Adsorption of Nitrogen Chemical Fertilizer on Volcanic Ash Soil and Electric Charge Characteristics

Abstract

Ammonium sulfate or ammonium nitrate solution was added repetitiously in volcanic ash soil. The difference in amount of anion adsorption or cation desorption, and the change in pH were compared with the simulated results by the four plane model. pH of soil solution was lowered by the addition of the ammonium nitrate solution, and pH was increased in the ammonium sulfate solution. The amount of desorption of the base cation in the ammonium nitrate solution was large than that of ammonium sulfate solution addition. The adsorbed amount of sulfate ion was increased, even if pH rose in the ammonium sulfate solution addition. The amount of sulfate ion adsorption was depended on concentration, and that didn’t depend on hydrogen ion concentration by adaptation of regression equation that composed with anion and hydrogen ion concentration. Sulfate and nitrate ion adsorption calculated by the four plain model were corresponded to the measurements well. Comparing the simulated charge density at each plain, addition of ammonium sulfate solution was large than that of ammonium nitrate solution addition. In the case of ammonium sulfate solution addtion, amount of hydrogen ion adsorption on S plain was large than that of hydroxyl ion compared with ammonium nitrate solution addition. These simulated results correspond with the pH measurements.