Raising Farm Output in Flood-Hit Areas: Floating Beds and Post-Flood Advice

Every monsoon, farmers in the beels of Gopalganj watch their fields disappear under water. In October 2022 the state news agency BSS reported from Mitradanga village in Tungipara upazila, where farmers pile water hyacinth into long rafts and grow vegetables and spices on top of the water. Gopalganj has 229 beels and wetlands, and they stay waterlogged for about eight months of the year, BSS said.

This report, written at the start of the 2025 monsoon, explains why Bangladesh floods so often, what the August 2024 floods cost farmers, and what the Department of Agricultural Extension (DAE) and the Bangladesh Rice Research Institute (BRRI) advise after a flood. It then explains the traditional floating bed, known locally as baira or dhap: how it is built, what grows on it, who spread it and where its limits lie.

Almost every year, between the Bengali months of Asharh and Ashwin, floods hit parts of the north, the centre, the south and the east of Bangladesh. The water comes from heavy rain falling in a short time, from the seasonal monsoon flood, from flash floods and coastal floods, and from water that flows down from the upstream countries, India, Bhutan and China.

Banglapedia, the national encyclopedia, describes three kinds of flood. The monsoon flood is seasonal: it rises slowly, falls slowly and covers vast areas, causing heavy losses of life and property. The flash flood rises and falls suddenly and usually strikes the valleys of hilly areas. The tidal flood is short, usually 3 m to 6 m high, and blocks the drainage of inland flood water.

In a normal year about 26,000 sq km, or 18% of the country, goes under water, according to Banglapedia. In a severe year the flooded area may exceed 55% of the country.

Banglapedia points to the low land, the major rivers that drain through Bangladesh along a congested network, and big river peaks that arrive together. From May to October, 844,000 million cubic metres of water flows into the country through its main rivers, and the hill catchments of the north-east and south-east bring short but unpredictable flash floods.

Bangladesh is low, but not below sea level. About half of its surface lies below the 10 m contour line, Banglapedia says, and a belt south and south-west of the Ganges tidal floodplain stands only 0.91 m above the sea. Inland, the Gopalganj-Khulna peat basin, with Baghia Beel and Chanda Beel, and the haor basin of the north-east are large low depressions.

Waterlogging is especially noticeable in Sunamganj, Sylhet, Netrokona, Nilphamari, Kurigram, Jamalpur, Faridpur, Gopalganj, Bagerhat, Barguna, Pirojpur, Madaripur and neighbouring districts. How much a flood or a long spell of waterlogging harms farming depends on how widespread it is and how long the water stays. Where water stands on the land for a fixed part of every year, that period can be used to grow crops on floating beds instead of leaving it idle.

In August 2024 a large flood struck the east of the country after heavy monsoon rain. On 7 September 2024 The Financial Express reported that the flood had caused Tk 33.46 billion worth of damage to agriculture across 23 districts in eastern Bangladesh, and that about 1.4 million farmers were affected.

The crop-by-crop figures in that report show which crops a flood at that time of year hits hardest. Transplanted (ropa) aman rice was damaged on 141,609 hectares and aus rice on 38,689 hectares. Ropa aman seedbeds were damaged on 14,908 hectares and vegetables on 11,290 hectares.

The same report said the government had allocated Tk 136.6 million in cash, free seeds and fertiliser for 80,000 small farmers in nine districts. The loss of so many seedbeds explains why much official advice after a flood is about finding seedlings and varieties that can still be planted late.

On 25 August 2024, as the Flood Forecasting and Warning Centre of the Bangladesh Water Development Board reported falling rivers in the north-east, east and south-east, the DAE's Agro-Meteorological Information Systems Development Project issued a special advisory for the post-flood period. Its main points for rice were these:

• In all flood-affected areas, sow BRRI's photoperiod-sensitive varieties such as BR5, BR22, BR23, BRRI dhan34, BRRI dhan41, BRRI dhan46 and BRRI dhan54, and local photoperiod-sensitive varieties such as Nigershail, Rajashail and Kajalshail, directly until 7 September, and transplant them by 15 September.
• Where there is no raised land for a seedbed, raise seedlings on a floating seedbed, a covered seedbed or in trays.
• If mud or silt sticks to the leaves of rice plants that survived submergence, wash the leaves with a spray of clean water after the flood water recedes.
• When new leaves appear 8 to 10 days after the water recedes, apply 7 to 8 kg of urea and 5 to 6 kg of potash per bigha, and later top-dress urea and potash as the crop's stage requires.
• Two or three tillers can be taken from aman plants in fields that were not flooded (up to 30 to 40 days after transplanting) and planted in damaged fields.
• Where older aman seedlings (at most 60 days old) are available, plant them after the water recedes at 20 x 15 cm, with 4 to 5 seedlings per hill; apply TSP (10 kg per bigha) and MOP (14 kg per bigha) at final land preparation and 20 to 25 kg of urea per bigha as a top dressing 7 to 10 days after planting.

