Study on the Greenhouse Gas (Ghg) Emissions from Rice Field Under Various Nutrient Management Practices

Abstract

Modernizing traditional farming practices and intensive cultivation on limited land has increased the reliance on fertilizers to maintain soil health. The study was conducted on rice crop from 2022 to 2023. The seven treatment combinations in which recommended dose of nitrogen applied through neem coated urea (NCU) and nano urea, viz., T1:Control (No nitrogen), T2: 1/3rd as  (NCU) as basal) + 1/3rd NCU at active tillering  (AT)) + 1/3rdNCU at panicle initiation (PI)), T3: 1/3rd NCU as basal + 1/3rd NCU at AT +  2sprays of NU at maximum tillering -MT and PI) @ 2 ml / litre), T4: 1/3rd NCU as basal + 1/3rd NCU at AT + 1 spray of nano-urea at PI @ 4 ml / litre), T5: 1/4 NCU as basal + 1/4 NCU at AT +2 sprays of nano-urea (at MT and PI) @ 2 ml / litre), T6 :1/3rd NCU as basal + 2 sprays of nano-urea (at AT& PI) @ 2 ml / litre), and T7: 1/3rd  NCU as basal + 3 sprays of nano-urea (at AT, PI, and heading) @ 2 ml / litre).  The study revealed significant differences in GHG emissions, particularly nitrous oxide (N₂O) and carbon dioxide (CO₂), among the different fertilizer management practices. The highest (p=??) N₂O emissions were observed in the T2 treatment {1/3rd RDN (NCU as basal) + 1/3rd RDN (NCU at active tillering) + 1/3rd RDN (NCU at panicle initiation)} at 352 kgCO₂eha⁻¹, while the lowest emissions were recorded in the T1 treatment (Control – without nitrogen) at 88.4 kgCO₂eha⁻¹. Similarly, CO₂ emissions were also the highest in the T2 treatment at 1376 kgCO₂eha⁻¹, with the control (T1) recording the lowest at 1165 kgCO₂eha⁻¹. Methane emissions, mainly influenced by water regimes, remained consistent across all treatments, each contributing 2112.3 kgCO₂eha⁻¹, due to similar water management across all treatments. Overall, total GHG emissions were significantly higher in fertilized treatments, with the T2 treatment exhibiting the highest total emissions of 3841 kgCO₂eha⁻¹, while the control had the lowest at 3366 kgCO₂eha⁻¹. These findings highlighted the complex trade-offs between enhancing rice yields through improved nutrient management and the associated increase in GHG emissions, emphasizing the need for strategies that balance productivity with environmental sustainability.