Low-input rice-fish farming system in irrigated areas in Malaysia
Large-scale transect of the north Kerian irrigated area of Perak, Malaysia
The rice-fish farming system is an old tradition practiced extensively in the North Kerian area of Perak, Peninsular Malaysia. The area is an alluvial coastal floodplain and receives irrigated water from the Tasik Merah reservoir. The soil is primarily clay with some acidity problems. Rice is double-cropped and short-season; high-yielding rice varieties are used.
There are approximately 352 000 ha of ricefields in Peninsular Malaysia, out of which 120 000 ha (34 percent) have sufficient water depth (15-16 cm) for rice-fish system.
- Two systems are distinguished: the traditional (System 1) and the improved (System 2). Both systems, which are essentially trapping and ongrowing of wild fish, require little labour and material inputs. Fish enter with water from the irrigation canals, ditches and ricefields and are trapped early in the rice-growing season, grown together with rice, and later harvested at the end of the season. In the improved system, more trenches are added, sump ponds are deepened, manured and limed, and dikes are improved, which all require additional investment.
- Ricefield sizes vary from 0.81 to 1.42 ha. A sump pond, which can also be an unused well or burrow pit, ranging in size from 6.5 to 8.0 m diameter, is located at the lowest part of the field. Sump pond, which is cooler and has higher dissolved oxygen content, provides shelter for fish during periods of low water level. Perimeter trenches (0.25 m wide and 0.1 m deep) may be dug around the field to enable fish to move to and from the sump pond. These open trenches also act as feeding areas for fish to feed upon zooplankton especially during the fry and fingerling stages when zooplankton is important for early growth. Mud obtained from digging the trenches is used to strengthen the dikes (0.3 m high) around the field.
- No supplementary feeding is provided. Fish obtain food from natural sources in the ricefields. The system fertility depends on rice fertilization which is applied twice during the growing season. Urea (46 percent N) and NPK (17.5-15.5-10.0) fertilizers are used at the rates of 56 and 112 kg/ha, respectively. To further increase productivity and food availability, liming of the sump pond (if required) and manuring (if available) should be done.
Transect of the north Kerian irrigated area of Perak, Malaysia,
with all resource types of traditional and improved systems
Farm layout of traditional system
Material flow on a traditional farm system
Farm layout of improved system
Material flow of an improved farm system
Local species grow well in ricefields. They have adapted to shallow water, high turbidity and temperature, and low dissolved oxygen conditions of the fields.
- The snakeskin gourami (Trichogaster pectoralis) is numerically the most important. This species and the three-spot gourami (T. trichopterus) are herbivore/planktivore and occupy the lower rung in the food chain.
- Climbing perch (Anabas testudineus) is an insectivore.
- The catfish (Clarias macrocephalus), an omnivore, and the mudfish or snakehead (Channa striata), a carnivore, are also important species.
Newly considered species
- Tilapia (Oreochromis spp.), a herbivore/planktivore/insectivore, is ecologically suitable and economically important.
- Another species to be considered is the freshwater prawn (Macrobrachium rosen-bergii).
- Fish sales provide an important supplementary income espe-cially to tenant farmers. Contributions from fish are 6.8 and 9.0 percent for owner and tenant farmers, respectively. Because little inputs are involved, the yields contribute significantly to farmers' seasonal income.
- Fish are sold to dealers who provide pump, nets and other accessories needed to harvest fish. Small fish are left behind as stock for the next growing season. Marketable-size fish are: snakeskin gourami, 14 cm; catfish, 20 cm; and snakehead, 25 cm.
Field preparation (herbicides application). Caution: use properly and only when necessary
Fertilization (urea-56 kg/ha; NPK-1.2 kg/ha)
Pesticide application (Carbofuran-5.6 kg/ha). Caution: use properly and only when necessary
- Provides additional food and income
- No additional expenses except when system is modified such as building trenches, strengthening dikes, etc.
- No major changes in normal farm practices: in the improved system (System 2), modifications to improve yields are adapted to traditional practices by farmers if affordable. The traditional system (System 1) is sustainable for limited labour/older couple situations.
- Optimises disused and under-utilized existing resources
- Maintains gene pool for locally valuable species
- Short growing season due to double dropping of rice
- Improper and excessive pesticide and herbicide use
- Uncontrolled flooding may result to fish loss
- Improper management/lack of human resources
- Low productivity and low-carrying capacity when no regular supplementary feed is provided
- Distance of sump pond from house
- Conflicting government programs in the form of subsidy for rice
Calendar of activities
During fallow season sump pond should be deepened once every five years to about 1.5-2.0 m. Perimeter trenches (0.25 m wide and 0.1 m deep) should be dug. Dike should be raised to about 0.4 m. Liming if needed should be done and manure if available should be applied.
Once water is available, field preparation should be done by cutting, raking and removing dead weeds. In about 7-10 days, all exits should be blocked to prevent fish from escaping.
Transplanting of rice seedlings. Weeding should be done especially in the trenches to provide feeding area (on plankton) for young fish.
First fertilization. Add 5.6 kg/ha Furadan (Carbofuran) mixed with urea (56 kg/ha) and NPK (112 kg/ha).
Second fertilization after 60-65 days. Same as above.
Check the ricefield as well as the fish. Stop all leakages to prevent fish from escaping.
When rice is about ready to be harvested, drain the pond to harvest the fish. Take only marketable-size fish (size depends on market demand). Leave smaller fish as stock for next season.
Estimated range of potential fish yields obtained from traditional and improved rice-fish systems
Estimated simplified budget (in US$) for the fish component of the two rice-fish systems
Notes: 1. Notice how in the first season, System 1 has no initial costs and thus a higher net income than 2.
2. However, in the second season, the costs for System 2 go down and farmer gets a higher return compared to 1.
Issues for further consideration
The technology requires relatively low amounts of material and labour inputs and hence is useful for low-income households.
In designing new applications of the system elsewhere, the following information may be necessary: (a) what are the roles of the newly introduced fish species; (b) elsewhere, tilapia recruits are a valuable source of feed for the snakehead leading to overall yield increases when these recruits are present; (c) does the improved system increase the inventory of fish stored between crops; and (d) which rice practices are being used: broadcasting transplanting or direct seeding?