The objective of this study was to evaluate the fixation of ammonium in the soils of Tokat region to find out the important factors influencing them. For this purpose 12 representative soil samples were collected from different Great Soil Groups in the region. The amount of ammonium fixed naturally in the samples was found between 41.62-66.90 ppm ammonium (0.29-0.47 me NH 4 -N/100 g. soil). The amounts of ammonium fixed by the soils where increasing amounts of ammonium applied were found between 0.63-1.29%. There was a significant effect from application of potassium to the soils on the fixation of ammonium. Potassium applied before ammonium decreased the ammonium fixation in all soils, but when it was applied with ammonium it increased the ammonium fixation in other soils except in Ustifluvent 1-2, Ustorthent 2 and Haplustalf 1-2.

The objective of this study was to evaluate the fixation of ammonium in the soils of Tokat region to find out the important factors influencing them. For this purpose 12 representative soil samples were collected from different Great Soil Groups in the region. The amount of ammonium fixed naturally in the samples was found between 41.62-66.90 ppm ammonium (0.29-0.47 me NH 4 -N/100 g. soil). The amounts of ammonium fixed by the soils where increasing amounts of ammonium applied were found between 0.63-1.29%. There was a significant effect from application of potassium to the soils on the fixation of ammonium. Potassium applied before ammonium decreased the ammonium fixation in all soils, but when it was applied with ammonium it increased the ammonium fixation in other soils except in Ustifluvent 1-2, Ustorthent 2 and Haplustalf 1-2.