Mekong garden goes with the flow

What's good for the farm is good for the agricultural research centre. So believes Dr Duong Van Ni, who aims to scale up a simple water-purification technique he helped develop for small rice farms to treat sewage generated by a modern multidisciplinary research facility.

Ni is a project manager in the Mekong Delta Farming Systems R&D Institute of Cantho University and the director of its 116-hectare Hoa An Biodiversity Application Research Centre, which the university founded in 1993. Ni has studied, among other things, how channelling water through groves of melaleuca trees cleanses it of acidity and pollutants.

Acid soils

Melaleuca originates in Australia but has been in Vietnam for at least 4,000 years. Much of the Mekong Delta was melaleuca marshlands until French colonial engineers began dredging canals to drain them. Pioneering rice farmers settled the newly opened land but struggled with soils that became acidic when seasonally exposed to air. Hoa An, most of which lies under nearly a metre of standing water from September to November, once had very acidic soils. "When I came here, the rice was so bad we fed it to pigs," Ni recalls. "Now we have a surplus of good rice to sell."

Since 1995, the centre has contracted half a dozen landless farm families to manage long, narrow, single-hectare demonstration farms ranked along a canal. Behind the farmhouse is the kitchen garden, where household wastewater flows around raised vegetable beds before entering half an hectare of rice. Beyond the paddies, each farm has 2,000 square metres of water-purifying melaleuca grove. Or each had a grove until it was lopped off by a new road, which foreshadows the farms' integration into a larger scheme.

"Melaleuca roots release organic acids that bind with acidic ions of iron and aluminium, turning them into safe organic compounds," Ni explains. He adds that, as the water wends through the grove, other pollutants are converted into less harmful forms or captured by the soil. "We recycle the water back to the rice, making it a closed system."

Integrated benefits

"Farmers that integrate melaleuca improve their water and gain cash-generating options to add to rice," he adds. "They can raise ducks and fish in the canals. Bee keeping is especially good with melaleuca because its flowers are the source of a highly valued honey. Farmers can also keep livestock in the shade of the melaleuca grove." The trees provide firewood and, when mature after 7-8 years, building materials. Regrowth from stumps matures in only 5 years.

Today, many of Hoa An's trees are being harvested for the centre's ambitious building programme. Near the entrance of the compound rises a 200-bed dormitory set for completion by the end of 2005. A 20-room guesthouse should be ready six months later. Under construction at the far end of the new road are laboratories and other facilities for researching and teaching animal husbandry, aquaculture and environmental engineering. These are scheduled to open along with the dormitory.

The melaleuca forest at the core of the facility is being embanked on all sides by raised roadbeds. The centre will maintain the forest year-round as a wetland for the final purification of wastewater before its release into the marshy wildlife reserve that buffers the compound's long northern border.

"It's an integrated system to maintain environmental quality," Ni explains. "We'll convert liquid waste from the dormitory and guesthouse into ammonium sulphate crystals to use as fertiliser. Toilet solids will be oxidised, then laid down in the melaleuca wetland. Wastewater from animal husbandry will also be oxidised before going to the environmental unit for chemical treatment. Depending on its quality, we'll use it for aquaculture or agriculture. Then it too will flow through the melaleuca wetland."

Model for development

The centre's established biodiversity reserve propagates 2,500 native rice species drawn from Cantho University's genebank. Agroforestry and native grasses occupy two other blocks. The completed centre will include facilities for breeding and field testing improved rice varieties, an area for agricultural machinery training, a biotechnology section, and staff housing. A shuttle bus now makes the 40-kilometre run between once-isolated Hoa An and the university campus in Cantho, the delta's largest city, four times daily.

Past visitors who may lament the eclipse of bucolic Hoa An should realise that development was coming one way or another. A new provincial capital to replace Cantho is under construction 14 kilometres beyond Hoa An at Vi Thanh. The road linking the old and new capitals, which runs past the centre's entrance, is being widened. In the 18 months following approval of the move, land around Hoa An became ten times more expensive. Perhaps the Hoa An Biodiversity Application Research Centre will provide, not only appropriate technologies for farmers in the Mekong Delta, but also a local model for sustainable development.