Agriculture's Air Pollution: What's The Real Damage?

Agriculture is a major source of air pollution in many parts of the world. While air pollution from agriculture includes emissions from tractors and farm vehicles, the greatest agricultural contributors to air pollution are animal-raising operations. The contamination produced by farming has a variety of causes, types, and effects, with air pollution being one of the most prevalent and impactful. Ammonia, which enters the air as a gas from heavily fertilized fields and livestock waste, is the dominant form of agricultural air pollution.

Livestock and manure

Livestock rearing and manure management are significant contributors to air pollution. According to the EPA, manure management alone accounts for 12% of all agricultural greenhouse gas emissions in the United States, and globally, it accounts for 14.5%, according to the United Nations' Food and Agriculture Organization.

The large number of animals kept in close proximity in concentrated animal feeding operations (CAFOs) results in a high concentration of pollution. These operations are challenging to regulate due to the varying factors that influence emissions, such as animal type, population size, geography, environmental conditions, feed additives, and manure management.

Manure emits ammonia, which combines with other air pollutants like nitrogen oxides and sulfates to form fine solid particles. These particles, when inhaled, can cause heart and lung diseases and are estimated to cause approximately 3.3 million deaths annually worldwide. Additionally, the widespread use of antibiotics in meat production contributes to the public health crisis of antibiotic resistance.

Livestock feed is often grown using pesticides and fertilizers made from fossil fuels, further contributing to air pollution. The practice of composting cow manure releases methane and nitrous oxide into the air, and the use of manure as fertilizer for crops can result in fertilizer runoff, impacting air and water quality.

To address these issues, accurate emission tracking, effective reduction strategies, and sustainable waste management practices are necessary. While some farms use manure as fertilizer for crops, it is crucial to implement practices that minimize environmental and health impacts, such as sustainable applications of livestock waste to fields.

Stubble burning

The practice of stubble burning also affects local biodiversity and ecosystems. The fires can destroy habitats for wildlife species, such as insects, birds, and small mammals, disrupting the balance of predator-prey relationships and leading to a decline in biodiversity. Additionally, the pollutants released from stubble burning can have direct and indirect harmful effects on both wildlife and aquatic ecosystems, further impacting their health and viability.

The burning of crop stubble also has negative consequences for soil fertility and economic development. The destruction of crop residues removes a potential source of economic benefit for farmers, as they could be used as fuel, raw material, or biomass for biofuel production. Instead, their burning contributes to climate change and global warming, with the released greenhouse gases (GHGs) preventing heat energy from escaping into space.

To address the environmental and health toll of stubble burning, there is a growing need to adopt more sustainable agricultural practices. Alternative methods such as mulching, incorporation of crop residues into the soil, no-till farming, and the use of stubble as a resource for power plants or the pulp and paper industries can help preserve soil health, reduce emissions, and protect human health and local ecosystems. By raising awareness about the availability of economically feasible options and the negative consequences of stubble burning, farmers can make more informed decisions and contribute to a greener agricultural future.

Fertilisers and pesticides

Fertilisers

The production of artificial fertilisers has increased dramatically, from 20 million tons in 1950 to approximately 190 million tons today, with about a third of them being nitrogen-based. During their manufacturing, soot and dust particles, as well as polluting gases such as sulphur oxide (SOx), ammonia (NH3), nitric oxide (NO), and nitrogen dioxide (NO2), are emitted into the air. These emissions directly affect the environment and human health.

Excess nitrogen from fertilisers returns to the atmosphere as nitrogen oxides, which have a greenhouse effect 300 times more potent than carbon dioxide. This contributes to global warming and climate change. Additionally, ammonia from heavily fertilised fields combines with industrial emissions to form tiny solid particles or aerosols, which can penetrate deep into the lungs, causing heart and pulmonary diseases.

Pesticides

Pesticides are semi-volatile organic compounds that include a range of chemicals. Both their active and inert ingredients can be organic compounds, contributing to the levels of airborne organics inside homes and other indoor spaces. Inert ingredients, while non-toxic to the targeted pests, may cause human health issues.

