Question

1. At 50% of field capacity, the matric potential of clay soils is:

A. less negative than loam and sand

B. more negative than sand and less negative than loam

C. more negative than loam and sand

D. less negative than sand and more negative than loam

E. matric potential is equivalent for all soils at the same water content

2. Factors that affect percentage base saturation of soil include (choose any/all that apply):

A. clay content

B. parental material

C. total precipiation

D, soil water content

E. depth of O horizon

F. soil microbial respiration

G. soil pH

3.Which of the following statements about symbiotic nitrogen fixation is true (select any/all that apply)?

A. It requires a symbiotic association between a plant and either a prokaryote or fungus.

B. it is only found in the plant family Fabaceae

C. It can be an important source of N to soils and protein to herbivores.

D. It occurs in specialized root structures of the host plant.

E. it is found in all species of Fabaceae

F.. it is found throughout the plant kingdom

G. Symbiotic N-fixers require photosynthetic carbon from their hosts