Solving the methane mitigation mystery? Effect of compost application on the atmospheric methane uptake of agricultural soils

This thesis aimed to solve the “methane mitigation mystery” by investigating the effect of compost application on the atmospheric methane uptake of agricultural soils, thereby advancing climate mitigation strategies. While agricultural soils are typically weak methane sinks, field and laboratory experiments showed that compost can significantly improve their methane oxidation capacity. The research identified soil aggregate stability as a major factor influencing greenhouse gas fluxes and demonstrated that compost reshapes microbial communities involved in methane cycling. Compost introduced and stimulated specific species of methane-oxidizing bacteria, which drive increased methane uptake. Mechanistic analyses revealed that enhanced oxidation is linked to microbial adaptation and activity at low methane concentrations. Different compost types varied in their intrinsic methane uptake potential, with green compost performing best. Overall, the findings provide a mechanistic explanation for improved methane mitigation and highlight compost application as a promising climate-smart agricultural practice.