What is the impact of low soil pH on nutrient availability?

Low soil pH significantly influences nutrient availability, particularly phosphorus, which is often most affected by acidic conditions. When the soil pH drops below 6.0, phosphorus tends to form insoluble compounds with iron and aluminum, making it less available to plants. The reduction in phosphorus availability can severely limit plant growth since phosphorus is a vital nutrient for processes like photosynthesis and energy transfer.

On the other hand, nitrogen availability is typically enhanced in moderately acidic soils due to increased microbial activity, which promotes the nitrogen cycle. Potassium, while it generally remains available over a broader pH range, does not increase in solubility due to low pH; rather, it remains relatively stable. Lastly, low soil pH does have a marked effect on nutrient uptake, contradicting the idea that it has no impact. Therefore, among the options provided, the reduction of phosphorus availability stands out as a critical consequence of low soil pH.