Suitability Rating for Coffee Production
In Opeula Area, Oahu, Hawaii

H. Ikawa

Emeritus Soil Scientist, Dept. of Tropical Plant and Soil Sciences, CTAHR,
University of Hawaii at Manoa, Honolulu, HI 96822.

November 2009

Introduction

Coffee Plant

The purpose of this web page is to show how soil suitability ratings can be used in land evaluation. Rating of soil map units in the Opaeula area of Oahu for coffee production is used as an example.

The basic principle of land evaluation is to match the characteristics of the soil or land, including the environmental factors, with the specified land use requirements (FAO, 1976; Dent and Young, 1981; USDA, SCS, 1983). Land evaluation should also include socio-economic factors. This presentation, however, is limited to physical land evaluation as influenced by the soil or land characteristics and rainfall and temperature.

Figure 1 is a soil order map, previously described in the soil classification web page (Ikawa et al., 2009a), and shows the general location of the Opaeula area. It is located approximately 10 miles north of Kunia and ESE of Waialua Bay. The Kunia and Honouliuli areas were also described previously in the soil interpretation web page, based on the taxonomic classification of the soil map units (Ikawa et al., 2009b).

Figure 1. Soil order map of Oahu, showing Opaeula area.

Figure 2 is a larger scale map of the Opaeula area, and the area enclosed in the rectangle contains 21 soil map units. Soil map units were defined in the web page on the Classification of the Soils of Hawaii (Ikawa et al., 2009a).

The median rainfall increases from 40 inches in the west to 60 inches in the east. The elevation of the interfluves also ranges from about 400 to 700 feet in the west and from about 1,000 to 1,200 feet in the east.

Figure 2. Detailed soil map of Opaeula area, including the rainfall isohyet.

Figure 3 is a photograph of an interfluve, which is the nearly level to moderately sloping elevated landforms, separated from similar landforms, for example, by gulches, revines, or rivers. This interfluve was once in pineapple production. The background is the northern part of Waianae Range associated with Waialua Bay.

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