The Future Use of Switzerland’s Organic Soils

Agroscope has compiled a new map of Switzerland’s organic soils, which forms the basis for developing a strategy for managing these soils.

Organic soils are carbon-rich soils which have formed under water-saturated conditions, typically in raised peat bogs and peat fens. In the past, many of these areas were drained and today, most organic soils are farmed. Draining these soils leads to rapid peat decomposition. This in turn leads to soil subsidence, which hampers agricultural production on these soils in the longer term and incurs high costs as the drainage systems need to be replaced every few decades. Furthermore, the drainage causes these soils to become greenhouse gas emission hotspots. The current use of these soils is at odds with the Swiss Soil Strategy as well as the concept of agricultural practices adapted to local conditions. Furthermore, it poses an obstacle to achieving national climate targets. Organic soils must be re-wetted to reduce peat decomposition and associated greenhouse gas emissions.

Over half of peatlands are farmed

A new map of Switzerland’s organic soils shows that these soils are mainly used for agriculture (32% grassland and 29% arable; 61% in total) and forestry (19%). It also shows that while only 1.2% of agriculture occurs on organic soils, these areas account for 10% of agricultural greenhouse gas emissions. These emissions equate to a quarter of the greenhouse gas emissions that need to be cut by 2050 to meet climate targets for food and agriculture.

Although at national level, organic soils account for only a very small percentage of agriculture in terms of area, at regional level the picture is somewhat different.  In some regions (e.g. Zealand, the Orbe plain) a substantial proportion of agriculture occurs on these soils. Thus, the acceptability and economic consequences of changes to the management or use of organic soils can vary considerably depending on the region.

Paludiculture as a solution

The re-wetting of farmed organic soils and their removal from food production would significantly reduce greenhouse gas emissions, but would at the same time lead to a deficit of around 1,200 hectares (<1 %) of ‘crop rotation surface’ (legally required minimum quota of land available for cropping). Paludiculture – the production of biomass, fodder or food on wetland soils – offers a solution to re-wet these soils while at the same time maintaining their agricultural function. However, paludiculture for pure biomass production, for example bullrushes of reeds, is often associated with a reduced income. On the other hand, 30% of farmed organic soils are already managed in a way that is compatible with a raised water table (e.g. extensively managed meadows and pastures). Although there are still technical and financial hurdles to overcome, greenhouse gas emissions for roughly a third of the farmed organic soil surface could be reduced without changing the crop or grassland type cultivated.