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Friday, January 27, 2023

Low carbon agriculture for better Bangladesh

It is necessary to use innovative means of agricultural production with relatively low environmental pressure (e.g., bio-fertilizers and bio-pesticides), implementing precision agriculture (using GPS), developing low emission energy sources on farms (e.g., agricultural biogas energy plants), using crop rotation plants with a positive index of reproduction of soil organic matter and adding nitrogen compounds to feed.

Carbon sequestration and reductions in greenhouse gas emissions can occur through a variety of agriculture practices. The term “low-carbon agriculture” is used here to cover actions to reduce the energy inputs to and GHG emissions from greenhouse gas effect. The primary greenhouse gases associated with agriculture are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N20). Although carbon dioxide is the most prevalent greenhouse gas in the atmosphere, nitrous oxide and methane have longer duration in the atmosphere and absorb more long-wave radiation. Therefore, small quantities of methane and nitrous oxide can have significant effects on climate change. On the other hand, carbon dioxide is removed from the atmosphere and converted to organic carbon through the process of photosynthesis. As organic carbon decomposes, it is converted back to carbon dioxide through the process of respiration. Conservation tillage, organic production, cover cropping and crop rotations can highly increase the amount of carbon stored in soils.

Low energy, low releasing, low polluting and high efficiency are characteristics of “low-carbon agriculture.” Low-carbon agricultural combines cleaner production and utilization of waste, and the concept is similar to the concepts of sustainable agriculture, ecological agriculture, and circular agriculture. Carbon efficiency is considered not only from a practical but also from a conceptual point of view. The evolution of agricultural activities toward carbon efficiency is an important condition for balancing economic, environmental and social goals. The main goal in this case is slowing down (limiting) climate change and promoting sustainable development. The bases of the low-carbon agriculture concept are created by different scientific fields and disciplines. 

Agriculture’s contribution to greenhouse gas emissions

Agricultural activities serve as both sources and sinks for greenhouse gasses. Agriculture sinks of greenhouse gasses are reservoirs of carbon that have been removed from the atmosphere through the process of biological carbon sequestration. The primary sources of greenhouse gasses in agriculture are the production of nitrogen based fertilizers; the combustion of fossil fuels used by farm machineries and waste management. Livestock enteric fermentation, or the fermentation that takes place in the digestive systems of ruminant animals, results in methane emissions. 

The main agricultural sources of greenhouse gas emissions are: N2O from soil, CH4 from enteric fermentation, CO2 from biomass incineration and CH4 from manure. The application of synthetic (N) fertilizer and incorporation of crop residues into soil results in nitrous oxide (N2O) emissions. Similarly, the application of urea and lime to the soil results in carbon dioxide (CO2) emissions.

The term “low-carbon economy” has no universally accepted definition. It was assumed that “low-carbon economy is a whole series of actions that contribute to reducing greenhouse gas emissions while respecting the principles of sustainable development, oriented for innovation and competitiveness on the global market”. The transformation toward a low-carbon economy is determined by the adoption of appropriate practical actions in all sectors and industries, including agriculture. 

Agriculture has a significant share in the total emissions of nitrous oxide (N2O) and methane (CH4). Due to the possibility of limiting carbon emissions from agriculture through its sequestration in soils, the share of agriculture in net CO2 emissions is relatively small. Agricultural emissions are linked to both plant and animal production. Fundamental emissions from the point of view of consideration include nitrogen oxide, commonly referred to as “nitrous oxide” (N2O), a greenhouse gas that is 300 times more efficient than CO2 in terms of heat absorption. Nitric oxide is poorly soluble in water, is not eluded with precipitation, and its duration in the air is estimated to be about 150 years (it accumulates in the atmosphere). 

Much of the N2O emissions associated with human activity are caused by undesirable decomposition of nitrogen fertilizers in the soil (natural and mineral fertilizers). N2O emissions are not only affected by nitrogen input in soils but also other factors: soil temperature, oxygenation, availability of hydrocarbons, pH and soil humidity. Taking into account the microbiological processes, nitrous oxide emissions correspond to denitrification and, to a lesser extent, nitrification. The N2O emission from agricultural soils occurs directly and indirectly. N2O direct emissions are mainly due to the use of nitrogen fertilizers and the emission of N2O from organic nitrogen in animal feces, while the indirect ones are related to ammonia (NH3) emissions and nitrogen leaching. An important source of N2O formation is the intensive supply of soil with nitrogen fertilizers.

Emissions of the aforementioned compounds contribute to adverse changes in agricultural soil (acidification) and to the eutrophication of natural ecosystems. In addition, nitrous oxide contributes to the intensification of the greenhouse effect and contributes to the disappearance of the ozone zone.

Greenhouse gas emissions from agricultural production are also affected by the mechanization of agriculture. It is important to consider the emissions of air pollutants as a result of the use of agricultural tractors, power tiller, harvester etc. Farm tractors, as well as other diesel-powered vehicles, produce gases containing carbon monoxide (CO), hydrocarbons (HC), particulate matter (PM) and nitrogen oxides (NOx). Agricultural tractors account for more than 6% of nitrogen oxide emissions from the total means of transport.

Ten major actions in low carbon agriculture

First is the action to reduce methane in rice fields, the second is the action to reduce the amount of chemical fertilizers and increase the efficiency, the third is the action to reduce low-carbon emissions of livestock and poultry, the fourth is the action to reduce the emission of fishery and increase foreign exchange, and the fifth is the action of green energy saving of agricultural machinery. 

