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Quantifying Metahne Emissions - New Method


It is presently not possible to quantify emissions of methane gas from livestock and livestock manure. This is a significant problem, especially at a time where the EU Commission is requiring Denmark to drastically reduce emissions of greenhouse gases from agriculture. With no method or procedure to quantify emissions, it's additionally impossible to document effects of changes in management.

A new published research article in the journal PLOS ONE, addresses this challenge and proposes a new technique that may well be a crucial step forward towards quantifying methane emissions and degradation processes related to manure management.

The specific challenge in the industry is that the primarily liquid manure (slurry) is collected in pits beneath animal confinements. This can then sit there for up to a month before being exported to an outside storage tank, or for treatment. During this time, while the manure slurry is just sitting, degradation of manure organic matter has already begun and will start emitting methane and greenhouse gas. However, animals themselves are a source of supply of both gases, and therefore, separating amounts of methane gas and greenhouse gas being emitted from livestock as opposed to the manure slurry becomes virtually impossible.

The new method proposed here is predicated on laboratory measurements of methane production in liquid manure samples collected on farms. Instead, a simple model is employed to calculate daily emissions. This model can then be used to evaluate effects of changes in management or treatment of the manure, for example, biogas treatment

Methane is, after carbon dioxide, the most important source of greenhouse gases from agriculture, and the most important on-farm source. Here the largest single source is animal digestion, especially in ruminants such as cattle, whereas on pig farms manure is the main source. Since the residence time of methane in the atmosphere is short compared to other greenhouse gases, a reduction of methane will be particularly effective in the short term at reducing climate forcing. Moreover, methods to reduce methane emissions from manure are already available (biogas treatment, slurry acidification). For these reasons methane emissions from livestock manure is an obviouos target for greenhouse gas mitigation.

Degradation of manure organic matter leads to emissions of methane, but even larger emissions of carbon dioxide. Both methane and carbon dioxide contain carbon from manure organic matter that is degraded. This loss of organic carbon is critical for the biogas potential of manure which is directly related to the degradable organic matter left in the manure. For example, a shorter collection period would likely increase biogas production while at the same time reducing methane emissions, but currently these effects cannot be documented. The article discusses this synergy and concludes that a new method must also be able to quantify the emission of carbon dioxide, in order to estimate the loss of degradable organic matter from slurry pits. Plans to further develop the method have been described in a new research proposal in collaboration with research institutions in Germany, Netherlands, Great Britain and Sweden, and a Swedish company.

Article cited from: https://goo.gl/lXmwSn