Which phosphorus uptake form is favored in higher pH soils?

The favored form of phosphorus uptake in higher pH soils is the HPO42- ion. In alkaline conditions (higher pH), the availability of phosphorus is influenced by the chemical form it takes in the soil. As soil pH increases, phosphorus tends to be found primarily in the form of HPO42-, which is more prevalent at pH levels above 7. This form is more soluble compared to other forms of phosphorus present in lower pH conditions.

When soils become more alkaline, the conversion of H2PO4- (which predominates at lower pH) to HPO42- occurs, making it the more accessible form of phosphorus for plant uptake. Thus, in high pH environments, crops are more likely to absorb phosphorus in the form of HPO42-, effectively meeting their nutrient requirements.

In contrast, other forms such as H2PO4- and PO43- are more prevalent in acidic conditions and may be less accessible in alkaline soils. Understanding the dynamics of phosphorus forms at different pH levels is essential for effective nutrient management and optimizing plant growth.