Effects of residue removal and tillage on greenhouse gas emissions in continuous corn systems as simulated with RZWQM2

Authors: CHENG, HAOMIAO - Yangzhou University; SHU, KEXIN - Yangzhou University; QI, ZHIMING - McGill University - Canada; Ma, Liwang; Jin, Virginia; LI, YOUJIA - McGill University - Canada; Schmer, Marty; Wienhold, Brian; FENG, SHAOYUAN - Yangzhou University

Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2021
Publication Date: 5/1/2021
Publication URL: https://handle.nal.usda.gov/10113/7275986
Citation: Cheng, H., Shu, K., Qi, Z., Ma, L., Jin, V.L., Li, Y., Schmer, M.R., Wienhold, B.J., Feng, S. 2021. Effects of residue removal and tillage on greenhouse gas emissions in continuous corn systems as simulated with RZWQM2. Journal of Environmental Management. 285. Article e112097. https://doi.org/10.1016/j.jenvman.2021.112097.
DOI: https://doi.org/10.1016/j.jenvman.2021.112097

Interpretive Summary: Agriculture is a major emissions source of atmospheric carbon dioxide (CO2) and nitrous oxide (N2O) globally. How the use of conservation management practices such as crop residue retention and no-till affects soil CO2 and N2O emissions is highly uncertain. Here, we used a long-term field dataset to validate the effects of residue removal and tillage in an irrigated continuous corn production system using the Root Zone Water Quality Model 2 (RZWQM2). The field study was conducted in eastern Nebraska, USA, and the validated model was used to predict soil CO2 and N2O emissions for 15 years into the future under different residue and tillage scenarios. Simulated results showed expected increases in soil CO2 emissions over time, but no change in soil N2O emissions. Overall, the results demonstrated that the RZWQM2 is a promising tool for evaluating CO2 and N2O emissions under conservation practices; moreover, the effects of conservation practices were long-term and enlarged year by year.

Technical Abstract: Agricultural production is a major source of carbon dioxide (CO2) and nitrous oxide (N2O) globally. The effects of conservation practices (i.e., residue retention and no-till) on soil CO2 and N2O emissions remain a high degree of uncertainty. In this study, soil CO2 and N2O emissions under different residue and tillage practices in an irrigated, continuous corn system in eastern Nebraska, USA, were investigated using the Root Zone Water Quality Model (RZWQM2). Combinations of no/high stover removal (NR and HR, respectively) and no-till/conventional tillage (NT and CT, respectively) field experiments were tested over the four crop-years (i.e., NRCT, HRCT, NRNT, and HRNT). The model was calibrated using the NRCT, and other treatments were used as validations. The simulation results showed that soil volumetric water content (VWC) in the NR treatments was 1.3%–1.9% higher than that in the HR treatments averaged across the four years. No significant differences in soil temperature (ST) and grain yield were measured and simulated between the treatments. A higher amount of CO2 and N2O emissions was emitted in the NRCT, and lower emissions were simulated in the HRNT. A long-term simulation (fifteen years) suggested that the CO2 and N2O emissions were closely correlated with the stover removal degree (SRD), tillage, cumulative years of management (Y), VWC, ST, and fertilizer application. Meanwhile, stover retention and tillage practices caused positive cumulative effects on CO2 emissions. Among the treatments, the annual CO2 emissions in 1st year were 7.8% for NRCT, 0.0% for NRNT and 7.7% for HRCT over HRNT, respectively; the annual CO2 emissions in 15th year would increase to 63.6% for NRCT, 47.7% for NRNT and 29.1% for HRCT over HRNT, respectively. No cumulative effects were simulated on N2O emissions in response to fast nitrification rates. Overall, the results demonstrated that the RZWQM2 is a promising tool for evaluating CO2 and N2O emissions under conservation practices; moreover, the effects of conservation practices were long-term and enlarged year by year.