A Chromatographic Approach to the Leaching of Fertilizer Salts in Soils1
- G. W. Thomas and
- N. T. Coleman2
The chromatographic theory of J. E. Walter was employed in the prediction of K distribution in four North Carolina surface soils representing extremes in texture and cation-exchange characteristics. The soils were made homoionic with respect to Ca, Al, or Na and packed in glass columns. A small volume of KCl solution was applied, then leached with water. K within the column was determined at 1-inch intervals and compared with the distribution predicted by the chromatographic equation.
In the cases of K-Ca and K-Al exchange an adaptation of the Gapon equilibrium constant combined with the Walter equation gave relatively good agreement with experimentally determined K distributions. K-Na exchange did not behave as predicted unless the amount of K added was large in comparison to the amount of Na in the column.
Cation-exchange capacity was an additional factor which influenced the retention of K by soils. Calcium soils adsorbed more K than did Al soils but this was confounded with an increase in “effective” exchange capacity with Casaturation. In general, the K distribution was described quite reasonably by the equation, but K retention at the top of the columns was consistently lower than predicted by theory.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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