Page 64 - Agriculture_Form_3

Agriculture for Secondary Schools

Broadleaf weeds: (example, aquatic fern-like weeds): These are characterised
by broad, flat leaves and, thus, are easy to distinguish from the crop plants. They
are more common in the upland paddy system and poorly managed lowland
paddy systems.
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Effective weed management in a paddy field includes the use of cultural methods
such as sowing weed-free seeds, maintaining proper field levelling, and managing
water depth to suppress weed growth. Another way is through mechanical control
methods, which involve hand-weeding at 15-30 days after transplanting and
rotary-weeding in wet conditions. In addition, chemical control methods can be
used, including the application of pre-emergence and post-emergence herbicides.
Also, the integrated weed management (IWM) method can be used, which
employs a combination of strategies for sustainable and effective weed control.

Activity 4.5
Visit your paddy plots and perform the following:

1. Observe the type of weeds found in the plot;

2. Categorise the identified weeds into broad and narrow leaves;

3. Which type of weed is dominant in the plots?
4. Apply a simple method of weed management in one part of your plot while
maintaining another part unweeded; then

5. Monitor the plots and observe the development of the crop in both weeded
and unweeded plots.

6. Write a report on your observation and put it in your portfolio.

Exercise 4.3

1. Define the term weeding and explain why it is important in paddy cultivation.

2. Point out at what stage of paddy growth weeding is most critical.
3. Describe three common weeding methods used in paddy fields.

4. Explain the effects of weeds on rice yield.

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AGRICULTURE F3.indd 55