The impact of agricultural soil management practices on GHG emissions

To reach Switzerland's net zero emissions target for 2050, significant reductions of greenhouse gas (GHG) emissions are needed. According to FOEN’s greenhouse gas inventory of Switzerland in 2021, the agricultural sector was responsible for 13% of Switzerland's total GHG emissions. Almost a quarter of these emissions originated from agricultural soils. 

Sus.lab conducted a literature review on the impact of soil management practices on GHG emissions, with the goal to identify the drivers of soil nitrous oxide (N2O) emissions. The review was conducted in collaboration with HofLabor, an on-farm innovation project to develop regenerative “mosaic farming” as a scalable approach to farming with high biodiversity above and within the soil. 

The review identified two drivers of N2O emissions: soil aeration and nitrogen (N) availability in the soil. Both are affected by soil characteristics and can be influenced by soil management practices, such as controlled traffic farming (CTF), tillage, fertilization or cover cropping. In addition, soil management practices are important in promoting a diverse soil biome, which plays a critical role in many soil functions, including the formation and turnover of soil organic matter and nutrient cycling. 

It is important to account for existing soil conditions when deciding which soil management practices to implement and combine. For example, CTF can be used to reduce soil compaction and alleviate the need for tillage as an aeration management practice while reducing tillage’s harmful effects on soil, such as destroying the soil’s physical structure or suppressing fungal activity. Furthermore, implementing cover crops during the fallow season can significantly reduce N2O emissions from otherwise empty fields. 

While agricultural soils are known emitters of GHGs, they can also act as sinks for methane (CH4) and play a major role in soil organic carbon (SOC) sequestration. These aspects can be influenced by soil management practices, such as decreased SOC loss from soils under no-till management. 

To conclude, there are different soil management practices available to mitigate net GHG emissions and promote healthy soils. Tailoring approaches to soil conditions is crucial when deciding on the combination of soil management practices to implement. 

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