###### Abstract  
Gardeners use organic and inorganic substances to enhance plant growth, which can inadvertently impact soil solubility and plant uptake of unknown contaminants. Consequently, human exposure can increase through gardening and consumption of produce grown in potentially contaminated soils. A greenhouse experiment was established to examine the effects of biochar, compost, and common inorganic fertilizer on soil lead (Pb) availability foradish (_Raphanus sativus_, L) and lettuce (_Lactuca sativa_, L) grown in a calcareous soil containing excessively high lead (Pb), along with Pb accumulation in radish tissue. Results indicate that soil amended with biochar and planted to radish saw an 18% reduction in available Pb and an 11% decrease in plant tissue content when compared to the control. Compost showed an 8% reduction in available Pb, but a 19% increase in tissue content. In contrast, soil with inorganic fertilizer planted to radish increased in both soil Pb availability by 11% and Pb tissue content by 40%. Adding water-soluble inorganic fertilizers to contaminated calcareous soils without added organic matter enhances soil Pb availability and often asymptomatic plant Pb bioaccumulation. In conclusion, gardeners are encouraged to test their soils for contamination and apply biochar in combination with compost, as this combination is recommended to improve soil health and aid in overcoming initial N deficiencies induced by biochar. biochar; compost; inorganic fertilizer; heavy metal; trace element; Pb bioconcentration factor; Pb translocation factor +
Footnote †: 2021: 11, 5777. [[https://doi.org/10.3390/app1113577](https://doi.org/10.3390/app1113577)]([https://doi.org/10.3390/app1113577](https://doi.org/10.3390/app1113577))  
Footnote †: 2021: 11, 5777. [[https://doi.org/10.3390/app11135777](https://doi.org/10.3390/app11135777)]([https://doi.org/10.3390/app11135777](https://doi.org/10.3390/app11135777))  
Footnote †: 2021: 11, 577. [[https://doi.org/10.3390/app11135777](https://doi.org/10.3390/app11135777)]([https://doi.org/10.3390/app11135777](https://doi.org/10.3390/app11135777))  
Footnote †: 2021: 11, 5777. [[https://doi.org/10.3390/app11135777](https://doi.org/10.3390/app11135777)]([https://doi.org/10.3390/app11135777](https://doi.org/10.3390/app11135777))  
Footnote †: 2021: 11, 577. [[https://doi.org/10.3390/app11135777](https://doi.org/10.3390/app11135777)]([https://doi.org/10.3390/app11135777](https://doi.org/10.3390/app11135777))  
Footnote †: 2021: 11, 5777. Though heavy metals exist naturally in the environment, their concentrations are often elevated in urban areas. For example, Pb occurs naturally in the Earth's crust at concentrations below 50 mg kg\({}^{-1}\)[9], but concentrations of Pb in urban soils can reach 150 mg kg\({}^{-1}\) or greater, with some soils having total Pb concentrations in excess of 1000 mg kg\({}^{-1}\)[3; 10]. The main sources of heavy metals in urban soils are atmospheric fallout from coal and fuel combustion, vehicle emissions, mining activities, fertilizer use, municipal solid waste disposal, and industrial waste [11; 12; 13; 14]. Lead specifically was historically used in Pb-based paints, leaded gasoline, and pest and weed control chemicals. Although the threat posed by Pb-based paint, which was common in the U.S. until 1978, is generally well-known, research on urban gardeners suggests a low level of awareness of soil pollutants [15]. For example, a survey of 121 urban farmers and gardeners from Kansas, Missouri, and Washington states, found that over 80% were interested in learning more about soil contamination and testing in urban areas [16]. Lead primarily accumulates in the surface layer of urban soils [9]. It exists as a free metal ion--the most available form for plants--in the soil solution and can also complex with organic and inorganic soil constituents, like humic acid and carbonate (CO\({}_{3}\)\({}^{2-}\)), respectively [9].