Interpretation of the Soils of Hawaii
H. Ikawa, Gordon Y. Tsuji, and Raymond S. Uchida
The purpose of this web page is to show how the taxonomic names of soils can be used to make interpretation for soil management, land use planning, or land evaluation. Figure 1 shows the soil order map of Oahu, Hawaii. As mentioned by Ikawa et al. (2009a), there are eight soil orders of Soil Taxonomy on Oahu, including associated areas, such as rocky, rough, stony and complex lands.
Soil order maps can be used to describe or differentiate a soil in a general way. Oxisols for example, make up most of the level and nearly level areas of Oahu. In the past, they were devoted to sugarcane and pineapple production, but today, these areas have gone into diversified agriculture and urbanization. These Oxisols are moderately to highly weathered, reddish soils, low in cation exchange capacity or nutrient-holding capacity. They, however, possess excellent physical properties, well-suited for crop production with fertilizer input. They are also highly suited for urbanization. Figure 1 shows the pink areas of Oxisols occurring along Northern Oahu and along the numerous dissected landforms of Central Oahu.
Ultisols occur mostly on sloping lands or adjacent to the rocky, rough, stony lands, They were also used for agriculture, usually for pineapple production. These infertile soils, however, require much input, such as lime and judicious amounts of phousphorus fertilizer for crop production. Figure 1 shows the light orange areas of sloping landscape along Windward Oahu and along the sloping landscape of Central Oahu.
Larger areas of rocky/rough/stony lands, shown in brown, represent the Koolau and Waianae Ranges on East and West Oahu, respectively.
The examples with Oxisols and Ultisols showed how the soil order could be used for interpretation. The choice of the category, however, will depend on the purpose of the interpretation. Each category provides information, with increasing amount and detailed information from the soil order to soil series.