Brown and red colors in subsurface horizons are caused by ________ in the soil.
A) aluminum oxides
B) organic matter
C) manganese
D) clay
E) iron oxides
Question 2
In which soil orders would recent alluvium most likely be a common parent material?
A) Ultisols B) Aridisols C) Entisols D) Andisols E) Alfisols