How does agriculture affect climate change?
In the previous article, I explored opportunities available to the livestock industry the world moves towards more planet friendly diets. Apart from reducing meat consumption, another significant way to mitigate food system related emissions is to change traditional agricultural production methods.
Conventional farming methods are designed to maximise crop yields and ensure a stable food supply, while sacrificing nutritional value and soil health. Aside from livestock production, a significant amount of food system emissions derives from (1) the release of nitrous oxide from the use of chemical fertilisers and (2) converting arable land into agricultural land, also known as ‘land use change’.
So, how does agriculture lead to increased carbon emissions?
There are several ways that farming increases the amount of GHG in our atmosphere, including the use of invasive farming methods, chemical inputs, monoculture farming systems and land use change.
[Note: The level of Co2 and N2O emitted depends on the type of crop grown, the nitrogen fertiliser applied and the climactic conditions where the crop is grown]
1. Unsustainable Farming Practices
Manual and mechanical tilling breaks up the soil, exposing carbon buried in the soil to oxygen, which then turns into Carbon Dioxide (Co2) via a chemical reaction involving microbes in the soil. Since the dawn of farming, most agricultural soils have lost 30% to 75% of their original soil organic carbon .
Destroying the soil also impacts our soil’s natural ability to act as a carbon sink. Healthy soils can absorb carbon from our atmosphere, a process known as carbon sequestration, by storing Co2 inside soil carbon pools. However, since the industrial revolution, soil’s carbon sequestration ability has been significantly depleted, causing the release of 50 to 100 GT of carbon .
Monoculture farming is a type of farming where only one type of crop is grown on the pasture. This became widespread since the industrial revolution, where industrial farming led to a need maximise crop yields and reduce costs. Since only one type of crop is grown at a time, this reduces the equipment and chemical input needed, easing crop management for farmers.
However, monoculture adversely impacts arable land by reducing biodiversity, impacting the soil and leading to more pests. Monoculture can lead to increased risk of pest infestation and disease because pests can move more quickly through an area when there is a lack of biodiversity. Farmers respond to this by using chemical fertilisers to protect crops; this can lead to a vicious cycle, as pests may sometimes develop an immunity to fertilisers, leading to even more amounts or concentrations of fertilisers. Fertilisers contain huge volumes of nitrogen oxide, which is one of the three key climate pollutants; when fertilisers are used, Nitrogen (N2O) is released in the atmosphere.
Further, reduced biodiversity impacts soil health by upsetting our soil’s natural balance, leading to lack of soil fertility and soil erosion. To continue farming on the land, farmers artificially boost the nutrients in soil via chemical fertilisers, further devastating soil health.
[Note that the impact of monoculture depends on intensity; less intense forms of monoculture may mean crops are rotated every few months, while the most intense form is where a single crop is crown year after year without change .]
What are the SOLUTIONS and CHALLENGES?
No Till Farming: A recent report found that no till farming could play a crucial role in reducing GHG emissions and increase and carbon sequestration. Some farmers are using a machine that drills small seed holes into the soil, creating pockets for farmers to sow seeds without tilling. The resulting smaller air pockets created led to a reduced amount of Co2 released, with findings showing a 30% reduction in total emissions.
Rotational Cropping : Moving away from monoculture means practicing methods that decreases the need for chemical fertilisers. Increasing crop rotations every year will reduce instances of pest infestations by interrupting pest cycles; introducing different crops will also help soils maintain a healthier composition.
Polyculture: Polyculture, a key method used in regenerative farming, is a method that has gained ground in recent years. A polyculture system introduces a variety of plants onto the land at one time, mimicking a biodiverse ecosystem full flora and fauna. The increased biodiversity renders the soil more nutrient rich, reducing the occurrence of pests and the need to use fertilisers.
The challenges of scaling regenerative practice are similar across the globe, due to systemic issues ingrained in global food systems.
The global food sector is commonly monopolised by a few large local or national corporations, whose procurement team focus on quantity and constant supply instead of quality and the ability to meet environmental standards. Many governments also subsidise staple crops such as corn, wheat and rice to ensure stable food supplies across the country. Met with these demands, farmers fear that a lapse in productivity by practicing new method will lead to a period of lower yield and directly affect their livelihoods.
