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Distribution of Soil and Plant Nutrients along a Trophic Gradient in the Florida Everglades
Author(s) -
Koch M. S.,
Reddy K. R.
Publication year - 1992
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1992.03615995005600050026x
Subject(s) - soil water , nutrient , typha , environmental science , surface runoff , hydrology (agriculture) , surface water , eutrophication , wetland , environmental chemistry , chemistry , ecology , soil science , geology , biology , environmental engineering , geotechnical engineering
Historically, atmospheric precipitation has been the primary source of N and P to the Florida Everglades. Alterations to the natural hydrology, surface water runoff from agricultural lands, and controlled releases from Lake Okeechobee have increased nutrient loading to the Everglades. A nutrient front encompassing approximately 8000 ha has developed in a northern Everglades marsh, Water Conservation Area 2A (WCA‐2A; 44 684 ha), during the last three decades from surface water P and N loading, in addition to atmospheric inputs. Soil cores (0–60 cm) and plant tissue were collected from sawgrass, Cladium jamaicense Crantz, and cattail, Typha domingensis Pers., stands at a distance of 1.6, 5.6, and 9.3 km south of major surface water inflows in WCA‐2A; Site N (northern), Site C (central), and Site S (southern), respectively. Although N loading was approximately 10‐fold greater at Site N compared with Sites C and S, no significant difference in total N was found between sites at any soil depth. In contrast, P accumulated threefold in soils at Site N compared with Site S ( P < 0.05). Organic P accounted for approximately 75% of the total P. Acid‐extractable inorganic P (HCl‐P l ), as an indicator of Ca‐bound P, accounted for 80% of the inorganic P and was significantly correlated to dissolved P concentrations of the soil pore water ( r = 0.89). Alkali‐extractable inorganic P (NaOH‐P l ), as an indicator of the Fe‐ and Al‐bound P, comprised 20% of the total inorganic P. High pH values (> 8.0) were measured from pore water associated with benthic algal mats. Interstitial P concentrations were 2 to 3 orders of magnitude higher at Site N (> 1000 µg L −1 ) than at Site S (<4 µg L −1 ) and plant tissue N/P ratios at Site N and C were lower, 11:1 compared with 40:1 at Site S. These data suggest P may be an important nutrient limiting primary productivity in the Everglades and that Ca‐P precipitation, catalyzed by algal photosynthesis, may be an important mechanism for soil P assimilation.