The Amazon Rainforest: Oxisol features (CS)

Question 1

Depth

Answer 1

Describe: 4-20m deep resting on regolith

Explanation:

• Ancient stable climate,
• Chemical and biological weathering due to the 2000mm+/20C+ and soil moisture and soil organisms promotes weathering of rock, increasing depth

Question 2

Colour

Answer 2

Description: Red, Red/brown “terra rossa”

Explanation:

• Iron and aluminium compounds are left on the top layer
• Lighter elements are leached downwards due to the 2000mm of rain

Question 3

Chemistry

Answer 3

Describe: Acid pH around 4-4.5

Explanation:

• Intense leaching and rapid organic decay
• Hydrogen cations in rainwater replace soil nutrients in B horizon
• Organic acids are released by decomposition.

Question 4

Fertility

Answer 4

Describe: 90% of amazonian soils lack essential nutrients, while 80% are lacking Aluminium and Potassium

Explanation:

• Extreme leaching due to 2000mm+
• Rapid transfer of plant nutrients through root systems after decomposition

Question 5

Structure

Answer 5

Description: Blocky structure, clay rich

Explanation:

• Chemical weathering (2000mm+/20C+) of parent material= in the release of clays.
• Clay is cemented by iron, the soil becomes blocky

Question 6

Draw an oxisol

Answer 6