Greenhouse gases are present in the atmosphere that absorb and emit infrared radiation. These gases are the main cause of temperature elevation in the atmosphere. Many agricultural practices and increasing industrialization trigger the production and release of these harmful GHGs (CH4, CO2, N2O, etc) in an environment that changes the climate.
This effect is referred to as the greenhouse effect. Further, fossil fuel burning is the major cause of 75% of CO2 emissions in our environment. The remaining GHGs are due to changes in land use, especially from deforestation. Moreover, CH4 emissions increased over the last 25 years due to increasing human-based anthropogenic activities. Monitoring and assessing the greenhouse gas emissions factors is necessary for controlling the negative impacts of climate change and global warming.
Moreover, knowing the stages, origin, and impacts of GHG emissions helps to make effective plans to reduce and modify to advance different environmental events. They encourage attempts regarding sustainability, the modification of different renewable energy resources, and global partnerships to talk about the harmful effects of climate change on biodiversity, human health, and economic development produced by GHG emissions.
What are Greenhouse gases (GHGs)?
Greenhouse gases are atmospheric gases, including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases, that possess molecular structures capable of absorbing and re-emitting infrared radiation. This property allows them to trap and retain heat within the Earth’s atmosphere, contributing to the greenhouse effect. Increased anthropogenic emissions of these gases, primarily from fossil fuel combustion, deforestation, and industrial activities, have resulted in an intensified greenhouse effect, leading to global warming and climate change.
Types of Greenhouse gases (GHGs)
- Carbon dioxide (CO2)
- Methane (CH4)
- Nitrous oxide, also known as N2O.
- Hydrofluorocarbons (HFCs)
- Perfluorocarbons (PFCs)
- Sulfur hexafluoride (SF6)
- Nitrogen trifluoride (NF3)
Greenhouse Gases Emissions Sources
There are two primary origins of greenhouse gases (GHGs): natural sources and human-induced ones.
Sources derived from nature.
Natural resources comprise the following contributions.
- Water Vapors: Tiny water droplets in the form of water vapors also serve as potent GHGs found in the environment. Interestingly, water vapors are present comparatively in a larger quantity than other GHGs. The quantity of water vapor rises with the rising Earth’s temperature. Unlike CO2, the shelf life of water vapor is very small than the CO2 gas present in air but these water vapors are critical to enhance the CO, which is a potent gas.
- Carbon Dioxide (CO2): CO2 also plays a major contribution to climate variability and greenhouse impact. Several biological activities generate it, for example, plant respiration, animal and human respiration, and eruptions of volcanoes.
- Methane (CH4): Methane is often regarded as being the most important greenhouse gas contributing to warming the earth’s atmosphere and climate variability. Various natural processes release it, but human actions have altered the natural equilibrium. Large volumes of CH4 originate from dairy farms, rice fields, waste dump landfills, and the oil and gas industry.
- Nitrous Oxide (N2O): Nitrous oxide gas plays a significant role in increasing the greenhouse effect. The application of chemical fertilizers in agricultural fields and the burning of fossil fuels are the main causes of N2O emissions.
Humans induced sources:
Humans-induced sources (anthropogenic sources) encompass the subsequent contributors.
- Burning of Fossil Fuels: GHGs imperatively increased with increasing fossil fuel burning. The burning of coal, petroleum, oil, and natural gas reservoirs has a substantial effect on GHGs emissions in the atmosphere.
- Deforestation: Cutting the trees is termed as deforestation which has a meaningful impact on greenhouse gas emissions. Forests act as a carbon sink and with deforestation, the removal of carbon stored in trees enters into the atmosphere in the form of CO2, consequently, it deteriorate the climate.
- Industrialization: The increasing mechanization evolved the process of industrialization. The increasing industrial (cement, fertilizer, electricity) processes resulted in environmental destruction that brought climate change under the influence of more GHGs emissions.
- Landfills: Improper storage and deposition of household and municipal solid wastes considerably enhance greenhouse gas emissions. Solid wastes encourage CH4 production in landfills through anaerobic decay. Moreover, N2O is emitted from the combustion of solid wastes.
Agricultural Fields GHGs Emissions
Nitrogen (N) is imperative to enhance crop yield. Almost all field crops get repeated fertilization. There is a rising tendency for N fertilization or modification to agricultural lands. The amount of N that is applied to crops but not used goes to the water table by leaching or releasing into the atmosphere as gaseous emissions. This is due to the lower nitrogen use efficiency by crops. The number of losses in such situations is affected by varying seasonal and climatic patterns.
The losses through seepage enhance with the enhanced proportion of precipitation. N fertilization usually suffers from volatilization, which results in losses of nitrogen (N) in the form of nitrogen gas (N2), nitrous oxide (N2O), and nitric oxide (NO). N2O is released not only due to N fertilization in the soil but also through the decay of different crops’ waste materials. The amount of carbon (C) and the rate of N release from the soil greatly impact this process.
