Soil organic carbon – the most precious substance on the planet

Society at large continues to ignore the importance and true value of the life-critical functions provided by soil. In almost all cases, the prevailing control of soil functions is related to soil organic carbon (SOC). Soils with low levels of OC, are unable to perform these functions effectively and many agronomists consider soils with less than 1% SOC to indicate the onset of desertification and trigger to a host of land degradation processes. While SOC in natural systems tend to be in equilibrium, anthropogenic activities, such as land use change, will affect these levels. An important driver of SOC decline is intensive arable agriculture. The harvesting of crops means that there is a net export of C from the soil to ‘market’. Unless replaced by other sources, such as manure, OC levels in the soil will gradually decrease. Repetitive tillage results in disturbance of the carbon pools and its removal through increased mineralisation or erosion. In parallel, the draining of peatlands represent a loss of habitat and natural water management locally while globally, the emission of carbon dioxide over extensive areas of drained peat is a significant contribution to global warming. There is increasing realisation that soils are a significant component of the global climate system that could significantly offset global emissions of carbon through changes in land management. Research carried out at the JRC has assessed the applicability of several agricultural and land management practices to sequester carbon in the soils of the EU. Modelling has shown that such practices are generally effective and can lead to an increased rate of carbon sequestration in soils, without significant impact on production systems and markets. However, regional effectiveness reflects limitations imposed by climate, soil conditions and actual agricultural practices – this means that a regional approach must be considered for implementation. Critically, the research shows that the impact of such practices are viable only over short to medium timescales after which a ‘saturation’ level is reached.JRC.D.6-Knowledge for Sustainable Development and Food Securit