The sixth is the action to improve the carbon sink in farmland, the seventh is the comprehensive utilization of straw, the eighth is the action to promote renewable energy, the ninth is the action of supporting scientific and technological innovation, and the tenth is the action of dissemination of scientific and technological innovation.

Carbon sequestration

Carbon sequestration in the agriculture sector refers to the capacity of agriculture lands and forests to remove carbon dioxide from the atmosphere. Carbon dioxide is absorbed by trees, plants and crops through photosynthesis and stored as carbon in biomass in tree trunks, branches, foliage and roots and soils. Forests and stable grasslands are referred to as carbon sinks because they can store large amounts of carbon in their vegetation and root systems for long periods of time. Soils are the largest terrestrial sink for carbon on the planet.

The ability of agricultural lands to store or sequester carbon depends on several factors, including climate, soil type, type of crop or vegetation cover and management practices. The amount of carbon stored in soil organic matter is influenced by the addition of carbon from dead plant material and carbon losses from respiration, the decomposition process and both natural and human disturbance of the soil. By employing farming practices that involve minimal disturbance of the soil and encourage carbon sequestration, farmers may be able to slow or even reverse the loss of carbon from their fields.

Agriculture’s role in mitigating climate change

Several farming practices and technologies can reduce greenhouse gas emissions and prevent climate change by enhancing carbon storage in soils; preserving existing soil carbon; and reducing carbon dioxide, methane and nitrous oxide emissions.

Conservation tillage and cover crops

Conservation tillage refers to a number of strategies and techniques for establishing crops in the residue of previous crops, which are purposely left on the soil surface. Reducing tillage reduces soil disturbance and helps mitigate the release of soil carbon into the atmosphere. Conservation tillage also improves the carbon sequestration capacity of the soil. Additional benefits of conservation tillage include improved water conservation, reduced soil erosion, reduced fuel consumption, reduced compaction, increased planting and harvesting flexibility, reduced labor requirements and improved soil tilth.

Improved cropping and organic systems

Recent reports have investigated the potential of organic agriculture to reduce greenhouse gas emissions. Organic systems of production increase soil organic matter levels through the use of composted animal manures and cover crops. Organic cropping systems also eliminate the emissions from the production and transportation of synthetic fertilizers. Components of organic agriculture could be implemented with other sustainable farming systems, such as conservation tillage, to further increase climate change mitigation potential. Generally, conservation farming practices that conserve moisture, improve yield potential and reduce erosion and fuel costs also increase soil carbon. 

Examples of practices that reduce carbon dioxide emissions and increase soil carbon include direct seeding, field windbreaks, rotational grazing, perennial forage crops, reduced summer fallow and proper straw management.

Land restoration and land use changes 

Land restoration and land use changes that encourage the conservation and improvement of soil, water and air quality typically reduce greenhouse gas emissions. Modifications to grazing practices, such as implementing sustainable stocking rates, rotational grazing and seasonal use of range-land, can lead to greenhouse gas reductions. Converting marginal cropland by planting trees,perennial crops or grass to maximizes carbon storage on land that is less suitable for usual cultivation.

Irrigation and water management

Improvements in water use efficiency, through measures such as irrigation system mechanical improvements coupled with a reduction in operating hours; drip,sprinkler irrigation technologies; and center-pivot irrigation systems, can significantly reduce the amount of water and nitrogen applied to the cropping system. This reduces greenhouse emissions of nitrous oxide and water withdrawals.

Nitrogen use efficiency

Improving fertilizer efficiency through practices like precision farming using GPS tracking can reduce nitrous oxide emissions. Other strategies include the use of cover crops and manures (both green and animal); nitrogen-fixing crop rotations; composting and compost teas; and integrated pest management.

Methane capture 

Large emissions of methane and nitrous oxide are attributable to livestock waste treatment, especially in dairies. Agriculture methane collection and combustion systems include covered lagoons and complete mix and plug flow digesters. Anaerobic digestion converts animal waste to energy by capturing methane and preventing it from being released into the atmosphere. The captured methane can be used to fuel a variety of on-farm applications, as well as to generate electricity. Additional benefits include reducing odors from livestock manure and reducing labor costs associated with manure removal. For more information on anaerobic digestion.

The low-carbon economy is a response to the challenges associated with climate change and the needs to counteract disturbances in ecosystems, and on the other hand it is a conscious creation of agribusiness development in a more sustainable way. Transforma­tion of the agriculture towards low-carbon practices is associated with the transformation of production and consumption processes along with simultaneous reduction in emissions of pollutants and greenhouse gasses, minimization of waste and ineffective use of natural resources, preservation of biological diversity, and improving energy security.

The necessity for a low-carbon transformation in agriculture results from the internal efforts of the state and society aimed at reducing greenhouse gas emissions. The condition of a low-carbon economy development in agriculture is smart growth based on knowledge and innovation. 

It is necessary to use innovative means of agricultural production with relatively low environmental pressure (e.g., bio-fertilizers and bio-pesticides), implementing precision agriculture (using GPS), developing low emission energy sources on farms (e.g., agricultural biogas energy plants), using crop rotation plants with a positive index of reproduction of soil organic matter and adding nitrogen compounds to feed. The problems of rational management of the environment in the context of a low-carbon economy are also related to the technical equipment used.

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Md. Akhteruzzaman is Executive Director, Cotton Development Board

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