1. Hawaiian Soils Part I

2. Hawai‘i has a range of soils Hilo Soil Profile Green Sand Beach

3. Some soils provide healthy agricultural land, others provide unique habitats for other species than humans. Acidified Soil

4. Conditions make soils in Hawai`i:  Rich in iron & aluminum  Free of quartz sand  Very permeable  Resistant to erosion

5. Hawaiian Soil Types 1.Low Humic Latosols Moderate slope 20” - 40” rain < 2000 ft No quartz sand Neutral to mildly acid

6. Low Humic Latosols cont’d… Largely composed of clay Modest ability to store water Organic content 3-4%

7. 2.Humic Latosols Wetter areas Often upslope of low humic Clay texture Less silica & alumina and more iron & titanium

8. Humic Latosols cont’d… High capacity for storage of water & nutrients Organic content 8-10% More acidic as rainfall increases

9. 3. Humic ferruginous latosols Upslope of low humic on old surfaces of Kaua‘i and Wai‘anae Range of O‘ahu Poor structure, erodibility Low capacity to store water and nutrients

10. Humic ferruginous latosols cont’d… Low permeability Fixation of phosphates

11. 4. Hydrol Humic Latosols Very heavy rain Volcanic ash High organic content Excellent water storage Shrink when dry Weak structure

12. 5. Red Desert Soils Young materials in dry places Kawaihae & Koko Head White calcium carbonate deposits Stony

13. Sponges as Soil Models Part II

14. Sponges show characteristics of soils & water … Dryness Neither of these sponges is truly dry How do these sponges model dryness in soil? How does soil behave as it dries?

15. Sponges show characteristics of soils & water … Infiltration & Run-off These sponges model how soil takes in water & how water may escape from soil.

16. Sponges show characteristics of soils & water … Wetting & Saturation Sponges model how soil can take in water upwards or saturates downwards. Even saturated soil traps pockets of air.

17. Sponges show characteristics of soils & water … Water Holding Capacity Watch carefully to see which pores fill with water as the sponge drains. Soil can still hold water plants can’t extract, just like squeezed sponges are still damp.

18. Sponges show characteristics of soils & water … Percolation & Drainage For drainage to begin, the bottom of the sponge must be approaching saturation

19. Sponges show characteristics of soils & water … Engineering & Bearing Capacity What happens to houses as soils get wet or dry?