EFFECTS OF FERTILIZATION ON NITROGEN DISTRIBUTION IN A SPARTINA-ALTERNIFLORA SALT-MARSH

In a year-long study of the effects of sewage sludge application on nitrogen distribution in a Spartina alterniflora salt marsh, plant biomass and consequently g N m2-2 were increased substantially. Sludge additions also resulted in higher total N concentrations in the top 5 cm of soil and in higher NH4+ concentrations throughout the 30 cm soil column sampled, but particularly from 0 to 15 cm. At the end of the study period, only about half of the added nitrogen could be accounted for. Tidal exchange was the probable mechanism of loss. Complete assessment of the impact of sludge disposal in the salt marsh ecosystem should include consideration of the impact of this loss on estuarine processes. Salinities in the sludge-amended areas were higher than in unfertilized areas, probably due to increased transpiration. The effects of this salinity increase on nitrogen utilization are discussed. © 1979.