Modeling Nitrous Oxide Emissions From Large-Scale Intensive Cropping Systems in the Southern Amazon

Authors

Ciniro Costa Jr., CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), Colombia
Gillian L. Galford, University of Vermont
Michael T. Coe, Woodwell Climate Research Center
Marcia Macedo, Woodwell Climate Research Center
KathiJo Jankowski, Woodwell Climate Research Center
Christine S. O'Connell, Chapman UniversityFollow
Christopher Neill, Woodwell Climate Research Center

Document Type

Article

Publication Date

12-9-2021

Abstract

Nitrogen (N) fertilizer use is rapidly intensifying on tropical croplands and has the potential to increase emissions of the greenhouse gas, nitrous oxide (N₂O). Since about 2005 Mato Grosso (MT), Brazil has shifted from single-cropped soybeans to double-cropping soybeans with maize, and now produces 1.5% of the world's maize. This production shift required an increase in N fertilization, but the effects on N₂O emissions are poorly known. We calibrated the process-oriented biogeochemical DeNitrification-DeComposition (DNDC) model to simulate N₂O emissions and crop production from soybean and soybean-maize cropping systems in MT. After model validation with field measurements and adjustments for hydrological properties of tropical soils, regional simulations suggested N₂O emissions from soybean-maize cropland increased almost fourfold during 2001–2010, from 1.1 ± 1.1 to 4.1 ± 3.2 Gg 1014 N-N₂O. Model sensitivity tests showed that emissions were spatially and seasonably variable and especially sensitive to soil bulk density and carbon content. Meeting future demand for maize using current soybean area in MT might require either (a) intensifying 3.0 million ha of existing single soybean to soybean-maize or (b) increasing N fertilization to ~180 kg N ha⁻¹ on existing 2.3 million ha of soybean-maize area. The latter strategy would release ~35% more N₂O than the first. Our modifications of the DNDC model will improve estimates of N₂O emissions from agricultural production in MT and other tropical areas, but narrowing model uncertainty will depend on more detailed field measurements and spatial data on soil and cropping management.

Comments

This article was originally published in Frontiers in Sustainable Food Systems, volume 5, in 2021. https://doi.org/10.3389/fsufs.2021.701416

Recommended Citation

Costa C Jr, Galford GL, Coe MT, Macedo M, Jankowski K, O'Connell C and Neill C (2021) Modeling Nitrous Oxide Emissions From Large-Scale Intensive Cropping Systems in the Southern Amazon. Front. Sustain. Food Syst. 5:701416. https://doi.org/10.3389/fsufs.2021.701416

Copyright

The authors

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This work is licensed under a Creative Commons Attribution 4.0 License.