Paddy rice is the predominant source of methane gas (CH4) emissions. When the field is flooded, it emits CH4 gas because of the fermentation of decaying organic materials in the field. Changes in land use, which includes cutting forests for agricultural extension, are the main reasons for carbon dioxide (CO2) release from agricultural fields. The process of cultivation of fields and growing crops increases the transformation of carbon into CO2 in the soils by microbe activities.
CO2 release from agricultural fields is because of changes in the use of lands, such as when forests are removed for agricultural growth and extensions. Cultivating fields for a long time usually slows down or completely stops the loss of soil carbon, and the proportion of C in the soil becomes stable, but at a minimum fraction. Carbon dioxide also results from the use of fossil fuel for farm operations, the combustion of fossil fuels in diverse agricultural activities leads to the production of carbon dioxide.
Globally, agriculture is responsible for around 20% of the annual increase in radiation force due to the release of carbon dioxide, methane, and nitrous oxide. When there are changes in land use, this contribution climbs to one-third. The agriculture sector is accountable for around 45 to 50% of all human-caused methane emissions and 20 to 70% of nitrous oxide emissions. Adopting various cultivation methods and land use significantly influences GHG emissions in an environment that underscores the importance of these agricultural practices.
Impacts of greenhouse gas emissions.
Greenhouse gas emissions have various negative impacts, which are listed below.
1. Global Warming
Greenhouse gas emissions greatly result in lowering the concentration of infrared radiation, thereby significantly contributing to climate change. This climate change comprises the warming of the earth’s atmosphere. Moreover, the lowest increase in earth’s temperature stimulates many other changes in the environment, such as changes in weather and wind patterns and cloud covering above the earth.
Additionally, the Intergovernmental Panel on Climate Change (IPCC) reports that the mean surface temperature of the earth will increase from 1.4℃ to 5.8℃ by the end of 2100. This prediction considers the influence of aerosols, which lower the temperature of the environment, also lingering the impacts of seas having a huge amount of heat capability. Although, certain doubts are linked with this prediction (e.g., greenhouse gasses release rates)
2. Rises in Sea levels
In the case of global warming, rises in sea levels occur because of different irregular processes. High temperatures result in rising sea levels as a result of seawater heat extensions. Moreover, glaciers and ice slips melting increase water in the oceans. It is projected that the mean level of the earth’s sea will increase from 0.09 m to 0.88 m between 1990 and 2100.
3. Economic Impact
About half of the people in the world live within the 100 km range of the sea. The majority of these people reside in urban locations that act as coastal areas. A noticeable increase in levels of sea significantly impacted these coastal areas and islands, as well as enhancing erosion levels in beaches along the coastlines, increasing levels of sea-changing freshwater in the ground for the considerable distance inland.
4. Agricultural Impact
Different experiments have scientifically proved that with huge amounts of carbon dioxide (CO2), plants can mature in faster way. However, the impact of global warming may influence the circulation of the atmosphere, which results in changing rainfall patterns and also alters the moisture percentage in the soils in different regions.
5. Effects on Aquatic Systems
Greenhouse gas emissions significantly impacted the aquatic ecosystems. Large amounts of salt in the sea could lower the species that depend on freshwater but could enhance the species present in the marine system.
6. Effects on the Hydrological Cycle:
Due to greenhouse gas emissions worldwide, rainfall is likably to be enhanced. Although, there is no prediction about precipitation patterns regionally. Some areas may have high precipitation, and some may have low precipitation. Moreover, evaporation rises due to an increase in temperature. The changing patterns can produce new problems for effective systems of water management.
Strategies to Mitigate Greenhouse Gases
Regardless of the major contribution of greenhouse gasses (GHG) releases, agricultural methods, and operations have a substantial role in enhancing soil carbon reserves at minimum cost while lowering the release of greenhouse gasses and adding biomass stocks of feed for energy use.
In agricultural fields, the reduction of GHG release is feasible by lowering emissions, such as by enhancing the efficiency of nitrogen fertilizers through increasing serves (e.g., managing grass and croplands) and emissions distribution (replacement of fossil fuels for bioenergy). Various techniques should be employed to mitigate greenhouse gas emissions from agricultural fields.
1. Controlled-release fertilizers
Controlled release fertilizers (CRF) (e.g., zinc-coated urea, sulfur-coated urea, resin-coated, neem-coated urea) can minimize the losses of nitrogen (N) as nitrate ion (NO3) from seepage, volatilization as ammonia (NH3), and emissions as nitrous oxide (N2O) to the environment, although enhancing nitrogen proportion for plant growth and development.
The use of controlled-release urea increases crop grain yield and the effectiveness of nitrogen use contrary to normal urea. In agriculture fields, controlled-release urea reduces the release of nitrous oxide; this is due to controlled-release urea reduces the release of available nitrogen, which can impact the cycling of C/N in soils and then change the emissions of methane (CH4) and nitrous oxide.
