Rice-Fish Culture for Improved Productivity of Rice Farmers
Introduction
The culture of fish in rice fields greatly improves the productivity of low-income rice farmers. However, this practice has yet to gain the wide acceptance it deserves.
Adaptability
A demonstration project for rice-fish culture was set up on a 0.25-ha farm in Leyte Province, Philippines. The project showcased the package of technology to twenty-four farmer-cooperators who participated in the project. Twelve farmers practiced the traditional rice farming system as a comparison. Strengths of the technology were emphasized to the farmer-cooperators, as follows: Simultaneous rice and fish production maximizes land utilization; It increases food production and income; and it helps attain food self-sufficiency.
Effectiveness
This technology combining fish culture and rice gave a higher net return compared to the traditional rice farming alone. Farmers noticed that there was less damage from weeds and pests because the fish fed on these, provided the water was kept at a depth of at least 20 cm. The number of farmers adopting this technology showed a significant increase once they had seen it in action.
The Technology
Fish Culture
Establish the pond by reserving 4% of the total rice field as a trench for fish production. Excavate a 2-m wide trench which is between 1m and 1.5 m deep. Surround the trench by a dike measuring 50 cm in height (steeply sloping downward) and 50 cm wide at the base. Provide the dike with an opening 30 cm wide for the fish to swim through, so they can feed in the rice field. Once the pond is established:
- Install water pipes, 15 cm above the water level. Pipes should be screened with fine (0.5 mm) mesh net to keep out wild fish and other predators.
- Empty the pond and allow it to dry for 3-5 days. Apply 50 kg organic fertilizer or chicken manure and 5 kg ammonium phosphate (16-20-0). Topdress the same rate of fertilizer once a month.
- Fill the pond with 30 - 40 cm water after fertilizer application. After two days, gradually increase water depth to 0.7 - 1.0 m. Add fresh water only when the pond water drops to 15 cm or less, or when signs of oxygen depletion occur.
(There is likely to be oxygen depletion if the water has an unpleasant odor, if the color of the water is brownish to grayish, or if the fish are gasping for air on the surface of the water).
- Stock the pond with Genetically Improved Farm Tilapia (Tilapia nilotica) fish at 5 fingerlings/m2. Before you release the fish, make sure that the water temperature in their oxygenated plastic bag is the same as that of the pond.
- Feed the fish twice daily with supplements consisting of 70% rice bran and 30% fishmeal. Harvest the fish after four months, or one month after harvesting the rice crop (Fig. 1).
Rice Culture
- Prepare the seedbeds, 1.5 m wide and 4 cm high, with a space 40 cm wide between the beds. Select a good-quality rice variety which matures in 90 - 110 days.
- Irrigate the seedbeds, and apply 2.5 kg ammonium phosphate if necessary. Prepare the field thoroughly with at least one plowing and three harrowings (Fig. 2).
- Transplant 20-25-day old seedlings at 2-3 seedlings/hill, 20 x 20 cm apart. Replant after 3 - 5 days. Irrigate, and keep the water 2 - 3 cm deep two days after transplanting.
- Make sure that the fish are not endangered if the amount of water in the field is getting low.
- Do not apply any pesticides. These will have a harmful effect on the fish, and kill the insects and other organisms which are their food.
- Harvest the rice when 80 - 85% of the grains turn a golden yellow. Prevent the fish from entering the field while the rice is being harvested.
Index of Images
Figure 1 Harvested Tilapia
Figure 2 Preparing the Rice Field for Planting
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