As climate change accelerates, many countries around the world are increasingly facing the risk of drought. Water scarcity has become one of the major constraints of food production in the 21st century, and a major threat for our current and future food security. In the Horn of Africa, four consecutive rainfall deficit seasons have led to more than 16 million persons facing severe hunger in Somalia, Ethiopia and Kenya. Droughts and other climate shocks like this summer heat wave become more frequent in the current climate crisis.
Because crops’ primary source of water is rain, they’re highly vulnerable to drought. Even where farmers have underground sources of water available, many are running dry. In Morocco, the water crisis and competition with other sectors may soon make farming in regions such as Agadir difficult or even impossible.
Yet in the next 20 to 30 years, we will need to boost agricultural production by as much as 70%, especially in Africa. Agriculture is the first user of water resources (70% to 80%) and thus needs to radically increase its efficiency to respond to declining resources and a growing demand for drinking water and other uses, including industry, tourism and ecosystem preservation.
Climate change: agriculture as contributor, victim and solution (Cirad).
Crop selection and farming techniques
So how can we sustainably grow crop production in the context of droughts that are more frequent, more intense and longer lasting? If we look over the science, this largely comes down to crop selection. More specifically, the capacity for a wheat or pea variety to produce more grain with less water is the combination of three phenomenons:
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Plants’ ability to pump soil water at the root level: this is how they create biomass through photosynthesis without losing too much water through evaporation. Plants have leaf surfaces with microscopic openings called stomata that open or close to allow the exchange of CO2 and water vapor. Research has shown that by modifying light-sensitive opening mechanisms of the stomata, the plant could save 25% water for the same biomass produced.
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Increasing the amount of grain produced by each crop, including by ensuring they use water as efficiently as possible. An innovative lysimetric system weighing individual plants and scanning leaf surface in real time has revealed that transpiration efficacy for plants like sorghum could vary a lot between individual, yet without necessarily yielding any differences. This could be a promising drought-tolerance trait to explore.
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Investigating the optimal combinations of plants – known as crop diversity. In drought conditions, pearl millet associated with cowpea, an important legume in West Africa, can produce the same millet yield as millet alone. This means that an additional protein-rich harvest of cowpea can be produced with the same quantity of…
La suite est à lire sur: theconversation.com
Auteur: Delphine Luquet, Écophysiologiste, Cirad
