Data from: Effect of soil pH and minerology on the sorption and desorption of phosphite and phosphate in Ultisols of the Southeastern Coastal Plain

The development of transgenic crop varieties capable of utilizing
phosphite (Phi) as a phosphorus (P) source is a promising strategy to
increase P use efficiency while decreasing reliance on phosphate
(Pi)-based fertilizers. However, little information is available on Phi
sorption and desorption in soils. We conducted batch experiments to
investigate the sorption of Phi and Pi by three Ultisols from the Coastal
Plain of the southeastern United States. At the soils' acidic field
pH (pH 4.7–6.2), Pi had a higher affinity than Phi for soil solids, where
maximum sorbed concentrations of Pi were an average of 44% greater than
those of Phi. The sorption of both P species decreased when experiments
were repeated adjusting soil pH to 6.5. More Phi than Pi was recovered
during desorption experiments, indicating that Phi was more reversibly
sorbed and, therefore, may be more plant-available than Pi. Multiple
linear regression between calculated linear distribution coefficients (KD;
10 mg P L−1 input solutions) and soil properties suggested that
amorphous Al- and Fe-oxides controlled Pi sorption. Alternatively,
amorphous Al-oxides and gibbsite controlled Phi sorption. Our results show
that a lower affinity of Phi than Pi in Ultisols could improve P
availability for plant uptake of Phi-based fertilizers but may increase
the risk of soil P buildup over time.