Farmers' Guide To Reducing Air Pollution

Agriculture is a significant contributor to air pollution worldwide, with food production responsible for a quarter of the world's greenhouse gas emissions. To reduce air pollution, farmers can adopt several practices, including improving soil health through cover cropping and streamside buffer cropping, and adopting sustainable agricultural practices such as agroforestry and regenerative agriculture.

Reduce livestock numbers

Reducing livestock numbers is one of the most effective ways for farmers to decrease air pollution. Livestock farming is a major contributor to air pollution, as animals emit methane through their digestive processes and waste. Methane is a greenhouse gas with 28 to 34 times the planet-warming power of carbon. Additionally, the vast amounts of manure produced by livestock contain harmful gases such as ammonia and hydrogen sulfide, which are released into the air and cause air pollution.

One way to reduce livestock numbers is to transition to more plant-based food production. This can be achieved by adapting to a plant-based food system, where farmers focus on growing crops for human consumption instead of rearing animals. This approach not only reduces air pollution but also has the potential to pause the increase in greenhouse gas emissions for 30 years. It is important to note that this transition should be gradual and include a variety of plant-based options to ensure a balanced and nutritious diet.

Another strategy to reduce livestock numbers is to improve the efficiency of meat production. This can be achieved by improving productivity and fertility, as well as modifying the diets of livestock to reduce methane emissions. For example, feeding cattle with high-energy, lower-protein feed such as maize silage may help decrease methane emissions. Additionally, treating livestock slurry using controlled anaerobic digestion can stabilize the slurry and produce biogas for heating or electricity generation.

It is worth mentioning that reducing livestock numbers alone may not be sufficient to significantly mitigate air pollution. Complementary measures, such as improving slurry handling, incorporating manure into the soil, and adopting sustainable farming practices, should also be implemented. These practices can help reduce ammonia and methane emissions and promote more environmentally friendly farming.

By implementing these strategies, farmers can play a crucial role in reducing air pollution, protecting the environment, and contributing to global efforts to combat climate change.

Improve productivity and fertility

Farmers can improve productivity and fertility by modifying the diets of their livestock. This can reduce agricultural methane emissions, which are mostly produced by the digestive processes of livestock.

Another way to improve productivity and fertility is to adopt nutrient management techniques. Farmers can do this by applying the right amount of nutrients (fertilizer and manure), at the right time of year, with the right method and placement. This will reduce the amount of fertiliser that reaches water bodies and improve water quality.

Additionally, farmers can use conservation drainage practices to manage water movement on and through their soils. This involves strategies such as modifying drainage system design and operation, and using woodchip bioreactors and saturated buffers.

By ensuring year-round ground cover, farmers can prevent periods of bare ground on their fields when the soil is most susceptible to erosion and nutrient loss into waterways. This can be achieved by planting cover crops or perennial species.

Modify livestock diets

Farmers can adopt several strategies to modify the diets of their livestock and reduce air pollution. Here are some detailed suggestions:

Reduce Protein Intake

Livestock diets can be adjusted to ensure animals are not fed more protein than is necessary for the desired level of milk, meat, or egg production. This approach reduces the amount of nitrogen excreted as urea in urine and faeces, which can lead to the formation of ammonia. Ammonia emissions contribute to air pollution and can cause environmental damage, including soil acidification and adverse effects on vegetation.

Phase Feeding

Pig and poultry farmers can implement phase feeding, a technique that closely matches the dietary requirements of animals with their specific growth stages. This method ensures that the animals receive a diet that meets their changing nutritional needs as they progress through different life stages.

Low-Nitrogen Feeds

Feeding pigs with low-nitrogen but production-maintaining feeds can help reduce nitrogen excretion and subsequent ammonia emissions. This strategy can be particularly beneficial for pig farming operations.

High-Energy, Lower-Protein Feed

For cattle and sheep farmers, switching to high-energy, lower-protein feed options such as maize silage may be advantageous. This dietary adjustment can help improve nitrogen efficiency and reduce excess nitrogen excretion, thereby minimising ammonia emissions.

Efficient Fertiliser Use

While not directly modifying livestock diets, efficient fertiliser use can indirectly impact the quality of feed crops and reduce air pollution. Farmers can use fertilisers at appropriate rates and timings, taking into account organic manures or sewage sludge already applied to calculate application rates. Regular maintenance of fertiliser spreaders and proper training for staff can also ensure accurate fertiliser application and minimise nitrogen losses.

Avoid burning waste

Burning agricultural waste is a common practice among farmers worldwide. However, it is essential to understand the negative consequences of this practice and explore alternative approaches to waste management.

The Impact of Burning Waste

The burning of agricultural waste, such as crop residues and vegetation, releases harmful pollutants into the atmosphere. This includes the emission of poisonous gases, grit, and dust, which contribute to air pollution. Additionally, toxic chemicals released during burning can contaminate the soil, groundwater, and surface waters, posing a threat to both human and environmental health.

Health Risks

The microscopic pollutant PM2.5, which is released during burning, can penetrate deep into the lungs and bloodstream, increasing the risk of heart and lung disease, stroke, and certain types of cancer. Exposure to this pollutant can also cause psychological and behavioural problems in children and has been linked to Alzheimer's, Parkinson's disease, and dementia in older individuals.

Environmental Impact

Burning agricultural waste is a significant source of black carbon, which is a short-lived climate pollutant. Although it exists for only a short period, its impact on global warming is substantial, with an effect 460–1,500 times stronger than carbon dioxide. Black carbon can also modify rainfall patterns, particularly the Asian monsoon, disrupting the weather events necessary for agriculture.

Alternative Approaches

Instead of burning waste, farmers can adopt more sustainable practices, such as:

• Changing processes to reduce or eliminate waste.
• Reusing and recycling materials, such as silage wrap.
• Sending waste for recovery, such as oils and solvents.
• Composting biodegradable waste.
• Using authorised incineration plants, furnaces, or boilers to burn waste, preferably to produce alternative energy.
• Disposing of waste at authorised landfill sites.

Benefits of Avoiding Waste Burning

By avoiding the burning of waste, farmers can not only reduce air pollution but also improve soil fertility and water retention. This, in turn, can reduce the need for expensive fertilisers and irrigation systems. Additionally, incorporating stubble back into fields or planting through the stubble can save farmers money and enhance the fertility of their land.

Use alternative energy sources

Farmers can reduce air pollution by using alternative energy sources such as solar, wind, geothermal, and hydroelectric power. These sources produce little to no global warming emissions, even when including "life cycle" emissions. In contrast, burning natural gas or coal for electricity releases a significant amount of carbon dioxide and other harmful gases.

Solar energy, for example, is responsible for only 0.07 to 0.2 pounds of carbon dioxide equivalent per kilowatt-hour (CO2E/kWh) on a life-cycle basis, whereas coal emits between 1.4 and 3.6 pounds of CO2E/kWh. Wind energy is even cleaner, with a responsibility of only 0.02 to 0.04 pounds of CO2E/kWh.

Farmers can also consider using biogas from manure digestion or straw-burning boilers as alternative energy sources. These options are more likely to be cost-effective when the amount of energy needed is consistent throughout the year. Before investing in such projects, farmers should calculate the set-up and running costs to ensure financial viability.

Transitioning to alternative energy sources for energy management in agriculture holds great promise for reducing greenhouse gas emissions, improving energy efficiency, and promoting sustainability in food production. However, it is important to address technical, economic, and policy barriers while fostering knowledge dissemination and capacity building among farmers and stakeholders to ensure successful implementation.

Frequently asked questions