Artificial carbon materials’ impact on soil fertility and greenhouse gas emission

Biochar (BC) and artificial humic acid (A-HA), both classified as artificial carbon materials, play crucial roles in enhancing soil fertility and promoting carbon sequestration. Despite their significance, limited research has explored the combined effects of these two components when applied to soil. This study aims to investigate the synergistic impacts of BC and A-HA under alternating wet and dry soil conditions.

We synthesized A-HA and BC as exogenous additives derived from corn stover. These additives were subsequently introduced into the soil in varying proportions during a 60-day alternating wetting and drying soil column experiment. The experiment encompassed six treatment groups, each consisting of three replicates.

The results of our study suggest that the simultaneous application of A-HA and BC addresses limitations observed with individual applications. A-HA proves more effective than BC in enhancing soil physical properties such as total nitrogen, total organic carbon, microbial biomass carbon, dissolved organic carbon, and cation exchange. Conversely, BC excels in improving effective phosphorus, effective potassium, and soil organic matter. Both A-HA and BC contributed to the reduction of net soil greenhouse gas (GHG) emissions, with A-HA notably effective in reducing net nitrous oxide emissions and BC excelling in reducing net carbon dioxide emissions. The findings also revealed an augmentation in the diversity and abundance of soil microorganisms, particularly those associated with carbon sequestration functions (e.g., Chloroflexi). Hence, the coapplication of BC and A-HA demonstrates a harmonious balance across these indicators, showcasing remarkable synergistic effects.

Analyzing these factors provides valuable insights into the synergistic effects of BC and A-HA on soil dynamics, particularly in realistic irrigation scenarios. This contributes to a comprehensive understanding of their applications in sustainable agriculture and climate change mitigation. Our study advances knowledge on the potential of BC and A-HA for soil carbon sequestration and quality improvement, providing practical guidance for field application.