Commercial sorghum

Commercial sorghum refers to the cultivation and commercial exploitation of species of grasses within the genus Sorghum (often S. bicolor). These plants are used for grain, fibre and fodder. The plants are cultivated in warmer climates worldwide. Commercial Sorghum species are native to tropical and subtropical regions of Africa and Asia, with one species native to Mexico.

A grain sorghum cultivar

Other names include durra, Egyptian millet, feterita, Guinea corn, jwari ज्वारी (Marathi), jowar, juwar, milo, maize, shallu, Sudan grass, cholam (Tamil), jola (Kannada), jonnalu (Telugu), gaoliang (zh:高粱), great millet, kafir corn, dura, dari, mtama, and solam.

Origin

The last wild relatives of commercial sorghum are currently confined to Africa south of the Sahara — although Zohary and Hopf add "perhaps" Yemen and Sudan — indicating its domestication took place there. However, note Zohary and Hopf, "the archaeological exploration of sub-Saharan Africa is yet in its early stages, and we still lack critical information for determining where and when sorghum could have been taken into cultivation."^[1] Although rich finds of S. bicolor have been recovered from Qasr Ibrim in Egyptian Nubia, the wild examples have been dated to circa 800–600 BCE, and the domesticated ones no earlier than CE 100. The earliest archeological evidence comes from sites dated to the second millennium BC in India and Pakistan — where S. bicolor is not native. These incongruous finds have been interpreted, according again to Zohary and Hopf,

as indicating: (i) an even earlier domestication in Africa, and (ii) an early migration of domestic sorghum, from East Africa into the Indian subcontinent. This interpretation got further support because several other African grain crops, namely: pearl millet Pennisetum glaucum (L.) R. Br., cow pea Vigna unguiculata (L.) Walp., and hyacinth bean Lablab purpureus (L.) Sweet show similar patterns. Their wild progenitors are restricted to Africa.^[1]

Most cultivated varieties of sorghum can be traced back to Africa, where they grow on savanna lands. During the Muslim Agricultural Revolution, sorghum was planted extensively in parts of the Middle East, North Africa and Europe.^[2] The name "sorghum" comes from Italian "sorgo", in turn from Latin "Syricum (granum)" meaning "grain of Syria".

Despite the antiquity of sorghum, it arrived late to the Near East. It was unknown in the Mediterranean area into Roman times. Tenth century records indicate it was widely grown in Iraq, and became the principal food of Kirman in Persia. In addition to the eastern parts of the Muslim world, the crop was also grown in Egypt and later in Islamic Spain. From Islamic Spain, it was introduced to Christian Spain and then France (by the 12th century). In the Muslim world, sorghum was grown usually in areas where the soil was poor or the weather too hot and dry to grow other crops.^[2]

Sorghum is well adapted to growth in hot, arid or semiarid areas. The many subspecies are divided into four groups — grain sorghums (such as milo), grass sorghums (for pasture and hay), sweet sorghums (formerly called "Guinea corn", used to produce sorghum syrups), and broom corn (for brooms and brushes). The name "sweet sorghum" is used to identify varieties of S. bicolor that are sweet and juicy.

Cultivation and uses

Sorghum is used for food, fodder, and the production of alcoholic beverages. It is drought tolerant and heat tolerant, and is especially important in arid regions. It is an important food crop in Africa, Central America, and South Asia, and is the "fifth most important cereal crop grown in the world" [1]. African slaves introduced sorghum into the U.S. in the early 17th century.

Top Sorghum Producers — 2008^[3]

United States	12.0 Mt
Nigeria	9.3 Mt
India	7.9 Mt
Mexico	6.6 Mt
Sudan	3.9 Mt
Australia	3.1 Mt
Argentina	2.9 Mt
China	2.5 Mt
Ethiopia	2.3 Mt
Brazil	2.0 Mt
World Total	65.5 Mt
Source: UN Food & Agriculture Organisation (FAO)[2]

Use as fodder

The FAO reports that 440,000 square kilometres were devoted worldwide to sorghum production in 2004. In the US, sorghum grain is used primarily as a maize (corn) substitute for livestock feed because their nutritional values are very similar. Some hybrids commonly grown for feed have been developed to deter birds, and therefore contain a high concentration of tannins and phenolic compounds, which causes the need for additional processing to allow the grain to be digested by cattle.

