What is the effect of high soil pH on nutrient availability?

High soil pH can lead to decreased availability of phosphorus for plant uptake. This happens because when the soil becomes more alkaline (higher pH), phosphorus tends to react with calcium and magnesium, forming insoluble compounds that plants cannot absorb. As a result, the phosphorus becomes less accessible to plants, which can lead to deficiencies even if there is an adequate supply in the soil. Understanding this relationship is crucial for managing soil health and ensuring that crops receive the nutrients they need for optimal growth.

In contrast, other options like increasing nitrogen or potassium availability at high pH are generally not accurate, as these nutrients' availability can also be influenced by soil pH fluctuations, but decreased phosphorus availability is a well-documented phenomenon in alkaline conditions.