SLU news

New thesis on addressing climate change in agriculture

Published: 23 September 2024
Portrait photo of Sandra Makaita Madamombe

On Wednesday, Sandra Makaita Madamombe will defend her doctoral thesis on how smallholder farmers in Zimbabwe are adapting their maize cultivation to changing climate conditions. The soils in the area are sandy and the climate is semi-arid. In a shifting and unpredictable climate, what matters is how farmers manage water and soil nutrients, and how many plants they sow.

How are Zimbabwean farmers adapting their maize cultivation to climate changes? Our doctoral student Sandra Makaita Madamombe has interviewed 245 smallholder farmers (with farms in the size of two to three hectares) in the Mutare district of Zimbabwe to understand their challenges.

– I have investigated what farmers know about climate change and what measures they have already taken, she explains.

The farmers are aware of climate changes because they have experienced extreme weather events (droughts, changes in temperature, and unusual rainfall patterns). They have adapted to the changes by harvesting rainwater, using cover crops to reduce evaporation, or switching to different crops.

– We also evaluated some 'climate-smart' farming methods that can be used to improve water management, soil fertility and crop production in the semi-arid region. We looked at different forms and timing of fertilization and the use of various seed densities to increase yield, she continues.

Sandra Makaita Madamombe highlights the following findings:

  • By installing a type of membrane, soil water retention near the maize roots can be increased. In the experiment, this led to a 21-24 percent increase in maize grain yield and a 13-22 percent increase in total biomass.
  • Increasing seed density from low (37,000 plants per hectare) to medium (74,000 plants per hectare) resulted in higher yields. However, further increasing the density to 111,000 plants per hectare led to a decline in yield.
  • Climate-smart practices can contribute to improved maize production on sandy soils in semi-arid areas. However, socio-economic factors that affect farmers’ work must also be taken into account.

Of the four years it takes to complete a PhD, Sandra has spent about three years collecting data in Zimbabwe and one year analysing the data in Sweden.

Sandra shares how much she has learned from meeting farmers in the field, talking with them about crop cultivation, and hearing their perspectives.

In the future, she hopes to continue working on issues related to ensuring food security and climate change adaptation while reducing agriculture’s climate impact.

– I want to inspire people to take action. I don’t want to only do research and write about climate change, but also make a difference in practice, she says.

Sandra believes there is a need for people working on climate issues both locally and globally.

– I would like to be one of those who work on these issues at a global level. We’ll see where this takes me in the future.

Sandra Makaita Madamombe grew up in rural Zimbabwe. She has completed her doctoral studies at the Department of Crop Production Ecology at the Swedish University of Agricultural Sciences (SLU) in collaboration with the Alliance Bioversity International-CIAT in Zimbabwe.

Facts:

Maize is one of the most common food crops grown without irrigation by small-scale farmers in Zimbabwe.

Sandy soils have poor water retention, making crops on such land particularly vulnerable to extended dry periods.

In the thesis "climate-smart agriculture" refers to farming practices that not only adapt to a changing climate but also limit agriculture’s impact on the climate.