Culinary use

In arid, less developed regions of the world, sorghum is an important food crop, especially for subsistence farmers. It is used to make such foods as couscous, sorghum flour, porridge and molasses.

Bhakri (jolada rotti in northern Karnataka), a variety of unleavened bread usually made from sorghum, is the staple diet in many parts of India, such as Maharashtra state and northern Karnataka state. In eastern Karnataka and the Rayalaseema area of Andhra Pradesh, roti (jonna rotte) made with sorghum is the staple food.

In South Africa, sorghum meal is often eaten as a stiff porridge much like pap. It is called mabele in Northern Sotho and "brown porridge" in English. The porridge can be served with maswi - soured milk - or merogo - a mixture of boiled greens (much like collard greens or spinach).

In the cuisine of the Southern United States, sorghum syrup is used as a sweet condiment, usually for biscuits, corn bread, pancakes, hot cereals or baked beans. It was used as the unavailable maple syrup is used in the North, although it is uncommon today.

In Arab cuisine, the unmilled grain is often cooked to make couscous, porridges, soups, and cakes. Many poor use it, along with other flours or starches, to make bread. The seeds and stalks are fed to cattle and poultry. Some varieties have been used for thatch, fencing, baskets, brushes and brooms, and stalks have been used as fuel. Medieval Islamic texts list medical uses for the plant.^[4]

Popcorn (for size comparison) left, and popped sorghum seeds, right

Sorghum seeds can be popped in the same manner as popcorn (i.e., with oil or hot air, etc.), although the popped kernels are smaller than popcorn (see photo on the right).

Sorghum sometimes is used for making tortillas (e.g., in Central America).^[5] In El Salvador, they sometimes use sorghum (maicillo) to make tortillas when there is not enough corn.^[6]

Since 2000, sorghum has come into increasing use in homemade and commercial breads and cereals made specifically for the gluten-free diet.

Alcoholic beverages

In China, sorghum is the most important ingredient for the production of distilled beverages, such as maotai and kaoliang, as seen in the 1987 film Red Sorghum.

In southern Africa, sorghum is used to produce beer, including the local version of Guinness. In recent years, sorghum has been used as a substitute for other grain in gluten-free beer. Although the African versions are not "gluten-free", as malt extract is also used, truly gluten-free beer using such substitutes as sorghum or buckwheat are now available. Sorghum is used in the same way as barley to produce a "malt" that can form the basis of a mash that will brew a beer without gliadin or hordein (together "gluten") and therefore can be suitable for coeliacs or others sensitive to certain glycoproteins.^[7]

In November 2006, Lakefront Brewery of Milwaukee, Wisconsin, launched its "New Grist" gluten-free beer, brewed with sorghum and rice. It is one of its most successful lines. It is aimed at those with celiac disease, although its low-carb content also makes it popular with health-minded drinkers.^[8]

On December 20, 2006, Anheuser-Busch of St. Louis, Missouri, announced the release of their new "Redbridge" beer product. This beer will be gluten-free and produced with sorghum as the main ingredient. Redbridge is the first sorghum-based beer to be nationally distributed in the United States.

African sorghum beer is a brownish-pink beverage with a fruity, sour taste. Its alcohol content can vary between 1% and 8%. African sorghum beer is high in protein, which contributes to foam stability, giving it a milk-like head. Because this beer is not filtered, its appearance is cloudy and yeasty, and may also contain bits of grain. This beer is said to be very thirst-quenching, even if it is traditionally consumed at room temperature.

African sorghum beer is a popular drink primarily amongst the black community for historical reasons. African sorghum beer is said to be a traditional drink of the Zulu people of Southern Africa. It also became popular amongst the black community in South Africa because the only exception to the prohibition, which was lifted in 1962 and only applied to black people, was sorghum beer. Sorghum beer is called bjala in northern Sotho and is traditionally made to mark the unveiling of a loved-one's tombstone. The task of making the beer falls traditionally to women. The process is begun several days before the party, when the women of the community gather together to bring the sorghum and water to a boil in huge cast iron pots over open fires. After the mix has fermented for several days, it is strained - a somewhat labor intensive task. Sorghum beer is known by many different names in various countries across Africa, including burukuto (Nigeria), pombe (East Africa) and bil-bil (Cameroon). African sorghum beer brewed using grain sorghum undergoes lactic acid fermentation, as well as alcoholic fermentation.

