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Sorghum sows seeds of promise


An ancient African crop could meet a very modern need: food plus biofuel. James Mitchell Crow reports.


Sweet sorghum is a highly nutritious and versatile plant.
Christopher Scott / Getty Images

Blame it on the sugar. It’s early May 2015, the middle of southern India’s mercilessly hot dry season, and I’m sheltering from the sun under a huge jerry-rigged shade cloth, pitched on a tractor-width finger of land between two fields. Joining me under the cloth are 40 or so Indian farmers, chatting excitedly as they graze on packets of sugary sweets.

But the sugar they’re buzzing about is not in these packets. It’s behind us, accumulating in the stems of towering sweet sorghum plants. Each stalk is almost twice my height, arrow- straight and reaching toward the cloudless sky.

Domesticated thousands of years ago in north Africa, sweet sorghum thrives here. But the farmers gathered amid these stalks don’t grow it. This is sugarcane country: the land we’re standing on belongs to the Madhucon sugar mill, which looms on the horizon.

The mill’s owners want to conduct an experiment. Working with scientists from the nearby International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), they’re hoping to sweet-talk the farmers into growing sweet sorghum during the dry season when sugarcane won’t grow. Leading the charm offensive is ICRISAT scientist Pinnamaneni Srinivasa Rao. Rao, tall, slim and clean-shaven, gestures towards the sweet sorghum he bred for the trial as he lists the plant’s merits.

It’s a long list. The sweet sap in its stalk is a high-grade starter for making environmentally sustainable bioethanol, Rao tells the farmers. Its fluffy seed head is packed with highly nutritious grain for hungry farmers, and all that towering foliage provides fodder for livestock. What’s more, it grows on meagre amounts of water. Sweet sorghum could be the first genuinely green biofuel – one that can help cut carbon emissions without competing for land with food crops.

Growing biofuels in a way that benefits everyone has proved far harder than many first thought.

In four more weeks, Rao’s little test crop of sweet sorghum will be harvested and tested for its sugar content. The best-performing plants will be taken on to the next step in the trial. And that’s the purpose of today’s outdoor meeting – to get 20 to 30 local farmers to grow sweet sorghum for the mill. Unless these farmers can be persuaded to try the new crop, there won’t be enough sweet sorghum to warrant starting up the mill, and the experiment will be over before it’s begun.

But the farmers are cautious. Any crop – even a super-crop – must obey the bottom line. From farmer to farmer, the same question rings out: what will the mill pay them for the crop? As India’s farmers are acutely aware, the biofuel industry is still reeling from the failure of jatropha, the last miracle crop. Not to mention the 2014 oil market crash, which took the price consumers would pay for biofuels down with it.

But the scientists and entrepreneurs behind the Madhucon sweet sorghum trial believe they have a way to make biofuels pay even if oil prices stay low. That would be good for the environment, and good for the farmers.

“Our research focus has been on improving the economics of sweet sorghum cultivation,” says Rao, which as well as improving the obvious traits such as the yield of sugary juice, has meant improving its resilience to salinity, drought and disease.

For the mill owners, sweet sorghum is a business opportunity – a way to keep the mill running when sugarcane isn’t available. For the ICRISAT scientists, establishing the plant’s commercial credentials is a way to empower some of the world’s poorest farmers. For the rest of us, it’s a small step – but one that could ripple outward – in the journey toward a fossil fuel-free future.

Pinnamaneni Srinivasa Rao talks to farmers about the benefits of sorghum.
James Mitchell Crow

Picture the tropics, and it’s tempting to envisage a verdant landscape blessed with bountiful rainfall. In fact, there’s a swathe of sub-Saharan Africa and central Asia where the wet season is brief and unreliable, and the dry season long and hot. Officially known as the semi-arid tropics, but often referred to as the drylands, the region is home to over 2 billion people, 644 million of them the “poorest of the poor”.

At the heart of this region, on a 14-square‑kilometre research station on the outskirts of Hyderabad in southern India, lies ICRISAT – a three-hour drive from the Madhucon mill.

It’s here that Rao’s and his team bred the supercharged seeds for the sweet sorghum trial.

Pulling off the jostling, dusty Hyderabad arterial road and easing through the gates into the ICRISAT grounds is like entering another world. A long driveway passes broad fields as we approach a cluster of buildings – a celebration of concrete. It’s like sweeping into a 1960s-built university campus. A jackfruit tree stands guard by the main entrance, and mighty mango trees shade the courtyards of the accommodation blocks.

