Unsaturated Flow Phenomena in Panoche Sandy Clay Loam as Indicated by Leaching of Chloride and Nitrate Ions

Moisture suctions greater than 15 atmospheres are a common occurrence in the subsoils and substrata underlying unirrigated soils of the Panoche series. One such soil which contained appreciable quantities of Cl ‐ and NO 3 ‐ was taken from the field at a moisture suction of 16 atmospheres and packed into a column measuring 117 inches in height. This column was partially leached under unsaturated flow conditions with a saturated gypsum solution. Subsequent analyses indicated that about half the original soil moisture was not displaced downward with the dissolved Cl ‐ and NO 3 ‐ . The Cl ‐ and NO 3 ‐ concentrations contained in the displaced portion of the soil solution were about double those in the original soil solution existing at 16 atmospheres suction.