Biochar Impacts on Soil Silicon Dissolution Kinetics and their Interaction Mechanisms

Area of Science:

• Soil Science
• Biogeochemistry
• Materials Science

Background:

• Silicon (Si) is crucial for plant health and soil fertility.
• The role of biochar in soil silicon dissolution kinetics is not well understood.
• Biochar properties vary significantly based on feedstock and pyrolysis temperature.

Purpose of the Study:

• To investigate the effects of biochar on soil silicon dissolution kinetics.
• To compare silicon dissolution from Si-rich and Si-deficient biochars.
• To elucidate the mechanisms governing silicon release and adsorption by biochar.

Main Methods:

• Preparation of biochars from rice husk, rice straw, wood sawdust, and orange peel at varying temperatures (300-700°C).
• Measurement of silicon dissolution from biochars and their impact on soil silicon dynamics in high-silicon and low-silicon soils.
• Analysis of silicon and carbon release mechanisms.

Main Results:

• Si-rich biochars exhibited higher silicon dissolution, increasing with pyrolysis temperature.
• Si-rich biochar addition improved soil silicon dissolution by 72.7-121% in high-silicon soil and 147-243% in low-silicon soil.
• Si-deficient biochars (wood sawdust, orange peel) decreased cumulative silicon dissolution due to silicic acid adsorption and protection of dissolved iron.

Conclusions:

• Si-rich biochar acts as a slow-release silicon source in agricultural soils.
• Si-deficient biochar can function as a silicon sink, mitigating silicon loss.
• Biochar's interaction with soil silicon is influenced by its composition and pyrolysis conditions.