Agriculture: in humid regions, terrace farming could have beneficial effects on the climate

An international study conducted in part at UCLouvain highlights the role of agricultural terraces – these “step-like” crops arranged on slopes – in carbon storage. However, their effects on the climate are not uniform: they depend closely on local environmental conditions.

Conducted among others by Pengzhi Zhao and Professor Kristof Van Oost from the Earth and Life Institute (UCLouvain), the study compared different agricultural landscapes. 

As revealed in an article published in Sciences Advances, the results show that in humid regions such as Belgium, terraces promote long-term carbon storage in soils. 

While their construction initially causes disturbance and carbon loss, plant growth subsequently makes it possible to gradually compensate for these losses, with a lasting stabilization of this element in soils.

"In regions with a relatively humid climate such as Belgium, terraces most often have a positive effect on soils and can act as genuine carbon sinks, while also providing other benefits: they limit erosion, retain water and improve growing conditions on sloped land." 

Contradictory results

Conversely, in drier or semi-arid regions, the results are more mixed. Vegetation is less productive there and soils stabilize carbon less effectively, which prevents compensation for the losses linked to terrace construction. Climate benefits are therefore uncertain, or even limited.

Kristof Van Oost, head of this project funded by an EU ERC grant, emphasizes that studies on the impact of terraces on soil carbon had so far produced contradictory results: “This work helps resolve this paradox by showing that climate plays a key role: it determines the balance between soil disturbance linked to terraces and the capacity to stabilize carbon in them.”

Agricultural terraces therefore do not constitute a universal solution to climate change. Their effectiveness depends on climate, soils and landscape characteristics. Hence the importance of adapting agricultural practices to local realities. 

A mapping tool to help farmers

To this end, the team is now working on developing a mapping tool for the carbon storage potential associated with terraces. 

Ultimately, this tool could help farmers and public authorities identify the areas where such developments would be most relevant and guide land management strategies.

Legend second photo: Agricultural landscape near Fouron-Saint-Martin in Belgium: the terraces were formed under the effect of long-term ploughing, erosion and the deposition of sediments downhill, which produced step-like forms bounded by vegetated embankments. This type of terrace, commonly called lynchets, is a characteristic feature of many temperate agricultural landscapes in Europe. 

This article was originally written in French by the AREC team of UCLouvain. It is available to be read here.