Sorghum remains a great choice amid climate challenge

Amid climate change and harsh weather, sorghum is emerging as a profitable crop option for farmers. This drought-resistant crop not only thrives in challenging conditions with minimal water but also ensures robust yields during challenging years, making it an excellent choice.

Sorghum, with its low-maintenance attributes, is reclaiming its market standing, proving to be a compelling choice for farmers in arid regions or areas with limited rainfall. Cultivated extensively in provinces such as Mpumalanga, Limpopo, Free State, North West, and KwaZulu-Natal, sorghum can grow to a height of up to two metres.

According to Siphiwe Sithole, founder of African Marmalade, a continental aggregator, custodian, and supplier of indigenous crops, sorghum can thrive with rainfall of 400 mm – 800 mm per annum.

Planting and soil requirements

Sithole says sandy soils are generally not good for sorghum growth unless there is a subsoil with a thick texture. In addition, because sorghum is more resistant to alkaline salts than other grain crops, it can be grown on soils with a pH of 5.5 to 8.5.

The plant prefers warmer regions as it can tolerate harsh soil conditions and survive/produce a good yield on minimal water. “That will be the range that you look at, even if you get very little rain, it will still be suitable because of the root structure of sorghum and how it is spread out,” she explains.

“Compared to maize, sorghum may withstand brief periods of water logging better. For sorghum production, soils [with] a [clay] percentage of between 10% and 30% are ideal.”

To fully utilise their innate yield potential, sorghum plants need optimal growth conditions. These include deep, well-drained fertile soil; fairly consistent rainfall throughout the growing season; temperate to warm temperatures (20 to 30 degrees Celsius); and a frost-free period of roughly 120 to 140 days.

“Sorghum is one of those crops that would just thrive and give you a good yield even in a bad year,” she explains.

Sorghum is usually planted from mid-October to mid-December. The ideal time to plant is when there is enough water in the soil, and when it is 10cm deep, Sithole adds.

The majority of sorghum is planted on shallow, low-potential soils that contain a lot of clay and are typically unsuitable for growing maize.

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Growth temperature

Following germination, temperature has a significant impact on growth and development. The ideal temperature range for growth and development is between 27 and 30°Celsius. Nonetheless, a temperature as low as 21°Celsius can exist without significantly impacting growth and production.

“Warm-weather crops like sorghum need high temperatures for healthy germination and growth. A minimum of 7 to 10°Celsius is required for germination; 80% of seeds germinate in 10 to 12 days at 15°Celsius,” says Sithole.

Four reasons why sorghum can withstand droughts:

It has an exceedingly well-developed root system with fine branches that ababsorbater very well.
Its limited leaf area per plant restricts transpiration.
In warm, dry weather, its leaves fold up more effectively than maize.
Sorghum can stay in a state of near dormancy during dry spells and resume growing as soon as the weather returns to normal.

Different varieties of sorghum

There are different types of sorghum varieties. Locally, two varieties of sorghum are red and white, which have a sweet and bitter taste. The sweet cultivars are given priority because bitter sorghum contains tannin, which imparts a bitter flavour, birds tend not to eat it and is therefore planted in locations where birds are an issue.

The colours of sorghum grain have very slight variations in terms of cellulose, fatty acids, protein or starch content, minerals, and vitamins. While bitter sorghum is used for indoor malting, sweet sorghum is mostly processed for meals, rice, and grits.

“We grow both the red and white sorghum. From our side, we are growing more seeds so we can have enough to grow on a large scale from 2024/2025,” Sithole explains.

She further says, “Sorghum is best harvested mechanically for silage, but it is also possible to harvest the grains by hand, in which case the heads are dried on the threshing floor or the ground. If the entire plant is chopped, let it ripen in the field for ten to fourteen days, then thresh it to get the seeds and husks separated.”

Watch out for common pests and diseases

Turcicum leaf blight: A foliar disease that Exserohilum turcicum causes in corn (maize).
Anthracnose leaf blight: Occurs early in the growing season affecting lower leaves initially with late season disease progression affecting the upper leaves.
Sorghum rust: Fungal species and plant pathogen that causes rust on sorghum.
Sorghum ergot: The disease can result in poor seed set, and lower grain quality, and can cause harvesting issues due to the sticky honeydew on sorghum panicles.
Grain mould: Affects the nutritional quality of the grain.

“Producers will occasionally apply fungicides as a preventative measure, but the timing of these applications must be optimised for each disease. This is challenging because each has a unique growing season peak,” she explains.

Where is the market?

According to Sithole, there has been a gradual increase in the market for sorghum.

“When you look at your market traditionally, it would have been used it would have been used mainly for brewing your homemade beer that is used as a staple in some of the provinces for pap fermented or unfermented.”

The rise of health-conscious consumers has helped to grow the sorghum demand in the country and the market in itself caters to the consumer.

“The main buyers of the grain have been the culinary industry. It has been amazing to see how the grain is incorporated in food varieties and a farming opportunity should not be missed. In order to gain scale, it is necessary to use mechanised planters to do more hectares. The reality is several countries in Southern Africa will not be able to grow Maize beyond 2030.

“No amount of introducing this or that variety will work, and therefore we need to scale up the production of sorghum. The sooner we get these countries to look at better ways to grow sorghum the better,” she says.

In essence, drought stress severely reduces sorghum’s productivity and nutritional quality in all of its main cultivation areas, even though the crop is widely resilient, the minimum requirements are important for a great yield.