6th Grade - Science

LESSON PROBLEM: Ecology: How does rice develop from a seed to ripened grain? Is it grown the same way as any other plant?


Preparing the Field for Growing Rice

Modern rice farms, such as those found in the United States, make efficient use of water through recirculating irrigation systems, precision-leveled fields and other modern farming methods. Rice grows best in water and grows on horizontal level land. Before the seed can be sown, the rice farmers must prepare the fields. Laser controlled earthmovers are used to precision level the land in the U.S. Machines are used to break up the dirt and soften the soil. In less developed countries, the farmer harrows the fields either by hand or with the help of animals. Harrowing is also helpful in uprooting any weeds that may have sprouted in the soil. The field is then leveled by dragging a flat piece of wood across its surface.

Flooding and Building Levees
Rice fields have heavy clay soils that hold water. This type of soil is often unsuitable for many other crops. To keep the water level in the field constant, small banks of soil called ‘levees’ are built throughout the fields to hold the water at a uniform depth. Maintaining constant water level is important during the growing season. Once the levees are built, the fields are flooded. Rice is one of the most water-efficient sources of nutrition available. According to the California Water Education Foundation, a single serving of rice requires about 25 gallons of water to grow. Compare this to 1,231 gallons per serving of beef, 33 gallons per serving of chicken or 40 gallons per serving of cantaloupe.

Rice Sowing in the United States
In the United States, rice seeds are planted directly into the permanent fields by a mechanical seed drill or by airplanes. This process saves a lot of labor. In the United States, tractors are used to build levees before planting. When the seedlings come up from the field, it is flooded. This form of mechanized planting is not used in the rice growing regions of China, Vietnam, and Thailand. Rice fields in these countries are small.

Two Phases of Rice Cultivation
Much of the world's rice cultivation is in less developed countries where farming methods are very labor intensive. Rice cultivation in these countries is a two-phase process. In the first phase, seeds are sown in nurseries. A nursery is usually a well-prepared corner of a paddy. After the seed is sown, it germinates. After germination, the seedlings are left to grow in the nursery beds for 25 to 50 days to take firm roots. The green shoots of the young plants become hardy enough to be transplanted to the flooded paddy field. For transplanting, they are carefully dug up in sections and transplanted in the paddy fields.

Transplanting of Seedlings
The process of transplanting seedlings is common in Asian rice producing countries. The transplanting of seedlings is done in straight rows and is very hard work. Three or four rice plants are gathered together in a little clump, and are pressed into the mud. Care must be taken to correctly space the rows of seedlings. Each clump of plants must be given enough room to grow. The transplanting is a long process and takes many days.

Once planting is completed, the farmer adjusts the water level in the paddy using water wheels, reservoir tanks, or channels.

Controlling Pests in the Paddy Fields
To control pests, small fish are encouraged to live in the paddy. The fish also offer a supplement to the farmer’s diet.


Borrow a video cassette on rice cultivation from the library, and view the process of rice cultivation. It will give you a better idea of what you learned today.


Gather information on the health hazards of manual rice cultivation.


  • harrowing
  • seedlings
  • broadcasting
  • levee
  • clump

Click here to play Rice Rampage!
How is Rice Grown:
Farming rice is hard work. Click here to learn more about the Stages of Farming Rice.
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