Soil Carbon Sequestration: A Sustainable Approach to Agriculture

Carbon sequestration in soil is the process that removes CO2 from the earth’s atmosphere and then stores it as carbon in the pool of soil. Plants primarily mediate this process through photosynthesis, and carbon is stored as SOC. In semi-arid or arid climates, the sequestration of carbon in soil may also result from the transformation of CO2 from the air in the soil to inorganic forms like secondary carbonates; however, the rate of inorganic carbon production is relatively minimal (Lal 2007 ).

Changes in the climate are a significant and urgent issue humanity faces in the global environment that we live in. It has had a broad and noticeable impact on the urban population and many industries. The summers are hotter, the winters are colder, and the glaciers in the poles have receded significantly due to the pressure caused by rising temperatures worldwide. One of the major causes of the global warming effect and climate change is the increasing concentrations of greenhouse gases (GHG), including methane, carbon dioxide, and nitrous oxides, found in the Earth’s atmosphere.

GHG emissions due to human activity have increased over time and destroyed our planet’s ecological balance. Scientists have discovered various pieces of evidence worldwide that indicate the source and impact of climate change. The effects of climate change caused by GHG emissions include severe weather patterns, rising sea levels, and coastal flooding, a more significant threat to human health due to lower air quality, an indirect increase in the spreading of illnesses, and increased wildfires.

GHG emissions can also be an issue when it comes to agriculture. The way these gases are produced can alter soil fertility as well as the health of crops and alter conditions to maximize yield. In contrast, the production and the use in the production of inputs to agriculture (such as pesticides and fertilizers) and farm equipment soil disturbance and poor irrigation practices make up the bulk of agriculture-related GHG emissions. While agriculture is responsible for climate change by releasing greenhouse gasses, it is also negatively affected by weather pattern shifts.

To ensure that clean energy is produced using sustainable techniques and to reduce the adverse effects on carbon emissions, farmers are beginning to implement the most innovative solution known as Carbon Sequestration.

What is Soil Carbon Sequestration?

Also referred to as carbon dioxide removal (CDR), it is the long-term procedure of eliminating carbon dioxide from the atmosphere and storing it for a long time in biological systems, geological formations, or industrial products. The process helps reduce pollution of the atmosphere CO2 pollution, and could even reverse global warming. 

The most efficient methods include:

  • Afforestation and reforestation.
  • Bioenergy utilizes carbon storage and capture farming techniques that improve soil carbon storage.
  • Using CO2 as biofuels, chemical polymers, and building materials.

Carbon sequestration describes the potential application of soil, land use, land-use change, and forestry to decrease the greenhouse effect. In agriculture, this process is often referred to as ” carbon farming” or ” regenerative agriculture,” which encompasses a variety of methods of managing land so that plants and soils can improve their absorption capacity and carbon storage capacity.

According to a specific report from the United Nations (UN) Intergovernmental Panel on Climate Change (IPCC), the sequestration of carbon in soils in croplands and grasslands is one of the options that have the greatest possibility of CDR that could yield as much as 8.6 gigatonnes CO2 which represents more than 20 percent of the present greenhouse gas emissions can be captured annually by locking carbon into the soil. In contrast, managing livestock and agriculture could reduce up to 3.4 gigatonnes (or 3.4 gigatons) of CO2 each year. 

A further benefit of this method is that, with the increase in soil carbon content, soil fertility also increases. Thus, the retention of nutrients increases, soil can hold water for longer, and its density will decrease.

How Does Soil Carbon Sequestration Work?

The plants absorb carbon dioxide from the atmosphere through photosynthesis, generating their food source in the form of sugars, then releasing oxygen as a byproduct. The plant tissues then store carbon until they are absorbed into the soil or die naturally, after which the CO2 is released into the atmosphere. At the same time, increasing the capacity of plant biomass to store and absorb carbon. It is an effective method to reduce the effects of climate change; the primary focus for soil carbon capture focuses primarily on practices for management that improve how much carbon is stored in the soil organic matter (SOM), which is particularly important in the grazing and agricultural lands.

Plants can also transform the atmospheric CO2 into solid and stable forms of carbon and store it in soil either directly or indirectly. Direct fixation refers to the natural transformation of CO2 into soil-based inorganic compounds (SIC), which comprise mainly magnesium carbonate and calcium. Additionally, indirect fixation occurs when the biomass plants created by photosynthesis are eventually put into the soil. The carbon is later stored in soil organic carbon (SOC) after the biomass breaks down. Soils can reduce GHG emissions when the carbon they accumulate in the soil is larger than what is released into the atmosphere.

SOC stocks are an essential indicator for assessing carbon sequestration in the soil since their proportion is directly related to the quantity of organic matter in the soil. Improving SOC stocks can help reduce or even eliminate carbon dioxide emissions. The capacity to hold or grow SOC depends on many aspects, including the soil’s characteristics, climate, as well as land use, and alteration. One way to boost SOC stock in crops is to reduce soil disturbance. However, unscientific tilling or plowing causes reductions in SOC stock and also the release of carbon dioxide back into the atmosphere. When this process is scaled to a global scale, it will increase GHG emissions and a rise in soil fertility.

