Grasslands in Hawaii

SUGAR, PINEAPPLES, AND GRASS

J. C. Ripperton

THE TERRITORY of Hawaii consists of seven inhabited islands, which are essentially volcanic domes. The maximum altitudes on the major islands are, roughly, Hawaii, 14,000 feet; Maui, 10,000; Kauai, 5,000; Molokai, 5,000; and Oahu, 4,000. The younger domes are relatively smooth and uneroded; the older ones have deeply desiccated slopes, great gulches, and steep ridges. The more arable lands are the coastal plains, the residual lands on volcanic slopes, and the plateaus on the islands that have two or more mountain domes.

The climate is consistently equable. At sea level the mean air temperature is 74 F. It fluctuates only 5 or 6 from season to season. The temperature decreases an average of 1 per 300 feet of altitude, so that at high elevations the mean temperature is that of the temperate zones. The relative humidity averages about 70 percent.

Hawaii lies in the belt of northeast trades, which prevail about three-fifths of the time during the winter and almost continuously during the summer. Rainfall increases on the windward slopes from about 20 inches to a maximum of 200 inches or more at the crest of the lower ranges. A corresponding decrease occurs downward on the lee slope to about 20 inches. On Maui and Hawaii the air tends to deflect around the higher mountains and there is less rainfall at higher levels.

The belt of maximum rainfall ranges on the different islands from 2,000 to 6,000 feet. Rainfall from the southwest (or "kona") winds falls principally in winter, and is an important part of the total precipitation in the leeward parts of the islands. The seasonal distribution of trade-wind rainfall is characteristically that of relatively dry summers and wet winters. It is subject to considerable fluctuation, however, in amount and distribution. Uncertainty of rainfall is a major obstacle in non-irrigated agriculture in Hawaii, even in areas with a relatively high average.

The soils are derived almost entirely from volcanic material. Differences in character result from the nature of such material, its age, depth of weathered material, and the rainfall and the temperature under which the soil-forming processes took place. Residual soils derived from lava vary from essentially undecomposed material to deeply weathered Lateritic clays. Soils derived from volcanic ash are common, particularly in the uplands. They range in depth from a shallow covering to deep layers. Such soils are usually friable and are productive when they have sufficient depth for any kind of use.

Erosion is a serious hazard on most lands used for cultivated annual crops. Rainfall is often torrential, and conservation measures are difficult to apply on steep and irregular slopes. Perennial crops like orchards, sugarcane, and soilage crops provide effective control of erosion. The relatively large areas devoted to forest reserve in the high-rainfall zones are necessary for water conservation and soil conservation. Pastures, however, are the best use for a large proportion of the total land of the Territory.

That such a use is possible in Hawaii arises from several economic factors. Hawaii, with a population of 520,000, is not overpopulated; the more intensive uses of all the land are thus not necessary. The sugar and pineapple industries provide employment at a relatively high economic level for a large part of the total population on only 6.6 percent of the total land area. These two export crops provide a favorable trade balance, which permits the purchase of needed articles of food and feed from other localities at lower cost than they can be produced locally. These industries set wage standards that must be met in general by producers of other crops. Of the major agricultural land uses, sugar uses 5.1 percent, pineapple 1.5 percent, diversified crops 0.35 percent, forest reserve 26.1 percent, and pastures 34.4 percent of the total land area of 4.1 million acres.

One looks almost in vain for fields of corn or cereal grains or legumes, for haystacks or silos, and for the diversified farm with its rotation of cultivated crops and temporary pastures. Corn, wheat, oats, soybeans, and other legumes are fairly well adapted, but their acreage is small. Production costs are high because of difficulties in mechanical operations in small fields and on sloping lands of irregular topography. Rainfall adds uncertainty in the drier zones; in the high-rainfall zones, the problems of disease, good pollination, and curing of the grain are serious.

Haymaking likewise is affected by climate as well as topography. The economy of the silo is an ever-present question where green forage is available throughout the year. All these factors are obstacles to attempts to make Hawaii more self-sufficient as to animal feed and stress the importance of grassland agriculture.

Total livestock products in 1946 were valued at 15.6 million dollars, 11.4 percent of the total agricultural income of the Territory. Of this amount, beef cattle sold for 4.5 millions, dairy cattle and milk for 5.1 millions, swine for 3.4 millions, and poultry and eggs for 2.6 millions of dollars. Beef cattle are grown and fattened almost entirely on pastures and dairy cattle are grazed or fed cut forage, but essentially all concentrates of grain or protein meals are imported. Swine and poultry are raised almost entirely on imported feeds or certain byproduct feeds.