Soil Losses of Dinitrogen and Nitrous Oxide from Irrigated Crops in Northeastern Colorado
1986
Mosier, A. R. | Guenzi, W. D. | Schweizer, E. E.
Emissions of nitrous oxide (N₂0) and dinitrogen (N₂) from irrigated fields were monitored during the 1982 and 1983 cropping season to assess the magnitude of N loss by denitrification. Miniplots were established within larger fields of corn (Zea mays L.) in 1982, and barley (Hordeum vulgare) in 1983. Soil inside the miniplots was amended at a rate of 200 kg N ha⁻¹ as 99 atom % ¹⁵N ammonium sulfate, and the vertical N₂0 and N₂ fluxes were measured periodically by sampling gases from a soil cover method, and analyzing the N₂0 by gas chromatography and the N₂ by mass spectrometry. Maximum N₂0 emissions occurred in May for barley and in July for corn, and emissions for both crops increased with increasing soil-water content. During 1982, total volatile N loss of N₂0 + N₂ from the moderately well-drained clay loam soil was about 2.5% of the applied fertilizer N, and about 70% of the total was N₂0. From the barley field in 1983, about 1% of the applied fertilizer N was emitted with about equal amounts of each gas. These data suggest that the role of denitrification as a N loss mechanism has been historically overemphasized for soils in this area.
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