Measured and simulated effects of residue removal and amelioration practices in no-till irrigated corn (Zea mays L.)

Authors: Li, Lidong; Ma, Liwang; QI, ZHIMING - McGill University - Canada; FANG, QUANXIAO - Qingdao Agricultural University; Harmel, Daren; Schmer, Marty; Jin, Virginia

Submitted to: European Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2023
Publication Date: 3/11/2023
Citation: Li, L., Ma, L., Qi, Z., Fang, Q., Harmel, R.D., Schmer, M.R., Jin, V.L. 2023. Measured and simulated effects of residue removal and amelioration practices in no-till irrigated corn (Zea mays L.). European Journal of Agronomy. 146. Article 126807. https://doi.org/10.1016/j.eja.2023.126807.
DOI: https://doi.org/10.1016/j.eja.2023.126807

Interpretive Summary: Computer modeling can help predict how agricultural management affects nitrogen (N) losses to the environment. An important N loss pathway from agricultural soils is the emission of a powerful greenhouse gas, nitrous oxide (N2O). Modifying agronomic practices such as irrigation, crop residue management, and winter cover crop use can help reduce these emissions, but few studies look at these practices in combination, either in the field or in computer simulations. In this study, we compared 9 years of measured field data with simulated data from the Root Zone Water Quality Model 2 to predict how irrigation, crop residue management, and winter cover crop use affects soil nitrous oxide (N2O) emissions. We found that using less irrigation (75% of full irrigation level) decreased soil N2O emissions compared to full irrigation levels. Removing corn stover also decreased soil N2O emissions compared to leaving all stover on the field. Winter rye cover crop had no impact on soil N2O emissions. Modeled results were similar to field-measured results, but the model did not fully capture the residue management effect on soil moisture which directly controlled soil N2O emissions. Using field-measured data to validate model simulations can be provide a valuable tool for quickly and cost-effectively evaluating management impacts on soil N2O, crop yield, and other soil dynamics.

Technical Abstract: Reducing nitrous oxide (N2O) emissions to the atmosphere is expected to provide substantial climate mitigation benefits. Agricultural soils are the main sources of global N2O emissions due to management practices. Herein, we measured soil N2O emission and crop yield responses in a nine-year, no-till continuous corn (Zea mays L.) system under contrasting management practices including irrigation (full; deficit), corn stover retention (100% retention; maximum mechanical removal), and cover crop use (winter cereal rye, Secale cereale L.; no cover crop). We used the Root Zone Water Quality Model 2 (RZWQM2) to simulate management effects on soil N2O, soil temperature, soil volumetric water content (VWC), grain yield, aboveground biomass, and grain and biomass nitrogen (N). Structural equation modeling was used for each field-measured data (SEMobs) and RZWQM2 simulated data (SEMsim) to quantify management relationships with soil and crop responses, and determine whether relationships observed in field data were captured by RZWQM2 simulations. Our experimental field results showed that stover retention combined with full irrigation and cereal rye cover crop increased soil N2O emissions relative to stover removal. Full irrigation alone increased soil N2O emissions compared to deficit irrigation. Cereal rye cover crop alone did not affect soil N2O emissions. RZWQM2 captured crop yield and in-season N2O dynamics adequately. The SEMobs and the SEMsim (R2 = 0.33 and 0.26, respectively) demonstrated that RZWQM2 adequately simulated the management effects on soil N2O emissions. These results furthered our understanding for mechanisms of soil N2O emissions and can help project and manage agricultural systems to reduce greenhouse gas emissions.