Floating agriculture: vegetables, spices and Aman seedlings on water hyacinth beds

Floating agriculture, the practice of growing vegetables, spices and rice seedlings on rafts of piled water hyacinth, was spreading across the waterlogged districts of Bangladesh in 2017, Jagonews24 reported in a feature published on 13 August 2017. The report described how farmers in the south had developed the method themselves to use land that stays under water for months, how floating beds were being used that year to raise Aman rice seedlings in flood-hit areas on the instructions of the Ministry of Agriculture, and why rotted water hyacinth could help return organic matter to the country's cropland.

The beds are known locally as dhap or baira. Two years before the report, in December 2015, the Food and Agriculture Organization of the United Nations (FAO) had recognised the floating gardens of Gopalganj, Pirojpur and Barishal as a Globally Important Agricultural Heritage System. This article sets out the practice as the Jagonews24 report described it, with background from FAO, Banglapedia and research published before August 2017.

Bangladesh is a land of rivers, and flooding is part of its yearly cycle. According to Banglapedia, the national encyclopedia published by the Asiatic Society of Bangladesh, about 26,000 square kilometres, or 18 per cent of the country, is flooded each year, and in severe floods the affected area can exceed 55 per cent of the country. The Jagonews24 report named Gopalganj, Jhalakathi, Barishal, Pirojpur, Satkhira, Chandpur, Cumilla, Brahmanbaria, Netrokona, Kishoreganj, Sunamganj and Habiganj among the many districts where a large part of the land is waterlogged in the monsoon and stays under water for about six months of the year.

During those months, the report said, there was no farm work and no crop in such areas, and many people had no work. The water was covered with water hyacinth and other aquatic weeds, especially in the beels, haors, canals, ditches and derelict ponds.

Banglapedia describes these two kinds of wetland. A beel is a saucer-like depression that collects surface runoff; many beels dry up in winter and spread into broad, shallow sheets of water in the rains, and thousands of them, of different sizes, are found across the country, including the Chalan Beel, the Gopalganj-Khulna Beel and the Arial Beel. A haor is a larger, bowl-shaped depression of tectonic origin, found mainly in greater Sylhet and greater Mymensingh. The haor basin includes about 47 major haors and some 6,300 beels, and during the rains it turns into a vast inland sea in which villages stand like islands. The entire Sunamganj district and most of Habiganj, two of the districts the report named, are covered by haors.

According to the report, farmers in the south devised floating agriculture to meet their own needs. They piled water hyacinth and other aquatic weeds into raft-like beds of the size they needed and grew different vegetables and spices on them through the year. The report called floating vegetable and spice production, and in some cases the raising of Aman rice seedlings in an emergency, a climate change adaptation strategy for flood-prone and waterlogged areas that had opened new doors for farming, and said the practice was gradually spreading across waterlogged areas.

In 2017, the report said, Aman rice seedbeds were made on floating beds in flood-hit areas on instructions from the top level of the Ministry of Agriculture, and by the time of the report at least 800 floating beds had been used as Aman seedbeds.

Aman is the main monsoon rice crop of Bangladesh. Banglapedia notes that transplanted Aman was the most important of the country's rice crops, occupying about 46 per cent of rice land in 2009-10, and that it is harvested from November to January. Transplanted Aman is grown throughout the country, while broadcast Aman is grown mostly in the south and south-east. Because it is planted during the rains, a flood that drowns the seedbeds can leave a farmer with no seedlings at the moment the field becomes ready.

That was the problem the floating seedbed was meant to solve. The report explained that in flood-hit areas there is usually no dry place for a seedbed in the monsoon, and once the floodwater recedes there is not enough time left to raise seedlings. With seedlings already growing on floating beds, 20- to 25-day-old Aman seedlings could be planted in the main field as soon as the water receded or the submerged land re-emerged. No time was lost, Aman could be grown in step with the season, and, according to the report, the yield was hardly affected. Where rain and floods had made ordinary seedbeds impossible, farmers could still plant Aman on time once the water drew back. The report said the technology had already become quite popular.

The report also gave figures for the seedbed. As with ordinary seedbeds, it said, the seed rate on a floating seedbed is 80 to 100 grams per square metre, and seedlings from 35 square metres, or about one decimal, of floating seedbed are enough to plant one bigha. The seedlings are lifted at 20 to 25 days and transplanted, cared for and managed like ordinary seedlings, and, according to the report, give the same yield. Because the bed floats, it usually needs no irrigation, though water can be sprinkled on it now and then. Farmers who want to check the seed rate and the variety for their area can ask the upazila agriculture officer of the Department of Agricultural Extension (DAE).

