Carla Wegscheidl, from the Queensland Wetlands Program recently hosted Terrain and local council staff on a visit to see a constructed wetland on the Gaia family banana farm near South Johnstone. Gaia Farm, operated by Mike, Rene and Brett Gaia is bordered by Cowley and Liverpool Creeks. Last year Reef Rescue helped to fund the construction of a wetland on 2.5 ha of the property to treat runoff from the farm and packing sheds.

Cavendish bananas are grown on 60 hectares of the 95 ha farm and the Gaia's pride themselves on producing an environmentally sustainable crop. Being located only 10 km from the Great Barrier Reef World Heritage Area has been a driving factor for the Gaia's to change their farming practices. Mike said, "Although we are not certified organic producers, our high farming practice standards make us close to being so."

Growcom extension officer George Russell says, "The family have done most of the improved practices at their own cost, and there is little financial gain in the short term. Best practices include grassed inter-rows, the use of compost to increase organic matter in the soil, application of nutrients through fertigation, minimising soil compaction and monitoring soil moisture and plant nutrition. "I don't think the farm would have got Reef Rescue funding if they were not already doing best practice," explains George, "whilst a wetland is good, unless you are doing everything else on the farm to reduce water quality impacts it won't be effective."

The best management practices reduce the risk of excess nutrient, sediment and chemicals leaving the banana production area, thereby reducing runoff to the adjacent creeks. 

The Gaia’s have seen improved plant health, a reduction in pests and disease and have reduced the application of granular fertilisers by a third. “We have cut the use of fungicides to around one third of the industry standard and haven’t used nematicides for years” said Mike.  An economic analysis undertaken of the farming practices indicates cost savings of up to $80,000/year from the reduced use of these chemicals..

The wetland was set up as a case study in partnership with the Gaia family, Terrain NRM, Growcom, the Queensland Wetlands Program and DEEDI. A consultant was employed to design the wetland based on urban stormwater modelling. The Gaia's received $40,000 in Reef Rescue funding from Terrain NRM for construction and $5,500 from the Queensland Wetlands Program for wetland plants. The Gaia's contributed an additional $50,000 in-kind to the project and planted about10,000 trees and shrubs.

The previously unproductive, flood prone land now forms two ponds (350 x 70m) that treat runoff from the banana production area, waste water from the banana packing shed and adjacent aquaculture farm. The constructed wetland was designed to replicate natural wetland filtering, by slowing water flow to capture sediment and remove nutrients through the use of dense wetland vegetation. Modelling showed that the wetland could reduce the phosphorous and sediment by nearly half and remove a third of the nitrogen for a 26 ha catchment. "It's working well now, explains Mike, "and the advice we got was most beneficial. We've never done this before and we've learnt a lot, there's more to it than planting trees. We expect it will take about 5 years to be established."

The wetland was designed to capture the first flush. Soils and water tolerant plants remove nutrients and sediments from the water as it passes through the wetland. The water takes a couple of days to pass through the wetland, maximising the amount of time pollutants are treated. The cleansed water then flows back into Liverpool Creek. "Seeing Burdekin ducks here was my greatest satisfaction, said Mike. "Once it's established I suspect birds from nearby aquaculture farm will move here because of the vegetation."

Since the field visit cyclone Yasi has caused widespread damage to the banana industry in North Queensland, including Gaia Farms.

Brett Gaia undertaking surveying of the wetland.  Photo Courtesy of DEEDI.

Attendees at the Gaia farm field visit.  Photo Courtesy of DEEDI.