Therefore, it is concluded that increasing carbon sequestration in soils is related to biomass growth and, consequently, soil fertility. Improved soil fertility is another method that can be used to increase the capacity of carbon sinks. Cultivating specific crops may aid in nitrogen fixation, increasing the amount of soil-based compounds and making the soil more fertile. Selecting the best crop by the geography of the soil will ensure that the soil’s carbon is kept in check. The roots of certain plants can hold the soil together and help keep carbon levels in the soil at the appropriate amount.

Carbon Credit Mechanisms

The genesis for Carbon Pricing and Carbon Credits dates back to the UN Framework Convention on Climate Change ( UNFCCC), which took place in Japan in 1997. The world nations agreed that carbon credits are the most effective method to cut CO2 and other GHG emissions. While the convention called for industrialized countries to maintain their GHG emissions and reduce their carbon footprint, they were also required to comply with the Kyoto Protocol adopted that year. As part of this protocol that was ratified by 192 nations to the present, 37 industrialized countries, together with Europe, which is the European Community, are committed to reducing their emissions.

The concept “put a price on carbon” is gaining traction across a variety of nations as a method to cut emissions and promote the use of cleaner options. In this context, according to the World Bank, there are two primary forms of carbon pricing: emissions trading systems (ETS) and carbon taxes. ETS is one of the cap-and-trade programs in which a limit can be set through law through several permits to restrict GHG emissions from utility companies or factories. Those who emit low levels can sell or trade their unutilized credits for more significant emitters. Therefore, ETS determines the market price for GHG emissions and guarantees an overall reduction in emissions overall. 

In contrast, a carbon tax can be described as a tax the government imposes on companies emitting GHGs. It encourages companies to shift to renewable energy sources or adopt new technologies to avoid paying the tax on their emission. Contrary to the ETS, the degree of reduction in emissions that businesses must achieve isn’t predetermined, and neither is the carbon price.

Also read – How does agriculture depend on industries?

In the agri-sector, several firms worldwide have implemented the carbon credit system, which rewards farmers for adopting climate-friendly methods. The programs educate farmers about and encourage sustainable agricultural techniques for managing land for carbon sequestration, including cover crop plantation trees, planting trees, no-tillage farming as well as precision nitrogen usage, and the return of organic material to the farmland that is being cultivated. In addition, these practices help the environment by improving the soil.

There are numerous ways that farmers can profit financially through these projects. For example, Syngenta, with the organization’s Good Growth Plan, works with farmers to assess their carbon footprint and increase soil health using climate-smart farming practices. Syngenta Foundation, however, is involved in initiatives being carried out in Zambia and Kenya that are backed with the help of the World Bank’s BioCarbon Fund. 

The US-based global food company Cargill also has committed resources to help farmers use regenerative practices in their farming. It is looking for avenues that allow farms to reap the benefits of their efforts to reduce carbon. 

Bayer AG‘s Crop Science Division rewards over 1,200 farmers across the US and Brazil by granting them half a million acres of farmland between them to adopt environmentally-friendly practices. 

Carbon Sequestration and SDGs

The Sustainable Development Goals (SDGs) stipulated by the UN are intended to serve as guidelines to ensure a sustainable future. The first of these SDGs, Responsible Production and Consumption, focuses on using sustainable methods for production based on scientific methods derived from data-driven analysis and are recommended to be applied on farmlands. Carbon sequestration is one of the methods of cultivation recommended according to the UN SDGs as it is highly efficient and helps build the future of agriculturists across the globe. 

Businesses should consider bringing carbon sequestration as a compulsory cultivation phase on their farms. This is a win-win situation for our planet and for us!

How Does Carbon Get Stored in Soil?

The soil is a carbon sink; however, since the invention of agriculture around 12,000 years ago, the transformation of natural ecosystems such as forests and grasslands has released 110 million tonnes of carbon from topsoil to the atmosphere. Scientists are now looking into different methods of managing land to reverse this process and utilize soil as a long-term carbon sink.

  • About 42 percent of the carbon found in the forest is in plant matter above the surface. The rest is composed of soil organisms and decayed matter in the soil.
  • The roots of the plant expand in more profound levels of soil. If the plant dies, the carbon within the roots is left in and is often beyond the reach of the majority of soil microorganisms which would take down organic matter.
  • Highly decomposed carbon produces particles that are small enough to chemically bond with clay or soils. These may remain in the soil for hundreds of years.
  • Certain carbon molecules are water-soluble, and rainwater slowly lowers them to deeper rock strata. A high amount of organic matter in soils improves water retention and helps to speed up this process but also increases the resistance of the soil to droughts.
  • Organic carbon-rich soils with a higher content also have more microorganisms and nutrients. This boosts plant growth and promotes a healthy cycle that benefits farmers and the natural ecosystem.

Conclusion

SOC (Soil Organic Carbon) is an essential element of soil that significantly impacts the terrestrial environment’s ecology. Storage of SOC is a result of interactions between the ecological processes that are dynamic, such as decomposition, photosynthesis, as well as soil respiration. 

Over the past 150 years, human actions have resulted in modifications in these processes and consequently reduced SOC and escalated global warming. However, these activities of humans also offer the possibility of recycling carbon back into the soil. The future climate is expected to warm and increase CO2. The patterns of past patterns of land use and management strategies, in addition to the physical diversity of landscapes, will create complicated designs that will affect SOC capacities in the soil.

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