2,4-Dinitrophenol (DNP) is a moderately weak acid that is expected to be highly labile (leachable and plant available) in high-pH soils. The adsorption and degradation behavior of DNP in two sludge-amended, calcareous soils was determined and used to explain DNP uptake by plants grown in the soils in the greenhouse. The DNP adsorption was minor in both soils and was only slightly affected by sludge. The DNP degradation was rapid in both soils and was unaffected by sludge. Thus, despite limited soil adsorption, plant uptake of DNP was minor in all crops and plant parts owing to rapid soil DNP degradation. Even if a municipal sludge highly contaminated with DNP was identified (an unlikely occurrence), concerns over possible plant contamination should not limit sludge applications to calcareous soils or leaching of DNP to groundwater, given careful water management.