Which statement about nutrient availability as soil pH changes is true?

Which statement about nutrient availability as soil pH changes is true?

• A. All nutrients are equally available at any pH.
• B. Nutrient availability increases linearly with pH.
• C. Some nutrients become less available when pH is too acidic or too alkaline.
• D. pH has no effect on micronutrient availability.

Answer: (C)

Nutrient availability in soil depends on pH because the chemical forms of many nutrients change with hydrogen ion concentration, determining whether they stay soluble and can be taken up by roots or precipitate as insoluble compounds. When pH moves away from the near-neutral range, some nutrients become less available. In acidic soils, phosphorus tends to get fixed with iron and aluminum, forming compounds that plants cannot easily absorb, and several micronutrients like iron, manganese, zinc, and copper can become more soluble—sometimes to toxic levels but also shifting availability. In alkaline soils, those micronutrients become less soluble and harder for plants to access, while phosphorus can precipitate as calcium phosphates, reducing its availability. So the true statement reflects that some nutrients become less available when pH is too acidic or too alkaline, reflecting how pH alters solubility and chemical forms of nutrients.

Nutrient availability in soil depends on pH because the chemical forms of many nutrients change with hydrogen ion concentration, determining whether they stay soluble and can be taken up by roots or precipitate as insoluble compounds. When pH moves away from the near-neutral range, some nutrients become less available.

In acidic soils, phosphorus tends to get fixed with iron and aluminum, forming compounds that plants cannot easily absorb, and several micronutrients like iron, manganese, zinc, and copper can become more soluble—sometimes to toxic levels but also shifting availability. In alkaline soils, those micronutrients become less soluble and harder for plants to access, while phosphorus can precipitate as calcium phosphates, reducing its availability.

So the true statement reflects that some nutrients become less available when pH is too acidic or too alkaline, reflecting how pH alters solubility and chemical forms of nutrients.