THE METHANE UPTAKE CAPACITY OF SOIL GARDEN

Abstract

Aerobic CH4 oxidation through methanotrophic bacteria is the only terrestrial sink and the only sink that can be altered directly or indirectly by human so far. However, the capacity of this sink is highly variable in different ecosystems depending on four key factors which are soil diffusivity, soil temperature, soil nitrogen status and soil moisture. While many studies in Australia experience the significant inverse correlation between soil moisture and CH4 flux magnitude in temperate forests in Victoria and New South Wales, there is a lack of research about the methane uptake capacity of garden soil. Consequently, we hypothesise that there is a similar pattern of CH4 uptake by garden soil. The aim of this study is to determine the capacity of CH4 oxidation along the soil garden profile. Our study was conducted at a native garden in Burnley Campus of the University of Melbourne, Victoria, Australia. Our results show three main findings. Firstly, garden soil can become a significant sink of CH4. Secondly, there was a significant correlation between soil moisture and the soil CH4 uptake rates. Finally, there was an expansion of the CH4 oxidation layer to deeper soil layers as the soil dries at the surface.