| Sumario: | Solute movement under saturated water-flow conditions was studied in undisturbed and disturbed soil columns and in the field under four methods of clearing: manual; shear blade; tree pusher; and root rake, and traditional farming. Soil under forest was included as a control.
Chloride (Cl−) appeared in the effluent at 0.1 pore volume after its application to the surface of undisturbed soil columns taken from plots cleared manually, with shear blade, or with tree pusher. In columns fron forest and traditional farming plots, no Cl− appeared in the effluent until 0.2 pore volume of solution had passed through the columns. The pore volume required to attain 0.5 relative Cl− concentration was 0.60, 0.60, 0.40, 0.40, and 0.26 for the columns from forest control, traditional farming, shear-blade, tree-pusher and manually cleared plots, respectively. This indicates preferential water flow in the columns from manually cleared plots as compared to others. Nitrate leaching in the undisturbed columns was nearly identical to chloride. Phosphorus appeared in the effluent after the passage of 0.34 pore volume of solution through the columns of forest control and manually cleared treatments, and of 0.7 pore volume in the shear blade treatment. The increase in the relative phosphate concentration was considerably slower than chloride and nitrate. Chloride appeared later in the repacked columns than in the undisturbed columns, indicating the absence of preferential flow pathways in the disturbed columns.
In the field, less than 100% Cl− and water were retained in the 0–70 cm depth, indicating some flow of chloride solution to below 70 cm depth.
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