The advisory also warned that floods can later bring sheath blight and leaf blight to rice. For sheath blight it advised a fungicide such as propiconazole at the approved rate, sprayed in the afternoon, along with balanced fertiliser, and an extra 5 kg of MOP per bigha against leaf blight. Fields should also be checked regularly for leaf rollers and brown planthoppers. Farmers should ask the upazila agriculture office before buying any pesticide.

The advice went beyond rice. Excess water should be drained from paddy, vegetable and other standing crops, and new vegetables sown once the land dries. Broken pond banks should be repaired quickly or fenced with nets, unwanted fish that entered with the flood water removed, and lime and salt applied to ponds as the local fisheries office advises. Because cattle and poultry may suffer from diseases such as foot-and-mouth disease, anthrax and black quarter, goats and sheep from PPR, and all of them from worms, the advisory asked farmers to arrange vaccination and deworming through the upazila livestock office and veterinary hospital as soon as the water recedes.

A BRRI fact sheet on rice in flood-prone areas adds that where transplanted aman may be submerged for 12 to 16 days, BRRI dhan51 and BRRI dhan52 can give a satisfactory yield, and that BR22, BR23 and BRRI dhan46 seedlings 30 to 50 days old still yield well when transplanted up to mid-September. If a flood delays aman too long, BRRI suggests an early boro crop instead, with seedlings raised by mid-November.

Rice advice helps where the water goes down. In the deepest beels it may stay for months, and there farmers rely on an older idea: crops grown on a raft of plants that holds compost and nutrients.

The Food and Agriculture Organization of the United Nations (FAO) describes the practice in the wetlands of southern Bangladesh, in parts of Gopalganj, Pirojpur and Barishal districts, where communities have long struggled to find farmland during the monsoon from June to October. Farmers there developed floating gardens, locally known as dhap, to grow plants and crops in nutrient-rich water without soil. FAO says local farmers have used the method for nearly two centuries. In 2015 FAO designated the Floating Garden Agricultural Practices of Bangladesh a Globally Important Agricultural Heritage System (GIAHS), covering 2,500 hectares.

Water hyacinth (Eichhornia crassipes) is of Latin American origin, and Banglapedia records that it was brought from Brazil in the latter part of the 19th century. By the 1920s it had choked the water bodies of Bengal, blocking river navigation and making deepwater aman and jute harder to grow, and the Water Hyacinth Act of 1936 required householders to clear it. Banglapedia also notes that decayed heaps of water hyacinth make a good fertiliser and that crops grew well on dressed heaps, which drew farmers to build floating fields.

Writing in The Daily Star in July 2021, Haseeb Md Irfanullah traced the history: heaps of paddy stubble once floated when the floods came, and water hyacinth became the main material from the 1960s, when high-yielding rice varieties replaced the old straw-based system. Banglapedia lists floating water hyacinth beds as a special feature of Banaripara upazila in Barishal district.

The materials are what a wetland village already has. The beds are built from:

• water hyacinth (kochuripana), the main body of the bed;
• straw of deepwater rice;
• other aquatic plants, such as khudipana, kutipana and shayala;
• pieces of bamboo, for the frame and for the poles that hold the bed in place.

FAO describes the core of the method in one line: bamboo is laid on a dense layer of water hyacinth. The steps farmers follow are these:

• Pile floating water hyacinth on the water and set a bamboo frame or raft on it.
• Stack more water hyacinth thickly on top. The thickness depends on how long the waterlogging will last, so that the bed stays afloat for the whole period.
• Add a layer of cow dung and compost to the top.
• Leave the bed to settle. The original report advises sowing 10 to 15 days later; FAO says farmers sow seed or transplant seedlings 8 to 10 days after the last stacking.
• Because a baira can drift, move it to a spot that is easy to tend and fix it there with bamboo poles.

