At low soil pH levels (5 or less), what can happen?

• A. Cation exchange will be enhanced, causing the plants to grow faster.
• B. Plant roots are eaten away by the acidic soil.
• C. Absorption of negatively charged ions is enhanced, causing the plants to grow faster.
• D. Absorption of calcium is enhanced, but iron is unavailable.
• E. Toxic aluminum ions become more available, stunting the plant's growth.

Answer: (E)

Verified step by step guidance

1. Understand that soil pH is a measure of acidity or alkalinity, with lower pH values indicating more acidic conditions.
2. Recognize that at low pH levels, certain ions in the soil become more soluble and available to plants.
3. Identify that aluminum ions, which are typically present in soil, become more soluble and available at low pH levels (5 or less).
4. Consider the effects of increased aluminum availability: aluminum can be toxic to plants, affecting root growth and function.
5. Conclude that the increased availability of toxic aluminum ions at low pH levels can stunt plant growth, rather than enhance it.