On a global scale, around 10 to 20% of drylands and 24% of world’s productive lands are degraded.
Do you know that a third of the planet’s land is severely degraded and fertile soil is being lost at the rate of 24 billion tons a year, according to a UN backed study?
Managing nutrients like the NPK for crop production has been a standardized practice but do you know that Carbon too forms a major component of soils?
Soil stores more than 4000 billion tonnes of carbon.
Unsustainable farming practices has driven the release of carbon from soils over a period, leading to the rising levels of carbon dioxide in the atmosphere. There are claims that we have only 60 years of farming left if this soil degradation continues.
What is Soil Carbon?
Soil Carbon is the carbon stored in soils that exists in organic and inorganic forms. This includes plant roots, fungi and microbes and decomposed organic matter from plant litter or animal products like manure. Soil contains inorganic carbon in mineral form. The ability of the soil to store or sequester organic carbon is determined by the physical structure, aggregation of the organic and inorganic particles in the soil profile and the biotic factors. The physical and biotic factors change with depth as the upper layers are closer to the surface and are influence by environment and also due to land use activities.
Soil is composed of layers called the Soil horizons. The organic layer is found on top of the soils made of decomposed organic matter. The topsoil is the mineral soil with high concentration of carbon and microbial activity. The subsoil is a result of soil accumulated from leaching of the above layers and the final layer is made of decomposed rock. Most of the soil carbon is found in the organic and topsoil horizons. Improper management can lead to soil erosion that strips the carbon from the soil making it difficult to accumulate additional carbon. This also has an impact on plant growth and the soil microbes leading to low carbon sequestration.
Let us understand the Soil Carbon cycle in order to know how important soil carbon is. Plants during photosynthesis, absorb carbon dioxide from the atmosphere and transform the carbon into biomass and release the organic content into the soils through roots. This stimulates the microbial growth and facilitate absorption of nutrients from the soil. During decomposition of organic matter, carbon dioxide is released into the atmosphere. The soil can act as a carbon sink or source, depending on the balance between soil carbon accumulation and soil carbon losses.
Organic matter decomposition is a microbial process and hence the environmental and biological factors influence the time carbon remains locked in the soil. Any practices that degrade the soil will decrease the soil carbon.
Practices that disturb soil like tillage can expose carbon to the oxygen in air which increases microbial activity that leads to breakdown of soil and reduction in microbial population. Whereas increasing the woody biomass in soils can increase the carbon sequestration as woody structures are rich in organic components.
Agriculture impacts Soil Carbon
Do you know that the expansion of agriculture lands has resulted in carbon losses of 40 to 90 Gt of CO2?
Croplands and grazing lands are of great significance in global carbon cycles because of their extent, the carbon stocks and environmental pressures due to degradation and unsustainable farming practices. These practices can affect the soil moisture, erosion levels, microbial activity and organic matter that impacts sequestration. This is a very crucial aspect with regards to both climate change and food security as low soil carbon can reduce crop productivity in croplands and grasslands. Agriculture practices like tilling, planting mono crops, excessive use of fertilizers and pesticides and removing crop residue expose the carbon in the soil to oxygen allowing it to burn off into the atmosphere.
The unsustainable management practices like excessive irrigation, over-grazing, excessive tillage, deforestation and draining of peatlands all cause soil carbon losses. The decomposition of micro-organisms and plant harvesting processes also cause soil carbon depletion. The amount of soil organic carbon is dependent on factors like the hydrology, climate, land use and vegetation. The reduction in soil carbon reduces the ability of soil to supply nutrients to plants thereby affecting crop yields. The global warming reduces the organic matter in the soil.
The rise in regenerative agriculture has triggered the importance of soil carbon. Before we get into the Carbon sequestration practices, let us see how soil organic carbon improves soil health
Benefits of Soil Organic Carbon
Carbon rich soils can contribute to greater yields and long-term sustainability.
- Increases nutrient availability.
The nutrient from decaying matter becomes a source of nutrition for crops.
- Reduces Soil Density
Soil organic matter helps to maintain the air passages that protect the air from compaction. Soils that are less compact and less dense promotes root development and penetration.
