaP = Exchangeable Calcium%, EMgP = Exchangeable Magnesium% EKP = Exchangeable Potassium% CEC = Cation Exchange Capacity, meq/100 gram soil K = Hydraulic Conductivity (Saturated) SI = Structure Index
  • 5. Prelude – page-1
    • Soil degradation is an environmental problem world-wide.
    • Under irrigated-agriculture, soil degradation is controlled by soil water-regime.
    • A principal change in soil-water regime started in the Nile alluvial-soils of Egypt about 150 years ago, through the replacement of the basin-irrigation by perennial-irrigation.
    • That change has resulted in humid soils with shallow water-table, almost everywhere in the Nile-delta and valley.
    • The over-recharge of the semi-confined (lower) and the unconfined (upper) aquifers was estimated by tritium data-series for GW, and construction of a tritium input-function for Nile water affected by thermo-nuclear bombs of the 1960’s.
  • 6. Prelude – page-2
    • Soil structure is extremely important soil property, expressing the stresses under which the irrigated-soils are cultivated . Unstable aggregates would be formed in clayey-soils under hydraulic and chemical problems (salinity/sodicity development) due to irrigation without field-drainage.
    • Elegant technique has recently been introduced for the evaluation of soil-structure status through estimation of the stable aggregates% under three treatments ( 1- Alcohol then Water, 2- Benzene then Water, and 3- Water alone.)
    • The Benzene will over-destruct the aggregates, while Alcohol protects the aggregates, and the Water alone treatment is somewhere in-between.
  • 7. Synopsis 1
    • Fourteen profiles were sampled in the Nile-Delta Apex, Bagour Monofya Govr. for estimation of Structure-Index .
    • The samples were also analyzed for salinity level, the exchangeable cations, and the cation-exchange capacity .
    • The obtained results are discussed in this work and compared to older results for saline soils at the north of the Nile Delta.
    • The increase of the Structure-Index value indicates significant soil-structure degradation (more unstable aggregates.)
    • The rise of the piezometric level of the semi-confined aquifer, hydraulically-connected to the unconfined aquifer, during the last 120 years is about 10m (as estimated from tritium model.)
  • 8. Synopsis 2
    • The chemical change of soil-water chemistry and the rise of the water-table is believed to be behind the observed soil-structure degradation in the study area.
    • The value of the Structure-Index, SI, of the studied samples was in the range of about 2-12.
    • The linear relationships obtained between the Structure-Index with salinity (EC) and sodicity (ESP) has a high scatter due the contribution of other factors.
    • The Structure-Index method seems more sensitive than the classic Structure-Factor method
  • 9. Tritium Prediction Model for Nile Water
  • 10. Stable Aggregates and the Structure-Index Values
  • 11. Structure-Index Values in Fourteen Profiles
  • 12. Structure-Factor Values in Five Profiles
  • 13. Structure-Index and Structure-Factor versus ESP
  • 14. SI versus EC, and ln ESP versus ln EC
  • 15. Exchangeable Cations versus ESP
  • 16. Log-transformation of K sat , ESP, and Structure-Index
  • 17. ملخص
      • أوضحت البيانات وجود تدهور ملحوظ بالبناء الأرضى فى نحو نصف عدد القطاعات محل الدراسة، حتى بالطبقات العليا لا السفلى فقط . وظهر أن ) دليل البناء ( structure-index, SI يمتاز بسهولته عند مقارنة عدد كبير من العينات ويعطى دلالة أوضح من ) مُعامل البناء structure-factor , SF( التقليدى، كما يمكننا ربطه بغيره من المتغيرات - كتملح وصودية التربة وتوصيلها الهيدروليكى المشبع - وهو أمر هام لما لتلك المتغيرات من علاقة بتدهور بناء التربة بفعل التغيرات المائية .
      • لاحظنا ارتباط قيم دليل البناء ( SI ) بتملح الترية ( EC ) والصودية ( ESP ) خطياً، وإن كانت نقاط البيانات فى العلاقتبن ( SI - EC ) و ( SI - ESP ) عالية التبعثر خصوصاً بالمراحل المتأخرة من تزايد التملح والصودية . وكان ميل الخط ( SI - EC ) أكبر من ميل الخط ( SI - ESP ) ، مما يعنى أن تدهور التربة يظهر بمجرد بدء تملحها وقبل تحولها لتربة صودية، ولاحظنا أن تزايد التملح عن dS/m 16 أدى لانخفاض رقم الدليل ( وهو تحسن وهمى سببه تزايد التماسك بفعل التملح المفرط ) مما جعل الخط المستقيم يلتوى لأسفل . تراوحت قيمة رقم الدليل بين حوالى 2 و 12 ، وظهرت علاقات خطية موجبة بين التملح ( EC ) والصودية ( ESP ) ، وانخفض التوصيل الهيدروليكى المشبع بنزايد رقم الدليل . ولحأنا لتحويل قيم التوصيل الهيدروليكى ودليل البناء والصودية ( ESP ) لوغاريتمياً لإيضاح الانحدارات الخطية .
      • لاحظنا نفع الدليل كمؤشر على حالة بناء التربة، ونعتقد أنه يفيد مشروعات صيانة الأراضى ثقيلة - القوام، خاصة المتأثرة بالأملاح، لأن التعرف على مدى التدهور هو أولى خطوات تحسين الأراضى .
  • 18. شكراً Thank You