between wide extremes; in some localities semiarid or even arid 
conditions prevail, but over a large part of the uplands the rainfall 
is sufficient for a great variety of crops. In portions of the windward 
side of Maui and Hawaii, i. e., the side first reached by the northeast 
trade winds, the rainfall is very heavy. Until recently the main 
portion of the upland on account of its inadaptability to sugar was 
thought to be unsuited to cultivated crops. Slowly, however, it is 
being brought under cultivation and with the advent of a more 
numerous small farming class it is likely that practically all of the 
tillable lands of the islands will be utilized for cultivated crops. 
There are no valid reasons why general farming could not be prac- 
ticed on these lands. The soils are rich and adapted to a wide 
range of crops. In the more arid sections the application of the 
principles of dry-land farming will doubtless insure the success of 
many crops. The increasing demands for land for cultivation in 
recent years have brought to the station many requests for infor- 
mation regarding the soils. A part of this information it is hoped 
will be supplied by this bulletin. 
It should be understood from the outset that the methods of 
classification and mapping usually employed in soil surveys are 
not adapted to Hawaiian conditions and that nothing less than a 
systematic sampling of almost every acre will suffice to give an 
accurate idea of the location of all soil types. This is especially true 
of Oahu, where both the chemical and physical composition vary 
greatly in passing over short distances. For this reason no attempt 
to map the soil areas will be made. Furthermore, the peculiar prop- 
erties of Hawaiian soils are such as to render the use of terms em- 
ployed in the description of soil types elsewhere of doubtful applica- 
tion. In some instances the common systems of classification have 
been used, however, but the reader is cautioned against too strict 
interpretation of these terms. 
The term "clay" especially requires definition. In the Tropics, 
where the soils have been formed from the disintegration of basaltic 
lava, the so-called clay is usually not composed of aluminum silicate, 
and its properties sometimes differ greatly from true clay. The soils 
of Hawaii, although usually very heavy in character and frequently 
containing as much as 50 per cent by weight of particles as fine as 
clay, are not clay soils in the true sense. They are characterized by 
a high content of iron and aluminum hydrates and low silica content. 
Such soils are designated as laterites, and recently the process leading 
to their formation has been designated as lateritization, in contradis- 
tinction to the term "kaolinization," used in reference to clay forma- 
tion. The clay seems to be composed mainly of iron and aluminum 
hydrates and a double silicate of iron and alumina. 
