ASHS 2024 Conference

Field trials were conducted to investigate the feasibility of applying commonly used soil amendments to reduce the accumulation of arsenic (As), cadmium (Cd), and lead (Pb) in sweetpotato storage roots. The cultivars Bayou Belle and Beauregard were grown on an experimental site with natural levels of As, Cd, and Pb. The following soil amendments were used: agricultural lime (AGL) (1 t·ac−1), gypsum (GYP) (1 t·ac−1), biochar (BIO) (1 t·ac−1), and silicon provided as wollastonite (WOL) (2.5 t·ac−1). Compared to the unamended plots, WOL and GYP were associated with elevated soil pH and sulfur levels while reducing Mn and Fe availability. There were no differences in storage root yield grades for both cultivars. The soil amendments were associated with reducing As and Cd extractability by 12 to 31% and 2 to 5%, respectively. A notable finding was the increase in Cd and Pb accumulation in the cultivar Beauregard amended with WOL. We hypothesize that the elevated pH was associated with reducing available binding sites and surface complexes such as with Mn and Fe, leading to the increased bioavailability of Cd and Pb. These preliminary findings support the hypothesis that AGL is a viable soil amendment under mixed toxic element conditions, reducing Pb accumulation without increasing the uptake of other toxic elements. The data also support the need for a systems-based approach for the long-term management of toxic elements in sweetpotato, where soil amendment application is integrated with the use of cultivars associated with low accumulation of specific toxic elements.