RICE-FISH CULTIVATION means growing rice and fish together at the same time on the same piece of land. In rice-fish farming, farmers introduce another crop into the paddy field and that crop is the small fish. It also includes growing fish and rice one after the other or simultaneously growing side by side in different compartments using the same water. This technique seems to be good for rice and fish. In this technique, the fish live in dense rice plants and in turn the fish provide fertilizer in the form of their droppings, eat the pest, and circulate oxygen in a paddy field. The researcher says that by keeping the fish in a paddy field, the rice yield can be increased by up to 10% and also additional fish supplies.
The production of fish in rice fields is as old as the practice of cultivating rice. The combined culture of fish and rice is also known as the Paddy-cum-fish culture. Rice-fish culture was introduced to Southeast Asia around 1,500 years ago from India, where it is now most developed. At the end of the 19th century, rice-fish farming was practiced in Italy. Now it has spread to the United States and is well established in other rice producing countries like China, Japan and Taiwan.
Preparation for rice-fish culture
The paddy field used for fish farming has different water properties from those of ponds and lakes. In rice fields, the water depth is generally shallow. Due to this shallow depth, the temperature is also affected by the air temperature. During photosynthesis by other vegetative plants, oxygen is released in large quantities. Thus, the dissolved oxygen of the water is increased.
Usually, a paddy field with adequate water supply, better drainage facility, abundant sunshine and high water-holding capacity is suitable for fish farming. In southern China, near lakes and rivers, there are deep-water rice fields in low lying areas. These low-lying fields are good bases for rice-fish culture.
Construction sheds and water structure
To maintain good water depth and prevent fish from escaping during heavy rains, bunds should be raised up to 33.3 to 50 cm. There should be a hiding place for the fish during the shallow irrigation season, at high temperature or during the application of fertilizers or insecticides. To this end, fish trenches or sumps are usually made after transplanting the nursery to facilitate fish. In addition, sheds are built above the sump to protect the fish when the water temperature reaches 39 ° C. In some places there are no fish wells and 50-65 cm holes are made deep in the side of the bund. This hole is used as a wintering place in winter and as a storage in summer. These holes are also better for fish that prefer semi-darkness.
The most commonly used fish species are tilapia, carp (common carp, crucian carp, European crucian carp, mirror carp), catfish, trout, snakehead argus, etc. However, viviparous and macro brachia are also suitable for paddy fields.
The fry and fry that are stored in the paddy fields must be sound, without damaged scales and robust intact with their body surface. The optimum storage size for common carp is 10cm or more and for silver and bighead carp is 20cm or more. Catfish, mud carp, tilapia and fry are repopulated after wintering.
Rice-fish crop management
For rice-fish farming, knowledge of rice farming and fish farming is necessary. In addition to this, the methods of drainage, filling, application of insecticides and fertilizers should also be understood.
Routine management of rice fields
In rice-fish culture, it is necessary to see the water structure for the proper amount of water and control the escape of fish from the structure. The optimum water depth of 16-17 cm should be maintained. Draining should be done gently so that the fish can reach the sumps or trenches. In addition, special attention should be paid to the change in water temperature, because when the temperature rises up to 40 ° C, it exceeds the tolerance of common carp. In such cases, the water should be changed with soft water so that the temperature decreases.
Rice-fish farming and fertilization relationship
He said that the development and growth of rice and fish are greatly affected due to the amount, type and method of fertilizer application. Fertilizers like nitrogen, phosphorus and potassium which are required by growing rice are also nutrients required by natural fish. Thus, the production of fish feed is directly influenced due to the availability of fertilizers.
Predator prevention for rice-fish farming
There are many predators of fish in the paddy field, such as animals, birds, snakes, Cybisters, Lactotrophs and frogs etc. Preventing predators is very important at the start because the rice is small and the field is fully exposed. Instead, the swimming movement of fish also makes them susceptible to predators. Again, during the harvest period when the water is low in the field, the fish are exposed to predators. Thus, it is essential to control the loss through proper management of predator control. This predation can also be minimized by increasing the water level in such a way that the growth of the rice is not affected.
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