Seasonal and Temporal Changes in Nitrous Oxide Emission with Fertilizer Application in Rice Ecosystem of North Bank Plain Agroclimatic Zone of North East India

Abstract

Fertilizer dosage can influence nitrous oxide (N2O) emissions in rice (Oryza sativa L.) fields. An experiment was conducted to find out the temporal and seasonal variations in N2O emissions under different doses of fertilizers and to identify the best fertilizer combination for lower N2O emission and adequate yield potential. Two rice varieties Phorma (local cultivar) and Luit (high yielding variety) were grown, with nine different fertilizer treatments. N2O fluxes were measured by a closed chamber technique. Temporal fluxes coincide with fertilizer application. Higher seasonal N2O emission (Esif) of 224.05 mg N2O-N/m2 (in Phorma) and 182.16 mg N2O-N/m2 (in Luit) was observed in treatment T9 (45:22:22 N-P2O5-K2O kg/ha as urea, single super phosphate and muriate of potash + farm yard manure). Whereas, lowest emission was recorded in T2 (35:18:18 N-P2O5-K2O kg/ha as urea, single super phosphate and muriate of potash). N2O emission also showed significant positive correlations with soil nitrate-N and soil organic carbon. The fertilizer dose N, P2O5, K2O @ 40: 20: 20 kg/ha as urea, single super phosphate and muriate of potash (T1) without farm yard manure was found to be suitable for sustaining productivity and lower N2O emission in this zone.