The steps in brewing African sorghum beer are: malting, mashing, souring and alcoholic fermentation. All steps, with the exception of the souring, can be compared to traditional beer brewing.

The souring of African sorghum beer by lactic acid fermentation is responsible for the distinct sour taste. Souring may be initiated using yogurt, sour dough starter cultures, or by spontaneous fermentation. The natural microflora of the sorghum grain maybe also be the source of lactic acid bacteria; a handful of raw grain sorghum or malted sorghum may be mixed in with the wort to start the lactic acid fermentation. Although many lactic acid bacteria strains may be present, Lactobacillus spp. is responsible for the lactic acid fermentation in African sorghum beer.^[9]

Commercial African sorghum beer is packaged in a microbiologically active state. The lactic acid fermentation and/or alcoholic fermentation may still be active. For this reason, special plastic or carton containers with vents are used to allow gas to escape. Spoilage is a big safety concern when it comes to African sorghum beer. Packaging does not occur in sterile conditions and many microorganisms may contaminate the beer. Also, using wild lactic acid bacteria increases the chances of spoilage organisms being present. However, the microbiologically active characteristic of the beer also increases the safety of the product by creating competition between organisms.^[10] Although aflatoxins from mould were found on sorghum grain, they were not found in industrially produced African sorghum beer.^[11]

Other uses

Sorghum straw (stem fibres) can also be made into excellent wallboard for house building, as well as biodegradable packaging. It does not accumulate static electricity, so it is also being used in packaging materials for sensitive electronic equipment.

Little research has been done to improve sorghum cultivars^{[citation needed]} because the vast majority of sorghum production is done by subsistence farmers^{[citation needed]}. The crop is therefore mostly limited by insects, disease and weeds, rather than by the plant's inherent ability^{[citation needed]}. To improve the plant's viability in sustaining populations in drought-prone areas, a larger capital investment would be necessary to control plant pests and ensure optimum planting and harvesting practices.

In November 2005, however, the US Congress passed a Renewable Fuels Standard as part of the Energy Policy Act of 2005, with the goal of producing 30 billion litres (8 billion gallons) of renewable fuel (ethanol) annually by 2012. Currently, 12% of grain sorghum production in the US is used to make ethanol.^{[citation needed]}

An AP article ^[12] claims that sorghum-sap-based ethanol has four times the energy yield as corn-based ethanol, but is on par with sugarcane.

Diseases

Main article: List of sorghum diseases

Growing grain sorghum

Sorghum requires an average temperature of at least 25°C to produce maximum grain yields in a given year. Maximum photosynthesis is achieved at daytime temperatures of at least 30°C. Night time temperatures below 13°C for more than a few days can severely reduce the plants' potential grain production. Sorghum cannot be planted until soil temperatures have reached 17°C. The long growing season, usually 90–120 days, causes yields to be severely decreased if plants are not in the ground early enough.

Grain sorghum is usually planted with a commercial corn seeder at a depth of 2–5 cm, depending on the density of the soil (shallower in heavier soil). The goal in planting, when working with fertile soil, is 50,000 to 300,000 plants per hectare. Therefore, with an average emergence rate of 75%, sorghum should be planted at a rate of 2–12 kg of seed per hectare.

Yields have been found to be boosted by 10–15% when optimum use of moisture and sunlight are available, by planting in 25 cm rows instead of the conventional 1-meter rows.

Sorghum, in general, is a very competitive crop, and does well in competition with weeds in narrow rows. Sorghum produces a chemical compound called sorgoleone, which the plant uses to combat weeds. The chemical is so effective in preventing the growth of weeds it sometime prohibits the growth of other crops harvested on the same field. To address this problem, researchers at the Agricultural Research Service found two gene sequences believed to be responsible for the enzymes that secrete the chemical compound sorogoleone. [3] The discovery of these gene sequences will help researchers one day in developing sorghum varieties that cause less soil toxicity and potentially target gene sequences in other crops to increase their natural pesticide capabilities, as well.^[13]

Insect and diseases are not prevalent in sorghum crops. Birds, however, are a major source of yield loss. Hybrids with higher tannin content and growing the crop in large field blocks are solutions used to combat the birds. The crop may also be attacked by corn earworms, aphids, and some Lepidoptera larvae, including turnip moths.

It is a very high nitrogen-feeding crop. An average hectare producing 6.3 tonnes of grain yield requires 110 kg of nitrogen, but relatively small amounts of phosphorus and potassium (15 kg of each).

