Old Soils (Ultisol)
Typical Characteristics of Ultisols
- Formation: Ultisols form through the processes of clay mineral weathering. Clays, with the possibility of oxides, accumulate in the B subsurface horizon. Ultisols are not as highly weathered as Oxisols. Generally, base-cations, such as calcium, magnesium, nitrate, and potassium have been leached.
- Climate: Ultisol usually develop in warm, moist climates on old land.
- Traits: The B horizon may be slightly acidic. The CEC is saturated with less than 35 % base-cations.
- Productivity: Unlike Mollisols, the clay in Ultisols is considered to be low activity, or low fertility. However, Ultisols usually contain clay that is not sticky and are very workable. With sufficient fertilizer and lime additions, these soils may be very productive.
Old Soils of Maui
Deep soils of old development and high humus content (Palehumults)
- Alaeloa Series
- Haiku Series
- Hamakuapoko Series
- Honolua Series
- Makawao Series
Minimal old soils with high humus (Haplohumults)
- Halawa Series
- Olelo Series
Minimal old soils with high humus and low activity silicate clays (Kanhaplohumult)
Unique Characteristics of the Old Soils of Maui County
The Ultisols of Maui are very weathered soils. There are two soil series in Maui of agricultural importance which are characteristic.
Haiku Series
- Location: The Haiku series, located in the uplands near Ulumalu, occupies 5,200 acres in land area. The elevation of the Haiku series ranges from sea level to 1,200 ft.
- Texture: Clay, silty clay
- Rainfall and Temperature: The average annual rainfall is 50 to 80 inches, and the average annual temperature is 72 degrees F.
- Slope: Gentle to moderate
- Parent Material: The parent material of the Haiku Series is basic igneous rock, with some deposits of tropospheric dust.
- Depth: Surface layer generally extends 14 inches, while the subsoil tends to be 31 inches in depth.
- Physical Traits: The Haiku Series has good drainage and slow to medium runoff. Permeability is also moderately rapid.
- Color of surface horizon: Dark brown
- Fertility: The Haiku is typically deficient in plant nutrients. Additionally, liming may be required.
- Acidity: Very strongly acidic
- Natural Vegetation: Grasses, guava, and lantana.
- Agricultural Use: Haiku series is predominately used in pasture. In the past, it has been involved in small pineapple production.
 
Photo by Tai McClellan
Pauwela Series
- Location: The Pauwela series is located west of the Haiku Series in the uplands. Elevations range from 150 to 1,500 ft. In extent, the Pauwela Series occupies 5,700 acres of land.
- Texture: Clay
- Rainfall and Temperature: The average rainfall is between 70 and 120 inches, and the average annual temperature is 72 degrees.
- Slope: Gentle to moderate
- Parent Material: The soil is highly weathered from basic igneous rock.
- Depth: Surface layer is typically 12 inches, while subsoil is 21 inches.
- Physical Traits: The Pauwela Series is well drained, with slow to medium runoff and moderately rapid permeability.
- Color of Surface Horizon: Dark, grayish brown
- Fertility: Pauwela Series is generally deficient in plant nutrients.
- Acidity: Acid
- Natural Vegetation: Grasses, guava and others.
- Agricultural Use: In cultivation, the Pauwela Series has been used for pineapple and pasture, as well as water supply.
 
Photo by Tai McClellan
Data for the Haiku and Pauwela Series is characterized by low calcium levels, a high iron percentage and extractable aluminum.
Depth (cm) |
Org. C |
Fe (%) |
Ca |
Extr. Al |
Haiku Series |
0-18 |
3.08 |
24.8 |
-- |
0.5 |
18-32 |
2.79 |
23.9 |
-- |
0.5 |
33-45 |
1.97 |
22.0 |
0.2 |
0.4 |
45-70 |
1.78 |
24.9 |
0.6 |
0.2 |
70-98 |
1.08 |
16.0 |
1.0 |
0.8 |
98-155 |
0.91 |
13.9 |
0.6 |
1.1 |
Pauwela Series |
0-18 |
2.88 |
15.3 |
-- |
1.3 |
18-30 |
2.86 |
15.4 |
-- |
1.3 |
30-43 |
2.58 |
24.6 |
-- |
1.5 |
43-60 |
1.66 |
30.9 |
-- |
0.3 |
60-75 |
1.68 |
27.1 |
-- |
0.3 |
75-103 |
0.82 |
16.7 |
0.3 |
0.6 |
103-138 |
0.61 |
12.9 |
0.2 |
0.5 |
|
