Urban agriculture soils are commonly amended with compost to improve fertility, yet the functional responses of these systems to biochar additions across application rates remain poorly understood.

The gap

Consensus across the literature

Supporting evidence — 7 representative gaps

• Cbr-based performance assessment of feedstock-specific biochars for sustainable clay soil stabilization under soaked and freeze-thaw conditions (2026) · doi

  1 Limitations and future scope While this study provides important insights into feedstock-specific biochar–soil inter- actions, it is limited to a single CI clay from Assam and therefore requires validation across different soil types (e.

  Keywords: soil limitations future scope provides important insights feedstock specific biochar inter actions limited single clay
• Identifying biochar production variables to maximise exchangeable cations and increase nutrient availability in soils (2024) · doi

  However, this influence is not satisfactorily understood due to contrasting data among literature for the cation exchange capacity (CEC) and the lack of standard analysis methods for CEC of biochar and soil-biochar mixtures.

  Keywords: biochar influence satisfactorily understood contrasting among literature cation exchange capacity lack standard soil mixtures
• Long-term effects of biochar one-off application on soil physicochemical properties, salt concentration, nutrient availability, enzyme activity, and rice yield of highly saline-alkali paddy soils: based on a 6-year field experiment (2024) · doi

  However, the long-term effects of one-off biochar application on soil physicochemical properties, salt concentration, nutrient availability, soil enzyme activities, and rice yield under highly saline-alkali paddy soils remain unclear.

  Keywords: soil long term effects biochar application physicochemical properties salt concentration nutrient availability enzyme activities rice
• Biochar‐Mediated Controlled Release of Mineral Nitrogen From Urea Enhances Wheat Yield in Low Fertility Alkaline Soil (2026) · doi

  Although biochar has been widely studied as a nutrient‐retentive soil amendment; however, its potential to assist fertilizer reduction under alkaline soil conditions remains insufficiently understood.

  Keywords: soil biochar widely studied nutrient retentive amendment potential assist fertilizer reduction alkaline conditions remains insufficiently
• Combined manure–biochar effects on soil carbon status and grain nutritional quality in an organic paddy system in Bac Ninh, Vietnam (2026) · doi

  Field evidence is still limited on how locally available manure and rice husk biochar jointly affect soil carbon status, biological soil indicators, yield formation and nutritionally relevant grain traits in transitional organic rice systems.

  Keywords: rice soil field evidence still limited locally available manure husk biochar jointly affect carbon status
• Biochar application rate regulates soil microbial processes and nutrient dynamics in compost-amended urban agricultural soils (2026) · doi

  Urban agriculture soils are commonly amended with compost to improve fertility, yet the functional responses of these systems to biochar additions across application rates remain poorly understood.

  Keywords: urban agriculture soils commonly amended compost improve fertility functional responses systems biochar additions across application
• THE DIFFERENT FACES OF BIOCHAR: CONTAMINATION RISK VERSUS REMEDIATION TOOL (2017) · doi

  The link between biochar’s inherent contaminants and toxicity to soil meso– and macro–fauna remains unclear, with data being often contradictory and influenced by feedstock and pyrolysis conditions.

  Keywords: link biochar inherent contaminants toxicity soil meso macro fauna remains unclear often contradictory influenced feedstock