Soil shear strength losses in two fresh marshes with variable increases in N and P loading

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We measured soil shear strength (SSS) from 2009 to 2018 in two hydrologically distinct freshwater marshes dominated by Panicum hemitomon after nitrogen (N) and phosphorous (P) were applied to the surface in spring. The average SSS averaged over 100 cm depth in the floating and anchored marshes declined up to 30% throughout the profiles and with no apparent differences in the effects of the low, medium, and high N+P dosing. Plots with only N or P additions exhibited significant changes in SSS at individual depths below 40 cm for the anchored marsh, but not the floating marsh. The average SSS for the anchored marsh over the entire 100 cm profile declined when N and P were added separately or together. At the floating marsh, however, the SSS decreased when N and P were added in combination, or P alone, but not for the N addition. Increasing nutrient availability to these freshwater marsh soils makes them weaker, and perhaps lost if eroded or uplifted by buoyant forces during storms. These results are consistent with results from multi-year experiments demonstrating higher decomposition rates, greenhouse gas emissions, and carbon losses in wetlands following increased nutrient availability.

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Publication type Article
Publication Subtype Journal Article
Title Soil shear strength losses in two fresh marshes with variable increases in N and P loading
Series title Wetlands
DOI 10.1007/s13157-020-01265-w
Volume 40
Year Published 2020
Language English
Publisher Springer
Contributing office(s) Lower Mississippi-Gulf Water Science Center
Description 11 p.
First page 1189
Last page 1199
Country United States
State Louisiana
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