Grain Sorghum

24.05.17

Sorghum refers to a range of species of grass plants, belonging to the genus Sorghum, that are native to tropical and subtropical regions of the world. Sorghum is a staple food for about half a billion people in sub-Saharan Africa and Asia; it is an important source of animal feed worldwide and a source of fibre; and it is emerging as a potentially valuable biofuel crop.

Overview

The various species of sorghum have been crossed and hybridised to suit different end uses and a wide range of growing conditions. Most sorghum varieties grown in Australia are hybrids, developed for grain or forage end use. Sorghum is a vigorous and quick growing plant but hybrids grown in Australia are generally not as tall as their traditional counterparts. Sorghum has branched, tillers, broad leaves (2.5–4cm) and a long dense seed head.

Grain sorghum is a major component of the dryland cropping system of subtropical Australia, with approximately 60% of the Australian crop grown in Queensland and the remainder in New South Wales (predominantly northern NSW). Small areas of the crop are produced in Western Australia and the Northern Territory.

Grain sorghum is Australia’s most significant summer grain crop, in terms of area sown and quantity of grain produced. It is a key feed grain for the beef, dairy, pig and poultry industries. Grain sorghum is generally produced on large agricultural enterprises (several hundred or thousands of hectares), as a dryland or irrigated crop, and it is grown in rotation with winter and summer crops (cereals, oilseeds and grain legumes) depending on climate and availability of soil moisture/irrigation.

Australia produces approximately 1.4 million tonnes of sorghum per annum, of which around one million tonnes was exported annually, mainly to Asia.

Facts and figures

  • Grain sorghum is grown mainly in Queensland and northern New South Wales for use as stock feed
  • Grain sorghum is the major summer grain crop for most regions in Queensland
  • Sorghum is emerging as a potentially valuable biofuel crop

Production status

Australia’s grain sorghum industry has grown from less than 2000 hectares of plantings just after World War II to, on average, about 470,000 hectares of plantings.

Australia’s annual sorghum production is variable depending on seasonal conditions. Production has been as high as 3.7 million tonnes in 2007 and as low as just under one million tonnes in 2016.

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Map of current and potential growing regions

Uses

Grain sorghum produced in Australia is used almost exclusively as stockfeed for cattle, pigs and poultry and a significant market exists in the pet food industry. Sorghum grain can be used as a feed substitute for maize (corn), as the nutritional values of both grains are very similar.

Sorghum is a staple food for half a billion people around the world. Australian grown sorghum is currently being used in Western Australia to produce a gluten free breakfast cereal biscuit. The sorghum is grown in Queensland and is transported to Western Australiaby rail. The cereal is then sold nation wide as well as overseas in several large supermarket chains.

Sorghum may play a large role in future biofuel production, which is likely to require large-scale plantings under irrigation.

Production Requirements

Growing regions

The main regions of sorghum production in Australia are the Darling Downs of Queensland and the northern cropping areas of New South Wales. Sorghum is produced on a smaller scale in the New South Wales central west and southern irrigation areas; and in Western Australia and the Northern Territory.

Soil type

Grain sorghum is normally grown on medium to heavy clay soils. Good soil structure, and good moisture storing and nutrient holding capacity will enhance yields. On northern cropping belt soil with marginal potassium levels, sorghum performs better than maize.

Climate

As a native to subtropical and tropical climates, sorghum tolerates heat and moisture stress but it is susceptible to frost. Sorghum prefers an annual rainfall range of 400–750mm.

Varieties

Various Sorghum spp. have been crossed and hybridised to suit different end uses and a wide range of growing conditions. Most sorghum varieties grown in Australia are hybrids, developed for grain or forage production, as well as other agronomic characteristics.

The choice of hybrid/variety will be determined by a number of factors including crop rotation, disease resistance requirements and proposed end use. Growing two or three hybrids with slightly different characteristics in the one season is recommended to spread production risk.

Hybrids are bred by seed companies that have developed many sorghum varieties and most companies provide online agronomy guides to support seed purchasing decisions. It is recommended that new entrants to sorghum production seek advice from an agronomist or advisor to ensure the correct selection of variety.

State governments occasionally provide information on sorghum varieties to assist decision-making, including these examples from departments of primary industries of Queensland and New South Wales.

Planting and crop management

The hybrid varieties of sorghum are infertile plants, therefore new seed needs to be purchased for each crop. Seed is available from a range of local and multi-national seed companies, most of which have comprehensive information about their products on-line, as well as supporting agronomic advice.

Planting times range from September to January depending on location; with crops in the northern parts of Central Queensland being planted earlier than those on the Darling Downs and in northern New South Wales.

Soil temperature is a critical factor for successful seed germination and seedling establishment. The optimum soil temperature range for seedling establishment is 21–33°C. Faster seedling emergence reduces the risk of soil-borne diseases and insects attacking the developing seedling. The lowest soil temperature for adequate germination is 17°C. When sown at 17°C, seedlings will take about seven days to emerge, while at 15°C they will take around 12 days.

Adequate soil moisture at sowing is another critical factor. As a rule of thumb, sorghum should be sown on at least one metre of wet soil. Soil type and seasonal conditions will influence the end result. Experience has shown that crops sown on heavy clay soils with 1.5m of wet soil and receiving 100mm of effective in-crop rain should yield about 4.8t/ha compared with crops starting with 1m of wet soil plus 50mm of in-crop rain yielding about 3t/ha.

