Impacts of intensifying or expanding cereal cropping in sub‐Saharan Africa on greenhouse gas emissions and food security

Abstract

Cropping is responsible for substantial emissions of greenhouse gasses (GHGs) worldwide through the use of fertilizers and through expansion of agricultural land and associated carbon losses. Especially in sub‐Saharan Africa (SSA), GHG emissions from these processes might increase steeply in coming decades, due to tripling demand for food until 2050 to match the steep population growth. This study assesses the impact of achieving cereal self‐sufficiency by the year 2050 for 10 SSA countries on GHG emissions related to different scenarios of increasing cereal production, ranging from intensifying production to agricultural area expansion. We also assessed different nutrient management variants in the intensification. Our analysis revealed that irrespective of intensification or extensification, GHG emissions of the 10 countries jointly are at least 50% higher in 2050 than in 2015. Intensification will come, depending on the nutrient use efficiency achieved, with large increases in nutrient inputs and associated GHG emissions. However, matching food demand through conversion of forest and grasslands to cereal area likely results in much higher GHG emissions. Moreover, many countries lack enough suitable land for cereal expansion to match food demand. In addition, we analysed the uncertainty in our GHG estimates and found that it is caused primarily by uncertainty in the IPCC Tier 1 coefficient for direct N2O emissions, and by the agronomic nitrogen use efficiency (N‐AE). In conclusion, intensification scenarios are clearly superior to expansion scenarios in terms of climate change mitigation, but only if current N‐AE is increased to levels commonly achieved in, for example, the United States, and which have been demonstrated to be feasible in some locations in SSA. As such, intensifying cereal production with good agronomy and nutrient management is essential to moderate inevitable increases in GHG emissions. Sustainably increasing crop production in SSA is therefore a daunting challenge in the coming decades.

Modelling climate change impacts on maize yields under low nitrogen input conditions in sub‐Saharan Africa

“…A substantial proportion of the farm households in SSA face food insecurity (Frelat et al., 2016). Sustainable intensification with increased nutrient inputs and efficient use could drastically increase crop production and improve household food availability, whilst maintaining other important ecosystem services and preventing further land expansion (Loon et al., 2019; Vanlauwe et al., 2014). Our modelling study indicates that farmers intensifying maize production will face a different impact of climate change.…”

Production technology, efficiency, and productivity of cereal farms: Prospects for enhancing farm performance in Ghana

“…Whilst some studies argued that it is possible to feed the world by narrowing the substantial gaps between actual and attainable yields on existing farmlands (Lal 2016;Mauser et al 2015;Pradhan et al 2015), especially of those in SSA, others have advocated for a combination of crop area expansion and food imports to complement yield gaps closure in SSA (van Oort et al 2015). However, concerns that crop area expansion could lead to increased greenhouse gas emissions and biodiversity losses (Bennetzen, Smith, and Porter 2016;Loon et al 2019), and the assertion that low-income economies do not have ample foreign reserves to incessantly meet their food demand through imports, as well as the requisite infrastructure to store food for onward distribution (Chang 2009;van Ittersum et al 2016), make yield gaps closure very crucial for SSA. Hence, on-farm productivity of all cereals must be improved in SSA if domestic supply is to keep pace with both current and future demand.…”

Systemic Design for Food Self-Sufficiency in Urban Areas

“…In this framework, the link between energy, water, and food should be prioritized through technological proposals in regions with restrictions on these resources, or the consumption of such resources should be reduced [63,75,76]. Subsequently, improvements in agriculture enabled human activity to raise awareness of the environment to reduce the effects of waste and greenhouse gas emissions [77][78][79].…”

“…In this sense, international organizations such as the UN and the World Bank highlight the importance of reducing the impact that cities have and helping them contribute to sustainable development. The contributions of Blandford et al [102], Brombin [2], Ward [30], Huang et al [103], Loon et al [78], Nadal et al [66], Wesener et al [104], and Sapozhnikova and Ryazanova [95] identified some benefits in urban agriculture to support these issues, such as recycling and minimizing waste, efficiently using water, and conserving energy; reducing air pollution and soil erosion; urban…”