Soil Morphology and Soil Carbon in a Constructed Sandy Freshwater Tidal Wetland.

Many wetlands in the United States are destroyed through development and road building, and constructed wetlands are sometimes used to mitigate these wetland losses. Constructed wetlands in the past have usually not provided the ecosystem services that natural wetlands provide, due to issues such as low organic carbon. Organic matter amendments help constructed wetlands achieve the functions of natural wetlands more rapidly. This study will be conducted to describe surface soil morphology, soil bulk density, and soil carbon, in a sandy freshwater tidal wetland in the Coastal Plain of Virginia, constructed in 2003. After excavation of upland soil (previously dredge material, predominantly quartz sand) to construct the wetland, five treatments were applied in 2003 (yardwaste compost at 35 ton/acre, yardwaste compost at 70 ton/acre, loamy topsoil plus yardwaste compost at 35 ton/acre, loamy topsoil without compost, and fertilized control). A detailed soil description between 0-30 cm at each plot was made in 2015. Samples were collected by horizon between 0-30 cm, and analyzed for bulk density and Total C. Pits and mounds were constructed in 2003 to mimic natural treethrow microtopography. One pit and one mound were constructed per plot. A soil sample was taken in each microtopographic position (including level areas), and analyzed for color, bulk density, and carbon. Soil color changed over time from a 10YR 5/3 matrix to higher value and lower chroma in the C horizons, but no significant differences were found between treatments. A horizons of the topsoil treatments had significantly higher BD. C horizon bulk density did not vary significantly by treatment. Soil bulk density in C horizons did not vary significantly by treatment. There was no significant difference in soil carbon in A or C horizons due to treamtnet. In the microtopography locations, pits had significantly lower chroma than mound and level plots. Pits also had lower bulk density, and higher soil carbon, due to trapping woody debris and leaf litter, as well as remaining wet longer than mound and level plots.