Cattle manure suppresses methane consumption and enhances denitrification-associated nitrous oxide production in farm dams.

backgroundFarm dams (or agricultural ponds) are often heavily polluted freshwater systems because of nutrient-rich manure entering the water through direct deposition and runoff. Accordingly, these systems have among the highest greenhouse gas emissions per area, accounting for 41% of global freshwater methane emissions. Sustainable management actions, such as limiting livestock access through fencing, can significantly reduce nutrient concentrations and greenhouse gas emissions. However, the microbes, processes, and factors controlling greenhouse gas cycling in these systems have not been described. Here, we systematically compared the composition, functions, and activities of the microbes in paired fenced and unfenced cattle farm dams in southeastern Australia.

resultsWe found that in situ methane (CH

conclusionsOur findings highlight how anthropogenic activities such as livestock farming can impact microbial communities and biogeochemical cycling, thereby increasing greenhouse gas emissions from freshwater systems, and how simple management actions like fencing can mitigate such emissions. Video Abstract.