A Decadal Scale Nutrient Loading Study in a Coastal Wetland: Impacts on Soil Microbial Processes.

Wetlands occupy a critical interface between terrestrial and aquatic environments, and can be impacted by anthropogenic activity in the upland system.  Increased use of fertilizer in agricultural lands and disposal of treated wastewater has increased loading of bioavailable nutrients linked to the global problem of eutrophication. Changes in macronutrients can potentially affect nutrient cycling and Microbial processes in wetlands.  Recently, there have been some conflicting results on the impacts of nutrient loading to wetland systems.  Though many studies have investigated the impacts from short term loading on wetlands, there has been little work in determining long term implications. This project investigated the effects of nutrient loading in a coastal wetland over a ten year period.  Treatments paired nitrogen levels of 0, 50, 200, and 1200 kg ha^-1 yr^-1 with phosphorus levels of 0, 131 kg ha^-1 yr^-1.   We measured the impact of long term nutrient loading on various soil physiochemical characteristics as well as microbial measures  (microbial biomass, potentially mineralizable nitrogen rates, and potential denitrification rates).  Preliminary results suggest that there is little to no effect from these levels of nutrient loading on microbial activity or soil enrichment.