Influence of season, ventilation strategy, and slurry removal on methane emissions from pig houses

About 60% of the global methane emission is related to anthropogenic activities such as agriculture, fossil fuel use, and waste disposal. A significant part of agricultural methane emissions originates from pig husbandry, with indoor stored pig slurry as the main source. In general, the release of methane from indoor slurry storage can be influenced by availability of oxygen and volatile solids, pH value, substrate temperature, retention time, and presence of inhibiting compounds. Investigations on methane release from a pig house with indoor slurry storage were carried out from October 1999 until February 2001 and from February 2003 until July 2004, respectively. The season, in which the fattening period was accomplished, had a significant influence on the level of the methane emission rate, with increased emissions during summer. However, a clear influence of the indoor temperature – and therefore of the ventilation strategy – on the level of the methane emission rate was only found for mean daily temperatures above 25 °C. Methane emissions were reduced significantly due to complete slurry removal between the fattening periods and subsequent cleaning of the slurry pits.