Green gold — Turning the invasive water hyacinth into agricultural wealth

Kate Mannle
May 29, 2019 · 5 min read
Video courtesy of Deutsche Welle

Recently, German news channel Deutsche Welle’s EcoAfrica program aired the above story about a community in Benin turning invasive water hyacinths that plague fishers, into an organic compost to help farmers. The story centered on a Campaigning for Conservation training led by Rare’s Kate Mannle, and held in partnership with ACED, a local NGO.

Only five minutes into our journey on the So River, the problem reveals itself. We have to move slowly on the wooden pirogue, the motor puttering and the hot morning breeze in our faces, as green waxy leaves floating on the water’s surface begin to encroach from all sides. We move deeper into the wetlands, winding our way through a vast 60km² wetland network that makes up Lake Nokoué in southern Benin. The motor chops through a few strands, leaving a trail of bright green breadcrumbs in the boat’s wake. Water hyacinth, an aquatic plant native to South America, may seem harmless enough, and with its lush purple flowers, some might even call it pretty. But here in Benin, in West Africa, and on waterways across five continents, water hyacinth is a persistent invasive pest.

As we make a hard-right turn and the waterway narrows even further, my host, Donald Houessou, points out there’s hardly enough room for the boat to navigate. Donald is an agricultural economist and the Program Director for the Benin NGO, ACED (Actions pour l’Environnement et le Developpement Durable). When ACED was founded in 2009, Donald began searching for a solution to the many problems caused by the water hyacinth. In addition to hindering navigation on the lake, the thick mats of plants block sunlight and deplete oxygen for native plants and animals, often killing fish that people in the surrounding communities rely on for protein. The plant’s roots below the surface also slow water flow to a standstill providing an ideal habitat for another pernicious pest, malaria-transmitting mosquitoes.

Farmers harvesting water hyacinth (credit: Deutsche Welle)

Donald and his colleagues at ACED found a promising solution while working with the community of Sô-Ava. A commune of approximately 118,000, almost everyone in Sô-Ava farms AND fishes to provide for their basic needs and any additional income. Donald and the cooperative in So-ava he works with began harvesting the water hyacinth, drying it, and mixing it with ash and manure to create an ultra-rich compost. The solution not only clears the hyacinth from the waterways, improving water quality in the lake, but the compost provides much-needed nutrients to the degraded soils without the use of costly chemical fertilizers.

As we make our way to shore and wind through shoulder high marsh grass, the women of the Sô-Ava farming cooperative welcome us with a song, a dance, and warm smiles. There’s a lot to be happy about. By improving soil moisture and adding nutrients, the water hyacinth compost has helped the farmers produce better quality crops of tomatoes, amaranth, and peppers. Madame Angel Nowdehouenou, a co-operative leader, notes that once harvested the produce grown with the compost lasts longer — so even if doesn’t sell it at the market, she’s able to bring it back a second or third day without any reduction in quality. This has helped improve her income in addition to the money saved from not having to buy chemical fertilizers to amend the soil.

Compost from water hyacinth.

The process of water hyacinth composting is not without its challenges, of course. It’s a lot of physical work to harvest the tangled weeds, and it takes some time to learn how to make the compost properly. To make the change a little easier, ACED has provided the cooperatives with wooden pirogues, machetes, and gloves to help with the harvest in addition to running training on composting methods and good agro-ecological techniques.

ACED is also tapping into the power of emotions to create a new social norm around water hyacinth composting. In coordination with Rare and IFOAM, ACED invited its network of partners from around Benin to join a 12-day Campaigning for Conservation (C4C) and organic agriculture training. Learning from the Sô-Ava farmers’ experience during field visits like this one, the C4C training participants designed and tested a behavior change campaign to help support the adoption of the water hyacinth compost.

A participant in the Campaigning for Conservation (C4C) training interviews a farmer from Sô-Ava to help design the behavior change campaign.

During the training, the team produced a billboard, poster, song, discussion board, and community speech to spread the message to adult farmers as well as a puppet theater- complete with fish, farmer, and tomato puppets- to engage school children (and ultimately their parents) around the topic of wetland conservation. Sounding catchy in Fon, the local language, the campaign slogan roughly translates to “Water hyacinth compost, best of fertilizers” while the message, “water hyacinth becomes wealth” promotes the benefits to the farmers.

For the farmers of Sô-Ava, the campaign is helping to reinforce the water hyacinth composting method while Donald and his colleagues at ACED will use the materials as a template for scaling the solution to other communities around Lake Nokoué to encourage them to sign-up for training to learn how to compost. The challenge now will be to spread the positive campaign messages faster than the water hyacinth can grow.

Women of the Sô-Ava farming cooperative welcome the C4C training to their farm.

In Rare Form

Stories and insights from the frontlines of community-led conservation

Kate Mannle

Written by

Loves the wild things and wild places. Director of Campaigning for Conservation at

In Rare Form

Stories and insights from the frontlines of community-led conservation

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