Nitrous Oxide Emissions from an Alluvial Soil with Different Nitrogenous Fertilizers and Nitrogen Levels

A study was conducted to examine the effects of different nitrogenous fertilizers on emissions of nitrous oxide (N₂O) from an alluvial soil at submerged and field capacity moisture regimes. Emissions of N₂O started from first day at both the moisture regimes. At submergence, soils fertilized with urea emitted the highest amounts of N₂O-N (0.25 mg kg⁻¹ soil) during 60 days, followed by ammonium sulphate (0.19 mg kg⁻¹ soil), ammonium chloride (0.16 mg kg⁻¹ soil), potassium nitrate (0.09 mg kg⁻¹ soil) and non-fertilized control (0.09 mg kg⁻¹ soil). At field capacity, corresponding emissions were 0.69, 0.49, 0.34, 0.15 and 0.14 mg kg⁻¹ soil. During 60 days of incubation, total emissions of N₂O-N accounted for 0.001–0.20 per cent and 0.005–0.72 per cent of applied N, at submergence and field capacity, respectively. In another experiment, the same soil was fertilized with 50, 100, 150, 200, 250 and 300 mg N kg⁻¹ soil through urea and incubated at 30°C at field capacity to study the effect of different N levels on N₂O emission. Total emission of N₂O-N during 51 days ranged from 0.21 to 0.50 mg kg⁻¹ soil. Nitrous oxide emissions were linearly related to nitrogen levels [N₂O emission (mg N₂O kg⁻¹ soil) = 0.302 + 0.0007* N level (mg N kg⁻¹ soil), (R² = 0.99*)]. Nitrogen lost through N₂O emission was 0.06–0.15 per cent of applied nitrogen.