Are you a Dhaka dweller? Are you satisfied with the quality of the vegetables you eat? Does the air pollution concern you? Do you miss greenery?
According to aquaculturalist Abdus Salam, the solution lies in aquaponics, hydroponics. They are the “alternative approaches to agriculture" for the future.
Hydroponics is a soil-less method of farming where water with mineral nutrient solutions is used for plants. Aquaponics is a combination of aquaculture with hydroponics. Plants and aquatic animals are raised in a symbiotic environment in aquaponics where the excretion of the aquatic bodies is fed to the plants.
Tight packed cities of the developed countries embraced the “soil-less, organic, environment-friendly” farming years ago, said the Bangabandhu national agriculture awardee professor from Bangladesh Agricultural University in Mymensingh.
The water consumption is about only one-tenth of that used in traditional soil-based agriculture and the methods contribute to lower temperature, added he.
All you need is a plastic tank, brick chips or gravel, electricity, and a pump for hydroponics plant. For aquaponics, the aquatic animal's tank is required. Used plastic bottles can be used again for plants. An electric pump is used for siphoning. Another water pipe releases the filtered water from the plant bed into the fish tank.
Indiscriminate use of crop land is leaving the arable land in an alarming state. This could be addressed by these techniques, suggests Abdus Salam's enterprise.
In a recent visit to his aquaponics and hydroponics plants in Bangladesh Agricultural University, Mymensingh, a team of Prothom Alo experienced the different farming methods implemented there.
“Look,” Abdus Salam pointed to a fish tank. As he fed the tilapias, the stout fish jumped about, splashing the water all around. “It’s a symbiotic system,” he said, “You see, the excretion of the tilapias pollute the water in the tank. The auto siphon system pumps the water into the plant bed. The plants use the nutrition from the water while it gets filtered and is returned to the fish tank again,” He shows us the odorless, fresh water flow.
Abdus Salam grew tomatoes, lettuce, strawberries, mint, okra, different types of spinach, papaya, eggplants, gourd, snake gourd, bitter gourd, potol and so on. He grew leafy plants on his veranda last year and also got a good harvest of cucumber, broccoli, pumpkin, spinach, local and American species of lettuce, and beans from his farms over the last several years.
Last year his okra yield was so huge that, "after keeping okra for my family I distributed them among our neighbours too," chuckled the satisfied farmer.
As we approached his rooftop garden, we discovered vertiponics plant beds were being filled with soaked coconut husks. There were bitter gourd, potol, eggplant and other plants along with the fish tanks. The fleshy fishes were caught in a net.
One of the professor's PhD student, Mosharraf Hossain, showed the water bottles re-used to plant mint and decorative plants. He shared his experience of how minimal nutrition needed for a leafy mint grow. “I filled a 1.5 litre water bottle with coconut husks, then planted the mint and after each of my three meals per day, I poured the water used to wash my plate in the plant,” he said, “And the result was magical. Within a few days the plant was full of leaves.”
Asked about the difference of the quantity of yield on a hydroponics-based one and a soil-based one, Abdus Salam explained, “It would be wrong to consider that these methods would yield more in quantity than the soil-based one. But the difference is in the continuous production.”
He showed the tomato plants with few tomatoes. “There were a good number of tomatoes a few months ago,” he said, “The ones in the field are finished with the yield, but the ones here won’t die and will continue to produce tomatoes, though less in number.” He drew our attention to the small new stems sprouting on the tomato plants. “The repeated yields make a difference with traditional harvest,” he remarked.
The aqualculturist explained not only tilapia but also catfish, koi, pangas and other local ones can be grown. But tilapia is less stressed by environment, and can grow at the normal pace, so "we prefer them more."
His 2000 litre tank produced 100-120 kg tilapia within eight months along with regular harvests of tomato, lettuce, taro, mint. A ten thousand taka plant produces leafy vegetables and fishes round the year for a four member family. The plant can be set on terrace, veranda, or yard.
The system can be carried out manually if electricity is unavailable. The water from the tank has to be poured into the plant bed time to time manually.
Abdus Salam first performed the aquaponics in a Japanese farm. "I read about it in the books, but it was my first practical," he said, "The owner of the Japanese farm, Tetsuya Oi, later came to Bangladesh and paid a visit to my hydroponics project."
"I was worried as my cucumbers were too ripe. I hurriedly planted strawberry plants among the cucumber plants. Within a few days there was a great harvest of strawberries," Salam said.
Later Tetsuya came along with a British professor Robert. "Tetsuya was stunned to see my garden" and "Robert said the strawberries were sweeter than the ones he ate in his country," Salam explained, "later I came to the conclusion that those grown in soil were sour due to acidity, but the hydroponics plant water is alkaline that made the fruits sweeter."
"There's the added satisfaction that you don't have to panic over any pesticides being used there," he said.
One of his students said, "Our teacher always prefers less expensive projects or else people will not implement these."
Asked on whether rainwater could be used in the plants, Abdus Salam said, "Absolutely. It's a worldwide practice to store rainwater in underground or flexible tanks and later use it for farming. It's a good option for a city like Dhaka that has scarcity of fresh water."
He had used powdered eggshell and dried banana peels, and even molasses for fertilizing. Every morning the enthusiastic agriculturist wakes up and the first thing he does is to manually pollinate his gourd flowers, “I can’t rely on natural pollination, it may not take place by chance.” He added, "It's a great pleasure to be with this greenery every day."
What was his dream with these enterprises? “I just want these to be useful for our country and people to get the real benefits. The training is an easy one and the harvest fast. Our people can implement this. I have a dream to build an institution on aquaponics,” said the researcher.