PM2.5 in Southern Thailand and the burning nobody talks about

PM2.5 in Thailand is usually associated with the North and crop burning. The South has its own source, and part of it comes from burning almost nobody discusses.

Photo: Nick van den Berg on Unsplash

The fire that happens every year in rubber plantations

A rubber tree yields economically for roughly 20–25 years. At the end of that cycle the plantation is felled and replanted. What remains in the field is not only logs but stumps, roots, branches and leaves.

The easiest and cheapest way to deal with it is to pile it and light it.

That burning has no air control, combusts incompletely, and releases considerably more fine particulate than the same wood burned in a purpose-built furnace.

With 13.6 million rai of rubber planted in the South and replanting running continuously, the aggregate is not small.

Why growers burn

Not because they do not know. Because it is the option available.

The stumps have to go regardless. A stump left in the ground harbours white root disease, which spreads to newly planted trees. Leaving it is not an option.

Hauling it out costs money. With no buyer, or with volumes too small to justify a truck, burning is what remains.

Time presses. The field has to be cleared for the replanting window.

Telling people to stop burning without offering an alternative does not work. There has to be a buyer and a haulage route that pays.

The alternative that exists

Stumps and roots that must be dug out anyway can be sold as biomass feedstock. The wood there is dense and burns well.

In an industrial furnace with combustion control and dust collection, particulate released per unit of wood burned is far lower than open burning.

And you get something back. A field fire produces smoke. A furnace produces steam or electricity displacing coal.

Limits worth stating plainly

Not every plantation is worth hauling from. If it is far from a plant, or the volume too small for a full load, freight consumes whatever the material is worth.

Grouping with neighbouring blocks felled at the same time helps, because it brings volume up to where a truck makes sense.

And a furnace still emits particulate and NOx. Not zero — but substantially below open burning.

What each party can do

Growers: ask about buyers in the area before deciding to burn.

Plants using this feedstock are pulling material off the fire while displacing fossil fuel.

Everyone else: the problem is not solved by prohibition. It is solved by making material that must be removed worth something.

Our plant is in Trang and takes rubberwood from local plantations. If you are planning a felling and want to know whether it is worth it, call and ask. +66 92 392 2292.