Mitigating cadmium accumulation in greenhouse lettuce production using biochar

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Cadmium (Cd) contamination in agricultural soils poses risks to food safety and human health.
• Phytoavailability of soil Cd influences its accumulation in crops, necessitating remediation strategies.

Purpose of the Study:

• To investigate the efficacy of rice straw biochar (RSB) in reducing soil Cd availability and lettuce accumulation.
• To evaluate the impact of different RSB application methods (banding vs. broadcasting) on Cd phytoaccumulation and lettuce yield.

Main Methods:

• Greenhouse experiments were conducted using four soil Cd concentrations.
• Rice straw biochar (RSB) was applied at varying rates (0-18 t ha⁻¹) either in bands or broadcast.
• Lettuce Cd concentrations, soil properties, and yield were analyzed.

Main Results:

• RSB application significantly reduced lettuce shoot Cd by up to 57%, falling below food safety thresholds.
• Hazard quotients for Cd consumption decreased from 0.70-1.11 to 0.42-0.65.
• RSB application improved soil properties, increasing water holding capacity and available nutrients, and boosted lettuce yield by 15%.

Conclusions:

• Rice straw biochar (RSB) is a viable soil amendment for mitigating Cd phytoaccumulation in lettuce.
• Banding RSB offers a cost-effective approach, halving costs while maintaining remediation effectiveness.
• RSB application reduces human exposure risks associated with consuming Cd-contaminated vegetables.