Effect of quail litter biochar on productivity of four new physic nut varieties planted in cadmium-contaminated soil

Tawadchai Suppadit1, Viroj Kitikoon2, Anucha Phubphol3, Penthip Neumnoi4

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 g kg-1 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.

Keywords: Adsorption, heavy metal, phytoremediation, plant production, pyrolysis, soil amendment.
1National Institute of Development Administration, School of Social and Environmental Development, Bangkapi, Bangkok 10240, Thailand. *Corresponding author (tawatc.s@nida.ac.th; stawadchai@yahoo.com).
2Mahidol University, Faculty of Tropical Medicine, Rajthevee, Bangkok 10400, Thailand.
3Mae Sot Farmer Group, Mae Sot District, Tak Province 63110, Thailand.
4Bureau of the Budget, Phaya Thai, Bangkok 10400, Thailand.