Evaluating Cropland N2O Emissions and Fertilizer Plant Greenhouse Gas Emissions With Airborne Observations. Issue 16 (21st August 2020)

• Record Type: Journal Article
• Authors: Gvakharia, A.; Kort, E. A.; Smith, M. L.; Conley, S.
• Is Part Of: Journal of geophysical research. Volume 125:Issue 16(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-08-21
• Subjects: nitrous oxide -- flux inversion -- mass balance -- airborne observations -- fertilizer -- greenhouse gas emissions; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2020JD032815
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Agricultural activity is a significant source of greenhouse gas emissions. The fertilizer production process emits N2 O, CO2, and CH4, and fertilized croplands emit N2 O. We present continuous airborne observations of these trace gases in the Lower Mississippi River Basin to quantify emissions from both fertilizer plants and croplands during the early growing season. Observed hourly emission rates from two fertilizer plants are compared with reported inventory values, showing agreement for N2 O and CO2 emissions but large underestimation in reported CH4 emissions by up to a factor of 100. These CH4 emissions are consistent with loss rates of 0.6–1.2%. We quantify regional emission fluxes (100 km) of N2 O using the airborne mass balance technique, a first application for N2 O, and explore linkages to controlling processes. Finally, we demonstrate the ability to use airborne measurements to distinguish N2 O emission differences between neighboring fields, determining we can distinguish different emission behaviors of regions on the order of 2.5 km 2 with emissions differences of approximately 0.026 μmol m −2 s −1 . This suggests airborne approaches such as outlined here could be used to evaluate the impact of different agricultural practices at critical field‐size spatial scales. Key Points: Reported N2 O and CO2 emissions from fertilizer plants agree with observations, but CH4 is underestimated by orders of magnitude We demonstrate mass balance quantification of N2 O emissions from agriculture at 10–100 km scales Airborne measurements can observe and quantify N2 O emission differences between agricultural fields of ∼2.5 km 2