Thickness matters. Researchers Asit Baran Mondal, Mohammad Bashir Ahmed and Md Abdul Mannan tested beds of water hyacinth 1.5 m, 2.0 m and 2.5 m thick in Gopalganj district in 2013 and 2014, growing okra, Indian spinach, cucumber and red amaranth. Their paper, published in 2023 in the International Journal of Horticultural Science and Technology, reports that the thickest beds gave the best growth and yield, with okra yields of 7.99 and 8.09 tonnes per hectare, while the thinnest gave the least. Weighing yield against cost, they found the 2.0 m bed suitable for those crops. The beds also became thinner every month as the water hyacinth decomposed and fell into the water, and the thinning sped up over time.

Floating beds also raise rice seedlings when the usual seedbed is under water. In August 2019 The Daily Star reported that farmers in Sundarganj, Gaibandha, had sown aman seed on heaps of water hyacinth mixed with mud after floods damaged 2,881 hectares of seedlings in the district.

FAO lists the main crops on floating beds as okra, ribbed gourd, Indian spinach, brinjal, cucumber, red amaranth, stem amaranth, wax gourd, bitter gourd, kangkong and melon. Farmers can complete two or three crop cycles on a floating garden in one monsoon season. In winter, when the water goes down, the beds are broken up and the residue is used to enrich the soil, where farmers grow rice and other vegetables.

The original report also lists spices for the beds: chilli, onion, garlic, ginger and mustard. In October 2022 BSS reported that farmers in Gopalganj were growing watermelon, muskmelon, onion, chilli, ginger, turmeric, cucumber, gourds, squash, tomato, amaranth, bottle gourd, cauliflower, ridge gourd, cabbage, broccoli, red amaranth and other leafy vegetables on floating beds.

FAO says the productivity of floating vegetable cultivation is estimated to be ten times higher than on a similar-sized piece of land. Because nitrogen, potassium and phosphorus are abundant in the decomposing bed, there is almost no need for fertiliser, and because the water keeps many pests away, almost no pesticides are used.

For a family in a waterlogged village, the beds mean vegetables and income when the fields give nothing, work during the flood season, and, once the water recedes, rotted water hyacinth and compost for the fields as organic fertiliser.

Around the turn of the century NGOs took the method up. IUCN Bangladesh and the Bangladesh Centre for Advanced Studies (BCAS) promoted baira in the Madhumati floodplain of Gopalganj under the Sustainable Environment Management Programme (SEMP, 1998 to 2005) of the government and the UNDP; in 2005 IUCN published the book "Baira: the floating gardens for sustainable livelihood" from that work.

Government programmes followed. In the second phase of the Comprehensive Disaster Management Programme (CDMP II, 2010 to 2015), the DAE trained and engaged 565 farmers in the practice. In 2012 the DAE began a project to extend floating vegetable and spice cultivation as a climate-change adaptation technology for flood-prone and waterlogged areas, working with 12,000 farmers in 40 upazilas of eight districts. A larger follow-up project, run by the DAE from 2017 to 2022, covered 46 upazilas in 24 districts.

In Gopalganj, BSS reported in October 2022, 1,800 farmers in five upazilas were taking part in a five-year project on vegetable and spice cultivation on floating beds, and the Bangladesh Agricultural Research Institute (BARI) has researched ways to make the method more efficient. Internationally, the UNFCCC's Technology Executive Committee featured the practice as a useful adaptation technology in 2014, and the Intergovernmental Panel on Climate Change's Fifth Assessment Report discussed its possible weaknesses.

A floating bed lasts only as long as its water hyacinth holds together; as the Gopalganj study found, it thins every month, so it has to be built thick enough for the whole flooded season.

The traditional bed also does not suit every water body. Researchers at the Horticulture Innovation Lab of the University of California, Davis, noted in 2016 that deep piles of water hyacinth are not suited to small fish ponds, because the decomposing plant removes oxygen from the water. For pond owners they designed a bamboo raft of coconut coir and vermicompost floated on empty plastic containers, and found no harm to the ponds' water quality.

Farmers who want to build floating beds, or need seed, seedlings or advice after a flood, can contact the sub-assistant agriculture officer of their union or the upazila agriculture office of the DAE. Fish farmers can turn to the upazila fisheries office, and livestock owners to the upazila livestock office and veterinary hospital for vaccination and treatment, as the DAE advises.

Photo: Nazmulhuqrussell / Wikimedia Commons (CC BY 3.0)

Sources: The Agro News (Staff Correspondent), Food and Agriculture Organization of the United Nations (GIAHS), Department of Agricultural Extension (BAMIS special agromet advisory, 25 August 2024), Bangladesh Rice Research Institute (BRRI) fact sheet, Banglapedia, BSS, The Financial Express, The Daily Star, IUCN, International Journal of Horticultural Science and Technology, Horticulture Innovation Lab (University of California, Davis)