Waikapu Series
This series consists of well-drained soils on uplands on the islands of Lanai and Molokai. These soils formed in fine-textured old alluvium. They are nearly level to moderately sloping. Elevations range from 100 to 1,250 feet. The annual rainfall amounts to 15 to 25 inches, most of which occurs from November to April. The mean annual soil temperature is 73° F. Waikapu soils are geographically associated with Holomua, Molokai, and Uwala soils.
These soils are used for pineapple, pasture, and wildlife habitat. The natural vegetation consists of lantana, bermudagrass, ilima, and feather fingergrass.
Waikapu silty clay loam, 0 to 3 percent slopes (WrA).
This soil is on uplands in depressions on old alluvial fans. Included in mapping was an area, about 1,50 acres in size that is severely eroded. This area is 1 1/2 miles southwest, of Molokai Airport. There are a few stones on the surface and a few shallow gullies.
In a representative profile the surface layer and the subsoil are dark reddish-brown, friable silty clay loam. The surface layer is about 12 inches thick. The subsoil, about 48 inches thick, has subangular and angular blocky structure. The soil is typically slightly acid to neutral but is strongly acid to very strongly acid in the surface layer in areas where pineapple is grown.
Permeability is moderate. Runoff is slow, and the erosion hazard is slight. The available water capacity is about 1.4 inches per foot of soil. In places roots penetrate to a depth of 5 feet or more.
Representative profile: Island of Lanai, lat. 20°47'13" N. and long. 156°56'12" W.
Ap1-0 to 4 inches, dark reddish-brown (5YR 2/3 moist, 3/3 dry) silty clay loam; weak very fine, granular structure; soft, very friable, sticky and plastic; few roots; many interstitial pores and common, very fine, vertical, tubular pores; many, fine, black concretions; violent effervescence with hydrogen peroxide; strongly acid; clear, wavy boundary. 3 to 5 inches thick.
Ap2-4 to 12 inches, dark reddish-brown (5YR 2/3) heavy silt loam or light silty clay loam, reddish brown (5YR 4/4) when dry; weak, medium and fine, sub angular blocky structure and some pockets of weak, very fine, granular structure; soft, friable, sticky and plastic; many roots; many, very fine, tubular pores and few, fine, tubular pores; common, fine, black concretions; violent effervescence with hydrogen peroxide; slightly acid; gradual, wavy boundary. 7 to 10 inches thick.
B1-12 to 24 inches, dark reddish-brown (2.5YR 3/4) silty clay loam, reddish brown (2.5YR 4/4) when dry; strong, fine and very fine, angular and subangular blocky structure; slightly hard, friable, sticky and plastic; few roots; many, very fine and fine, tubular pores and few, medium, tubular pores; patchy glaze on ped faces; firm in place; common, fine, black concretions- violent effervescence with hydrogen peroxide; common, fine, hard, earthy lumps that disappear slowly when rubbed; neutral; gradual, wavy boundary. 10 to 14 inches thick.
B21-4 to 34 inches, dark reddish-brown (2.5YR 3/4), moist and dry, silty clay loam; moderate, medium, subangular blocky structure breaking to strong, fine and very fine, angular blocky; soft, friable, sticky and plastic; many, very fine and fine, tubular pores and few, medium, tubular pores; moderately firm in place; weakly developed, patchy pressure cutans; many, fine, black concretions commonly as much as 2 millimeters in diameter; violent effervescence with hydrogen peroxide; neutral; gradual, wavy boundary. 8 to 12 inches thick.
B22-34 to 44 inches, dark reddish-brown (5YR 3/3 moist, 5YR 3/4 dry) silty clay loam; weak, medium and fine, subangular blocky structure; soft, very friable, sticky and plastic; many, very fine and fine, tubular pores and common, medium, tubular pores; few weakly grooved slickensides; many black concretions; violent effervescence with hydrogen peroxide; neutral; clear, wavy boundary. 8 to 12 inches thick.
B3-44 to 60 inches, dark-red (2.5YR 2/6) silty clay loam, dark reddish brown (2.5YR 3/4) when dry; weak, medium, subangular blocky structure breaking to moderate, fine and very fine, subangular blocky; soft, friable, sticky and plastic; many, very fine and fine, tubular pores and common, medium, tubular pores; patchy glaze on some penis; common, fine, hard, earthy lumps that disappear when persistently rubbed; few slickensides; few, fine, black concretions; slight effervescence with hydrogen peroxide; neutral.
Black concretions that range from fine specks to 3 millimeters in size occur throughout the solum. Effervescence with hydrogen peroxide ranges from strong to violent in the A and 112 horizons. The solum ranges from 5YR to 2.5YR in hue. The A horizon ranges from 2 to 3 in value and chroma when moist and from 3 to 4 in value when dry. The B horizon ranges from 2 to 3 in value when moist and from 3 to 4 when dry. It ranges from 3 to 6 in chroma when moist. Slickensides range from few to common in the lower part of the B horizon.
This soil is used for pineapple, pasture, and wildlife habitat. (Capability classification I if irrigated, IVc if nonirrigated; pineapple group 1; pasture group 2)
Waikapu silty clay loam, 3 to 7 percent slopes (WrB).
This soil is on smooth alluvial fans on Molokai. Runoff is slow, and the erosion hazard is slight to moderate. Included in mapping were small areas where the slope is 7 to 15 percent.
This soil is used for pineapple, pasture, and wildlife habitat. (Capability classification IIe if irrigated, IVc, if nonirrigated; pineapple group 2; pasture group 2)
Waikapu silty clay loam, 3 to 7 percent slopes, severely eroded (WrB3).
This soil occurs as two areas in the northwestern part of the Hoolehua Plains on Molokai. It is similar to Waikapu silty clay loam, 0 to 3 percent slopes, except that it is severely eroded. Most of the surface layer and, in many places, part of the subsoil have been removed by erosion. The erosion is caused by strong winds, as well as by water. There are a few bare blown-out spots. Runoff is medium and the hazard of wind and water erosion is severe.
This soil is used for pasture and wildlife habitat. (Capability classification IIIe if irrigated, IVe, if nonirrigated; pineapple group 2; pasture group 2)
Waikapu silty clay loam, 7 to 15 percent slopes, severely eroded (WrC3).
This soil is similar to Waikapu silty clay loam, 0 to 3 percent slopes, except that it is severely eroded. Runoff is medium and the hazard of wind and water erosion is severe. Most of the topsoil and, in most places, part of the subsoil have been removed by erosion. Moderately deep gullies occur in many areas.
This soil is used for pasture and wildlife habitat. (Capability classification IVe, irrigated or nonirrigated; pineapple group 3; pasture group 2)