Before sprouted Aman seed is sown, the report said, the bed is coated with a thin layer of pond-bottom mud or soil slurry, 2 to 3 centimetres thick, to make a wet seedbed. The bed is tied with rope to a stake so that floodwater cannot carry it away, and after sowing the farmer has to keep birds and other animals from eating the seed. Raising seedlings this way also means the main field is not needed for a seedbed, so newly exposed land can be planted with the desired crop sooner.

The main material for a floating bed is water hyacinth. The report listed other materials that can be used: duckweed, algae, various aquatic weeds, the dulali creeper, rice straw or other crop residues, sugarcane bagasse and sawdust. Beds made with mature, dark green, large and long water hyacinth last longer. Where the dulali creeper is not available, jute rope is used instead to bind small balls of growing medium, and coconut coir dust is also used for raising seedlings.

FAO's description of the heritage site explains how the traditional dhap is built. The bed sits on the water surface and grows plants without soil. Bamboo is laid on a dense layer of water hyacinth; this first layer gives the bed stability, buoyancy and thickness, and the upper layers serve as compost. Farmers sow seed or transplant seedlings 8 to 10 days after the last layer has been stacked. FAO says farmers usually take two or three crop cycles in one monsoon season, most often with mixed intercropping.

FAO lists the summer vegetables grown on the beds as okra, ribbed gourd, Indian spinach, brinjal, cucumber, red amaranth, stem amaranth and wax gourd, along with bitter gourd, kang kong and melon. A 2016 report in the Indian magazine Down To Earth described the same tradition: farmers pile water hyacinth or paddy stalks on standing water and compact them into rafts called dhap or baira, on which they grow vegetable seedlings and spices, and when the rafts break down they are used as compost for winter crops on land.

Because floating beds are rich in the nutrients plants need, the report said, seed can be sown or seedlings planted more densely than on level ground. The high organic content also makes crops grow faster than in conventional fields, and the report said that in many cases yields are about three to five times higher. FAO, for its part, estimates the productivity of the floating gardens at ten times that of land-based cultivation of a similar size, and notes that because nutrients are naturally abundant almost no fertiliser is needed, while the standing water limits pests so that almost no pesticide is applied.

The beds also feed the land after the flood. When the water level falls at the end of the season and the beds settle on the ground, the report said, they can be broken up and spread on the field or mixed into the soil, and different crops can then be grown successfully. Rotted water hyacinth can also be placed at the base of fruit trees as manure to raise fruit production. FAO describes the same cycle: in winter the beds decompose, and their residue enriches the soil for winter vegetables, while rice and other vegetables are grown on the other land.

The report argued that the cultivated land of Bangladesh does not receive the organic fertiliser it needs. Using water hyacinth from waterlogged low-lying areas to grow vegetables and spices, and monsoon Aman seedlings, would supply safe food, it said, and spreading rotted water hyacinth as organic fertiliser would raise the fertility and productivity of the soil and support organic, environment-friendly farming. It would also save land and allow fallow land to be used.

According to the report, by following the method farmers could make up their losses, take on several kinds of work, get the yields they wanted and earn more. Farming on floating beds would save time, let cropland be put to use earlier, cut costs and help environment-friendly production to spread.

The plant at the heart of the practice is not native to Bengal. Banglapedia describes water hyacinth (kachuripana, Eichhornia crassipes) as a free-floating aquatic plant of Latin American origin that grows so fast it often blocks boats by blanketing the water. It is said to have been brought to Bengal from Brazil in the latter part of the 19th century by a visitor attracted by its orchid-like flowers. By the 1920s, Banglapedia says, the waterbodies of Bengal had become clotted with it; river navigation was obstructed, and the cultivation of wetland crops, including deepwater Aman paddy and jute, became difficult.

The government of Bengal answered with the Water-hyacinth Act of 1936, which prohibited householders from keeping or tolerating water hyacinth on their holdings and made cooperation with clearing drives a public duty. Banglapedia records that heaps of decayed water hyacinth were found to make a good fertiliser, that crops and vegetables grew well on the heaps, and that this attracted many landless peasants to pile up water hyacinth to make floating fields. By 1947 the weed had come under control. It still grows in many parts of Bangladesh, particularly in the haors and beels, where it multiplies quickly during the monsoon and spreads over newly flooded land; today it is chiefly used as manure, and its leaves serve as fodder in the floodplains when fodder is scarce.

