Nitrate Adsorption: III. Desorption Movement and Distribution in Andepts

Abstract

Abstract A peak of NO 3 ‐ accumulation occurred in the 1‐ to 2‐cm depth of an 11‐cm soil column when 0.2 meq of KNO 3 was applied in sufficient solution (16 ml) to fill the pore space in a column of air‐dry San Gregorio soil. Practically no NO 3 ‐ was found below the 4‐cm depth. The greater portion of the NO 3 ‐ applied was displaced from the soil column by the addition of 3 pore volumes of water. The anion distribution coefficient obtained from a column of San Gregorio soil was 2.2 ml/g and was similar to that obtained from a batch‐type method when the soil was in equilibrium with the same concentration of NO 3 ‐ . The rate of NO 3 ‐ desorption was described by a first‐order reaction equation. The effect of adding SO 4 2‐ and NO 3 ‐ in the same column was to increase the rate of movement of NO 3 ‐ . Sulfate movement was much slower than that of NO 3 ‐ .