ICRISAT is one of a network of public good institutions devoted to improving the world’s most important crops – and the lot of the developing world farmers who grow them. There’s the International Maize and Wheat Improvement Centre (CIMMYT) headquartered in Mexico, and the Philippines-based International Rice Research Institute (IRRI).

High-value cash crops like those won’t grow in the semi-arid tropics. ICRISAT is charged with improving the crops that will grow here. In its fields grow low water-demand crops including chickpea, peanut, millets – and sorghum.

As a multi-use crop that grows reliably in the drylands, providing food for a subsistence farmer’s family plus fodder for its animals, sweet sorghum has always been a focus for ICRISAT. Add in its biofuel potential, and it’s an even better fit for the ICRISAT mission. The big promise? “Income generation,” says Rao, who led the sweet sorghum program until late 2015, when he left ICRISAT to join the University of Florida. Subsistence farmers could keep the grain for their own use and sell the rest of the plant for bioenergy production, Rao explains. “We’re trying to help farmers move from self-sufficiency to excess production.”

Rao and his colleagues have calculated that a little over 2 million hectares of sweet sorghum cultivation – about half the area on which grain sorghum is currently grown in the wet season in India – could provide almost 10% of the country’s gasoline requirements.

The strategy is to start small, establish the process at a few sugar mills, and build from there. But even that first small step might falter if the local farmers gathered at the Madhucon mill can’t be convinced to embrace the crop.

Sweet sorghum is processed into biofuel.
ICRISAT

Growing biofuels in a way that benefits everyone has proved far harder than many first thought. In fact, in the beginning, biofuels were downright bad news for the world’s poor.

In the early part of the last decade, governments including the EU were beginning to introduce policies aimed at curbing their carbon emissions. Biofuels seemed like a quick win. By mandating that these carbon-neutral fuels must be blended into petrol and diesel, the transport sector’s carbon footprint would shrink at a stroke.

But where would these crops grow? Land was diverted from food to fuel production, helping precipitate a global spike in food prices that led to riots across the developing world in 2007 and 2008, from Egypt to Bangladesh. The same policies led farmers in countries such as Indonesia and Malaysia to cut virgin rainforest to create fields.

The EU was forced to scale back its biofuel targets. Governments and scientists – as well as investors keen to make a buck – cast around for ways to produce biofuels without compromising food security or valuable natural habitats. The spotlight fell on jatropha.

This scrubby-looking small tree originated in Central America, but today is found growing all over the tropics – including on land so marginal even the poorest farmers don’t try to grow crops on it. Jatropha’s pod-like fruit contains large seeds that release a good quantity of oil when crushed. That oil can be converted into biodiesel.

In the late 2000s, investors piled in. Oil prices were at an all-time high; global warming remained high on the global political agenda; and here was a biofuel crop that didn’t compete for land with food crops. Huge plantations were established around the tropics. In India, the national government set a target that 20% of its diesel should be biodiesel by the end of 2012.

ICRISAT’s scientists could have foretold what would happen next, but in the headlong rush to commercialise the plant, they were not consulted. Jatropha will grow in very poor dry soil, but it won’t fruit, and so it won’t produce any oil. Even in better soils, the plants sometimes still return disappointing yields, for reasons scientists are still trying to understand.

India planted an estimated half a million hectares of jatropha. But according to the government Ministry of Petroleum and Natural Gas, biodiesel production from jatropha was essentially zero.

The jatropha miracle turned out to be a mirage.

sweet sorghum has been grown as a crop for millennia, honed by generations of farmers

It’s hardly a surprise, then, that the farmers gathered at the Madhucon mill are wary of what they’re hearing. What’s to stop the sweet sorghum dream evaporating too?

What makes sweet sorghum different, the plant’s champions say, is that it provides fuel and sustenance. And where the jatropha rush was almost akin to attempting to commercialise a roadside weed, sweet sorghum has been grown as a crop for millennia, honed by generations of farmers. “It’s not like we’re introducing a new crop,” Rao says.

“I don’t think jatropha’s failure should be seen as any indicator,” adds Ian O’Hara, a bioenergy researcher at Queensland University of Technology. “There are – and always were – far more important and scalable opportunities for biofuels.”

And where jatropha had been virtually untouched by crop scientists, sweet sorghum has undergone intensive improvement. Over the past four decades, Rao and his predecessors at ICRISAT have scoured the drylands region for the best performing sorghum varieties – from the most drought tolerant to the highest yielding.

