Nutrient Management Research Database

Innovative management practices are required to increase the efficiency of N fertilizer usage and to reduce nitrous oxide (N2O) and carbon dioxide (CO2) emissions from agricultural soils. The objectives of this study were to evaluate the feasibility of using conservation till- age and N fertilizer placement depth to reduce N2O and CO2 emissions associated with corn (Zea mays L.) production on clay loam soils in Eastern Canada. A 3-yr field study was established on a wheat (Triticum aestivum L.)-corn-soybean (Glycine max (L.) Merr.) rota- tion with each phase of the rotation present every year. Investigations were focused on the corn phase of the rotation. The tillage treatments following winter wheat included fall moldboard plow tillage (15 cm depth), fall zone-tillage (21 cm width, 15 cm depth), and no-tillage. The N placement treatments were ''shallow'' placement of sidedress N (2-cm depth) and ''deep'' placement of sidedress N (10-cm depth). Nitrous oxide emissions were measured 53 times and CO2 emissions were measured 43 times over three growing seasons using field-based sampling chambers. There was a significant tillage and N placement interaction on N2O emissions. Averaged over all three tillage systems and site-years, N2O emissions from shallow N placement (2.83 kg N ha 21 yr 21 ) were 26% lower than deep N placement (3.83 kg N ha 21

This field study looked at the effects of tillage and N fertilization practices (application rate and placement depth) on soil N₂O and CO₂ emissions. N fertilization consisted of a planting rate of 20 lbs N/ha and sidedress of ammonium nitrate at a rate of 142 lbs N/acre. All plots were fertilzied with 80  P₂O₅ and 40 lbs K₂O per acre.

Tillage treatments included a conventional moldboard plough treatment (CT) along with fall zone tillage (ZT), and no-tillage (NT). Fall zone tillage refers to the use of a "Trans-till" that tills only the crop rows.

Yields and soil water and N levels were also measured.

Yields

Corn yields were similar between CT and ZT in 2 of 3 years. NT generally had lower yields.

Deep N placement (6 inch) had about 4% higher yields than the low N placement (1 inch).

Nitrous Oxide Emissions

N₂O emissions spiked after sidedress fertilization, returning to lower emissions after a few weeks.

In the first year, deeper N placement showed higher N2O emissions. However, in the second year no differences were observed between the two placements levels.Overall, shallow N placement reduced emissions by 26%.

Emissions in the second year were significantly reduced from the first and third year. These differences reflect differences in soil water content, with the second year being much drier.