NONEXCHANGEABLE AMMONIUM BEHAVIOR OF A GRASSLAND SOIL OF THE FLOODINGPAMPA UNDER WATERLOGGING

A representative grassland soil of the lowland areas of the Flooding P ampa (Argentina) was sampled to study the dynamics of the nonexchangea ble ammonium under waterlogging conditions. Most of the external facto rs determining fixed ammonium release and fixation were considered. Th ere was no net release of ammonium from the clay fixing-sites to the s oil solution, when this soil was flooded under laboratory conditions. We conclude that the non-exchangeable ammonium fraction in this soil i s very stable and with little importance as a nitrogen source for plan ts.