Cocoa goes au naturel

Organic farming techniques are giving farmers on the Indonesian island of Sulawesi new hope for a long-term future. Elizabeth Finkel reports.

La Trobe University plant pathologist Phil Keane with Indonesian colleagues Ir Nur Lailla (left) and Dr Ayu Parawansa. – La Trobe

Since the 1980s the Indonesian island of Sulawesi has become the world’s third-largest producer of cocoa. But in the past few years, declining soil fertility, pests and diseases have ravaged yields. The solution may well be organic farming, believes La Trobe University plant pathologist Phil Keane.

Cocoa farming in South Sulawesi is a remarkable story of subsistence farmers making good. Back in the 1980s, you’d have been hard-pressed to find a single cocoa farm. Many islanders found employment on large corporate cocoa plantations in Malaysia. But, with international cocoa prices rising, many returned home to try their hand at farming cocoa on two- to five-hectare rainforest plots. The Indonesian government provided free seed; the decaying rainforest litter provided free nutrients. It was a stunning success.

Then, in the early 2000s, yields plummeted sometimes to a third of what they’d been. One reason: the rainforest’s fertile soil ran out. The other problem, perhaps linked, was that pests and diseases took hold. The cocoa pod borer can reduce yields by 40%. The fungus-like Phytophthora palmivora can take 30% and another fungus causes “vascular streak dieback” that can kill susceptible cocoa trees. Keane first identified it ravaging cocoa farms in New Guinea in the late 1960s. Thanks to the selection of naturally resistant varieties, the damage was reduced but now it seems to be back on the rise.

Coco beans inside a cacao pod. – iStock

Since 2000, the Australian Centre for International Agricultural Research (ACIAR) has helped find solutions by bringing together an expert consortium. It includes the Australian universities, La Trobe and the University of Sydney; Indonesian universities, the University of Papua and Hasannudin University; Indonesian agricultural institutes; and the chocolate company, Mars. Keane has been the project leader since 2001. The current A$2 million ACIAR grant aims to test sustainable soil and pest management techniques to manage the declining yields – in other words, organic methods. Sulawesi may be the world’s third-largest cocoa producer, but the farmers are mainly smallholders and cannot afford to manage their problems using chemicals.

Remarkably the ACIAR team has found that composting may solve both the soil and pest problems. Most of the farming families keep chickens and goats, which supply manure, and the cocoa tree itself provides a lot of rich compostable materials, especially infested pods that should be removed from the trees frequently to break the pest and disease cycles. Indonesian scientists have developed a method of composting these wastes directly in shallow trenches between the tree rows. The composting process raises the temperature high enough to kill the pod borer’s larvae and the pathogen’s spores. Trials show yields are as high or higher than with commercial fertiliser. These methods should keep the Sulawesi farmers in business for the long-term, says Keane. “Those who want to be professional farmers and apply these simple methods will survive.”

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