Carbon Sequestration techniques

With carbon sequestration (CS) techniques we mean farming practices that store carbon in agricultural soils for the longer term. These techniques are very much related to sustainable soil management practices.

A higher carbon content in the soil offers many benefits for soil health and fertility: improved soil structure, increased soil biodiversity and a better water holding capacity and nutrient availability. Some examples of CS techniques are:

  • The use of cover crops: cover crops are crops planted after the harvest of the main crop, to prevent the land to be fallow. They fix additional carbon from the atmosphere by photosynthesis and offer additional biomass to the soil. They protect soils against erosion, can break infections with soil borne diseases, increase infiltration of water, fix nutrients and might increase agrobiodiversity and the overall resilience of agricultural systems.
  • Enriched crop rotation: When growing a wider diversity of crops and perennial forage crops, a more diverse agroecosystem is created. With increased diversity of soil life, roots and improved soil structure as a consequence. Such soils have a greater ability to store carbon. Introducing less intensive crops, such as cereals and grass and clover species, in the crop rotation, increases the carbon content in the soil through the extensive rooting system. 
  • Agroforestry: Agroforestry is the practice of introducing trees in agricultural systems. This can be in grasslands, but also on arable fields. Trees fix CO2 from the atmosphere in stems, leaves and their extensive rooting system. Especially roots will increase the soil carbon content also in deeper soil layers.
  • Reduction of soil tillage: Tillage is normally used to loosen and aerate the soil and to remove initial weeds. However, tillage often has a negative impact on soil life, soil structure and erosion. Additionally, it increases C mineralization leading to CO2 emissions from the soil. Reducing of soil disturbance therefore is a useful tool to protect soil organic matter. Due to the accumulation of carbon in the upper topsoil layer with shallow cultivation in reduced or no-tillage systems the additional net CS effect is doubtful.   
  • Fertilisers rich in organic carbon: Fertilisers such as compost and solid manure with wide C/N ratios will have a slow carbon turnover compared to other materials. They should be part of the farming system. As all organic fertilisers today are traditionally used in agriculture their transfer from one place to another prohibits their use and CS at the place of export. Organic fertilisers therefore should be additionally produced on farms to really improve CS.
  • Permanent grassland: Below grassland, organic matter is building up. When grassland is renovated (and therefore ploughed), the soil get in contact with more air and the organic matter mineralizes. Also enrichment of swards with legumes and controlled grazing might increase CS there.

Download full report

Please find attached the full report on Inventory of techniques for carbon sequestration in agricultural soils. In this inventory the authors list different techniques to improve organic carbon stocks in soil with adequate local farm efforts. The recommendations can be used as basis for further development of climate friendly farming systems.