FAO places the heritage site in Gopalganj, Pirojpur and Barishal in south-central Bangladesh, on about 2,500 hectares of water and flooded land with a subtropical humid climate, where people earn their main income from agriculture and fisheries. Down To Earth put the area at about 25 square kilometres of low-lying wetland.

Banglapedia gives the setting. Gopalganj district, with an area of 1,468.74 square kilometres, was established in 1984; its main rivers are the Madhumati, the Hunda, the Ghagar and the old Kumar. Pirojpur district, 1,277.80 square kilometres, was also formed in 1984; its main rivers are the Baleshwari, the Swarupkati, the Katcha and the Kaliganga, and the Chatar Beel is its best-known wetland. Nazirpur upazila of Pirojpur, 228.69 square kilometres, lies between Tungipara and Kotalipara in Gopalganj to the north and Pirojpur Sadar to the south, with the Chatar Beel inside its borders.

These basins also have some of the country's most unusual soils. Banglapedia notes that organic soils cover about 74,000 hectares in low-lying basins across Bangladesh, and that the Gopalganj-Khulna Beel area has the largest extent of them. Before mechanised dry-season irrigation arrived in the 1960s, deepwater or broadcast Aman rice was the main crop of the country's wetlands in the rains.

On 15 December 2015 FAO announced that the floating gardens of Bangladesh had been designated a Globally Important Agricultural Heritage System (GIAHS), together with three sites in Japan. In its announcement FAO described the floating gardens as a unique hydroponics production system built with natural grasses and plants, in which crops grow on the water on a floating organic bed of water hyacinth, algae and other plant residues, so that wetland resources can be used to grow vegetables and other crops almost all year round.

FAO launched the GIAHS programme in 2002, during the World Summit on Sustainable Development in Johannesburg. The four designations of December 2015 brought the total to 36 sites in 15 countries. FAO's site page names the Ministry of Agriculture as the responsible ministry and says local farmers have used the system for about two centuries; Down To Earth reported that some estimates put the tradition at 300 to 400 years. FAO lists the system's contributions as food security, extra income, access to land for poor and landless people, a better gender balance, and the use of an invasive plant in a way that helps preserve aquatic life.

The practice was also honoured at home. On 18 June 2017, according to the Press Information Department, commemorative postage stamps on floating agriculture and floating markets were released at the Department of Post and Telecommunications in Dhaka.

Researchers had been studying the system for years before the 2017 report. A 2007 paper by T. Islam and P. Atkins in the journal Development in Practice described floating-bed cultivation in the freshwater lakes and wetlands of Bangladesh, where vegetables, flowers and seedlings are grown without additional irrigation or chemical fertiliser, and noted that no detailed study of this indigenous technique had been published until then. The authors said local farmers had shown the potential for the sustainable use of such common-property water resources.

A review by R. Chowdhury and G. Moore in the Journal of Cleaner Production, published in May 2017, examined the literature on floating agriculture as a way of adapting to climate change. It concluded that the technique holds enough potential to help farming communities in flood-prone regions sustain lives and livelihoods during floods and long waterlogging, by allowing vegetable production for daily food and income, community mobilisation and greater access to land. The review also pointed to sustainability challenges, which it said could largely be overcome through proper planning and long-term management.

Down To Earth, in March 2016, reported that several non-profit organisations had promoted floating gardens across the country over the previous 15 years. It said the government had approved US$1.6 million in 2013 for a large-scale effort involving 12,000 families in eight districts, that IUCN and CARE had trained about 2,000 families in 10 districts since 2007, and that Practical Action had trained about 800 families displaced by river erosion. The magazine also recorded a note of caution from the aquatic ecologist Haseeb Md Irfanullah: "Unpredictable rainfall, shifting of seasons and salinity are going to affect hyacinth. We have to look into alternatives."

It was against this background that the Jagonews24 report of August 2017 saw floating beds as more than a heritage: a way to raise vegetables, spices and Aman seedlings on water that would otherwise lie idle for half the year, and to return the rotted beds to the soil as organic matter once the floods had gone.

Photo: Nazmulhuqrussell / Wikimedia Commons (CC BY 3.0)

Sources: Jagonews24, Food and Agriculture Organization of the United Nations (FAO), Banglapedia (Asiatic Society of Bangladesh), Down To Earth, Development in Practice (Islam and Atkins, 2007), Journal of Cleaner Production (Chowdhury and Moore, 2017), Press Information Department