Effect of Fertilizer Source on Denitrification and Nitrous Oxide Emissions in a Maize-field1
- J. M. Duxbury and
- P. K. McConnaughey2
The C2H2-block method was used to measure denitrification in a maize (Zea mays L.) field over the 85-d period between sidedressing with N fertilizer and harvest. Measurement locations were changed weekly in order to avoid problems associated with microbial utilization of C2H2 and inhibition of nitrification. Nitrous oxide (N2O) fluxes were measured both with and without C2H2 addition to soil. Without C2H2 addition to soil, 0.3 kg N ha−1 was evolved from both unfertilized and Ca(NO3)2 treated soil, whereas 2.5 kg N ha−1 was evolved from urea treated soil. This difference was attributed to formation of N2O during nitrification of NH+4 liberated from urea. With C2H2 addition to soil, 1.6, 2.0, and 2.4 kg N ha−1 were evolved as the result of denitrification in the zero N, Ca(NO3)2, and urea treated sites, respectively. Total gaseous N loss from a particular N treatment was approximated by adding together the N2O-N loss with and without C2H2 addition to soil. The gaseous N loss associated with fertilizer addition was <3% of that applied. The ratio of N2/N2O evolved without C2H2 addition to soil was estimated to be in the range of 4:1 to 7:1 for the zero N and Ca(NO3)2 treatments and about 1:1 for the urea treatment. Denitrification was responsible for at least 80% of the measured gaseous N loss from the zero N and Ca(NO3)2 treatments. About equal amounts of gaseous N loss from the urea treatment occurred via denitrification and during nitrification of liberated NH+4.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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