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This article in JEQ

  1. Vol. 26 No. 3, p. 706-713
    Received: Apr 23, 1996

    * Corresponding author(s): ebeaucha@lrs.uoguelph.ca
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Intensity and Duration of Denitrification following Application of Manure and Fertilizer to Soil

  1. P. J. Loro,
  2. D. W. Bergstrom and
  3. E. G. Beauchamp *
  1. N ew Brunswick Dep. of Agriculture and Rural Development, Fredericton, New Brunswick, Canada, E3B 5H1;
    A griculture and Agri-Food Canada, Ottawa, ON, Canada, K1A 0C6;
    D ep. of Land Resource Science, Univ. of Guelph, Guelph, ON, Canada N1G 2W1.



Denitrification and nitrous oxide production rates were determined in a field/laboratory study following application of N fertilizer (255 kg N ha−1 as NH4NO3) and liquid (450 kg N ha−1) and solid (600 kg N ha−1) cattle manures. We measured the three proximal regulators, O2 supply (water content, air-filled porosity), NO3 concentration and C supply (CO2 production, extractable-C content) along with denitrifying enzyme activity (DEA) and NH+3 concentration, using a soil core technique. Part 1 of the study involved measurements with soil cores collected from the 10-, 20-, and 40-cm depths following N-fertilizer and manure applications in the fall 1991 and spring 1992. At the 40-cm depth, denitrification rates and DEA were very low, indicating that little soluble C was leached from the manured soil. Air-filled porosity, CO2 production and NH+3 concentration were most closely related to denitrification rates at the 10- and 20-cm depths with the manure treatments. Denitrification rate with different manures depended on time (season) of application and was influenced by soil water content. Solid manure promoted denitrification for a longer period than liquid manure. In Part 2 of the study, denitrification and nitrous oxide production rates in the tilled (0–15 cm) layer were measured over a 49-d period. Both were most closely related to soil water content, but neither was related to NO3 content. Peak rates of denitrification and N2O production occurred early in the sampling period with liquid manure but later with solid manure. Cumulative production of N gases was greater with solid than liquid manure, which, in turn, produced more N gases than with the fertilizer or control treatments.

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