A coir geotextile, sometimes called a coconut geotextile or, in India, coir bhoovastra, is a biodegradable fabric made from coir, the fibre found between the hard shell and the outer skin of a coconut. Laid on or in the ground, it holds soil in place, separates layers or lets water through while keeping soil back, and then slowly returns to the earth.
Why coir?
Most plant fibres rot quickly in wet soil. Coir does not. According to the UN Food and Agriculture Organization, brown coir is about one-third lignin, the tough, woody substance that microbes find hard to digest, and the FAO describes coir’s resistance to microbial degradation and salt water as unique. That is what lets a natural product protect soil for several seasons.
The main forms
- Woven mesh (netting). Coir yarn woven into an open grid, commonly 400, 700 or 900 grams per square metre. Heavier grades have a tighter weave and more strength.
- Blankets. Loose coir fibre held between light netting and stitched together, giving full ground cover rather than an open grid.
- Logs and rolls. Dense cylinders of coir fibre in a net tube, staked along the foot of banks and shorelines.
- Wattles. Lighter rolls laid across slopes to slow run-off and catch silt.
What it does on site
Erosion control
The best-known use is soil erosion control. Coir netting or coir erosion control blankets laid over bare slopes stop raindrops dislodging soil, slow surface run-off and keep seed in place until vegetation can hold the ground on its own.
Separation and reinforcement
In road building, woven coir laid over soft soil keeps the base material from mixing with the subgrade and adds strength while the ground consolidates. Indian field work has found coir staying intact for five to ten years when buried under fill.
Filtration
In drains and behind walls, coir lets water pass while holding soil particles back, until a natural soil filter forms behind it.
How long does it last?
It depends on the job and the climate. California’s transport department rates coir netting at about three years of functional life on the surface. A Tamil Nadu Agricultural University handbook reports coir lasting four to six years within the soil. Either way, the aim is the same: protect the ground until plants or the soil itself can take over.
Standards
India, the world’s main producer, has Bureau of Indian Standards specifications covering coir geotextiles, including IS 15868 for test methods such as mass and opening size, and IS 15872 for coir geotextiles used against rainwater erosion on roads, railway embankments and hill slopes.
New to coir? Our grade guide explains how to pick the right weight for your site.