Agriculture and food systems are partly responsible for climate change, but they are also part of the solution. Agriculture is contributing a significant share of greenhouse gas (GHG) emissions, which are causing climate change – 17% directly through agricultural activities and an additional 7-14% through land use changes.
Farmers are on the frontline of the resulting climate change, with limited access to resources to help cushion the disruptions that climate change can cause to their operations and their daily lives.
The main GHGs directly produced by agriculture are nitrous oxide emissions – from soil disturbance, the application of fertilisers and the degradation of grazing lands – and methane production by ruminant animals and paddy rice cultivation. These emissions currently account for 58% of total anthropogenic nitrous oxide and 47% of total anthropogenic emissions. Such levels remain a huge threat to the global climate, especially in the context of an increasing global population and the high demand for food and food products, both for animals and humans. There are many potential adaptation options available for existing agricultural production systems to help manage climate risk. Adoption of such measures ensures that farmers will become more climate resilient, as well as help to reduce GHG emissions to the atmosphere.
Successful adaptation necessitates the integration of climate related issues with other risk factors, such as climate variability and market risk, and with other policy domains such as sustainable development. Appropriate actions in agriculture, forestry and fisheries – some of which I have outlined below – can mitigate GHG emissions and promote climatic adaptation. The Eastern Africa Farmers’ Federation (EAFF), a regional organisation representing approximately 20 million farmers in East Africa, promotes the adoption of climate-smart agriculture (CSA) practices – a climate adaptation approach, which also has potential to reduce GHG emissions.
The promotion of improved methods for storing manure to prevent methane from escaping into the atmosphere – by converting it into methane gas for cooking/lighting, for example – is an important CSA practice. When it is burned, methane gas only releases carbon dioxide and water. However, raw methane is a potent GHG with a global warming potential of 25 and 72 times that of carbon dioxide over 100- and 20-year periods, respectively. Any gains made in reducing GHG emissions by substituting biogas for solid fuels, such as manure, could be offset by methane leaked from biogas systems directly into the atmosphere. Manure management is therefore an essential practice in minimising GHG emissions.
Denitrification is the process of nitrogen gas production (a harmless gas found in the atmosphere) from nitrate in the soil, fertilisers or plants. EAFF encourages farmers to help denitrify their soils through the use of mixed cropping systems, where they intercrop legumes together with cereal plants that require nitrogen during their growth stages. Such practices decrease the need for fertilisers that release nitrous oxide, which has one of the longest atmosphere lifetimes of the GHGs.
Conservation agriculture practices like the promotion of no-till cultivation may help to reduce disruption of the soil, which can release carbon dioxide to the atmosphere. Promotion of agroforestry and particularly the protection of indigenous trees is another key conservation agriculture practice. The conservation of indigenous trees is important because they regulate nutrients, build the organic matter of topsoil, fix nitrogen and create a habitat that is beneficial for soil micro-organisms. Growing trees can help to maintain agricultural productivity by reducing erosion and enriching the soil or increasing the carrying capacity of shallow soils. Mulching and the planting of cover crops in a mixed farming system or monoculture will significantly help to sequester carbon from the atmosphere.
Soilless farming is another way in which farmers can help to decrease their GHG emissions. Innovations in soilless farming include hydroponics, which involves growing crops in a nutrient solution without soil and is currently being embraced by many young farmers. Aquaponics is another soilless practice, where farmers integrate both aquaculture and hydroponics. In an aquaponics system, plant waste products are utilised by fish and vice versa in a symbiotic relationship.
The world is a complicated place – the many different processes that make up global carbon and nitrogen cycles interact in complex ways that are still being studied by researchers. In addition to the solutions that engineers have devised to help reduce emissions in other sectors such as energy, we need to continue working on the agricultural piece of this puzzle.