Wetlands are identi ed as key ecosystems in the UN Decade on Restoration initiative because of their water management and global warming bene ts. Wetland restoration sometimes includes adding organic matter (+ OM) to accelerate hydric soil development and provide nutrients for new vegetation. We conducted a manipulative eld experiment to identify the most effective type of + OM and loading rate for soil and vegetation development in a freshwater wetland restoration site that was a former agricultural eld. The + OM included municipal waste biosolids, composted wood chips, and cow manure at various application rates. We found that + OM had little in uence on soil bulk density or hydric soil indicators, and resulted in the growth of undesirable vegetation and increased greenhouse gas ux. For example, manure, which contains nitrogen (N) and phosphorus (P), increased aboveground biomass but favored non-native species that lowered plant diversity and oristic quality. All + OM increased methane (CH 4 ), but the range varied greatly (1.04-7.3 times). Hydrology also had a strong in uence on CH 4 emissions, and areas that experienced wet-dry cycles had 1.7-3.0 times more estimated annual CH 4 emissions that those that were constantly inundated. Organic soil amendments were not necessary to support wetland plant growth or develop hydric soils, and may unnecessarily exacerbate atmospheric warming and invasive species spread.