Agriculture plays a crucial role in mitigating climate change by reducing greenhouse gas emissions and enhancing carbon fixation in soil. Organic fertilizers are rich in organic matter and are an important tool to increase the organic carbon content of the soil.
Carbon sequestration is the process of capturing atmospheric carbon dioxide (CO2) and storing it in soil, plants, and other natural reservoirs. Agricultural soils are one of the largest terrestrial carbon sinks, with the potential to store large amounts of carbon. The use of organic fertilizers can enhance carbon sequestration in agricultural soils by increasing soil organic matter, promoting soil health and reducing the carbon footprint compared to mineral fertilizers.
Soil Organic Matter
Soil organic matter is made up of plant and animal residues that have decomposed into various stages in the soil. This includes leaves, roots, animal manure, and other organic materials. As the organic matter is cycled through the soil food web it becomes more stable.
Soil organic matter is important for many reasons. It helps to improve soil health by feeding the soil microorganisms, increasing soil fertility, improving soil structure, and enhancing water-holding capacity. This, in turn, can lead to increased crop yields and healthier plants which capture more carbon by increased photosynthesis. Moreover, certain microbial communities, such as mycorrhizal fungi, can also form symbiotic relationships with plants that facilitate carbon sequestration.
Carbon sequestration
Soil organic matter is primarily made up of carbon. On average organic matter consist of 56% of organic carbon. The exact amount of carbon can fluctuate depending on the composition of the organic matter and the stage of decomposition by the soil food web. When the organic matter content of the soil is increased, the carbon stored in the organic matter is effectively removed from the atmosphere, which helps to mitigate climate change. To increase the soil organic matter content, more organic matter should be added to the soil than is annually removed by harvesting and decomposition. The usage of organic fertilizers is key to achieving a positive organic matter balance and sequestering carbon. Organic fertilizers are derived from plant or animal sources and are naturally rich in organic matter and carbon.
Carbon input by fertilizers
Figure 1 shows the effective carbon input of different organic manures and fertilizers per ton of product. This is the amount of carbon that will still be present in the soil after one year and contributes to carbon sequestration. Every ton of ORGEVIT (pelleted chicken manure) will add around 115 kg C per hectare. Dried and compressed organic fertilizers in e.g. pellets or granulates can have a high contribution to the overall addition of organic matter to soils since they are more efficient to transport to areas with a lower animal density. Organic fertilizers and soil improvers with a high organic matter content and a high Organic Carbon/Nitrogen (Corg/N) ratio like MONTERRA Insect generally add the most effective carbon to soils.
Mineral fertilizers contain no organic matter. To combine the benefits of predictive mineralization rates of mineral fertilizers and the positive effects of organic matter in organic fertilizers, MeMon also offers a wide range of organo-mineral fertilizers.
Figure 1: Effective carbon input for different fertilizers (source: Carbon Calculator by Eurofins Agro)