Nitrogen and phosphorus mass balances in natural and sewage-enriched cypress domes.
Nutrient balance was studied in two small Taxodium distichum swamps in Florida, one of which had been treated with secondary sewage effluent from 1975 to 1977. Annual nutrient inputs from sewage were 14.9 g/m2 for N and 11.4 g/m2 for P, representing 90 and 99% respectively of total inputs. Total annual inputs to the untreated swamp were 2.19-4.26 g/m2 for N and 0.051 g/m2 for P. N fixation represented 34-66% of total N input in the untreated swamp, but only 3% in the treated swamp. Denitrification was greater in the treated swamp. N and P contents of above-ground cypress biomass were greater in the treated swamp, though the fraction of total inputs stored was much less than in the untreated swamp. In the treated swamp, 74% of N and 92% of P were retained, mainly in below-ground biomass and peat.