Phosphorus uptake in alkali soil is in the form of ______.

Correct option is C

Phosphorus uptake in alkali soil is influenced by the pH level of the soil. In alkaline conditions, the form of phosphorus that is most available and taken up by plants is typically in the form of ions that are stable at higher pH levels.

·         Option a (HPO42-) is the hydrogen phosphate ion, which is prevalent in slightly alkaline conditions.

·         Option b (H2PO4-) is the dihydrogen phosphate ion, which is more common in acidic to neutral conditions.

·         Option c (PO43-) is the phosphate ion, which is stable in highly alkaline conditions.

·         Option d (H3PO4) is phosphoric acid, which is more common in acidic conditions