High yielding crops of sorghum require adequate nutrition, and fertilisers will need to be applied to compensate for nutrients that may be lacking. Rates of fertiliser will vary depending on locality, soil type, previous crop and fertiliser history. The main nutrients required will be nitrogen and phosphorus, while sulphur, potassium and zinc may also benefit crops in some areas. Timing of fertiliser applications is critical and it is recommended that new sorghum growers seek advice from an agronomist or advisor to plan a fertiliser program.

The crop requires a warm, summer growing period of 4–5 months. The rate of growth is influenced mainly by temperature and moisture, but will be affected by soil fertility, insect and disease damage. With good management practices, long-term average yields on rainfed crops range from 2–6t/ha, and irrigated crops from 5–10t/ha. Location, hybrid and season will influence yield.

State governments provide agronomic advice on sorghum, including these examples from Queensland and New South Wales, as do seed companies.

Weeds, pests, and diseases

Weed control is important in sorghum crops, as it is for all crops, as weeds will compete with the crop for light, moisture and nutrients, therefore reducing yield potential.

The major insect pests are a complex of soil-borne insects, the sorghum midge and heliothis. The sorghum midge is a widespread insect pest that breeds in sorghum, causing an estimated AU$10 million in damage annually in Australia. Resistance traits were introduced in all commercial sorghum hybrids in the 1980s and have reduced the impact of midge. However, growers in the northern regions of Australia still incur significant costs to reduce potential midge damage. GRDC has developed an Sorghum midge economic thresholds that enables growers to calculate the costs and benefits of spraying sorghum to treat sorghum midge outbreaks.

The major disease of grain sorghum is sorghum ergot, which was first reported in Australia in 1996. Other diseases are sporadic and have relatively minor significance.

State governments provide advice on weed, pest and disease management in sorghum, including these examples from Queensland and New South Wales.

Infrastructure Requirements

Large scale agricultural machinery, including tractors, cultivation equipment, seeder/disc drills, boom sprayers, combine harvesters (headers), chaser bins and grain trucks, will be required for a successful sorghum crop.

Some or all of the operations required to produce a sorghum crop can be carried out by contractors, which may alleviate some capital investment in the significant amount of machinery required for crop production. Grain silos will be required if the grain is to be stored on farm.

Harvesting & Processing

Grain from a sorghum crop is ready for harvest about 4–5 months after planting. Combine harvesters (headers) with a sorghum fingers attachment are used for harvesting.

If drying facilities are available, harvesting can commence at 25% grain moisture, and then the grain is dried to 13–14% moisture for delivery. If the grain is to be stored for the long-term, aiming for a moisture content of 12% is recommended.

Because sorghum is a perennial plant with vigorous growth attributes, a pre-harvest application of glyphosate (desiccation) is a useful way to terminate crop growth, desiccate the thick green foliage and accelerate grain drying; making it easier to harvest the crop. Desiccation also prevents the plant accessing soil moisture beyond its optimum harvest stage, and saves water in the soil profile for the following crop. Once glyphosate has been applied, harvest should not be delayed.

Sorghum grain is usually delivered to a receival point immediately after harvest but it may also be stored on farm, and sold later.

Markets & Marketing

Growers have a number of options when choosing to sell their sorghum. They can forward contract the grain to a marketer, accept the best cash price at the time of harvest or after storage, or deliver to a grain pool, run by a marketer. Most advisors would recommend that a market for sorghum be secured and contracted before planting.

Determinants of price include the amount of crop planted, overseas demand and production status of alternative crops, both in Australia and overseas.

Risks & Regulations

Risks/challenges

As with all agricultural pursuits, risk is inherent in sorghum production and can include:

  • the crop failing to establish or mature properly due to adverse weather events, thus resulting in reduced harvest tonnage and/or poor quality grain
  • commodity prices falling during the growth period impacting on the returns projected at planting
  • not recouping the costs of inputs and capital invested in the crop, like fertiliser or the costs of running large equipment, if the crop fails

It is recommended that new entrants to the market seek advice from an advisor or agronomist before making planting decisions.

Regulatory considerations

Apart from the regulatory considerations that apply to all Australian farms, including laws applying to chemical use and management, occupational health and safety and transport (including machinery movements and the loading / unloading of harvested grain), there are no regulations specific to sorghum operations. More information about laws and regulations affecting new sorghum growers (and grain growers generally) can be obtained from the relevant government authority.

Information and advice can also be sought from the relevant state farming organisation, some of which are listed on the National Farmers’ Federation website or Grain Producers Australia.

Publications

Publications/information

Tactical sorghum agronomy for the central west NSW and key decision points affecting success – GRDC Update

Overview of the sorghum industry – Queensland Department of Agriculture, Fisheries and Forestry (2012)

Summer crop production guide – NSW Department of Primary Industries

Sorghum midge economic thresholds – GRDC (2013)

Other resources

Agforce (Queensland)

NSW Farmers

National Farmers Federation

Australian Summer Grains Conference – Conference proceedings and presentation

Image Gallery

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Sorghum crop

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Harvesting grain sorghum

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Head of Sorghum Grain Kernels

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Sorghum grain