Comparison of plant nutrient and environmental soil tests to predict Pb in urban soils

Most urban soils are not tested for Pb because of the high costs associated with sampling and laboratory analysis of soil contaminants. However, soil testing for plant nutrients is inexpensive and routinely performed for agricultural soils used for food production. The objectives of this study are to determine the ability of 1 M HNO3, Mehlich 3, and Modified Morgan soil tests to predict total Pb and other contaminants in urban soils. Total Pb was determined from 65 urban vacant residential lots being considered for urban gardens and food production in Cleveland, OH. Extractable Pb was determined using common soil nutrient test methods Mehlich 3 and Modified Morgan extraction, and a 1 M HNO3 extraction. Significant linear regressions between total Pb and Mehlich 3 (r2 = 0.83), 1 M HNO3 (r2 = 0.92), and Modified Morgan (r2 = 0.77) in study soils were found. Most commercial and university soil testing labs use Mehlich 3 which could be implemented as a screening tool for soil Pb, Cu, and Zn. The Mehlich 3 soil test is widely used and is relatively inexpensive (<$15). Our results show that total Pb can be conservatively estimated by the following equation Total Pb (mg kg− 1) = Mehlich 3 Pb (mg kg− 1) × 2.

► The ability of soil tests to predict total Pb and other contaminants in 65 urban soils was determined.
► Most soil testing labs use Mehlich 3 which could be implemented as a screening tool for soil Pb, Cu, and Zn.
► Total Pb can be conservatively estimated by the following equation Total Pb (mg kg− 1) = Mehlich 3 Pb (mg kg− 1) × 2.