Date released
14 December 2023

Charcoal has been an essential tool for millennia. Made from plant waste that is burned under low oxygen conditions, we cook and heat with it, use it in cosmetics, in medicine and metallurgy, and in horticulture, where it is known as ‘biochar’.

Made mostly of carbon, biochar also contains valuable traces of nitrogen, potassium, zinc and phosphorous, all of which help to improve the physical, chemical and biological characteristics of soils.

During the charring process, called ‘pyrolysis’, pores develop and these provide habitats for important soil microbes and fungi and increase the soil’s water-holding capacity.

As a country with inherently poor soils, Timor-Leste is in urgent need of all the benefits that biochar offers, as it transitions from ‘slash-and-burn’ agriculture to permanent farm production.

Slash-and-burn clearing of rainforest to grow crops for 2 to 4 years before moving on essentially mines the soil of nutrients and results in low crop yields.

ACIAR Timor-Leste Country Manager, Mr Luis Almeida said the combination of low production with a rapidly growing population has led Timor-Leste to import 60–80% of its food.

‘As a result, increasing on-farm production and on-farm income have become key national policies for the Timor-Leste Government,’ said Mr Almeida.

And biochar has the potential to do both, exemplifying the circular economy by creating new value and enhanced productivity from waste streams.

In a previous role, Mr Almeida was part of the ACIAR-supported project investigating agricultural innovations for small farms, including biochar’s effect on soil productivity, on a wide range of crops and soils.

He said the success of the original research led to a follow-on project now underway. This has been designed to better understand the country’s soils, to identify the extent of potential for biochar production and to share the learnings of the initial project.

The amount of biomass available for conversion to biochar – in a sustainable manner – will provide a natural limit on the area that can be improved by biochar, with future use expected to focus on high-value and high-nutrition crops such as vegetables, fruits and pulses.

Low-tech innovation to improve soils

The original project ran from 2017 to 2022, as a collaboration with the National University of Timor Larosa’e (UNTL), the Timor-Leste Ministry of Agriculture and Fisheries, University of Western Australia (UWA), University of the Sunshine Coast and World Vision.

The project pioneered a simple, effective, chimney-based pyrolysis method that smallholders could easily replicate, using rice or coffee hulls, or sawdust, as biochar feedstock, thanks to UNTL lecturer Dr Antonio da Costa.

The burning process ran at a relatively cool 350oC, to preserve nutrient content, and the chimney system was easy to construct. The resulting biochar increased yields in 95% of soils tested, with production increasing up to 230% on some acidic soils.

Also working in Timor-Leste on this project was Mr Rob Williams, an adjunct senior research fellow at UWA, who said the trials succeeded because the country’s soils are so inherently poor.

‘Communities are now asking: “What can we turn into charcoal and use in our fields?”,’ said Mr Williams. He noted one community that, on hearing about the trials, converted an invasive weed to biochar for their vegetable gardens.

Mr Williams said several rice millers have also scaled up production, making and selling both rice husk biochar and a version fortified with phosphorous and nitrogen (Biochar Plus) to expanding local markets to improve horticultural productivity.

However, there is still a long way to go before biochar use is widely adopted throughout Timor-Leste.

This is a goal that is supported by the follow-on project that started in 2022 and which Mr Williams is also working on.

This more recent 5-year project is being led by his UWA colleague Dr Louise Barton.

The creation of a Timor-Leste Biochar Collective is a central component of the new project, bringing together NGOs, government, rice millers and biochar makers and users to share ideas over the project’s lifetime.

Women farmers watching a man give a presentation.
Women farmers in Papua New Guinea learn about using biochar for coconut disease management. Photo: University of Queensland

Disease control in Papua New Guinea

New research in Papua New Guinea examined biochar’s potential for controlling the spread of basal stem rot, a fungal disease threatening smallholder and commercial oil palm plantations.

The Papua New Guinea Oil Palm Research Association (PNG-OPRA) and University of Queensland (UQ) recently completed a 2-year ACIAR-supported pilot project, turning infected, dead oil palms into biochar.

UQ project leader Dr Agnieszka Mudge said the biochar process reduced fungal infection, thus reducing risk of disease spread.

It also created a new product that could generate additional income streams for oil palm farmers.

‘The biochar supported capsicums and cos lettuce growth during trials and there is also potential to use the oil palm biochar combined with compost to raise new oil palm seedlings,’ said Dr Mudge.

‘The project made and used a relatively low-cost, mobile pyrolysis unit, possibly the first of many such units to combat the disease in PNG.’

The key will be sharing the trial results and opportunities with PNG farmers. ‘Our partners at OPRA are well-placed to disseminate this information at all levels,’ noted Dr Mudge.

Men burning a large pile of rice hulls
A simple chimney-based system has been developed to help smallholders turn rice hulls into biochar in Timor-Leste. Photo: University of Western Australia

ACIAR PROJECTS: ‘Agricultural innovations for communities for intensified and sustainable farming systems in Timor-Leste (AI-Com)’ (CIM/2014/082); ‘Agricultural innovations for communities – Intensified and diverse farming systems for Timor-Leste (AI-Com 2)’ (CROP/2021/131); ‘Managing basal stem rot in oil palm by converting infected logs to biochar’ (CROP/2019/147)