- Resilience to weather extremities
Organic carbon in soil increases water holding capacity helping in water absorption and retention of soil moisture. The water absorbed during excessive rainfall can be stored and used as a reservoir during drought.
- Boosts Soil biodiversity.
The microbial life in the soil feeds on carbon and organic matter for energy to convert them into plant nutrients.
Building Soil Carbon
Sequestering carbon in soil is a natural way of removing carbon dioxide from the atmosphere with a lesser impact on land and water with a lesser need for energy at reduced costs.
Earth’s soils contain 2500 gigatons of carbon which is three times more than the amount of carbon in the atmosphere and four times the amount stored in plants and animals.
Better land management and agriculture practices are a must to increase soil carbon storage to combat climate change Soil carbon storage is a vital ecosystem. There are different practices to promote carbon storage in soils. Increased carbon sequestration in farms can be achieved by adopting carbon farming practices which increases soil productivity and enhances soil health.
- Zero tillage is an effective means to avoid carbon loss in soils. Tillage contributes to soil disturbance breaking up soil organic matter. No till practices have found to have 71% lower greenhouse gas intensity than conventional tillage.
- Reducing the use of chemical fertilizers maintains soil fertility. Replacing chemical fertilizers with organic fertilizers and manure helps to restore soil health. It also optimizes the nutrient application costs.
- Cover crops and leaving straws in fields conserve soil. The organic inputs added minimises losses and prevents soil from eroding. They reduce the surface disturbance thereby maintaining soil fertility.
- Rotation of crops improves soil condition and productivity. Crop rotation reduces fallow frequency and boosts organic carbon stock. Sowing nitrogen fixing crops can increase the carbon in the soil
- Agroforestry practices help to mitigate emissions and store carbon in soils and trees.
- Rotational grazing keeps carbon in the soil by moving herds to new pastures after grazing and carbon in the form of manure gets spread around.
Benefits of Soil Management in Agriculture
Soil being the largest terrestrial carbon pool, play a key role in GHG mitigation. It is estimated that about 50% of the mitigation potential of crops and grasslands comes from soil organic carbon conservation and sequestration. 20% of this mitigation potential is associated with GHG emissions from other gases.
Along with the carbon benefits, sustainable agriculture practices that increase soil carbon enhance the adaptation and mitigation potentials and contribute to increased yields, reduced poverty and healthier ecosystems. Sustainable practices also give the farmer access to premium markets.
Soil Management is important for sustainability of croplands and soil carbon has a tremendous potential for impact. The productivity and profitability for farmers is defined by soil carbon and building it is a long-time commitment.
Way ahead with Carbon Farming
Carbon farming can add new revenue steams for farmers. The added incentives in carbon farming can provide short term gains and can provide long term sustainability of farmlands. Carbon farming generates Carbon credits by committing to agriculture practices that sequester carbon.
In Carbon farming it is important to keep track of data for accounting of the sequestered carbon. Recording of important farm data with rigorous measurement, reporting and verification is crucial to generate high quality carbon credits. TraceX is building a DMRV tool to help project developers monitor the carbon sequestration through regenerative practices followed. The capture of digitized data helps in establishing accurate baseline scenarios and monitor the reduction in emissions in a transparent way. The DMRV solution brings credibility to the Carbon credits generated and can be verified by the Verification bodies to issue faster and quality credits.
Soil carbon is critical for productive and healthy soils ensuring food security and sustenance of biodiversity. Soil carbon is one of the nature-based climate solution that food and land systems can use to sequester carbon and reduce emissions, thereby helping companies accelerate to their net-zero journey.
For every 1 ton of real soil carbon added to the soil, 3.67 tons of carbon dioxide gets removed from the atmosphere. l carbon underpins healthy and productive soils, landscapes. Soil carbon is t one of many nature-based climate solutions that the food and land use system can draw on to sequester carbon and reduce emissions – however, significant efforts e required to reduce emissions and limit warming to 1.5°C.
or food and fibre production and to sustain biodiverse landscapes. Soil carbon is just one of many nature-based climate solutions that the food and land use system can draw on to sequester carbon and reduce emissions – however, significant efforts across all sectors are required to reduce emissions and limit warming to 1.5°C.