| Abstract: | Fate of fertilizer ammonium in soils with different composition of clay minerals in an incubation experiment In an incubation experiment with three different soils (gray brown podsolic soil from loess, alluvial gley, and brown earth, derived from basalt) the specific adsorption (fixation) and release of fertilizer NH4+ was investigated. In one treatment 120 mg NH4–N/kg soil was added, while the other treatment (control) received no nitrogen. Soils samples were taken every ten days and analyzed for nonexchangeable and exchangeable NH4+ and NO3?. The experimental results are showing that the specific adsorption of applied NH4+ was related to the type of clay minerals. While the loess soil, rich in illite, and the alluvial soil, rich in expansible clay minerals, bound about 40% of the added NH4+ specifically, the soil derived from basalt with mainly kaolinite bound only about 10 %. From the recently “fixed” fertilizer NH4+ about a half was nitrified during the incubation period of about 9 weeks. In the control there was no significant release of specifically bound NH4+. Obviously this NH4+ is located more deeply in the interlayers of the clay minerals and not available to microorganisms. |