2. Decreased application of fertilizers.
The fast increase in the use of fertilizers plays a great role in greenhouse gas emissions and a variety of environmental-related challenges, which ultimately leads to climate variability and greenhouse impact. Inappropriate nitrogenous fertilizer use contributes significantly to increased N2O emissions.
Nitrogen (N) application to agricultural fields enhances N2O generation, typically through distinct chemical processes (e.g., aerobic and anaerobic) of denitrification and nitrification. The most apparent way to reduce the release of greenhouse gases from fertilizer application is to reduce the amount of fertilizer used, particularly N fertilizers. Fertilizers should be employed following crop requirements and needs.
3. Revisiting the time of fertilizer application.
Fertilizer application timing also has a tremendous influence on GHG emissions. Nitrogen (N) is the principal element of fertilizers, which considerably adds to GHGs emissions. When N is added to the soil, it is released as N2O and CH4. Modifying the time of application greatly reduces GHG emissions, Such as split application of fertilizers or application at the right time.
In split application of fertilizer, plants get nutrients at their required stage. Moreover, fertilizers application at the right time also significantly reduced the GHG emissions.
4. Selection of fertilizer use
The selection of fertilizers has a considerable impact on the release of greenhouse gases from regions of agriculture. Organic fertilizers, as opposed to commercial fertilizers, provide not just micronutrients and NPK to crops and soils but also organic carbon when solid fertilizers, such as composts and solid manure, are employed.
Different nitrogenous fertilizer supplies influence both CH4 and N2O emissions. When contrasted with urea, nitrate fertilizers can minimize CH4 emissions. Additionally, applying organic fertilizers in crop fields instead of chemical fertilizers reduces N2O production.
5. Selection of fertilizer application methods
The application methods of fertilizers greatly impact greenhouse gas emissions. The choice of fertilizer application can vary with the type of fertilizer. Some studies reported that fertigation is the most effective method to reduce greenhouse gas emissions from agricultural lands. Besides, deep placement of urea in soil is considered the most effective method but, it promotes the N leaching losses and volatilization. Whereas, studies also stated that the deep placement of fertilizers can minimize N2O emissions.
Adaptive Strategies for Greenhouse Gas Emissions in Agriculture.
Various adaptive strategies should be used for greenhouse emissions from agricultural lands.
- Cover crops should be planted because they can increase soil carbon stocks and reduce erosions of soils; also, they improve soil physical structure and water retention properties, chemical composition, and faunal activity, which enable the system to recover from stress caused by more extreme weather conditions due to climate change.
- The promotion of agroforestry and reforestation has the potential to boost natural biodiversity and soil organic matter (SOM) percentage. The increased SOM improves the soil structure and water dynamics.
- No-tillage cropping should be fostered as it will result in improved soil texture and structure and will lead to enhanced soil organic matter.
- Overgrazing should be lowered because it will increase soil carbon sinks and ultimately will lead to mitigating greenhouse gas emissions from agricultural lands.
- Various efficient irrigation practices should be implemented, such as sprinkler and drip irrigation, to efficient utilization of water that will result in mitigating greenhouse gas emissions from agricultural lands.
- Special types of crop varieties should be selected that can adapt to climate change and greenhouse gas emissions during their growth periods.
Government Policies and Strategies
The government should adopt such policies and strategies that can reduce greenhouse gas emissions from agricultural lands. The government should provide sufficient funds to farmers to promote biodiversity and conservative farming practices. Research projects, activities, and innovative ideas should be undertaken to reduce greenhouse gas emissions. Additionally, agriculture extension agencies and education departments should raise awareness.
However, the government should support the use of efficient fertilizers that have a lower role in greenhouse gas emissions. Moreover, deforestation should be quickly stopped, and the growing of new forests should be promoted. Furthermore, animal feeding should improve, that have less effect on greenhouse gas emissions. It is necessary to promote global agencies to exchange knowledge that will reduce different agricultural emissions and have a positive impact on the environment.
Conclusion.
Knowing the reasons behind greenhouse gas emissions (GHGs) from agricultural fields is necessary for making effective management strategies to mitigate its emissions, thereby focusing on climate changes and environmental concerns. Adapting effective, sustainable techniques, managing fertilizer methods, and applying precision practices can significantly reduce greenhouse gas emissions.
Widespread effective techniques that contain essential rewards, financial incentives for research, and collaboration with different countries are crucial for the promotion of a sustainable agriculture industry. By applications of these strategies, authorities may significantly play a role in a better future that is both sustainable and resistant to climate change factors, therefore increasing the safety of biodiversity, ecosystems, and human populations.
aFarhan Rasheed, bSajid Usman, aMuhammad Umer Chattha, aImran Khan, aMuhammad Talha Aslam*, cUmair Ashraf and dMuhammad Umair Hassan.
- aDepartment of Agronomy, University of Agriculture Faisalabad, Pakistan.
- bInstitute of Soil and Environmental Sciences, University of Agriculture Faisalabad, Pakistan.
- cDepartment of Botany, University of Education, Lahore.
- dCollege of Agriculture, Jiangxi Agricultural University, Nanchang, China.
