Evaluation of five soil tests for predicting responses of apple trees planted in lead arsenate-contaminated soil

Abstract

Soils used for tree fruit production before 1950 often contain residues of lead arsenate insecticide in sufficient quantity to impair the performance of replanted fruit trees. A four-year field study was conducted to evaluate the ability of five soil testing procedures [concentrated HCl (HClc), EPA 3050, Mehlich-3, 0.5 M NaHCO3, and Toxicity Characteristic Leaching Procedure (TCLP)] to predict growth and arsenic (As) content of ‘Gala’/EMLA.26 apple trees (Malus×domestica Borkh.) planted in a lead arsenate-contaminated orchard soil. EPA 3050 soil As concentrations in the tree planting holes ranged from 122 to 357 mg kg− 1, substantially higher than natural background. Relative tree trunk cross-sectional area increased each year, but was independent of soil As regardless of testing procedure. Leaf and fruit As were unrelated or very poorly related to soil As extracted by HClc, EPA 3050, and Mehlich-3. Leaf and fruit As were better related to soil As extracted by 0.5 M NaHCO3 or TCLP, with the latter procedure yielding the best correlations. Although the significant correlations between plant tissue As and 0.5 M NaHCO3- or TCLP-extractable soil As persisted throughout the experiment, the absolute magnitude of leaf and fruit As concentrations varied from season to season. This variation indicates need to identify and quantify influential factors before accurate multi-year predictions of fruit tree responses to soil As can be made.