Is floating agriculture a nature-based solution?

Farmers of the south-central districts of Bangladesh, namely Barishal, Gopalganj, Madaripur, and Pirojpur, have been practicing floating agriculture for decades, if not centuries. But over the last two decades, this indigenous, wetland-based agrosystem has turned into something of a "climate celebrity".

During monsoon months, floating beds are traditionally made with compactly intertwined water hyacinths and other plant materials. Once the bed surface gets rotten, farmers plant different crop seedlings and grow vegetables on these buoyant platforms.

Since the turn of this century, first NGOs and then different agencies of the government have been extensively promoting floating agriculture as a livelihood option for poor farmers, a means to achieve nutrition security, a measure to reduce flood risks and, of course, as a climate-smart agricultural practice.

In 2014, leading global bodies, namely the United Nations Framework Convention on Climate Change (UNFCCC) and the Intergovernmental Panel on Climate Change (IPCC), recognised Bangladesh's floating farming as an adaptation option in their publications. The following year, the Food and Agriculture Organization (FAO) declared this practice as one of the Globally Important Heritage Agricultural Systems—the only one from Bangladesh.

The reason for this tremendous interest in floating agriculture is simple. Since we have been experiencing prolonged floods and waterlogging because of changing climate, growing crops on floating beds can help us cope with this adverse situation and ensure our food security. By raising winter crop seedlings on floating beds, farmers can transfer the seedlings to the soil as soon as flood water recedes, thus avoiding potential crop damage from cold weather. The simplicity of this organic way of agriculture is also an attraction.

Since Bangladesh's floating agriculture depends on nature—wetlands, flood waters, aquatic plants—can it be called a nature-based solution (NbS)?

In the last couple of years, there has been a lot of discussion about NbS as a means to fight climate change. NbS involves actions we take to protect, restore, create, and sustainably manage our ecosystems to tackle different challenges facing our society such as climate change, food insecurity, and biodiversity loss. Protecting the 5000-year-old Sundarbans, creating green belts of trees along Bangladesh's coast over the last 55 years, or restoring mangroves of Nuniarchhara (near Cox's Bazar town) are examples of NbS initiatives. Such forests around the world offer protection against coastal flooding—a 20-km mangrove stretch could protect us from up to USD 250 million worth of damage every year. These also trap carbon dioxide from the atmosphere, thus helping to keep the earth cooler.

All our biodiversity conservation related work to save our plants and wildlife may seem to fall in the category of NbS. Similarly, when we manage the fisheries of a wetland to reduce poverty in the surrounding villages, it may also seem to be an NbS. But these examples are not of NbS.

To be an NbS, an ecosystem-based action should provide both human wellbeing and biodiversity benefits. The two aforementioned examples either give biodiversity benefits through conservation or community development benefits through poverty alleviation, but not both. The restored mangrove forest in Nuniarchhara, on the other hand, not only stands as a natural wall against storm surges and captures carbon dioxide, but also significantly increased bird and fish diversity in the area and improved livelihoods of the villagers with the rise in nature-based tourism.

Now, let us compare the characteristic features of floating agriculture with those of NbS. First, the main purpose of floating agriculture is not managing, protecting or restoring any wetland ecosystem where it is practiced. It, however, does support human wellbeing by providing income and nutrition from crops grown on the floating beds made up of natural resources, like water hyacinth and other aquatic plants.

Second, floating agriculture does not give any obvious biodiversity benefits, like a protected forest or river would do. If farmers grow indigenous crop varieties on floating beds, it can indeed contribute to maintaining the agro-biodiversity of a region. But if we dig into this farming system—from making floating beds to cultivating on them to disposing of them later—we will see its environmental benefits.

Since water hyacinth is a notorious alien invasive species, using it to make floating platforms supports its control, thus allowing other aquatic species to survive and flourish in wetlands. Floating agriculture does not require a lot of pesticides and fertilisers to grow crops, and hence does not cause huge water pollution as the conventional land-based agricultural system does. Moreover, when water recedes after the monsoon, the rotten floating beds are dismantled and mixed with soil as organic fertiliser to grow winter crops. In this way, it reduces chemical fertiliser use and improves soil health.

Third, an NbS should address one or more societal challenges, and floating agriculture addresses at least three: by ensuring food security, contributing to social and economic development through creating livelihood opportunities, and adapting to climate change.

So, based on its contributions to nature, biodiversity, and human society by tackling societal challenges, floating agriculture is indeed an NbS.

There is a different form of floating farming called aquageoponics. Here, a raft is made with bamboo or iron frame which is kept suspended above the water by plastic containers as floats. Earthen or plastic pots with soil placed on the frame are used to grow vegetables. Beneath the floating structure, a net cage is installed to culture fish. This innovative and integrated system was first tried by WorldFish and its partners in Barishal in 2013. Since then, it has been piloted in other parts of coastal Bangladesh. It is a useful adaptive option in low-saline areas as it uses a small amount of non-saline soil to grow vegetables and culture salt-tolerant fish, like tilapia, both providing economic and nutritional security to rural households. But this artificial production system is not an NbS, as it does not offer any biodiversity benefits.

What an NbS is and is not may seem like an academic debate. But it is not. The rapidly increasing global interest in NbS is expected to increase flow of funds to implement NbS worldwide, including in Bangladesh. A relatively new concept like NbS is at the risk of being miscommunicated, misinterpreted and misused, if the policymakers, funders supporting NbS programmes, and development practitioners implementing NbS initiatives are not well-informed about the essential features, standards and boundaries of NbS.

Since all NbS efforts depend on ecosystems and natural processes, their effectiveness very much relies upon climatic and environmental factors. Changing social and economic conditions also influence the impacts of an NbS. Bangladesh's water-hyacinth-based floating farming is no different. While we are proud of our traditional floating agriculture and have been investing in its expansion as an adaptation option to climate change, it is crucial that we continuously measure its effectiveness under the changing climate and different social contexts. Otherwise, instead of being a solution, an NbS could become a burden.

Dr Haseeb Md. Irfanullah is an independent consultant working on environment, climate change, and research systems. His Twitter handle is @hmirfanullah