Solute Movement Through Disturbed and Undisturbed Soil Cores

Displacement of nitrate and 36 Cl through disturbed (reconstituted horizon by horizon) and undisturbed soil profiles of Aberdeen loam and Beotia loam representing strong and moderate soil structure, respectively, were investigated. Each soil core was 30 cm in diameter and at least 80 cm high. Mean water content θ̄ of the undisturbed soil profile was greater and mean bulk density D̄ b less than the corresponding values for the disturbed cores for each soil. For example, disturbance increased θ̄ by 0.07 cm 3 /cm 3 for Beotia with a 0.01 g/cm 3 decrease in D̄ b ; disturbing Aberdeen decreased D̄ b from 1.47 to 1.30 g/cm 3 but increased θ̄ only 0.03 cm 3 /cm 3 . The disturbed soils required greater throughout volume of distilled water to displace the solutes and had smaller dispersion coefficients ( D ) than the undisturbed soils although not even a twofold difference in D was found. For a given effluent sample, relative nitrate concentration was consistently greater than relative 36 Cl concentration due to nitrification occurring within both the disturbed and undisturbed soil profiles during the 24‐week period.