What is the primary soil uptake form for Zinc (Zn)?

The primary soil uptake form for Zinc (Zn) is the zinc ion. This involves the absorption of zinc in its ionic form by plant roots, which is essential for various physiological functions within the plant. Zinc plays a vital role in enzyme function, protein synthesis, and overall plant growth and development. In the soil, zinc typically exists as a divalent cation (Zn²⁺), which is readily available for uptake by plants.

In contrast, nickel, molybdate, and manganous ions are related to other nutrients and elements needed by plants but are not the forms in which zinc is primarily taken up. Each of these elements has distinct roles and can contribute to plant health, but they do not directly pertain to the uptake form of zinc, which is why they do not represent the correct answer. Understanding the specific form of nutrient uptake is crucial for effective soil and crop management practices.