21 July, 2019

FAISAL MAHMUD, Dhaka

Amid stories of agrarian crisis everywhere, Tanvir Hossain Siddiqui has a happy tale to tell.

The founder of Agro Circuit at Uttara has no problem selling 25-30 kg of exotic green vegetables he produces every day and that too at premium prices. Tanvir’s clients include Gourmat Bazaar, Unimart and families at Uttara and Gulshan.

If Tanvir’s story sounds different at a time when farming is becoming unsustainable due to falling yields, increasing costs and low prices along with water scarcity and soil degradation, his farm looks different too.

Green leafy vegetables such as spinach, tomato and lettuce grow on a one-foot bed of flowing water—and, no soil—in a specially designed 2,000-sq-ft greenhouse at Agro Circuit Farm.

There is no need to spray insecticide or pesticide, or even use fertilizers. The nutrition for plant growth comes from 8,000 freshwater fish—Telapia and Carp—cultivated in separate water tanks inside the greenhouse.

Fish & Veggies

Tanvir uses what is called ‘aquaponics’ to grow leafy vegetables.

The method combines aquaculture—cultivating fish and other aquatic animals in tanks—with hydroponics, in which plants are cultivated in water.

The water from the fish tank is pumped onto the beds where the plants grow. While the fish excretions provide nutrients for the plants, the clean water is recirculated back to the fish tank. While the initial cost to set up the facility would be high, the recurring cost is low in aquaponics and there are two sources of revenue: fish and vegetables.

Moreover, the water requirement is as less as a tenth of that in conventional agriculture.

Tanvir who completed his bachelors in electrical engineering from Ahsanullah University of Science and Technology in Dhaka, went to Australia in 2010 to complete his masters. There he quickly developed an interest for agriculture, especially for aquaculture and hydroponic agriculture.

“When I used to go to Australian supermarkets, I saw that the most fresh and priciest vegetables were tagged as hydroponic vegetables. They were also the juiciest and tastiest. Then I started studying about hydroponic agriculture,” he told The Independent.

Tanvir said studying about hydroponics was not that hard. “These days, studying about anything is easy. You just need to do a Google search or search for it in YouTube. There are numerous tutorials and learning materials.”

He, however, added that the practical work is obviously a bit challenging than learning through a virtual medium. “I first bought a two planter startup kit from a farmers’ market in Sidney and started growing kale on an experimental basis. I succeeded and it boosted my confidence. Then in 2015, I came back to Bangladesh and started building the greenhouse in my father’s Uttara house,” he said.

Challenges of Hydroponics Farm

Tanvir said the first climate management challenge that hydroponic farmers must overcome is figuring out how much cooling, dehumidification and heating are required to manage the temperature and humidity of the space for growing.

“In an aquaculture or hydroponic farm, lighting is the greatest source of heat, followed by motors used to operate fans, pumps and automation. Because hydroponic farms are often well-insulated and designed to operate day and night throughout the year, cooling is usually required 24/7 and year-round to remove the heat generated inside the space,” he said.

Dehumidification is also constantly required to remove moisture added to the air via evapotranspiration from the plants and irrigation system. The rate and quantity of evapotranspiration depends on several variables, including light intensity, air temperature and humidity (or vapor pressure deficit), air movement and the irrigation method, he explained.

The second biggest challenge is figuring out how to deliver the conditioned air everywhere within the hydroponic farm to create a uniform growing environment. “When racks are spaced tightly together—both vertically and horizontally—it is difficult to create uniform conditions everywhere,” said Tanvir.

The third biggest challenge is to properly set up the location of the cooling equipment or the HVAC equipment of the hydroponic farm. HVAC equipment can include air conditioners, dehumidifiers, circulation fans, ductwork, chillers, boilers, pumps and pipes.

The cooling and dehumidification equipment are best located outside the building, where heat and moisture can be ejected to the outdoor air. Some equipment (air conditioners, dehumidifiers, etc.) are ideally located on the roof of the building or on the ground outside and next to the room they serve, helping to limit ductwork.

“No matter what crop is grown, managing humidity control and air movement in a hydroponic farm is essential to plant productivity, harvesting schedules, quality control and, ultimately, profitability,” Tanvir added.

A Growing Trend

Many aspiring young farmers like Tanvir are taking to hydroponic farming professionally. The Facebook page “Hydroponic in Bangladesh” has over 1,900 members and they engage in various discussions on different problems and prospects of hydroponic agriculture.

Dohar-based Mizanur Rahman, who is a textile businessman, is an amateur hydroponic vegetable grower. He has a 3000-sq-ft green house at Dohar in which he cultivates tomato through the hydroponic system with technical help from the local agriculture department and Agriculture Research Institute.

The nutritional requirements of the plants in his system of soilless farming are met by the nutrient mixtures, called hydroponics fertilizer mixtures, added to the water in which the plant roots are kept submerged. These mixtures are made of chemical plant nutrients.

“I grow my tomatoes without the use of any pesticide, so they are very organic. They taste better than any other tomatoes in the market,” he said.

Mizanur said some hydroponics enthusiasts abroad have been experimenting with various kinds of organic manures and mixtures of plants, but successful and commercially viable organic hydroponics models are still not available. “In fact, even globally accepted principles for certifying organic hydroponics products are also not yet available,” he said.

Highlighting the advantages of hydroponic farming, agriculturist and Professor of Bangladesh Agricultural University in Mymensingh Dr Abdus Salam told The Independent, “It requires 90 per cent less water than the conventional soil-based farming. Since it is water based, it has macro and micronutrients directly fed to the plants and they grow 50 per cent faster and also have a better yield.”

Giving an example, he explained, “If lettuce grown conventionally requires 60 days, lettuce grown using hydroponics yields double the produce in 28-30 days.”

Emphasizing on its water efficiency, Salam said, “Regular soil-based farming with 1,500 plants would require about 200 liters of water a day, but with hydroponics, only 20 liters of water is enough.”

EA