Influence of Phosphorus on Soil Organic Nitrogen Pools in Subtropical Wetlands
EMSL Project ID
48399
Abstract
Soil organic nitrogen (SON) is a major source of bioavailable nitrogen (N) to biological communities, and therefore, is an important component of soil organic matter (SOM). In wetland systems, approximately 95% of total soil N is in the form of organic N . Although the importance of SON is recognized, SON is not well characterized. This study compares SON pools along an existing phosphorus (P) gradient, from enriched to unenriched P, in the Water Conservation Area 2A (WCA-2A), Florida Everglades. The WCA-2A has been impacted by anthropogenic drainage, channelization, and nutrient loading that have resulted in a vegetation community shift, as well as long term changes in soil nutrient concentrations. Therefore, we hypothesize that N/P ratios will decrease with increasing P enrichment; however, the proportions of labile and nonlabile pools of SON will not be affected. To test this hypothesis, soil cores were obtained from enriched, intermediate, and unenriched P sites . Soil cores were separated into floc (unconsolidated detrital material), 0-10, 10-20, and 20-30 cm sections . Physico-chemical characteristics of each sample were analyzed at University of Florida for percent moisture, bulk density, loss on ignition, total carbon (C), N, and P, extractable NH4+, potentially mineralizable N (PMN), microbial biomass C and N, and leucine aminopeptidase and ?,4-N acetylglucosaminidase hydrolytic N enzymes. Soil organic N pools were determined by the diffusion method, with modification, to separate N pools into total hydrolyzable N, NH4-N, amino sugar N, amino acid N, and acid insoluble N. In conjunction with gross organic N pools, the use of high resolution mass spectrometry at EMSL will aid in the identification of specific organic N compounds across this P and vegetation gradient.
Project Details
Start Date
2014-04-25
End Date
2014-09-30
Status
Closed
Released Data Link
Team
Principal Investigator