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Accueil du site → Doctorat → États-Unis → 1985 → RELATIVE ERODIBILITY OF NINE SELECTED MOROCCAN SOILS AS RELATED TO THEIR PHYSICAL, CHEMICAL AND MINERALOGICAL PROPERTIES (EROSION, SIMULATION)

University of Minnesota (1985)

RELATIVE ERODIBILITY OF NINE SELECTED MOROCCAN SOILS AS RELATED TO THEIR PHYSICAL, CHEMICAL AND MINERALOGICAL PROPERTIES (EROSION, SIMULATION)

MERZOUK, ABDELAZIZ

Titre : RELATIVE ERODIBILITY OF NINE SELECTED MOROCCAN SOILS AS RELATED TO THEIR PHYSICAL, CHEMICAL AND MINERALOGICAL PROPERTIES (EROSION, SIMULATION)

Auteur : MERZOUK, ABDELAZIZ

Université de soutenance : University of Minnesota

Grade : Doctor of Philosophy (PhD) 1985

Résumé
Soil erodibility was studied in three regions of Morocco (Settat, Rabat, Tangier). Field experiments were conducted using a portable rainfall simulator to estimate a relative erodibility index (grams of detached soil/m(’2)) at 50 sites representing nine soils. This index permitted distinction of a high erodibility group Biad (calcixeroll), Vert (vertisol) , a moderate group P. Vert (vertic palexeroll), Trias (xerortent), Hamri (vertic xerortent) , a low group Calci (petrocalcic palexeroll), Tleta (vertic xerofluvent) and very low group Aine A. (ochraqual) and Sand (quartzipsament) . The soils were chemically, physically and mineralogically characterized. Aggregate stability was tested using a laboratory rainfall simulator. The relationship between soil properties and erosion was studied using simple and multiple regression analysis. The high relative erodibility of the Calcareous soil (Biad) was partly attributed to the occurence of active CaCO(,3) mostly in the silt fraction, which made this soil behave like a silty soil. The smectitic nature of the clay minerals and low organic matter content resulted in rapid swelling and slaking upon wetting of Biad and Vertisol. The slaking produced small aggregates that were easily removed from the plot by runoff. The new method for testing aggregate stability based on rainfall showed a better correlation with soil erodibility than conventional wet sieving method (% W.S.A). The stepwise multiple regression analysis yielded a six-term predictive model for relative soil erodibility. The selected parameters were (1) % soil fraction > 2mm + % sand, (2) % active CaCO(,3), (3) % smectite, (4) Electrical Conductivity (EC), (5) saturated hydr. conductivity, K and (6) % W.S.A x MWD of aggregate before rainfall. Three soil parameters that are easily obtained in laboratory were selected to form a simple relative erodibility index in the following equation : Erodibility index = SL = 311.83 - 4.48(% SM > mm + % sand) + 6.45(% active CaCO(,3)) + 613.4 EC, where SL = Soil Loss, SM = Soil Material, R(’2) = 0.98. Results of the present study indicate that relative erodibility ranking based on simulated rainfall tests can provide a rapid and economic means of assessing erosion risks on soils from widely separated areas.

Mots clés : Agronomy, Biological sciences

Accès au document : Proquest Dissertations & Theses

Page publiée le 28 février 2015, mise à jour le 27 décembre 2016