The southern African region is battling with drought at present. This is the result of El Niño, a natural climate cycle characterised by changes in Pacific Ocean temperatures. It has effects on global weather patterns, particularly rainfall and temperature.
The drought has hit the region’s agricultural productivity hard. Malawi, Zambia and Zimbabwe have declared a state of disaster with respect to their current agricultural outputs. They are seeking humanitarian assistance in the form of food aid to feed their people. The downturn also has economic implications, since over 70% of people residing in the region’s rural areas rely on agriculture for their livelihoods.
The dire situation underscores how important it is for the agricultural sector to prevent, avoid or prepare for the impacts of climate change, which will also bring extremes of weather.
One measure the sector can take is to cultivate biofuel crops. These are crops rich in starch, sugar or oils that can be converted into bioethanol directly or through a fermentation process. Bioethanol, a type of ethanol produced from biological or plant based sources, emits fewer greenhouse gases compared to fossil fuels like petroleum, natural gas and coal. Commonly used biofuel crops include sugarcane, maize, grain sorghum, sugar beet, rapeseeds and sunflower.
These conventional biofuel crops do have drawbacks, however. They are highly susceptible to extreme weather events. They require high upfront investment for fertilisers, chemicals and irrigation. And they compete with food production – if they’re grown as biofuels they can’t also be used as food because of how they have to be processed.
So, researchers are always on the lookout for crops that might be good biofuels without those problems. Sweet sorghum, which is indigenous to the African continent, is one such crop. Unlike the better-known sorghum, it has sweet juice in its stems. In a recent study, I reviewed scientific literature to analyse the potential significance of sweet sorghum to African farmers because of its multipurpose nature and ability to adapt under harsh climatic conditions.
Multiple uses
Sweet sorghum has many uses. It can produce grains, animal feed and sugary juice, making it unique among crops. The grains from sweet sorghum are prepared as steamed bread or porridge malt for traditional beer, as well as in commercial beer production across the continent.
They’re nutritionally rich, with high energy values (342 calories/100 g), proteins (10g/100 grains), carbohydrates (72.7g/100 grains), and fibre (2.2g/100 grains) as well as essential minerals such as potassium (44mg/100 grains), calcium (22mg/100 grains), sodium (8mg/100 grains) and iron (3.8mg/100 grains).
The nutritional value of maize is fairly similar: proteins (8.84g/100 grains), carbohydrates (71.88g/100 grains), fibre (2.1g/100 grains), potassium (286mg/100 grains), calcium (10mg/100 grains), sodium (15.9mg/100 grains) and iron (2.3mg/100 grains).
What sets sweet sorghum apart from a crop like maize is that it’s also resilient in arid climates and has multiple other uses. For instance, it produces a lot of plant material (biomass) as it grows, which is left over after harvest. That’s why it’s useful as animal feed too.