Rice

Rice is a cereal crop just like wheat, oats and barley. It is a member if the grass family of plants. It belongs to the genus oryza.

There are thousands of rice varieties. A world collection of over 40000 varieties is held in the International Rice Research Institute Genetic Resource Centre in the Philippines.

Rice is an annual plant, in that it completes its life cycle within 12 months. One mature rice plant can yield more than 3000 grains.

Cultivated rice is classified as long, medium and short grain. This world–wide classification into three categories is based on the size of the grain:

History

Archaeological evidence suggests that rice plants are an identifiable form of grass found about 12000 years ago. Further evidence suggests that about 5000 years ago rice was being cultivated in China. 

Rice, however, goes deeper into the Chinese culture than just cultivation and consumption. Its use seems to coincide with the development of the Chinese language. For example, the words for agriculture and for rice culture are the same in Chinese. Indeed, the words for rice and food are identical in several Asian languages. This indicates that rice was already embedded into the culture at the time the language was taking form.  The interconnection of rice, language and culture is further highlighted by many Asian countries' ceremonies connecting the planting and harvesting of rice.

The spread of rice around the world has been happening for around 5000 years. Rice is now grown on every continent except Antarctica and in more than 110 countries in the world. Asia grows about 92 per cent of the world's rice, with the largest volume coming from just seven countries – China, India, Indonesia, Bangladesh, Viet Nam, Thailand and Myanmar.

Biology

The rice grain is made up of three main layers:

Australia – growing many different varieties of temperate rice

Long grain rice makes up 15% of production in Australia. Long grain rice is thin and generally 4 to 5 times long as it is thin. Long grain rice has firm looking grains. Langi is the most popular variety of long grain japonica rice grown in Australia. Long grain rice is often used in soups.

Medium grain japonica rice makes up about 78% of rice production in Australia.  Medium grain rice has short and wide soft-cooking grains. Amaroo and Namaga are the most popular varieties of medium grain Japonica rice grown in Australia. Medium grain rice is often used in desserts.

Short grain rice makes up 7% of production in Australia.  This is especially for the Japanese market as it is the preferred rice for sushi. Short grain rice is almost round in appearance and in cooking absorbs less water, because of its endosperm, than the other two categories. The Koshihikari variety is popular because it is used often in traditional Japanese meals.

Download pdf of varieties of rice grown in Australia. (pdf- 38kb)

Rice growing

Preparation of the rice fields

Rice fields are divided into bays, or smaller sections, with banks of earth separating the bays. Each bay is level, but slightly lower than the next one, allowing the water to move with gravity across the entire field. For the preparation of the rice farm, the farmer must grade the rice fields to ensure each bay is level. This is to maximise water efficiency and movement, and to provide the same water depth throughout the field.

Tractors harvesting rice

Tractors pull a disc banker which is used to construct new rice banks, as well as maintain and control weeds on established banks. Tractors are also needed to pull a ridge roller which presses small furrows every 15-20 centimetres across the paddock. When the rice seeds are planted using aerial sowing, they fall into these furrows to ensure the crop is grown uniformly across the field.

To ensure that rice seedbeds are ready for planting the farmer must have no weeds and other plants in a very loose soil. The tractor pulls a range of cultivation equipment. If fertilisers are applied to the rice fields the farmer uses a tractor to apply liquid or gas or biological fertiliser evenly along the rice fields.

Planting the rice seeds

To sow the rice seeds the rice farmer has three options:

(i) aerial sowing, using a small plane which drops the rice seeds into the prepared rice fields, which are already covered with water, or

(ii) sod sowing, using a disc seed drill which places the rice seed neatly into the uncultivated soil.

(iii) drill sowing, using a tyne drill to sow seed into a cultivated seedbed.

Irrigation

Harvesting

Rice in storage

When the rice plant is mature, a combine harvester is used to gather the rice crop, thresh and separate the grain from the stalks. The harvester has special rice tyres, which are used especially for the heavy, wet soils of the rice field.

During the rice grain harvesting, the grain is moved from the harvester to a mobile field bin towed by a tractor which then moves it to a bigger bin or a grain truck. The grain is then transported to storage facilities. Using a modern harvester, field bins and trucks, a farm can harvest and deliver around 200 tonnes of rice paddy per day. From the aerated storage facilities the rice is moved to the rice mill where the grain is processed.

A lot of rice stubble remains in the fields after harvest. The stubble is usually slashed by a stubble mulcher. The stubble is then evenly distributed over the rice fields to help keep the ground moist for the next crop or in some instances is allowed to dry, then baled and sold as hay. Or, it may be incorporated back into the soil where it helps build soil organic matter. The stubble is sometimes burnt while still in the field. Burning the stubble helps prevent the spread of diseases which may get into the stubble after harvest.

The Australian Rotation System of Rice Growing

Most rice producing countries of the world grow rice as a monoculture. The main concern with growing rice as a monoculture is the build up of pests and diseases, together with the depletion of soil nutrients. The Australian rice growing system, however, uses a rotation cycle across the whole farm. It is designed for maximum efficiency, sustainability and safety.

The average size of an Australian rice farm is approximately 300 hectares and as a requirement of the Rice Environmental Policy no more than one third of each farm is allowed to be sown with rice each year. In this way the soil nutrients are replenished by planting it with crop pastures or running stock on it.

During the rice growing phase, when the rice bays are flooded with water, the dry land weeds die. The bird, animal and water life builds up nutrients in the soil by providing lots of organic matter. The deep fibrous roots of the rice plants also help break up the soil. This makes it easier for the rice farmer to work the ground after harvesting the rice, ready for planting cereal crops.

Crops grown immediately after the rice harvest use up the remaining moisture in the soil. In the livestock and pasture phase, micro-organisms in the roots of the pasture convert nitrogen into a form that the next rice crop can use. Indeed, this often provides almost all of the nitrogen needs for the next rice crop. This reduces the need for the rice farmer to use artificial fertilisers for the rice crop.

Further Internet resources:

Rice growing in Australia
How rice is grown

resource:
Student handout : Word meaning list