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Soils
The soils of Zamboanga del Sur are largely clay
because of the extent of fine-grained volcanic rocks, various sedimentary
derivatives and pyroclastics,. However, on slopes over 20 percent,
stone content is often high. The upland soils are low in fertility
due to the high rates of leaching and these have generally low organic
matter content. (Table 2-6)
| Table 2-6 Major Soil and Infiltration Rates |
| Soil Group |
Infiltration Rate (Cu./Hr.) |
| Brown and reddish clays |
Yellowish Clay |
Deep Yellow Clays |
Dark Clays |
Shallow Clays |
Shallow Stony Clays |
| 1. Alluvial Soils |
2.9 |
6.0 |
- |
- |
- |
- |
| 2. Limestone |
- |
- |
- |
5.3-6.4 |
8.0 |
- |
| 3. Pyroclastics |
3.0-13.5 |
- |
5.7 |
- |
- |
- |
| 4. Basalts |
6.7 |
6.6 |
- |
- |
- |
- |
| 5. Sedimentary Rocks |
- |
- |
1.0-12.3 |
- |
- |
- |
| 6. Andesite |
- |
- |
- |
- |
- |
0.8-11.5 |
| 7. Ultrabasics |
- |
- |
- |
- |
- |
5.0 |
| 8. Volcanic Agglomerate |
- |
6.4 |
- |
- |
- |
- |
| 9. Basement Complex |
2.7 |
- |
- |
- |
- |
- |
| Source: LRES, An Evaluation of Land Resources
of Zamboanga del Sur |
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