Flemish arable land, intensively cultivated and driven over by heavy machinery, has the lowest soil carbon stock per hectare, particularly in the topsoil. Even the average Flemish garden performs better. Frequent tillage, heavy machinery, and limited long-term organic inputs accelerate the decomposition of organic matter, thereby increasing CO₂ emissions.
This is evident from the latest report by the Department of Environment, ILVO, Flanders Research Institute for Agriculture, Fisheries, and Food (Vlaams Instituut voor Landbouw, Visserij en Voedingsonderzoek), and INBO, the Institute for Nature and Forest Research (Instituut voor Natuur- en Bosonderzoek).
Although cropland still accounts for the largest share of total soil carbon in Flanders, owing to its large surface area, recent measurements indicate that Flemish soils have been a net carbon source since 2018.
“But if soils emit more carbon than they store, they undermine climate objectives instead of supporting them. This makes soil management a key climate issue,” explains Dr. Lieve De Smet, researcher involved in the CMon soil carbon monitoring network.
Carbon storehouse
Besides the ocean, soils are the most significant carbon storehouse. Capturing CO2 in the form of soil organic matter (carbon) not only contributes to the fight against climate change, but this carbon also plays a key role in the proper functioning and fertility of the soil.
“Soil organic carbon is essential for both climate mitigation and soil resilience,” says Dr. Wim Sleutel, soil scientist at ILVO. “It improves water retention, soil structure, and fertility. But once carbon is lost through intensive disturbance, it is complicated to rebuild.”
Global picture
The total amount of organic carbon in Flanders’s unpaved soils is 155 million tons to a depth of 1 meter. This stock is essential to the fight against climate change, as it increases soil resilience to extreme weather and reduces atmospheric CO2 levels.
“What we observe in Flanders fits perfectly within the European and global picture,” says Dr. De Smet. “Intensive arable farming is among the land uses most at risk of soil carbon depletion.”
Significant potential
The study shows that the carbon stock in the top 30 centimeters of arable land is 61.1 tons per hectare. At the same time, gardens perform considerably better, with 78.6 tons of carbon per hectare. Permanent grasslands and forests are among the highest-carbon stocks, with carbon stocks of approximately 89 tons per hectare.
Despite its low per-hectare score, arable land accounts for the largest share of the total carbon stock in Flanders (33 percent) and therefore offers the greatest potential to increase carbon storage.
Several measures
Both ILVO and international studies identify similar measures with the strongest evidence for maintaining or increasing soil carbon: continuous ground cover through cover crops, organic amendments (e.g., compost or manure), agroforestry systems, rewetting of organic soils, and shifts toward perennial vegetation where feasible. These measures also improve soil fertility, water retention, and biodiversity.
“Building soil carbon is a long-term process, not a quick fix,” ILVO emphasizes. “It requires consistent management, reliable monitoring, and realistic expectations.”
With soil carbon stocks increasingly used in European climate reporting, the ILVO report reinforces a message echoed worldwide: restoring carbon in agricultural soils is essential for climate and soil health—but only sustained, well-monitored practices can turn soils back into a meaningful carbon sink.
