1. Soils

2. Soil Textural Triangle

4. Porosity vs. Permeability

5. Soil Structure – Costa Rica
What happens to soil structure when a tractor drives over the surface?

6. Soil Profile

7. Costa Rica Road Cut

8. Soil Horizons

9. Mosaic
of closely
packed
pebbles,
boulders
Alkaline,
dark,
and rich
in humus
Weak humus-
mineral mixture
Dry, brown to
reddish-brown, with
variable accumulations
of clay, calcium
carbonate, and
soluble salts
Clay,
calcium
compounds
Desert Soil
(hot, dry climate)
Grassland Soil
(semiarid climate)

10. Tropical Rain Forest Soil (humid, tropical climate)
Forest litter
leaf mold
Acid litter
and humus
Acidic
light-
colored
humus
Humus-mineral
mixture
Light-colored
and acidic
Light, grayish-
brown, silt loam
Iron and
aluminum
compounds
mixed with
clay
Dark brown
firm clay
Humus and
iron and
aluminum
compounds
Tropical Rain Forest Soil
(humid, tropical climate)
Deciduous Forest Soil
(humid, mild climate)
Coniferous Forest Soil
(humid, cold climate)