Biochar benefits carbon off-setting in blue-green infrastructure soils - A lysimeter study

Area of Science:

• Environmental Science
• Soil Science
• Climate Change Mitigation

Background:

• Blue-green infrastructure soils offer potential for carbon sequestration to offset greenhouse gas emissions.
• Urban soils require effective amendments to enhance their carbon storage capacity and environmental benefits.

Purpose of the Study:

• To investigate the effects of wheat straw biochar and wheat straw on carbon sequestration in urban landscaping soils over three years.
• To compare the efficacy of biochar versus raw straw as soil amendments for carbon storage and soil properties.

Main Methods:

• Two large-scale lysimeters were used under realistic outdoor conditions to study amendments in urban soils.
• Wheat straw and its biochar were incorporated into soil at a 0-15 cm depth, with an equivalent initial total carbon input.
• Key parameters measured included soil carbon (organic and inorganic), carbon isotope ratios, leachate carbon, CO2 emissions, vegetation growth, water content, and infiltration rates.

Main Results:

• Biochar amendment resulted in significantly higher soil organic (28.8%) and inorganic (41.5%) carbon content compared to wheat straw.
• Carbon isotope analysis indicated greater stability of added carbon in biochar-amended soil.
• Despite 17.2% lower vegetation growth, biochar enhanced soil carbon sequestration potential, estimated at 30 tonnes per hectare.

Conclusions:

• Wheat straw biochar is a promising amendment for enhancing carbon sequestration in urban blue-green infrastructure soils.
• Stakeholder interviews highlighted concerns regarding biochar production and application practicality, suggesting a need to emphasize co-benefits like stormwater management.