Keep manure fresh, get more!

During manure storage (1–6 months), valuable nutrients and organic contents are degraded, emitting substantial amounts of greenhouse gases (GHGs) and odors. Through the application of acidification and cooling-down, the less emissions during storage and beneficial outcomes in further treatment can be expected. However, there is a concern whether these storage technologies really deserve or not. In the present work, at first, a comprehensive review was conducted on (1) the amount of GHGs and odor emissions from manure, (2) the reduction in emitting gases by acidification and cooling-down with mechanisms behind them, and (3) its consequences on the increased biogas production and crop yield. Considering all these, an environmental and economic assessment was performed for three climatic regions (warm, temperate, and cool). It was found that H2SO4-acidification can reduce GHGs emissions by 12.6–97.2 kg CO2 eq/ton manure (>75 % during the storage process), while the significant reduction was attained in warm region. And, except one case (cool, pH 5.5, and carbon price of 30 USD/kg CO2 eq.), the profit of 0.31–8.69 USD/ton manure was expected. To our knowledge, this is the first systematic review addressing the importance of “keeping the freshness of manure” to save the planet and get more income.