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Research: Seaweed supplements and the impact on manure

Increasingly, researchers have looked to seaweed as a potential supplement in feed for dairy cows, that could aid in the efforts to reduce greenhouse gas emissions.

Now, new research published in the Journal of Sustainable Agriculture and Environment shows that the positive impact of seaweed as a dietary supplement may also extend to the impact of manure in pasture soils.

The paper, authored by Kyle Arndt of the Woodwell Climate Research Center, argues that although there is plenty of research into the effects of seaweed on enteric methane emissions from ruminant animals, “these studies have yet to analyze downstream impact that may arise from the deposit of affected manures on pastures or agricultural fields.”

Researchers conducted a 28-day soil and manure incubation utilizing manures collected from dairy cousin a seaweed feeding trial to analyze the impacts of manure on greenhouse gas fluxes and nutrient cycling. The team found that manure from seaweed-fed cows reduced emissions of carbon dioxide and had similar emissions of methane and nitrous oxide to the control. Higher moisture levels increased methane and nitrous oxide emissions. While some of the results were mixed, the study concluded that seaweed supplements may partially reduce climate impacts of manures, or at least not cause harm or impact manure quality.

Read the full study here.