Nitrous oxide emissions from soybean in response to drained and undrained soils and previous corn nitrogen management

Authors: FABRIZZI, KARINA - University Of Minnesota; FERNÁNDEZ, FABIÁN - University Of Minnesota; Venterea, Rodney - Rod; NAEVE, SETH - University Of Minnesota

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2024
Publication Date: 5/24/2024
Citation: Fabrizzi, K., Fernández, F., Venterea, R.T., Naeve, S. 2024. Nitrous oxide emissions from soybean in response to drained and undrained soils and previous corn nitrogen management. Journal of Environmental Quality. 1-11. https://doi.org/10.1002/jeq2.20566.
DOI: https://doi.org/10.1002/jeq2.20566

Interpretive Summary: Nitrous oxide (N2O) is a potent ozone-depleting and greenhouse gas that is emitted from agricultural soils to the atmosphere following application of nitrogen (N) fertilizers. Corn-soybean is a predominant rotation system in the USA Midwest. While N2O emissions from the N-fertilized corn phase of this rotation have been well studied, N2O emissions during the soybean phase of the rotation are less well quantified. Little is known about how N2O emissions during the soybean phase are impacted by specific N management practices used during the corn phase. In this study, we measured season-long N2O emissions from soybean fields in which the N fertilizers were managed differently during the previous year of corn production. The experiments were done in a poorly-drained soil both with and without the installation of subsurface tile drainage which enhanced the movement of water through the soil. Drainage reduced N2O emissions in 1 of 3 growing seasons but had no effect on soybean yield. Nitrogen management in the previous corn crop had no effect on soybean grain yield or N2O emissions during the soybean phase. Even though soybean symbiotically fixes N and removes more N in grain than corn, N2O emissions were more than two times greater during the corn phase due to N fertilization than during the soybean phase. Also, N2O emissions in the corn years were increased possibly due to decomposition of the previous year’s soybean crop residue compared to corn residue decomposition in the soybean years. This study demonstrated that tile drainage, especially where wet soil conditions are prevalent, is a viable option to mitigate agricultural N2O emissions, and that emissions during the soybean phase of a corn-soybean rotation were insensitive to N management during the corn phase. These results will be helpful to scientists, land managers, and policy makes in developing targeted practices to reduced N2O emissions and also to improve models that estimate emissions at the farm to global scale.

Technical Abstract: While corn (Zea mays L.)-soybean (Glycine max. Merr. L) is a predominant rotation system in the USA Midwest, the residual effect of nitrogen (N) fertilization to corn on the following year’s soybean and N2O emissions under different soil drainage conditions have not been studied. Our objective was to quantify agronomic parameters and season-long N2O emissions from soybean as affected by N management (0-N and optimum N rate of 135 kg N ha-1 as single or split application) during the previous corn crop under Drained and Undrained systems. Urea was applied to corn and residual effects were measured on soybean the following year in a poorly-drained soil with and without subsurface tile drainage. Drainage reduced N2O emissions in 1 of 3 growing seasons but had no effect on soybean yield or N removal in grain. Nitrogen management in the previous corn crop had no effect on soybean grain yield, N removal, or N2O emissions during the soybean phase. Even though soybean symbiotically fixes N and removes more N in grain than corn, N2O emissions were more than two times greater during the corn phase (mean=1.83 kg N ha-1) due to N fertilization than during the soybean phase (mean=0.80 kg N ha-1). Also, N2O emissions in the corn years were increased possibly due to decomposition of the previous year’s soybean crop residue compared to corn residue decomposition in the soybean years. Tile drainage, especially where wet soil conditions are prevalent, is a viable option to mitigate agricultural N2O emissions.