By crossbreeding these local heroes, ICRISAT scientists have developed sweet sorghum super‑hybrids with grain and sugar yields up to 160% higher than traditional varieties – and they are still only scratching the surface of the natural genetic diversity of the crop.

If ICRISAT can make a success of the crop, the payoff could be huge – kickstarting the biofuel industry in a part of the world where progress has stalled, and meeting the world’s need for sustainable fuels while simultaneously meeting the needs of the world’s poorest people.

Can the economics stack up? If sweet sorghum can get a toehold anywhere, it’s the Madhucon mill, where the key factors seem to be in its favour.

The Madhucon sugar mill.
James Mitchell Crow

Visit the Madhucon sugar mill late in the year, at the end of the wet season, and it will be humming with noise and activity, processing sugarcane. The mill site is dominated by a vast building several storeys high, containing the huge machinery to chop and crush the sugarcane, squeeze out and boil up its juices, and then evaporate the remaining liquid to leave pure white sugar crystals.

Adjacent to the main structure stands a new building. Sugarcane juice that will yield no more sugar crystals is sent here, entering bioreactors that will ferment the sweet liquid into bioethanol.

At the moment, neither the bioethanol nor the sugar price is strong. “The sugar industry is not happy,” says Nama Nageswara Rao, the company’s founder who, in smart shirt and neatly combed hair, looks every inch the Indian entrepreneur.

“We’re losing 1,000 rupees per tonne of sugar."

To stay in business, the Madhucon sugar mill relies on a third income stream: a small, 25-megawatt electricity plant that generates renewable power by burning sugarcane waste. “We’re surviving by selling power”.

Now, in late May, last year’s monsoon is a distant memory and the mill sits shuttered and silent. Sugarcane needs about 36,000 cubic metres of water per hectare to grow. In the dry season, that amount of water simply isn’t available. And when the supply of sugarcane waste runs out, the electricity plant must be switched to run on coal.

A sweet sorghum crop yields only about one‑third the bioethanol of sugarcane. But it does so on just 4,000 litres per hectare. It’s fast-growing, too. The local farmers could easily produce a sweet sorghum crop during the sugarcane offseason.

For the mill’s management, sweet sorghum is a way to keep the mill running when sugarcane is not available. Sweet sorghum doesn’t yield nice white sugar crystals like sugarcane does, so all its sugary juice would be sent to the fermentation plant for making bioethanol. And the leftover leaves and stalks could keep the power plant running on renewable biofuel, rather than coal.

For the owners of the mill, the motivation for introducing sweet sorghum to the region is clear. For the scientists at ICRISAT, this field trial is one small step in a wider mission to alleviate poverty across the drylands.

The commercial farmers gathered at the Madhucon mill are relatively well off. They aren’t the subsistence farmers ICRISAT would ideally target. “The major purpose of this initiative is to make the best use of the existing infrastructure,” Rao explains. Once sweet sorghum is established as a commercially viable crop, subsistence farmers could grow it to share the benefit.

Like any would-be superhero, the plant has its weaknesses. It thrives in heat, but can’t tolerate cold – growing it outside the tropics is not an option. Keeping insect pests away from its juice can be a challenge. And its use as a dual-purpose crop that can feed humans as well as their cars could be undermined by the decreasing human consumption of sorghum grain. Though consumption in Africa is increasing, in India the locals see it as a poor man’s food and aspire to eat wheat or rice, even though sorghum is nutritionally superior to both.

ICRISAT is trying to address this end of the sweet sorghum value chain too, creating demand through its Smart Foods marketing initiative to incorporate it into Western-style food products such as breakfast cereals. Perhaps sorghum might one day grace the menu of fashionable Western cafes, the way traditional grains such as quinoa and faro now do.

Pinnamaneni Srinivasa Rao examines the sweet sorghum crop.
ICRISAT

At the meeting by the mill, the farmers want to know what price they will get for the sweet sorghum they grow. It’s a fair question. Even by exploiting the existing infrastructure at the mill, when oil prices are low – as they were at the time of writing – biofuel margins are likely to be vapour thin. Just how thin, at this stage in the trial, is a chicken‑and‑egg question. Until the trial has progressed, and they know how much sugar the crop will yield, the amount the mill will be able to pay the farmers long-term is unknown.

