Abstract
Synthetic fertilizers have long been used to boost soil nutrients and maximize crop yields. However, this approach can contribute to increased greenhouse gas (GHG) emissions and pose long-term risks to the environment and soil health. Our research focuses on identifying organic amendments, such as compost, biochar, wood ash, and gypsum, that could help reduce these emissions while maintaining effective farming practices. These amendments were tested and compared to synthetic fertilizer control, over multiple years to assess their impact on CO₂ and N₂O emissions. Our findings indicate that organic amendments generally lower GHG emissions compared to treatments with synthetic fertilizer alone, with organic treatments showing reduced CO₂ and N₂O fluxes. Data exploration using boxplots of seasonal CO₂ and N₂O fluxes per treatment per year revealed a decreasing trend in seasonal CO₂ flux over time, while seasonal N₂O flux remained stable in 2022 and 2023 but decreased in 2024. This reduction in 2024 may be attributed to the crop type, a legume, known for fixing atmospheric nitrogen. To determine whether these year-to-year variations were statistically significant, a two-factor ANOVA was conducted. The results showed that the interaction between year and treatment did not significantly affect seasonal CO₂ (p = 0.4416) or N₂O fluxes (p = 0.1812), suggesting that other environmental factors may have influenced the observed differences. An effect size analysis, combining data across years and blocks, indicated that none of the treatments showed a statistically significant reduction or increase in GHG emissions compared to the synthetic fertilizer control for both CO₂ and N₂O. Future work should focus on including additional variables to better account for these variabilities, such as soil moisture, temperature, and crop productivity. Investigating the relationship between treatments and crop yield will provide a more comprehensive understanding of their sustainability and productivity impacts.