1. Soil pH
- Optimal Range: 5.5 – 6.5 (slightly acidic)
- Tolerance: 5.0 – 7.0, but extremes reduce nutrient uptake
- Management:
- Acidic soils (<5.5): Apply lime (CaCO₃) to raise pH gradually
- Alkaline soils (>7.0): Incorporate organic matter or sulfur to lower pH
2. Soil Texture
- Preferred Texture: Sandy-loam to clay-loam
- Importance:
- Sandy-loam: Good drainage and root penetration
- Clay-loam: Retains moisture and nutrients but may require drainage management
- Avoid: Heavy clay with poor drainage or loose sand with low water/nutrient retention
3. Drainage
- Requirement: Well-drained soils; waterlogging is detrimental
- Indicators:
- Standing water after heavy rain signals poor drainage
- Root rot or slow growth often linked to drainage issues
- Amendments / Management:
- Raised beds or mounds for poorly drained areas
- Incorporate sand, gravel, or organic matter to improve structure
4. Organic Matter
- Optimal Content: 3–6% for healthy growth
- Sources:
- Compost (farm or plant-based)
- Leaf litter or forest mulch
- Well-rotted manure (cow, chicken, or goat)
- Benefits:
- Improves nutrient retention and cation exchange capacity
- Enhances microbial activity, which supports resin-producing fungi
- Increases water-holding capacity
5. Nutrient Amendments
- Macro-nutrients: N, P, K
- N: Promotes vegetative growth
- P: Root development, flowering, and resin support
- K: Disease resistance and stress tolerance
- Micro-nutrients: Mg, Mn, Fe, Zn
- Critical for enzymatic activity and photosynthesis
- Amendment Strategies:
- Basal application of organic fertilizers during planting
- Periodic foliar feeding for micronutrients
- Soil testing every 2–3 years to adjust amendments
6. Soil Testing Protocol
- Sample Collection:
- Collect soil 15–20 cm deep from multiple locations
- Mix samples to create a composite sample
- Analysis Parameters:
- pH, texture, organic matter, nutrient levels (N, P, K, Mg, Mn, Zn)
- Drainage observation (percolation test or infiltration rate)
- Interpretation & Amendment:
- Adjust pH, improve structure, and supplement nutrients as needed
7. Key Takeaways
- Ideal agarwood soils: Well-drained, slightly acidic, sandy-loam to clay-loam, with good organic matter.
- Waterlogging is the biggest threat, followed by nutrient-poor, degraded soils.
- Regular soil testing and amendments ensure optimal growth, tree health, and resin production.
- Incorporating organic matter and minor nutrients also supports beneficial fungi for resin induction.