In the end, though, the towering sweet sorghum plants practically sold themselves. As we strolled between the rows, the scientists cut a few stalks and measured the sugar content of the juice with a handheld device known as a refractometer. Sweet sorghum may be new to the sugarcane farmers, but sugar content is a concept they know. In the end, the mill was able to strike a deal with enough farmers – helped by the free seed from ICRISAT during the trial phase – to move the project forward.

At the time of publication, the gradual scale‑up of sweet sorghum production around the Madhucon mill was progressing. The initial test with a few local farmers had promising results, says Ashok Kumar, who now leads the ICRISAT sweet sorghum team.

“Some farmers got very high yields,” he says, beating typical sweet sorghum yields by almost 20%. But the farmers are new to the crop, and some will need a little more help. “The farmers need to be trained on sweet sorghum cultivation to achieve higher yields,” he adds. Sweet sorghum crushing at the mill was a success, requiring no modification to the machinery used to crush sugarcane. Kumar and his colleagues plan to enrol more farmers in a larger-scale trial, although persuading farmers to grow the unfamiliar crop remains a challenge. Meanwhile, other sugar mills in the region are joining the project.

So far, the Madhucon sweet sorghum experiment seems to be working.

So far, the Madhucon sweet sorghum experiment seems to be working. It’s slow progress – but then, jatropha is a salient reminder of what happens to those who rush in.

India is far from the only country on the cusp of commercialising sweet sorghum as a biofuel crop. The US, Brazil and China are all weighing its potential as part of the transition to a low-carbon economy – as is Australia (see box).

“Will sweet sorghum ever be the main crop for biofuels? Probably not,” concludes Peter Carberry, ICRISAT’s deputy director general – research. “But for filling niches, there might be an opportunity. Sweet sorghum adds another option for small farmers.”


Sweet sorghum in Australia

Ian O’Hara of the Centre for Tropical Crops and Biocommodities at QUT.
Erika Fish / QUT

A crop that thrives in hot, dry conditions with minimal water requirements? And can be processed in idle sugarcane mills? Sounds like sweet sorghum might do well in Australia.

Winter never comes to the Pilbara. Only the Atacama Desert receives more sunshine and less rain. This remote region of Australia’s northwest is prized for its palette of rusty reds, burnt orange and yellow hues.

Now Lawrence Kirton wants to introduce a new colour: green. Despite the parched conditions, Kirton, who heads Perth-based company AgGrow Energy, thinks the place is perfect for sweet sorghum. And he’s grown the crop here to prove it.

And Ian O’Hara, a researcher from the Centre for Tropical Crops and Biocommodities at QUT, recently completed a three-year study confirming sweet sorghum’s potential in Australia.

In Queensland, as in India, a lot of sugarcane factories sit idle several months a year. “Sweet sorghum may have some opportunities as a crop to extend the sugarcane crushing season in Queensland,” O’Hara says. “But the companies really seriously looking at sweet sorghum are looking in areas where sugarcane is not currently grown.”

Such as AgGrow Energy and their Pilbara project. The mineral-rich region is better known for mining than farming, and Kirton sees an opportunity in the wastewater from mining. At the height of the mining boom, companies were pumping almost 300 billion litres of water a year out of their mines and into the river: the pumps consumed 3 billion litres of diesel.

Kirton plans to use that water to irrigate a biofuel crop that the mines could use as a renewable alternative to fossil fuels to drive their pumps and trucks. The plantation would provide employment opportunities for traditional owners looking to move back to their lands.

The company assessed several energy crops, but sweet sorghum was a clear favourite. “We planted the seed at just under 50 degrees, and everyone said it wouldn’t grow. What happened was the seed germinated in 48 hours – normally sorghum takes a week,” Kirton says. The plants thrived under the Pilbara irrigated conditions, growing so fast it was possible to produce three crops per year.

The end of the mining boom has slowed Kirton’s expansion plans, however. In February 2016, the Woodie Woodie manganese mine AgGrow Energy had partnered with throughout the trial was mothballed, after manganese prices collapsed from US$5 per tonne in 2014 to $1.80 per tonne. “We’re in discussions with other mines,” Kirton says.

Kirton – a Zimbabwean by birth – says sweet sorghum could be grown anywhere the weather is warm enough. “I’d love to take this technology back to central Africa,” he says. “As a biofuel crop, if the climate is correct, we don’t believe there’s anything to touch it.”

James’ trip to India was funded by the Crawford Fund, whose mission is to increase Australia’s engagement in international agricultural research, development and education for the benefit of developing countries and Australia, after he won the 2014 Food Security Journalism Award.

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James Mitchell Crow is a freelance writer and editor.
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