GS Paper III

News Excerpt: 

With the help of machine learning, researchers have come up with detailed estimates of ammonia emissions from rice, wheat, and maize crops.

Key findings of the study:

• A cropland-specific assessment of the potential for emission reductions indicates that effective management of fertilizer in the growing of rice, wheat, and maize could lower atmospheric ammonia emissions from farming by up to 38%.
• This optimized strategy involves placing enhanced-efficiency fertilizers deeper into the soil using conventional tillage practices during the growing season.
• The researchers found that under the fertilizer management scenario, rice crops could contribute 47% of the total reduction potential, and maize and wheat could contribute 27% and 26%, respectively.
• Without any management strategies, the authors calculated that ammonia emissions could rise by between 4.6% to 15.8% by 2100, depending on the level of future greenhouse gas emissions.

The methodology adopted in the study:

• Researchers from the Southern University of Science and Technology, Shenzhen, China, and others used machine learning to model ammonia output from rice, wheat, and maize agriculture worldwide based on variables that include climate, soil characteristics, crop types, irrigation, tillage, and fertilization practices.

• To inform the model, the researchers developed a dataset of ammonia emissions from over 2,700 observations obtained via a systematic review of the published literature.
• Using this model, the researchers estimated that global ammonia emission reached 4.3 teragrams (4.3 billion kilograms) in 2018.

Why the reduction in ammonia emissions is necessary?

• Atmospheric ammonia is a key environmental pollutant that affects ecosystems across the planet, as well as human health.
• Around 51-60% of anthropogenic ammonia emissions can be traced back to crop cultivation, and about half of these emissions (25-30%) are associated with three main staple crops: rice, wheat, and maize.
• Ammonia (NH3) plays an important role in several different environmental issues such as acidification and eutrophication. 
• Ammonia also acts as a precursor to secondary particulate matter, therefore contributing to the related health impacts. 
• Secondary particulate matter is formed in the atmosphere through complex chemical reactions.
• Recent studies have indicated that NH3 emissions have been increasing over the last few decades on a global scale & it negatively influences environmental and public health as well as the fight against climate change.

About Ammonia (NH3):

• Gaseous ammonia (NH3) is the most abundant alkaline gas in the atmosphere. In addition, it is a major component of total reactive nitrogen. 
• The largest source of NH3 emissions is agriculture, including animal husbandry and NH3-based fertilizer applications. 
• Other sources of NH3 include industrial processes, vehicular emissions, and volatilization from soils and oceans.
• Ammonia is also produced in the human body and is commonly found in nature. 
• It is essential in the body as a building block for making proteins and other complex molecules. 
• In nature, ammonia occurs in soil from bacterial processes. It is also produced when plants, animals, and animal wastes decay.

Properties of ammonia: 

• Ammonia is a colorless highly irritating gas with a sharp suffocating odor. It dissolves easily in water to form an ammonium hydroxide solution which can cause irritation and burns. 
• Ammonia gas is easily compressed and forms a clear, colorless liquid under pressure. It is usually shipped as a compressed liquid in steel cylinders. 
• Ammonia is not highly flammable, but containers of ammonia may explode when exposed to high heat.

Uses of ammonia:

• About 80% of the ammonia produced in industry is used in agriculture as fertilizer. 
• Ammonia is also used as a refrigerant gas, to purify water supplies, and in the manufacture of plastics, explosives, fabrics, pesticides, dyes, and other chemicals. 
• It is also found in many household and industrial-strength cleaning solutions. 

Conclusion: 

This research emphasized the environmental significance of addressing ammonia emissions from rice, wheat, and maize cultivation, offering a pathway to mitigate the impact on ecosystems and human health.