Does biochar application in heavy metal-contaminated soils affect soil micronutrient dynamics?

Area of Science:

• Soil Science
• Environmental Chemistry
• Agronomy

Background:

• Biochar is used as a soil conditioner, especially in degraded or contaminated soils.
• The simultaneous impact of biochar on micronutrient bioavailability in heavy metal-contaminated soils requires investigation.

Purpose of the Study:

• To investigate the effect of rice straw biochar on the bioavailability of iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in lead (Pb)- or cadmium (Cd)-contaminated soils.
• To assess changes in heavy metal fractions and soil microbial community structure.

Main Methods:

• A 90-day incubation experiment using rice straw biochar with Pb- or Cd-contaminated soils.
• Analysis of DTPA-extractable, acid-extractable, reducible, oxidizable, and residual fractions of heavy metals and micronutrients.
• Assessment of soil bacterial richness and diversity.

Main Results:

• Biochar amendment decreased DTPA-extractable, acid-extractable, and reducible Pb and Cd, while increasing oxidizable and residual fractions.
• DTPA-extractable Fe decreased significantly (73.8% in neutral, 23.1% in acidic soil), while DTPA-extractable Mn increased (9.8% in neutral, 44.3% in acidic soil).
• Biochar increased soil bacterial richness and diversity.

Conclusions:

• Rice straw biochar effectively immobilizes heavy metals in contaminated soils.
• Biochar application alters micronutrient bioavailability, reducing Fe availability and increasing Mn availability.
• These changes can influence soil micronutrient fertility and agricultural productivity.