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Accueil du site → Master → Etats Unis → 1996 → Soil chemistry and hydrodynamics of irrigation with drainwater

University of Nevada, Reno (1996)

Soil chemistry and hydrodynamics of irrigation with drainwater

Faulkner, Barton Richard

Titre : Soil chemistry and hydrodynamics of irrigation with drainwater

Auteur : Faulkner, Barton Richard

Université de soutenance : University of Nevada, Reno

Grade : Master of Science (MS) 1996

Résumé
A study was conducted on a semi-arid irrigated field to evaluate the effect of irrigating spring wheat (Triticum aestivum) with brackish (1,255 mg/L TDS) drainwater on soil chemistry and trace element mobility. An evapotranspiration model was used for irrigation scheduling to minimize drainage. Lysimeters (2.4 m deep, 3.05 m dia.) showed no measurable deep percolation during the 1995 season. Stable isotope data suggest a significant contribution of evaporation to drainwater salinity. Application of Gapon-type exchange equations indicated a less than 7% increase in exchange-phase Na$\sp+$/Ca$\sp2+$ under extreme evapotranspiration. Measured transect-averaged SAR values in soil samples (sandy, mixed, mesic, Xerofluvent) ranged from 5.0 in the upper profile to 16.8 below 1 m. Mechanistic models for observed behavior of arsenic, phosphate, and boron are presented, based on equilibrium geochemical modeling. The models explain observed non-conservative behavior, and can be used to help manage trace element concentrations in soils.

Mots clés : Agricultural chemicals, Triticum aestivum, Soil sciences, Hydrology, Pure sciences, Earth sciences Biological sciences

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