Climate change impacts on rainfed maize yields in Zambia under conventional and optimized crop management

Siatwiinda M Siatwiinda,Olusegun Yerokun,Gerard H Ros,Iwan Supit,Wim De Vries,Bert Van Hove

doi:10.1007/s10584-021-03191-0

Siatwiinda M Siatwiinda, Olusegun Yerokun + Show 4 more

Open Access

https://doi.org/10.1007/s10584-021-03191-0

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Abstract

Maize production in Zambia is characterized by significant yield gaps attributed to nutrient management and climate change threatens to widen these gaps unless agronomic management is optimized. Insights in the impacts of climate change on maize yields and the potential to mitigate negative impacts by crop management are currently lacking for Zambia. Using five Global Circulation models and the WOFOST crop model, we assessed climate change impacts on maize yields at a 0.5° × 0.5° spatial resolution for RCP 4.5 and RCP 8.5 scenarios. Impacts were assessed for the near future (2035-2066) and far future (2065-2096) in comparison with a reference period (1971-2001). The surface temperature and warm days (above 30 °C) are projected to increase strongly in the southern and western regions. Precipitation is expected to decline, except in the northern regions, whereas the number of wet days declines everywhere, shortening the growing season. The risk of crop failure in western and southern regions increases due to dry spells and heat stress, while crops in the northern regions will be threatened by flooding or waterlogging due to heavy precipitation. The simulated decline in the water-limited and water- and nutrient-limited maize yields varied from 15 to 20% in the near future and from 20 to 40% in the far future, mainly due to the expected temperature increases. Optimizing management by adjusting planting dates and maize variety selection can counteract these impacts by 6-29%. The existing gaps between water-limited and nutrient-limited maize yields are substantially larger than the expected yield decline due to climate change. Improved nutrient management is therefore crucial to boost maize production in Zambia.

Highlights

Rainfed agriculture in Sub-Saharan Africa (SSA) is characterized by threats of crop failure due to multiple stresses with the most important ones being climatic conditions and nutrient deficiencies
This study focuses on options to increase maize yields by improving management that mitigate climate change impacts, measures that have been identified as a promising way to improve wheat yields in Australia (Richards et al 2014)
Results show that without countermeasures, maize yields will decline by 20-40% in particular for the southern and western regions

Summary

Introduction

Rainfed agriculture in Sub-Saharan Africa (SSA) is characterized by threats of crop failure due to multiple stresses with the most important ones being climatic conditions and nutrient deficiencies. A balance is needed between achieving food security without degrading the environment by sustainably improving yields in places where yield gaps exist (Foley et al 2011; Van Ittersum et al 2016). This is true for maize, being one of the most important staple crops in SSA, used for consumption, livelihoods, and food security (Schlenker and Lobell 2010). In Zambia, as in many countries in SSA, maize is commonly grown by rainfall-dependent smallholder farmers affecting both the national economy and household food security (Arslan et al 2015; Love et al 2006; Schlenker and Lobell 2010). Understanding maize yield responses to climatic changes and impact of adaptation measures is key to a climate-resilient maize cultivation (Becsi et al 2020; Lobell and Burke 2008)

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