Question

1. which soil horizon is primarily composed of partially weathered parent material?

a) a horizon
b) b horizon
c) c horizond) o horizon

1. why is the a horizon (topsoil) generally the most productive for crop growth?

a) it is made entirely of solid bedrock.
b) it contains a rich mixture of minerals and organic matter.
c) it collects all leached minerals from the layers above.
d) it is the only layer that contains water.
plant physiology & nutrition checkpoint

Explanation:

Question 1

Soil horizons: O horizon has organic matter, A horizon is topsoil with organic and mineral mix, B horizon has accumulated materials, C horizon is partially weathered parent material. So the C Horizon matches the description.

A Horizon (topsoil) is productive for crops because it has a rich mixture of minerals from weathering and organic matter from decomposed organisms, supporting plant growth. Option a is wrong (bedrock is in lower horizons), c is B horizon's role, d is false (water in other horizons too).

Answer:

c) C Horizon

Question 2