Determining the nitrous oxide transfer velocity and emission factor of an agricultural drain

Abstract

ABSTRACTThere have been few studies examining indirect nitrous oxide emissions associated with nitrogen (N) leaching from agricultural soils. For agricultural drainage water, equals the water’s concentration in excess of the atmospheric value multiplied by the transfer velocity . Using this equation, tracers and chamber methods, and were measured from an agricultural drain. Estimates of were made by measuring water speed and depth using the relationship developed by O’Connor and Dobbins [1958. Mechanisms of reaeration in natural streams. Transactions of the American Society of Civil Engineers. 123:641–684]. The measurements and estimates were not significantly different and averaged 5 m d−1. Alternatively, for the method developed by the Intergovernmental Panel on Climate Change, equals the mass of N flowing in the water multiplied by an emission factor (EF). By additional measurements of the drain’s width, the water’s flow rate and nitrate () concentration, the estimated EF was 1.2 × 10−4 kg kg−1 .