Queensland sugar is produced from the juice of a tropical grass called sugarcane (saccharum officinarum). From this comes one of Australia's largest export crops - raw sugar.
The majority of Queensland's sugarcane lands stretch along a coastal strip from Mossman in north Queensland to Beenleigh, south of Brisbane and also the Tableland region. Around 38 million tonnes of sugarcane is crushed annually producing 5.0 million tonnes of raw sugar (enough to fill more than 1,000 Olympic swimming pools). Queensland produces 95 percent of all Australian raw sugar.
Raw sugar is Australia's second largest export crop, earning around $1.2 billion in export sales each year. This major industry is directly and indirectly responsible for the employment of many thousands of Queenslanders.
In addition to its contribution to Queensland's economic growth, the sugar industry has been responsible for the development of many of the State's coastal cities.
From its humble beginnings, Queensland's raw sugar industry has grown into one of the world's most efficient and highly organised sugar industries.
Sugarcane grows best in warm, sunny, frost-free weather. It needs fertile, well-drained soil and around 1,500 millimetres of water each year from rain or irrigation supplies. These ideal conditions are found along the Queensland coastline where about 4,000 cane growing entities operate sugarcane farms.
In Queensland more than 400,000 hectares of land is devoted to cane farming.
Sugar is made in the leaves of the sugar cane plant by a natural process called photosynthesis and is stored as a sweet juice in its fibrous stalks.
Sugarcane is grown from setts or cuttings which are planted by special machines. These machines cut the mature sugarcane stalks into lengths of about 40 centimetres, drop them into furrows, add fertilizer and cover them with soil.
After a few weeks new shoots grow from buds on the joints of the setts and break through the surface of the soil. Up to 12 stalks grow from each sett, forming what is called a stool of sugarcane. The crop is cultivated to control weeds and let air and water into the soil.
Ongoing research into cane growing practices aims to improve land use, produce new and improved cane varieties, advance farm machinery and improve irrigation and drainage methods.
Sugarcane grows for 12 to 16 months before being harvested between June and November each year. When harvested, the cane stands two to four metres high. Queensland's sugarcane is harvested by self-propelled harvesting machines. Some growers contract machine owners to harvest their crop, while others own their machines or share ownership with other growers.
There are two methods used to harvest cane. In some cane growing areas it is possible to harvest the cane green. The left over cuttings form a mulch which keeps in moisture, stops the growth of weeds and helps prevent soil erosion. In other areas, the sugar cane is burnt to remove leaves, weeds and other matter which can make harvesting and milling operations difficult.
In both processes the harvester moves along the rows of sugarcane removing the leafy tops of the cane stalks, cutting the stalks off at ground level and chopping the cane into small lengths called billets. These are loaded into a haul-vehicle travelling alongside the harvester. The cane is then taken to a tramway siding or road haulage delivery point for transport to the mill.
After harvesting, the stubble left behind grows new shoots, producing a ratoon crop. Two or three ratoon crops can be grown before the land is rested or planted with an alternative crop such as legumes, ploughed and replanted for the cycle.
Milling and Refining
Queensland's sugar mills are in close proximity to the farms which supply them with cane. The mills operate during the harvesting and crushing season which extends from June to November. Raw sugar produced by these mills is stored at bulk sugar terminals before being sold to Australian and overseas refineries.
To avoid deterioration in the sugar content levels, sugarcane is delivered to the mill with minimal delay after harvesting. This has led to the development of an extensive transport system which allows harvested cane to be moved quickly and efficiently to sugar mills by either road or rail. Queensland mills own and operate approximately 4,000 kilometres of narrow gauge railway.
At the mill, the sugarcane is crushed by large rollers. The extracted juice is then clarified to remove soil and impurities. This juice is concentrated into a syrup by boiling off excess water, seeded with raw sugar crystals in a vacuum pan and boiled until sugar crystals have formed and grown. The boiled mixture is centrifuged to separate the molasses from the crystals, which are tumble dried and placed in large storage bins for transport to bulk sugar terminals or refineries.
Recent technological advances in milling procedures and mill equipment have contributed to the efficiency and high quality of Queensland's raw sugar industry.
Most raw sugar requires further processing at refineries in order to meet food manufacturers' and consumers' needs.
The main products from Australia's refineries are white crystal sugars, brown sugars, liquid sugar, golden syrup and treacle.
