Nitrogen(N)cycling in boreal peatland ecosystems may be influenced in important ways by freeze-thaw cycles(FTCs). Adsorption and desorption of ammonium ions (NH4+)wetland, riverine wetland, and farmland reclaimed from natural wetland in response to the number of FTCs. The results indicate that freeze-thaw significantly increased the adsorption capacity of NH(4+) and reduced the desorption potential of NH4+ in the wetland soils.There were sinificant differences in the NH(4+) adsorotion amount between the soils with and without freeze-thaw treatment.The adsortion amount of NH4+ increased with increasin FTCs.The palustrine wetland soil had areater adsorption capacity and a weaker desorption potential of NH4+ than the riverine wetland soil because of the significantlv higher cla content and cation exchange capacity(CEC)of the riverine wetland soil. Because of the altered soil physical and chemical properties and hydroperiods,the adsorption capacity of NH4+ was smaller in the farmland soil than in the wetland soils, while the desorption potential of the farmland soil was higher than that of the wetland soils. Thus, wetland reclamation would decrease adsorption capacity and increase desorption potential of NH4+,which could result in N loss from the farmland soil. FTCs might mitigate N loss from soilsandreduce the risk of water pollution in downstream ecosystems.