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This article in SSSAJ

  1. Vol. 75 No. 2, p. 595-604
    Received: May 21, 2010

    * Corresponding author(s): bernard.gagnon@agr.gc.ca


Fertilizer Source Influenced Nitrous Oxide Emissions from a Clay Soil under Corn

  1. Bernard Gagnon *a,
  2. Noura Ziadia,
  3. Philippe Rochettea,
  4. Martin H. Chantignya and
  5. Denis A. Angersa
  1.  aSoils and Crops Research and Development Centre, Agriculture and Agri-Food Canada, 2560 Hochelaga Blvd., Québec City, QC, Canada G1V 2J3


Synthetic N fertilizers are a major source of N2O emissions from soil. A field experiment was conducted during three growing seasons (2004–2006) on a clay soil (fine, mixed, frigid Typic Humaquept) under corn (Zea mays L.) to evaluate the impact of N fertilizer source and application rate on N2O emissions. Treatments consisted of three sources of N fertilizer (urea–NH4NO3 32% [UAN], Ca–NH4NO3 [CAN], and aqua NH3 [AA]) at four different rates (0, 100, 150, and 200 kg N ha−1). Fertilizers were banded 5 cm below the soil surface between corn rows at the six-leaf stage and N2O emissions were measured weekly. For all 3 yr of this study, cumulative N2O emission decreased in the order UAN ≥ CAN ≥ AA. Averaged across years, fertilizer-induced post-sidedress emissions were greater than the Intergovernmental Panel on Climate Change default factor (0.01 kg N2O-N kg−1 N), with values of 0.038, 0.033, and 0.027 kg N2O-N kg−1 N for UAN, CAN, and AA, respectively. The N2O emissions increased linearly with N rate, even at rates exceeding the optimum level for grain yield. Peaks of N2O flux occurred on the days following fertilizer application and in early fall when the soil was re-wetted. Emissions of N2O were higher at water-filled pore space >0.57 m3 m−3 and were also related to soil inorganic N and water-extractable organic C contents. Our results confirm that N fertilizer source and application rate can impact N2O emissions but these effects are modulated by soil environmental conditions.

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