soil map units where To Bonriki series (variant) is dominant
Soil properties
| Property | Value |
|---|---|
| Geographic distribution | Tarawa, Abatao |
| Landscape position | Immediately behind the coastal rampart in slight depressions but generally flat areas with microtopography due to the presence of coral boulders |
| Soil parent material | Coralline rubble |
| Slope | Flat (0 - 3°) |
| Surface outcrops | Surface covered with variable-sized coral rubble from rocks and boulders to fine grits. |
| Brief soil profile description | There is considerable variation in topsoil texture, depth and development. In some areas patches of unaltered sand are found on the surface and in other areas there is a dominance of coarse frgaments throughout the profile with sand in the intersticies. Due to the rugged nature of the surface of the underlying rock there is an intimate association of soils having the lithic contact above and below a depth of 50 cm. Where lithic contact is > 50cm soils are considered to be the variant Bonriki. |
| Soil profile texture | Typically shows a shallow dark brown stony structureless sand overlying a mixture of coralline sand and coarse fragments with the coarse fragments dominant below about 20 cm; a shallow lithic contact is frequently encountered. |
| Minimum effective rooting depth | > 50 cm |
| Soil pH (acidity) | Highly calcareous, having high pH and free lime throughout the profile |
| Salinity | - |
| Soil fertility under natural conditions | Organic carbon and nitrogen levels are high in the most developed A horizons but very low in the less developed epipedons and subsoils; phosphorus and potassium levels are low while exchangeable magnesium content is moderate as in the phosphate extractable sulphate sulphur in the topsoil. |
| Soil moisture regime | Ustic |
| Susceptibility to drought | Dries out in dry periods. |
| Soil drainage | Well drained |
| Susceptibility to waterlogging | Not susceptible to waterlogging |
| Susceptibility to flooding | Never floods |
