Purpose
Greenhouse gases (GHGs) are major reasons for climate change. The intensity of GHGs is continuously increasing in agricultural soils due to intensive practices. Biochar (BC) is an effective measure to mitigate GHGs and improve ecosystem services. However, the efficiency of BC in mitigating nitrous oxide (N2O) emissions remains debatable. In recent years, BC, when combined with other amendments, has shown promising results in mitigating N2O emissions. Recently, seaweed-based fertilizers (SBF) have shown promising results in improving crop productivity; however, their role in reducing GHG emissions is still unclear.
Method
This study investigated the impact of BC, SBF, and co-application of BC and SBF on N2O emissions, soil rejuvenation, canonical ammonia oxidizers, and comammox, bacterial abundance, and rice growth and yield. The study contained different treatments: control, BC (2%), SBF (2%), and BC (1%) + SBF (1%).
Results
The co-application of BC + SBF increased soil pH (> 20%), triggered the transformation of soil nitrogen dynamics, increased soil carbon (92.74%), nosZ genes abundance (107%) and decreased ammonia-oxidizing archaea (AOA) (27%), and ammonia-oxidizing bacteria (AOB) (45%) abundance leading to a significant decrease in N2O emissions (63.15%). The integrative application of BC and SBF also significantly increased Acidobacteriota, Bacterioidetes, Chloroflexi, Proteobacteria, and Nitrospirae, contributing to a significant decrease in N2O emissions. Integrative BC and SBF also enhanced rice productivity and quality, which was linked with improved soil nutrient availability, carbon sequestration, and soil enzyme activities.
Conclusion
In conclusion, the BC and SBF blend could be a promising amendment to mitigate N2O emissions and improve soil fertility, microbial activities, and rice productivity.