Oil content in agarwood is the main determinant of resin quality, market value, and wood grading. Understanding the relationship between oil content and wood grade helps farmers assess harvest timing and optimize production.
1. What Is Oil Content?
- Definition: The proportion of essential oil and resin compounds (sesquiterpenes, chromones, and other volatiles) in the wood.
- Purpose:
- Determines resin grade (premium, medium, low)
- Guides harvest timing
- Supports market pricing and extraction planning
More oil = higher quality = darker, aromatic wood.
2. Wood Grade Categories
| Grade | Oil Content | Color / Resin Zone | Aroma | Farmer Observation |
|---|---|---|---|---|
| Premium (A/B grade) | ≥10% | Dark brown to black, thick streaks | Strong, complex, layered | Dense, aromatic, resin-rich core |
| Medium (C grade) | 5–10% | Medium brown, moderate streaks | Moderate aroma | Firm, less dark wood, resin scattered |
| Low (D/E grade) | <5% | Light yellow to pale brown | Faint aroma | Soft wood, thin or patchy resin zones |
3. Factors Affecting Oil Content & Wood Grade
| Factor | Effect |
|---|---|
| Tree age & diameter | Older, thicker trees → higher oil content, darker wood |
| Induction method | Microbial + chemical + mechanical → increases oil accumulation |
| Induction cycles | Secondary cycles → layered resin → richer aroma & oil |
| Stress intensity | Moderate stress → optimal oil; excessive stress → necrotic zones, reduced oil |
| Environmental conditions | Adequate water, sunlight, and nutrients → better oil deposition |
4. Farmer Tips
✔ Monitor resin color, smell, and density to estimate oil content
✔ Use core sampling or visual inspection to check streak thickness
✔ Avoid harvesting too early → oil content still low
✔ Plan secondary inductions to enhance oil accumulation and upgrade wood grade
✔ Record tree ID, induction method, and resulting oil content for future optimization
Farmer Key Message
“Dark, dense, aromatic resin = high oil = premium wood grade.
Light, soft, faintly scented resin = low oil = lower grade.
Observe color, smell, and wood density together to estimate quality before harvest.”