At the refinery, the raw sugar crystals are washed and dissolved in hot water to form a syrup. Phosphoric acid and lime are added to the melted sugar to remove any impurities in the clarification process. The syrup is pressure filtered through cloth, passed through decolorizing columns containing activated carbon, boiled in a vacuum pan and seeded with fine sugar crystals. When the crystals are large enough, they are discharged from the pan, centrifuged to remove excess liquid and then tumble dried. The dried sugar is then graded into required sizes prior to packaging and supply to customers.
All by-products from Queensland sugar mills are recycled adding to the efficiency of the industry's milling process.
Bagasse, the expended cane fibre remaining after the juice has been extracted, provides nearly all of the fuel required to power the mills. Bagasse can also be used to manufacture paper and can be applied as a mulch to gardens.
By-products, ash and filter mud, are used as a fertilizer on cane farms and gardens. Boiler ash is washed from the mill chimneys and filter mud is the residue left after the sugar has been clarified.
Molasses is the dark syrup separated from the raw sugar crystals during the milling process. Molasses is used in feed for animals such as cattle, and is sold to both the domestic and export markets. It is also used as a raw material in distilleries where industrial alcohol (such as ethanol), rum and carbon dioxide are made.
Queensland has one of the world's largest bulk raw sugar storage and handling systems. There are seven Queensland bulk sugar terminals at Cairns, Mourilyan, Lucinda, Townsville, Mackay, Bundaberg and Brisbane. These bulk sugar terminals can store more than two million tonnes of raw sugar, allowing year round deliveries to refineries in Australia and overseas.
The technology installed at the bulk sugar terminals enables more than 25,000 tonnes of raw sugar to be loaded in less than a day. Bulk sugar is transported by either road or rail from the mills to the terminals where it is carried by conveyor into the storage shed.
When required for shipment the sugar is fed through hoppers in the terminal shed floor to underground conveyor systems. These conveyors transport the sugar to the wharf where it is loaded into the ship's hold.
Australia is one of the world's largest raw sugar exporters with a reputation as a reliable producer and supplier of a high quality product. Nearly 80 percent of Queensland's raw sugar is exported, earning valuable income for Australia.
Queensland's major overseas markets for raw sugar include Canada, China, Japan, Korea, Malaysia, New Zealand, Singapore, USA and Russia.
While the tropical conditions of Queensland's east coast are ideal for growing sugarcane, they can have an impact on the environment. Consequently, many growers are adopting new farming practices to reduce soil erosion.
One such practice is green cane harvesting. This involves harvesting the cane green without burning the leaf trash and spreading the trash cuttings over the harvested field. These cuttings act as a protective blanket for the soil, preventing soil erosion, naturally assisting in weed control, improving soil structure and conserving moisture in the soil.
This process greatly reduces the need for soil cultivation which also minimises soil erosion on Queensland's cane lands.
In areas of heavy rainfall, green cane harvesting may not be suitable as the trash blanket can lead to waterlogging of the crop. In other areas, the trash blanket can adversely affect the temperature of the soil. However in those areas where it is suitable, adoption of green cane harvesting is increasing. More than 35 percent of Queensland cane farmers practice green cane harvesting with 98 percent of all cane in the South Johnstone area now harvested green.
Sugar in the Home
People in Australia use sugar every day. The photograph below shows some of the different types of grain sugars, but there are also liquids such as Treacle and Golden Syrup.
Sugar is not just used by itself either, there are dozens of products in every home which have sugar added. Sugar added in this way is used to:
- sweeten foods (such as bran based cereals, making them tastier)
- stop food going bad (for example, sugar in jam prevents the fruit from going mouldy)
- keep bread moist and pleasant to eat
If you go to your kitchen, you'll find sugar listed as an ingredient on many items.
Sometimes the sugar listed in the ingredients is known by different names:
- Glucose which usually comes from grain
- Fructose which comes from fruit
- Lactose which comes from milk
All sugar produced in Australia comes from the juice of sugar cane.
Commercial Uses for Sugar
Australia produces over 5 million tonnes of raw sugar each year... that's a lot of sugar! In fact Australia is one of the world's leading sugar producers.
Very little of the sugar cane grown in Australia gets used to make the sort of sugar you buy at the supermarket.
For a start, approximately 85 percent of the raw sugar produced by the mills gets sold overseas to be refined.
The remaining raw sugar is sent to Australian refineries to be made into a variety of white and specialty sugar products.
Only 22 percent is made into retail packs for home use. The rest gets used in other ways such as:
- Bakery Products
- Preserved Food
- Alcoholic Beverages
- Dairy Products