Kr. Reddy et al., PHOSPHORUS STORAGE CAPACITY OF UPLANDS, WETLANDS AND STREAMS OF THE LAKE OKEECHOBEE WATERSHED, FLORIDA, Agriculture, ecosystems & environment, 59(3), 1996, pp. 203-216
Lake Okeechobee, a subtropical, shallow lake in south Florida, is seve
rely affected from eutrophication resulting from non-point source agri
cultural phosphorus (P) loading. The Lower Kissimmee River and Taylor
Creek/Nubbin Slough watersheds are major contributors of P to Lake Oke
echobee with 57% of the total P load attributed to these two watershed
s. Major land use in these watersheds are dairy and beef pastures. Soi
ls are dominated by Spodosols. The P storage capacity of uplands, wetl
ands and streams in the Lake Okeechobee Watershed was estimated based
on the analysis of soil and vegetation, and imports of P into the wate
rshed. Results showed that about 70% of the total P imported into the
watershed is stored in uplands, and an additional 18% is stored in wet
lands and streams. Phosphorus retention in soils was strongly associat
ed with Al and Fe oxides and total organic carbon. Phosphorus storage
in vegetation was found to be short-term and accounted for less than 5
% of the total P storage, Phosphorus retention characteristics of soil
s and sediments suggest that about 75% and 45% of the storage capacity
is still available for additional retention in uplands, wetlands and
stream sediments, respectively. Although the watershed has a large cap
acity to store P, continuous loading can decrease the P buffering capa
city of soils and sediments and increase P levels in surface and sub-s
urface flow.