Rice (Oryza sativa) is the one of the major staple food in the world .About half of the world’s population feed on it. It is cultivated in more than 100 countries, predominantly in the Asia. About 90% of the rice production and consumption is related to Asia. Pakistan ranks at 4th number in the rice production. Every year, it produces an average of the 6 million tons of rice. Pakistan supply 30% of the world’s paddy output. It contribute about 1% in GDP and added value of 4.9% in agriculture. But in past few years, the export of rice is decreased to 19%.which badly affected the economy.so there is the need to introduced such techniques and methods which not only increases the yield but also has significant increase in the farm income.one of the such method is the aquaponics method.
What is the Aquaponics?
It is a system that combines the Hydroponics (cultivating plants in water) along with conventional Aquaculture (rearing of the aquatic animals e.g. cray fish, snails, prawns) in a symbolic environment.
In ordinary Aquaculture, the excretions of the animals accumulated in to the water and increases the toxicity. In Aquaponics system, the water is diverted to the Hydroponic system where the nitrifying bacteria breakdown the harmful products in to the nitrates and nitrites, which are taken up by the plants and they utilized it as a nutrients and in this way the water is clarify and again diverted towards the Aquaculture system. This technique can be use in the paddy fields to increase the farm income. Where the fishes provide the organic matter to the rice in turn rice serves as natural filter which clarify the water by absorbing the organic matter from it and provide a safe medium for fishes to live in. This technique can be used in the areas where the rice and fish are consumed as staple food. It only requires the little input but can provide the employment to farm labors in off season.
The fishes may be stocked and may be naturally enter in the fields by flooding. Wild fishes can be forced to enter in the fields by the different ways e.g. by keeping the bunds low and entrance of the fields open. The eel and catfish can be attracted by placing the buffalo and cow skins or by placing the branches that give shelter to the fishes. Harvesting of the fishes from the fields can be done by trapping, hooking, harpooning, and throwing nets and by draining the fields. Or they can also be channeled into the adjacent trap pond areas where they can be kept alive until required.
Fishes in the paddy fields can be stocked at the different rates e.g. 2500 common craps, 1250 silver barb and 1250 tilapia per hectare. If it is possible economically, feed supplements e.g. termites, earth worms, and rice bran can be provided. Fishes are stocked usually 10 to 15 days after the rice plantation in the fields so that rice can adjust in the field first.
Species suitable for the fish cum rice culture:
Fresh water species are mostly used for this purpose e.g. nielm craps (Osteochilus hassltii), sepat saim (Trichogaster pectoralis), catfish (Clarias), snakehead (Channa), java crap (Puntius gonionotus), tilapia, common crap etc.
The most successful species used for this culture are those which can tolerate the high temperature and high turbidity or can thrive in shallow water. Which has the high growth rate and can attain the marketable size in few months. The size and stoking rate can be determined by the period available for the fish farming. The duration of the culture is usually 3 to 4 months.
Beneficial impacts of aquaponics (fish-rice culture):
The herbivorous fishes which are raised in the paddy fields can control the weeds to a significant extent.
Fish eats many harmful insects and organisms thus improving the paddy yield by saving them from insect pest.
Increase the tillering by their movement which is helpful in higher paddy production.
It prevents the digging of the bunds by the rodents due to the greater depth of the water.
The proprietary system increases 6 times more per square foot as compare to the traditional farming.
Due to the naturally fortified water by the fishes, plants grow more rapidly.
Aquaponics protects our lakes and rivers. No harmful fertilizer runoff in to the lakes and rivers.
These technique uses less water as compare to the traditional farming.
Water recycling and nutrient recycling has been done.
Aquaponics also has its beneficial impacts on the health and is a good source of the nutrition because the fishes are the swift converter of the plant protein in to the animal protein.
An increase in the yield of rice can be expected up to 700kg/ha in well managed fields. The fish cum rice culture provides 2 source of income to the farmer at a time which not only saves the time, place but double the income from the same piece of the land. There is no need of the dispose off the fish waste. It’s an organic culture it provides the pesticide free fish and paddy with good taste thus provide the healthy and nutritional food. The aquaponics culture can be practiced on a small scale or on the large scale. This culture provides the symbiotic relationship between the plants and fish. So it is the need of the time to adopt those techniques which are human friendly, environmentally safe and give economic benefits.
Co Authors : Farwa shehzadi , Bakhtawer zafar ,Muhammad usman tahir , Hassan Ahmed.
University of Agriculture Faisalabad Pakistan.