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Sorghum: a sweet alternative

Sweet sorghum is high yielding, and tolerant to drought, water logging, and soil salinity (ICRISAT)
Sweet sorghum is high yielding, and tolerant to drought, water logging, and soil salinity

Sweet sorghum (sorghum biocolor) can certainly boast an impressive list of advantages: it is high yielding, and tolerant to drought, water logging, and soil salinity. With high oil prices and petroleum reserves in decline, perhaps one of sweet sorghum's most attractive assets is that it can be used to produce ethanol - the world's largest fuel additive whilst still meeting food, feed and fodder needs of smallscale farmers. Biofuels, such as ethanol, are becoming increasingly attractive to oil importing countries. Among them are India and China - both countries are turning to sweet sorghum with the intention of increasing ethanol production, decreasing dependence on imported fossil fuels and enhancing sustainable development. But can sweet sorghum meet the challenge?

The sugar-liquid produced from sweet sorghum can be fermented into alcohol in larger quantities and more cost-effectively than molasses from refined sugarcane. The crop is also less water thirsty than sugarcane. But in India, sorghum production has declined as a result of changing urban preferences and subsidies for crops such as rice and wheat. This has limited the economic opportunities for poor farmers in dryland areas, where sorghum remains an important crop. Using sweet sorghum to produce ethanol could provide smallscale farmers in dryland areas with a good source of income particularly as ethanol production in India is set to increase. The country aims to use ethanol in ten per cent of its national supply, which would save an estimated 80 million litres of petrol each year, reducing carbon emissions, and providing farmers with an alternative market for their sorghum.

According to William Dar, director general of ICRISAT, it is not cost but an inadequate supply of sweet sorghum that hinders increased ethanol production in India. After developing a range of improved varieties of sweet sorghum, ICRISAT approached the private sector and teamed up with Rusini Distilleries Ltd in Hyderabad. The partnership enabled the best varieties of seeds to be distributed to smallscale farmers, together with technologies including stalk-crushing techniques to remove sugar from the sorghum, allowing more cost-effective transport to the processing plant. "By linking the distillery with sorghum farmers we have helped empower small farmers to realise an additional end use and thereby increase their income and improve livelihood security."

Ethanol for car fuel in China

In the Northeast and Northwest arid regions of China, saline or alkaline land and drought cause low crop yields and failed harvests of traditional summer crops such as maize and cotton. Sweet sorghum, however, is well suited to these conditions, and its use as a good quality fodder is an important factor in areas where grazing has been banned to prevent desertification. In China petroleum reserves are expected to run out by 2016, and ethanol is already being used either alone or combined with petrol or diesel, to fuel cars. Alternative sources of ethanol such as sugarcane, or sugarbeet, and starch crops such as corn and cassava, are not as well adapted to harsh environmental conditions.

After crushing, the sweet sorghum stalks can be used for cattle fodder or to fuel ethanol production facilities (ICRISAT)
After crushing, the sweet sorghum stalks can be used for cattle fodder or to fuel ethanol production facilities

To develop and test the use of sweet sorghum in the Northwest and Northeast of China, the Food and Agriculture Organisation (FAO) has funded a project to add value to the grain, sugar, feed, fibre and by-products of the crop. The project, supported by the Chinese Adademy of Sciences developed a sustainable sweet sorghum agro-ecosystem to utilise each part of the crop. The system developed promotes the inter-planting of black mushrooms, using the grain as food or forage, and feed the leaves to cows or fish. The chopped stem can be also used to provide fodder or silage or for producing wine or ethanol. After brewing or juice extraction, the residue can be fed to cows. Sweet sorghum has been well received by farmers, and with improved technology and knowledge, sweet sorghum production in the region is expected to reach 500,000 hectares by 2010.

Sweet or sour?

The high cost of producing alcohol makes crops with increased yield and low costs very attractive. The FAO emphasises that in China the agro-ecological and industrial systems of sorghum production provide employment, and help to reconstruct degraded rural plantation systems. If small farmers receive a good price for sweet sorghum, and efficient links can be made with ethanol producers, it seems that the crop offers energy efficiency and an income- generating alternative for smallscale famers. However questions are being raised about whether sweet sorghum production will replace more valuable food resources and drive up their costs. ICRISAT has stated that those in dryland areas need food - but they also need better economic opportunities, and if production of other crops grown to provide ethanol such as sugarcane or maize were increased, the most fertile land would be displaced, limiting food production. The sustainability of sweet sorghum to produce ethanol in the long term remains to be seen.

Date published: November 2006


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Soils with too much alkali can be restored by planting sweet... (posted by: george peckham)


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