The Effect of Gypsum Content on Ammonium Adsorption in Some Gypsiferous Soils

The aim of this study was to investigate the capability of gypsiferous soils to adsorb ammonium. Ammonium adsorption by gypsiferous soils is a significant process that can be used to identify the route of ammonium nitrogen in soil and water systems. Three different samples of gypsiferous soils were collected from the Al-Alam city and the fields of College of Agriculture, Tikrit University. All the samples had various content levels of gypsum: low (65 g kg−1), medium (130 g kg–1) and high (235 g kg−1). Soil columns were utilised as part of the constant head method and various concentrations of ammonium (5, 10, 20, 40, 80, 100, 120 and 150 mg(NH4)L−1) were added. The samples were collected after different time intervals: 1, 2, 4, 8, 24, and 48 h. The equations evaluated in this research included the first order, zero order, power function, diffusion, and Elovich equation models. The ammonium adsorption in gypsiferous soils was found to conform to the zero order equation more than the other equations. The results showed that the ammonium adsorption process was not influenced by the content of gypsum in soils.