Soil Emissions of Nitric Oxide and Nitrous Oxide from Injected Anhydrous Ammonium and Urea

Abstract

Abstract This study characterizes soil emissions of NO and N 2 O from banded applications of anhydrous ammonium (AA) and urea over the period from 6 May 1994 to 12 Sept. 1994 from a loess soil in western Tennessee. The N application rate for both sources was 168 kg ha −1 . Fertilizer type strongly influenced emissions of N 2 O ( F = 231; P = 0.0001) and NO ( F = 69; P = 0.0001). During the 129 d measurement period, the AA treatment lost 12.33 kg of N 2 O‐N or 7.33% of the applied N. The N 2 O‐N loss from the urea treatment was about one‐half that from AA; 6.34 kg ha −1 or 3.77% of the applied N. Loss of NO‐N from both treatments was small compared with N 2 O‐N loss. The urea treatment lost 0.27 kg ha −1 as NO‐N and the AA treatment lost 0.2 kg ha −1 during the study period. While the measured loss rate of N 2 O‐N from AA is similar to previous literature estimates, our values for urea are 20 to 40 times greater than the current literature reports of N 2 O‐N loss of 0.1 to 0.2% of the urea applied. Higher N 2 O losses from urea in this study may be related to the fact that urea was banded below the soil surface, whereas urea has been broadcast on the soil surface in other N 2 O emissions studies.