Secondly, though ‘regenerative agriculture’ has become a global buzzword, there is still a lack of knowledge and resources to help farmers with their transition. Some corporations are using A.I systems to speed up the learning curve by monitoring successful regenerative practices and then recreating similar conditions on other farms
The lack of suitable financial mechanisms to support farmers is also a significant barrier. Smallholder farmers are especially disadvantaged when it comes to raising money to restructure farms, as most of the agricultural budget goes to larger commercial farms. The high upfront costs of purchasing new farming equipment or restructuring farms is what puts farmers off from changing their practices.
Innovative financial mechanisms offered by both financial institutions and corporations are essential to incentivise farmers to make the initial switch. Continuous technical assistance will also provide added assurance, helping farmers de risk their investments and further scale effective practices.
2. LAND-USE CHANGE
According to the IPPCC’s 2019 report, nearly ¼ of global emissions derived from land-use change due to agriculture, forestry and other land uses. Out of the six different categories of land-use change, approximately half of the single change (where land is converted permanently for a particular use) events are due to agricultural expansion .
Our soils’ ability to sequester carbon and act as a ‘sink’ is adversely affected by land-use change. Agricultural land-use change mainly involves removing the land’s original vegetation and replacing them with crops. Deforestation and unsustainable forest management practices lead to increased GHG emissions by removing trees and destroying soil, both of which are significant carbon sinks.
What are the SOLUTIONS and CHALLENGES?
Improving agricultural productivity: Improved farming practices such as better soil and livestock management can deliver up to 9 MtCO2e (metric tons of carbon dioxide equivalent) annual emissions reduction. Practices that focus on improving animal health and fertility and more efficient nitrogen use can improve yield rates. However, improving agricultural productivity itself is insufficient, as this still leaves agriculture as one of the biggest emitting sectors .
Releasing Agricultural Land for Other Uses: Releasing agricultural land for other uses, including afforestation (increasing forest cover), peatland restoration and catchment management . Afforestation and peatland restoration also provides added benefits including increased biodiversity, improved water quality and flood alleviation.
Moving horticulture indoors: It unlikely that land will be released for other uses unless a food production alternative is found. Countries such as the UK and Singapore are experimenting with indoor horticulture, growing crops ‘off farm’ via hydroponics and vertical production systems. Despite this, the electricity intense nature of indoor horticulture means a significant reduction in electricity costs is required to render this option globally viable.
Policy changes that can support a more sustainable food system: Despite the increasing availability of plant-based products, making them a viable alternative requires price parity with conventional proteins, which requires reducing the costs of production of plant-based products. This requires a combination of innovation, to develop low-cost production systems, as well as governmental policy. For example, reducing agricultural subsidies and investing these funds into production of plant-based products.
Alongside reducing meat consumption and promoting plant-based diets, it is essential for us to transition to low carbon agricultural production systems. This necessitates a longer-term outlook on agricultural productivity; stakeholders must understand that sustainable practices that benefiting soil health and biodiversity will result in better yields in the long run.
- Rodale Institute, Regenerative Organic Agriculture and Climate Change, < https://rodaleinstitute.org/wp-content/uploads/rodale-white-paper.pdf>
2. The Nature Education, Soil Carbon Storage, < https://www.nature.com/scitable/knowledge/library/soil-carbon-storage-84223790/>
3. Earth Observing System, Monoculture Farming in Agriculture Industry, < https://eos.com/blog/monoculture-farming/>
4. Carbon Brief, Land-Use change has affected ‘almost a third’ of the world’s terrain since 1960, < https://www.carbonbrief.org/land-use-change-has-affected-almost-a-third-of-worlds-terrain-since-1960>
5. The Climate Change Committee, Land Use: Policies for a Net Zero UK, < https://www.theccc.org.uk/wp-content/uploads/2020/01/Land-use-Policies-for-a-Net-Zero-UK.pdf>
6. Catchment Management: Efficient catchment management prevents soil, fertiliser and pesticides washing from fields into rivers and groundwater