A large segment of the African population depend on a very small number of food crops, like maize, rice and wheat. Africa is actually blessed with a wealth of crop diversity. Much of it – including sorghum, yam and cowpea – is native to the continent. But many other crop types have arrived via trade, like banana, pigeon pea and wheat from Asia, and beans, cassava and maize from the Americas. But rather than capitalize on this full basket of food options, we’ve bet too heavily on just a few crops.
Take the case of maize in Eastern and Southern Africa. Yes, it can grow in different farming environments and supply large amounts of calories. But the crop has weaknesses. It’s susceptible to drought and pests and its nutritional quality is mediocre.
And while recent research has delivered more resilient and nutritious maize varieties, these are not sufficient. The fact remains that in many regions, rising temperatures and increasingly erratic rainfall will cause maize yields to fall—by up to 22 percent in many areas and up to 60 percent in South Africa and Zimbabwe, according to a 2015 report from the Montpellier Panel.
There is a strong body of research showing that farmers are much less likely to suffer catastrophic losses from pests, disease or drought if they plant a broader array of crops. Today, the devastation caused by outbreaks of lethal necrosis in maize and stem rust in wheat is greatly intensified by the lack of alternative crops. In Malawi, while drought ruined maize and bean crops this year, farmers growing naturally hardy, nutritional crops like chickpea and sweetpotato fared much better.
If the benefits are so clear, then why don´t farmers just spontaneously diversify? The answer is that they may want to diversify, but often don’t due to policy and institutional barriers. When crops like maize started to dominate, governments and the private sector accelerated their take-over by providing subsidies, research and other support. Meanwhile, other potentially useful crops like cassava and sorghum were neglected, sometimes acquiring derogatory labels like the “poor man’s crop” or “crop for marginal lands.”
In the case of sweetpotato, we bred for higher levels of beta-carotene (the chemical precursor of vitamin A), better drought tolerance and virus resistance.
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