Dairy cow excreta patches change the boreal grass swards from sink to source of methane

Authors

• Marja Elisa Maljanen University of Eastern Finland Faculty of Science and Forestry Department of Environmental Science P.O.Box 1627 70211 Kuopio, Finland
• Perttu Virkajärvi
• Pertti J. Martikainen

DOI: https://doi.org/10.23986/afsci.5016

Keywords:

methane – emission, dung, urine, agriculture, grazing

Abstract

We studied methane (CH₄) flux rates from experimental excreta patches on a dairy pasture with a chamber technique during snow free seasons and with a gas gradient technique during winter from timothy-meadow fescue sward with mineral N fertilization (220 kg ha^-1) and from grass-white clover mixture without fertilization. The dung and urine patches were applied in June or August two consecutive grazing seasons and the measurements were carried out for a year following each application. There were no significant differences in CH₄ fluxes between plant species and emissions originated mainly from the fresh dung pats. The average annual CH₄ fluxes from the control sites without excreta were -0.60±0.1 and with the excreta 0.47±0.3 kg CH₄ ha^-1. Thus, excreta originating from dairy cows can turn boreal swards from weak sinks to small sources of CH₄. However, these emissions are only 0.2% of the total CH₄ emissions from a dairy cow.