Reevaluating the Efficacy of Buckwheat (Fagopyrum esculentum) in Improving the Solubility of a Low-Reactive Phosphate Rock

Low-reactivephosphate rocks are generally ineffective for direct agricultural application because of their limited ability to release phosphorus (P) for plant uptake. A greenhouse experiment evaluated the potential of buckwheat (Fagopyrum esculentum) to solubilize P from PR from Togo to enhance P availability. Buckwheat was grown for eight weeks in six Alabama soil series under five treatments in three replications: control, PR, PR + KNO3, TSP, and TSP + KNO3. P (200 mg P/kg) and nitrogen (120 mg N/kg) were applied to the soils. Following buckwheat harvest, corn was grown in the same pots to evaluate residual treatment effects. Buckwheat in TSP-treated soils exhibited significantly higher P uptake (6.3 mg P/plant) than PR-treated (1.6 mg P/plant) or untreated soils (1.2 mg P/plant). Average available P following buckwheat harvest was highest in TSP-treated soils (0.09 mg P/g soil), compared with PR-treated (0.02 mg P/g soil) or untreated soil (0.01 mg P/g soil). Corn grown following TSP + KNO3 treatment had a higher average P uptake (70 mg P/plant) than corn following PR (8.1 mg P/plant) or untreated soil (4.11 mg P/plant). These results indicate that buckwheat did not significantly enhance P availability under the tested conditions, demonstrating its limited potential to solubilize P from Hahotoe PR.