Effects of nitrogen split application on seasonal N2O emissions in southeast Norway

• Published in: Nutrient cycling in agroecosystems Vol. 115; no. 1; pp. 41 - 56
• Main Authors: Russenes, Aina Lundon, Korsaeth, Audun, Bakken, Lars R., Dörsch, Peter
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.09.2019; Springer Nature B.V
• Subjects: Agriculture; Biomedical and Life Sciences; Blurring; Cereal crops; Correlation analysis; Emission; Emission measurements; Fertilization; Fertilizers; Levels; Life Sciences; Nitrates; Nitrogen; Nitrous oxide; Original Article; Snow; Snow cover; Snowpack; Soils; Spring (season); Spring wheat; Thawing; Wheat; Winter; Norway; Split-N application rate; Nitrous oxide; Yield-scaled emissions; Spring wheat; Off-season emissions
• ISSN: 1385-1314; 1573-0867
• DOI: 10.1007/s10705-019-10009-0

Nitrous oxide (N 2 O) emissions from cultivated soils correlate positively with the amount of N-fertilizer applied, but a large proportion of the annual N 2 O emission occurs outside the cropping season, potentially blurring this correlation. We measured the effect of split-N application (total N addition varying from 0 to 220 kg N ha −1 ) on N 2 O emissions in a spring wheat plot trial in SE Norway from the time of split-N application until harvest, and during the following winter and spring thaw period. N 2 O emissions were largest in the two highest N-levels, whereas yield-scaled emission (N 2 O intensity) was highest in the 0 N treatment. Nitrogen yield increased by 23% when adding 80 kg N ha −1 compared to adding 40 kg N ha −1 as split application, while corresponding N 2 O emissions were reduced by 16%. No differences in measured emissions between the N-fertilization levels were observed during the winter period or during spring thaw. Measurements of soil air composition below the snow pack revealed that N 2 O production continued throughout winter as the concentration in the soil air increased from 0.37 to 30.0 µL L −1  N 2 O over the 3 months period with continuous snow cover. However, only 7–28% of the N 2 O emitted during spring thaw could be ascribed to accumulated N 2 O, indicating de novo production of N 2 O in the thawing soil. The direct effect of split-N fertilizer rate on N 2 O emissions in sub-boreal cereal cropping was limited to the first 15–21 days after N-addition.