Spatial distribution of B horizon properties in a pine flatwood landscape: New Hanover County, NC

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Carolyn Gomes (Creator)
The University of North Carolina Wilmington (UNCW )
Web Site:
Michael Benedetti

Abstract: The warm humid climate, sandy parent material, needleleaf vegetation, and high water tables of southeastern North Carolina lead to the development of acidic, leached soils known as Spodosols. These soils are defined by a subsurface accumulation of organic matter (Bh horizon). This study tests for relationships between Bh horizons and topography, grain size, depth to water, and surface organic litter in a pine forest on the campus of the University of North Carolina Wilmington. Two study units were established for sampling: one on a higher, hummocky former dune environment and the other on a lower, flatter shoreface environment. A topographic survey was conducted and point samples were collected to measure soil properties in each study unit. Two soil pits in each unit were described in detail and sampled for laboratory analysis. Piezometers were installed near each pit in order to determine depth to the water table. The results show that Bh horizons are closely related to topography. In the upper unit, greater depth to the water table (> 2.3 m) allows for greater leaching and decomposition of organic matter restricting the development of B horizons. In the lower unit, a much shallower water table (0.55-1.5 m) creates an environment that favors precipitation of organic matter and inhibits decomposition. Piezometer data show that in the lower unit, the lower portions of the Bh horizons were saturated about 25% of the time during the study period. In the upper unit, the permanent water table was never observed within the solum. However, in the lower elevations of the upper unit, subsurface clay accumulation in Bt horizons cause episaturation of the overlying soil allowing thin Bh horizons to form. The relationship between surface leaf litter and Bh horizons is not clear. Leaf litter mass is significantly greater in the upper study unit, but the B horizons contain significantly less organic carbon. These results support the concept of southeastern Coastal Plain Spodosols being controlled mainly by parent material and topography. They also show that prior pedogenesis (development of Bt horizons) can be a precursor to development of Bh horizons in drier landscape positions.

Additional Information

A Thesis Submitted to the University of North Carolina Wilmington in Partial Fulfillment of the Requirements for the Degree of Master of Science
Language: English
Date: 2009
Soil science--North Carolina--New Hanover County, Soils--North Carolina--New Hanover County, Spodosols--North Carolina--New Hanover County
Spodosols -- North Carolina -- New Hanover County
Soil science -- North Carolina -- New Hanover County
Soils -- North Carolina -- New Hanover County

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