The overuse or incorrect use of pesticides can lead to a harmful residue buildup. When pesticides are sprayed, their droplets can settle on various surfaces, and their chemicals can evaporate into the air. This residue can be dangerous to humans and pets if inhaled, touched, or ingested.

To minimise the impact of pesticides on indoor air quality, it is recommended to use non-chemical pest control methods, increase ventilation during and after application, and store or dispose of pesticides properly.

Machinery and vehicles

The use of machinery and vehicles in agriculture has a significant impact on air pollution. While the use of mechanical equipment has made farmers' lives easier, it has also contributed to the emission of pollutants into the atmosphere. Diesel-powered farm equipment, for instance, releases diesel emissions, which are a major source of air pollution. The burning of fossil fuels to power farm machinery releases carbon into the atmosphere, contributing to climate change and global warming.

Tractors and other farm vehicles also emit pollutants such as nitrogen dioxide and sulfur dioxide, which can have detrimental effects on human health and the environment. These emissions can reduce air quality, impacting the growth of plants and crops. Additionally, the application of fertilisers and pesticides, often using machinery, can result in chemical drift, where these compounds reach nearby lands or neighbourhoods, further contributing to poor air quality.

The use of heavy-duty machinery in agriculture, such as tractors and ploughs, can also contribute to air pollution through soil disturbance. Soil plowing and tilling release stored carbon into the atmosphere, adding to greenhouse gas emissions. No-till farming practices, on the other hand, help to retain soil carbon and prevent erosion, reducing the amount of particulate matter (dust) that enters the air.

To mitigate the impact of machinery and vehicles on air pollution, farmers can adopt sustainable practices. This includes reducing the use of chemicals and transitioning to more efficient and environmentally friendly equipment. Implementing regulations and initiatives, such as the National Clean Diesel Campaign, can also help farmers finance clean diesel projects and reduce diesel emissions.

Furthermore, agroecology and organic practices can be employed to work with natural ecosystems and reduce the need for chemical inputs. By keeping animals on pasture, manure can break down aerobically, reducing emissions and improving air quality. Additionally, sustainable farming practices, such as cover crops and no-till farming, can help retain soil moisture and avoid greenhouse gas emissions, ultimately playing a crucial role in improving air quality and combating climate change.

Climate change

Agriculture is a significant contributor to air pollution and climate change. The sector's impact on the environment is complex and multifaceted, and it is important to understand the various ways in which agricultural practices can lead to air pollution and contribute to climate change.

One of the main ways agriculture contributes to air pollution is through the release of ammonia, which is a byproduct of livestock farming. Ammonia can react with other pollutants in the atmosphere to form fine particulate matter, which can be harmful to human health. Livestock farming also produces large amounts of methane, a powerful greenhouse gas that contributes to climate change. Methane is released during the digestive process in ruminant animals such as cows and sheep, and it is also emitted from manure storage and handling.

Another source of air pollution from agriculture is the burning of crop residues, such as straw and stubble. This practice, known as agricultural burning, releases large amounts of smoke and particulate matter into the atmosphere, which can travel great distances and contribute to air pollution in distant places. Agricultural burning is a major problem in many parts of the world, particularly in regions with large-scale agriculture, such as the United States, Europe, and South Asia.

To address and adapt to these challenges, farmers are adopting various strategies. These include altering planting and harvesting times to align with shifting weather patterns, selecting crop varieties that are more resilient to extreme conditions, and implementing water-saving irrigation techniques. Additionally, sustainable agricultural practices, such as agroecology and conservation agriculture, are gaining traction as they promote climate resilience while also benefiting the environment and rural communities. By focusing on biodiversity, ecological processes, and sustainable resource management, these approaches help mitigate climate change impacts while enhancing food security and supporting rural livelihoods.

Additionally, integrated crop-livestock systems, agroforestry, and the use of cover crops are also being employed to improve soil health and further enhance carbon sequestration. These practices not only benefit the climate but also improve soil fertility, increase crop yields, and provide multiple ecosystem services. They contribute to more sustainable and resilient agricultural systems, helping to ensure food security and mitigate climate change impacts in the long term.

Frequently asked questions