Effect of fertilizer nitrogen management on N2O emissions in commercial corn fields

Corn crops receive higher fertilizer nitrogen (N) application rates than many other crops. Pre-sidedress soil nitrate tests (PSNT) are used to determine how much fertilizer N is applied at the sidedress of corn crops, and can provide an opportunity to reduce fertilizer N application rates and delay the timing of fertilizer N applications which contribute to nitrous oxide (N2O) emissions into the atmosphere. This study examined how the rate and time of fertilizer N application influence N2O emissions in corn crops grown in alluvial soils in Atlantic Canada. Starter fertilizer was applied at 45 and 59 kg N per hectare (ha) in 2004 and 2005. Treatments included the application of 75 or 150 kg N per ha banded at a sidedress, and 150 kg N per ha broadcast at the emergence of the crops. Soil mineral N content was measured using a soil core method. Cumulative N2O emissions were calculated using a linear interpolation method between sampling dates. Results showed that delays in fertilizer application to the sidedress, and reductions in fertilizer N application reduced nitrate (NO3) intensity but had no impact on cumulative N2O emissions. It was concluded that further research is needed to understand controls on denitrification and N2O emissions. 28 refs., 2 tabs., 3 figs