soil map units where La1 Lapaha soils is dominant
Soil properties
| Property | Value |
|---|---|
| Geographic distribution | Tongatapu |
| Landscape position | Uplifted and ash- mantled coral surface. |
| Soil parent material | - |
| Slope | Flat to gently undulating slopes (0-3°) |
| Surface outcrops | - |
| Brief soil profile description | 0-30 cm Dark brown friable clay; 30-76 cm Brown firm, heavy clay; 76-99 cm Brown firm, heavy clay;on Coral limestone. |
| Soil profile texture | - |
| Minimum effective rooting depth | 100 cm |
| Soil pH (acidity) | Moderately alkaline to near neutral |
| Salinity | - |
| Soil fertility under natural conditions | High to very high Base saturation (%) and exchangeable calcium (Ca) and magnesium (Mg); phosphorus (P) very high becoming low with depth; sulphur (S) low in A horizons increasing to high with depth. |
| Soil moisture regime | - |
| Susceptibility to drought | - |
| Soil drainage | Well drained |
| Susceptibility to waterlogging | Slight limitations of slow subsoil permeability leading to poor aeration after heavy rain. |
| Susceptibility to flooding | - |
