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Literally, sawah tambak means ricefield pond (brackishwater). However, this term refers here to the 12 152 ha rice-fish farm area in East Java that involves 15 000 households. Depending on the depth of floodwater in each area, and fish or rice culture intensity, the sawah tambak rice-fish systems can be classified as follows:
1. Concurrent rice-fish system during wet season: appropriate in areas where inundation and the risk against submergence of rice is low. On the other hand, water is not sufficient to support a dry season rice crop.
2. Concurrent rice-fish (wet season) followed by dry season rice: done in areas where standing water is not so deep and water is sufficient to support dry season rice crop.
3. Fish culture (no rice) in wet season followed by dry season rice: appropriate in areas where flooding is deep.
4. Fish culture throughout: done in areas where farmers prefer to raise fish instead of rice in the entire flood season.
Fish species grown are a combination of milkfish (Chanos chanos) and tawes or silver barb (Barbodes gonionotus). Common carp is also added if available.
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Field components
1. Peripheral dike. This is built by excavating the inner peripheral canal of the field. Base width: 4-5 m; top width: 2-2.2 m; height: 1.4-1.8 m.
2. Peripheral canal/trench. This serves as a fish refuge, nursery, holding/transition place, catching canal and source of water for dry season rice. Bottom width: 2-4 m; top width: 2.8-3.2 m; depth: 0.3-0.7 m.
3. Ricefleld area. The area used for planting rice is surrounded by a temporary bund 0.5 m high. This retains the water required by rice for its growth. The bund is also needed especially in concurrent rice-fish system.
Water supply
Water comes from rainfall or seepage. Thus, there is no need to provide water inlet or outlet gates. When it is necessary to reduce or add water, pumping or bailing it out by traditional method is used.
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Prevention of fish escape during floods
Farmers have ready grasses, plant leaves and similar materials to spread on top of dikes when floods overtop dikes.
Preparation of ricefield area
The ricefield enclosed by the dikes is prepared just like an ordinary one. Land preparation begins in September just before the onset of the rainy season, either by dry or wet method.
Nursery/holding and transition areas
These are constructed in the peripheral canal. The nursery is 10 m long, 5 m wide and 0.75 m deep. Water filling from outside is done through pumping or by traditional bailing method. Fry stocking is done 2-3 days after water filling.
Oftentimes, prior to stocking fish in the entire sawah tambak, the milkfish and tawes fry are cultured separately in a nursery/holding corner in the peripheral canal. The milkfish (stocking rate: 500 mē) are raised here up to 45-60 days. The tawes (220 mē) are kept at the holding place (with about 50 mē water depth) for one month before releasing them into the field.
Fertilization
Organic (compost, animal manure, green aquatic plants, etc.) and inorganic (urea and triplesuperphosphate) fertilizers are applied. The application rates (in t/ha/year) are:
Rice hay |
10-15 |
Plant leaves |
1-4 |
Green aquatic plants |
2-5 |
Urea is applied at the rate of 100-150 kg/ha/year and triplesuperphosphate is at 300-450 kg/ha/year.
The total amount of urea and triplesuperphosphate is each divided into three equal parts and applied thrice. As an example, the first application is a mixture of 25-50 kg/ha urea and 100-150 kg/ha triplesuperphosphate.
Culture management and harvesting
Stocking sizes and rates per hectare are as follows:
Milkfish |
Fry |
11 000 |
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Tawes |
Fry |
22 000 |
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Culture period is 4-7 months, depending on the available standing water. In areas with deep water, culture period extends to one year. Stocking of fish can be done more than once. Harvesting is done twice or thrice. With no feeding, yield is about 2 000-3 500 kg/ha.
Issues for further consideration In considering if the method is useful to adopt, other occupations of the farmers, aside from rice-fish farming, will be essential information. How important is this part of their livelihood system? This can be accessed through comparative economic resource analysis. Farmers will want to know what benefits the addition of the fish component brings, in comparison to rice culture alone. Of further interest is the access to benefits from the system within household. The risk of floods and the possible escapes of fish should be assessed. How effective and costly are simple methods against this risk? In rearing fish during the initial period of 6-8 weeks, more detailed information will be necessary to ensure success, also in respect to manuring and feeding schedules. The salinity ranges in the targeted area will have influence on the choice of species and management decisions. |
