Certified Crop Advisor Practice Exam

Which nutrient is associated with increasing availability in neutral to alkaline soils?

1. Iron

2. Phosphorus

3. Calcium

4. Molybdenum

The correct answer is: Molybdenum

The nutrient associated with increasing availability in neutral to alkaline soils is molybdenum. In these types of soils, the chemistry often favors the solubility and bioavailability of molybdenum, which is critical for certain biological processes in plants, such as nitrogen fixation in legumes. Molybdenum acts as a cofactor for enzymes that facilitate these processes, particularly those found in the symbiotic bacteria in root nodules of legumes. In neutral to alkaline conditions, molybdenum tends to remain in forms that are more readily available for plant uptake. This contrasts with other nutrients that may become less available due to precipitation reactions or complex formation in similar pH environments, thereby highlighting molybdenum's unique behavior in those soil conditions. This understanding is essential for optimizing nutrient management in agriculture, particularly in soils that are naturally alkaline.