To test the hypotheses that nutrient enrichment and sediment deposition interact to influence vegetation structure, belowground plant productivity and decomposition, a field experiment was implemented in three marshes in Barataria Bay, LA (healthy oligohaline [OL], brackish deteriorating [DT] and intermediate created [CR]) across experimental plots receiving one of six treatments: control, low nutrients (LN; 100 g N m^-2 yr^-1 and 11g P m^-2 yr^-1), high nutrients (HN; 1000 g m^-2 yr^-1 and 50 g P m^-2 yr^-1), sediment addition (47 kg m-² [5 cm elevation increase]), and their combination (n = 5). Datasets here include (1) root ingrowth rates; and (2) belowground decomposition rates; (3) vegetation structure; and (4) porewater nutrient concentrations.