SOIL CARBON SEQUESTRATION TO FIGHT CLIMATE CHANGE: INDIAN PERSPECTIVE

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There is a growing concern about the increase in atmospheric concentration of carbon dioxide (CO2) and other greenhouse gases with attendant effects on observed and projected climate change. There is an urgent need to identify ways to minimize carbon loss and maximize retaining C in land thereby reducing the effects of Carbon on global climate change. Agricultural soils are among the planet's largest reservoirs of carbon and hold potential for expanded carbon sequestration, and thus provide a prospective way of mitigating the increasing atmospheric concentration of CO2. It is estimated that soils can sequester around 20 Pg Carbon in 25 years, more than 10 % of the anthropogenic emissions. Degraded soils in dry lands often have less than 0.5% of soil organic carbon (SOC), whereas through good Sustainable land management the SOC can be significantly increased (to 2-3%).

However, improved agricultural practices can help mitigate climate change by reducing emissions from agriculture and other sources and by storing carbon in plant biomass and soils. Increasing carbon content in the soil, through better management practices, produce a number of benefits in terms of soil biodiversity, soil fertility and soil water storage capacity and hence productivity. Soil carbon sequestration through the restoration of soil organic matter can further reverse land degradation and restore soil “health” through restoring soil biota and the array of associated ecological processes. In particular, through improved soil water storage and nutrient cycling, land use practices that sequester carbon will also contribute to stabilizing or enhancing food production and optimizing the use of synthetic fertilizer inputs, thereby reducing emissions of nitrous oxides from agricultural land. Conservation tillage practices also reduce significantly the use of fuel and hence gaseous emissions.  It is   very cost effective and could take effect very quickly. It also constitutes a valuable win-win approach combining mitigation (CO2 is removed from the atmosphere) and adaptation, through both increased agro ecosystem resilience to climate variability and more reliable and better yields (production and income generation).

Soils have the potential to sequester carbon from the atmosphere with proper management. Based on global estimates of historic carbon stocks and projections of rising emissions, soil’s usefulness as a carbon sink and drawdown solution appears essential (Lal, 2004, 2008). Since over one third of arable land is in agriculture globally (World Bank, 2015), finding ways to increase soil carbon in agricultural systems will be a major component of using soils as a sink. A number of agricultural management strategies appear to sequester soil carbon by increasing carbon inputs to the soil and enhancing various soil processes that protect carbon from microbial turnover. Uncertainties about the extent and permanence of carbon sequestration in these systems do still remain, but existing evidence is sufficient to warrant a greater global focus on agricultural soils as a potential climate stability wedge and drawdown solution. Furthermore, the ancillary benefits of increasing soil carbon, including improvements to soil structure, fertility, and water holding capacity, outweigh potential costs.

Carbon farming describes a collection of eco-friendly techniques that have the ability to increase carbon sink into soil, i.e. carbon sequestration. Increasing C sink in the soil will help reduce the amount of CO2, CH4 and N2O emissions in the environment. Carbon farming that leads to reduction in greenhouse gas (GHG) emissions is referred to as abatement activities. It holds carbon in vegetation and soils, and reduces GHG emissions. Carbon farming includes a single change in land management, such as zero tillage, agro forestry, methane-reducing feed supplements or stubble retention which maximizes capture of carbon and reduction of emissions. In carbon farming, the amounts of CO2, CH4 and N2O will be reduced with increasing C sinks in the soil because of increased soil aeration from organic carbon addition, which reduces denitrification and increases sink capacity for CH4.

Soil organic carbon adds electron acceptors and increases the redox-potential of the soil to decrease its N2O source capacity. Carbon farming induces microbial immobilization of available N2 in the soil, which decreases N2O source capacity of the soil. In carbon farming, there are some promising options that reduce GHG emissions; storage of carbon in soils and degraded rangelands through forests, tree plantings and regrowth, carbon storage through incorporation of biochar which is carbon negative, and substitution of biofuels for fossil fuels. Carbon farming gives land managers an opportunity to earn carbon credits through carbon storing or reducing GHG emissions on their own land. These carbon credits can then be sold to the Government-nominated authority who wishes to offset their emissions. Actually carbon farming is a voluntary carbon offsets scheme that provides economic rewards to landholders who take steps to reduce GHG emissions. Carbon farming reduces emissions by sequestration, where carbon is stored on land, and emissions avoidance, which prevents the GHG emissions from entering the atmosphere. It involves implementing practices which improve the rate at which CO2 is removed from the atmosphere and converted to plant material and/or soil organic matter. Carbon farming is successful when the gain of carbon resulting from enhanced land management and/or conservation practices exceeds the carbon losses. Its benefit includes GHG reduction, carbon sequestration, increased biodiversity, buffering against drought and greater water efficiency. Development of different programmes will facilitate the buying and selling of carbon credits between landholders and Government agencies. Landholders receive carbon credits for storing carbon in the soil and then the credits are assembled and sold desiring to reduce emissions. These credits are often bought independently of an exchange, and can boost the financial status of the client, and help prove how the practices are useful in mitigating the effects of the industrial society.


Soil organic carbon detection kit:


The Soil Carbon (SOC and SOM) is the basic resource in agricultural and forest land use, it is the central element of most agriculture land management technologies. Soil carbon has a direct correlation with soil quality. It is a major determinant of the soil’s ability to hold and release water and other nutrients that are essential for plants and their root systems to grow. Soil carbon also plays an important role in maintaining the biotic habitats that make land management systems sustainable, resilient, and able to resist degradation. To understand the soil organic carbon content by the farmers, BARC has developed a technology which helps the farmers to analyse the results on the field within short period of time. This technology has been commercialized and transferred to different entrepreneurs. The products based on this technology are available in the market for the farmers use.

 

Posted By : Sayaji Mehetre, PhD
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