Agronomy Agronomy MCQ 4

Question 1

Which tillage practice leaves at least 30% crop residue on the soil surface?

Accepted Answer

Conservation tillage

Answer

Conservation tillage is defined by the USDA as any system leaving at least 30% residue cover, reducing erosion and improving soil health.

Question 2

The law of the minimum, attributed to Justus von Liebig, states that:

Accepted Answer

Growth is limited by the nutrient present in the least relative amount

Answer

Liebig's Law of the Minimum states that plant growth is constrained by the single most limiting nutrient, regardless of other nutrient levels.

Question 3

Which soil pH range is generally considered optimal for most agronomic crops?

Accepted Answer

6.0–7.0

Answer

Most agronomic crops grow best between pH 6.0 and 7.0, where nutrient availability is maximized and toxic elements are minimized.

Question 4

What is the primary function of phosphorus in plant metabolism?

Accepted Answer

Energy transfer via ATP

Answer

Phosphorus is a key component of ATP (adenosine triphosphate), which drives energy transfer in virtually all metabolic processes.

Question 5

A field with a soil compaction layer (hardpan) would most likely benefit from which practice?

Accepted Answer

Subsoil tillage (deep ripping)

Answer

Subsoil tillage or deep ripping mechanically breaks up compaction layers, improving root penetration, drainage, and aeration.

Agronomy Practice Test