GT-0421 · Ultisol
Boca Costa Ultisol
Deep red, washed by centuries of rain.
Soil profile
Tap a horizon to see its details.
A0–15 cm
A thin layer that depends on leaf litter to stay fertile.
- Munsell colour
- 5YR 3/3
- Texture
- Clay loam
Bt115–55 cm
Clay washed down from above accumulates here and coats the aggregates.
- Munsell colour
- 2.5YR 4/6
- Texture
- Clay
Bt255–105 cm
Bright red from iron oxides, like rusted metal.
- Munsell colour
- 10R 4/8
- Texture
- Clay
BC105–135 cm
Less clay and yellowish mottles.
- Munsell colour
- 2.5YR 5/6
- Texture
- Clay loam
C135–160 cm
Fully decomposed rock that keeps its original shape.
- Munsell colour
- 5YR 6/6
- Texture
- Loam
This soil is red because it has iron, just like a rusty nail. So much rain has fallen on it that the rain carried away many of its nutrients. Trees look after it with their leaves.
Ultisols are old soils of very rainy areas. Water has leached the nutrients and moved clay downward, forming a Bt horizon. They are acidic and low in fertility, so they work best with perennial crops, shade and added organic matter.
Core idea: climate and time can impoverish a soil. Activity: measure pH with a homemade red-cabbage indicator and compare it with another soil. Links to acids and bases, and to agroforestry systems.
Typic Hapludult with a 90 cm argillic horizon, base saturation below 35% and very strongly acid reaction. Low effective CEC and likely exchangeable aluminium toxicity below 15 cm. Requires liming and cover management.
- USDA Soil Taxonomy
- Typic Hapludult
- WRB 2022
- Haplic Acrisol (Clayic)
See the scientific data
Analytical data by horizon
| Horizon | Depth (cm) | Munsell colour | Texture | pH (H₂O) | O.M. % | CEC |
|---|---|---|---|---|---|---|
| A | 0–15 | 5YR 3/3 | Clay loam | 4.9 | 3.6 | 14 |
| Bt1 | 15–55 | 2.5YR 4/6 | Clay | 4.7 | 1.4 | 11 |
| Bt2 | 55–105 | 10R 4/8 | Clay | 4.6 | 0.7 | 9 |
| BC | 105–135 | 2.5YR 5/6 | Clay loam | 4.8 | 0.3 | 8 |
| C | 135–160 | 5YR 6/6 | Loam | 5 | 0.2 | 6 |
CEC: cmol(+)/kg
- 4.9A
- 4.7Bt1
- 4.6Bt2
- 4.8BC
- 5C
- 3.6A
- 1.4Bt1
- 0.7Bt2
- 0.3BC
- 0.2C
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