Sorghum’s growth habit is similar to that of maize, but with more side shoots and a more extensively branched root system. The root system is very fibrous, and can extend to a depth of up to 1.2 m. The plant finds 75% of its water in the top metre of soil, and because of this, in dry areas, the plant’s production can be severely affected by the water holding capacity of the soil. The plants require up to 70–100 mm of moisture every 10 days in early stages of growth, and as sorghum progresses through growth stages and the roots penetrate more deeply into the soil to tap into hidden water reserves, the plant needs progressively less water. By the time the seed heads are filling, optimum water conditions are down to about 50 mm every 10 days. Compacted soil or shallow topsoil can limit the plant's ability to deal with drought by limiting its root system. Since these plants have evolved to grow in hot, dry areas, it is essential to keep the soil from compacting and to grow on land with ample cultivated topsoil.

Wild species of sorghum tend to grow to a height of 1.5–2 m; however, due to problems this height created when the grain was being harvested, in recent years, cultivars with genes for dwarfism have been selected, resulting in sorghum that grows to between 60 and 120 cm tall.

Sorghum's yields are not affected by short periods of drought as severely as other crops such as maize, because it develops its seed heads over longer periods of time, and short periods of water stress do not usually have the ability to prevent kernel development. Even in a long drought severe enough to hamper sorghum production, it will still usually produce some seed on smaller and fewer seed heads. Rarely will one find a kernelless season for sorghum, even under the most adverse water conditions. Sorghum's ability to thrive with less water than maize may be due to its ability to hold water in its foliage better than maize. Sorghum has a waxy coating on its leaves and stems which helps to keep water in the plant, even in intense heat.

Sorghum bicolor

References

1. ^ ^{a b} Daniel Zohary and Maria Hopf, Domestication of plants in the Old World, third edition (Oxford: University Press, 2000),p. 89
2. ^ ^{a b} Watson, p. 12–14.
3. ^ "FAOSTAT". FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS. http://faostat.fao.org/site/567/default.aspx#ancor. Retrieved 2010-05-21. 
4. ^ Watson, p. 9. In Northern Karnataka in India, they make chappathis from jola.
5. ^ . PMID 7872831. 
6. ^ "Cultivarán el maicillo para producir miel: 8 de Agosto 2005 .::. El Diario de Hoy". Elsalvador.com. http://www.elsalvador.com/noticias/2005/08/08/negocios/neg5.asp. Retrieved 2011-10-17. 
7. ^ "glutenfreebeerfestival.com". Carolyn Smagalski, www.glutenfreebeerfestival.com. 2006. http://www.glutenfreebeerfestival.com. 
8. ^ "JSOnline.com Story on Lake Front Brewery". JSOnline.com. Milwaukee Journal-Sentinel, www.jsonline.com.com. 2006. http://www.jsonline.com/story/index.aspx?id=451408. 
9. ^ Van der Walt, H.P., 1956. Kafficorn matling and brewing studies II-Studies on the microbiology of Kaffir Beer. J. Sci. Food. Agric. 7(2) 105–113.
10. ^ Haggblade, S., Holzapfel, W.H., 1989. Industrialization of Africa's indigenous beer brewing. In: Steinkraus K.H. (Ed,), Industrialization of Indigenous Fermented Foods, 33. Marcel/Dekker, New York, pp. 191–283.
11. ^ Trinder, DW. 1998. A survey of aflatoxins in industrially brewed South African sorghum beer and beer strainings. J. INST. BREW. vol. 95, no. 5, pp. 307–309
12. ^ Sweet Sorghum Sap^{[dead link]}
13. ^ "Tapping into Sorghum’s Weed Fighting Capabilities to Give Growers More Options". USDA Agricultural Research Service. June 15, 2010. http://www.ars.usda.gov/is/pr/2010/100615.htm. 

External links

• FAO Report (1995) "Sorghum and millets in human nutrition"
• FAO "Compendium on post-harvest operations" — Contains discussion on origin, processing and uses of sorghum
• Alternative Field Crops
• National Grain Sorghum Producers
• National Sweet Sorghum Producers and Processors Association
• Sorghum Growth Stages
• Sequencing of the Sorghum Genome
• Sweet Sorghum Ethanol Association
• Examples of projects using sweet sorghum as an input feedstock for the production of renewable energy