Biochar can improve soil structure and water retention, enhance nutrient availability and retention, ameliorate acidity, and
reduce heavy metal toxicity to plant roots. In this study, a basin experiment was conducted to investigate the effects of quail
litter biochar (QLB) on the availability of Cd to physic nut ( Jatropha curcas
L.) plants. QLB was applied to the soil in which
four new physic nut varieties (Takfa, Doi Saket, Lao, and Rayong) in factorial combinations at four levels (0, 5, 10, and 15
soil) to soil that contained 60.8 mg Cd kg-1
. After transplanting plant height and canopy radius were measured every
2-mo and the number of leaves and branches at 6-mo, while yield components and Cd residues were measured at 8-mo
intervals. The contaminated soil was analyzed for chemical characteristics, nutrients, and Cd residue after the plant harvest.
The addition of QLB to soil caused a significant increase in the soil's growth potential and physic nut yield components
(P < 0.05), a significant decrease in the Cd residue in the plant (P < 0.05), and a significant increase in the chemical
characteristics, nutrients, and Cd residue in soil (P < 0.05). In conclusion, QLB application can significantly decrease the
bioavailability of Cd to physic nut plants, increase plant growth potential and yield, and has potential to remediate Cd-contaminated
soil. However, QLB levels higher than 15 g kg-1
soil mixture were not advisable because QLB is alkaline in
nature, and this can affect soil pH.