CAN fertilizer agronomy (calcium ammonium nitrate): In calcium ammonium nitrate, which statement correctly describes the plant availability (speed of action) of the nitrogen forms present?

Introduction:
Calcium ammonium nitrate (CAN) is a granular fertilizer containing a mix of nitrate nitrogen (NO3−) and ammoniacal nitrogen (NH4+), often with a liming component (calcium carbonate/dolomite). Understanding the relative speed with which plants can absorb these forms informs timing and placement decisions.

Given Data / Assumptions:

• CAN typically comprises roughly half nitrate and half ammoniacal nitrogen (formulations vary).
• Soil conditions are typical agricultural field conditions.
• Focus is on comparative speed of plant uptake.

Concept / Approach:
Nitrate nitrogen is immediately available and mobile in soil water, making it fast-acting for crop uptake. Ammoniacal nitrogen is retained on cation exchange sites and generally must nitrify (biological oxidation to nitrate) before rapid plant uptake, making it slower-acting relative to nitrate under many field conditions.

Step-by-Step Solution:
Identify nitrogen forms in CAN: nitrate and ammonium.Recall mobility and uptake: nitrate is readily absorbed and moves with soil moisture.Conclude: nitrate nitrogen is quick acting compared with ammoniacal nitrogen.

Verification / Alternative check:
Agronomy references consistently describe nitrate as immediately available and ammonium as slower due to nitrification dynamics, particularly in cooler or less aerated soils.

Why Other Options Are Wrong:

• Ammoniacal quick acting or nitrate slower: Opposite to observed field behavior.
• None/equally slow: Misrepresents the distinct kinetics.

Common Pitfalls:
Overapplication leading to nitrate leaching; while quick acting, nitrate is also more prone to losses, so split applications are often recommended.

Final Answer:
nitrate nitrogen is quick acting