Soil N₂O emissions as affected by long‐term residue removal and no‐till practices in continuous corn

Abstract

The environmental consequences of residue removal practices to support cellulosic biofuel production remain poorly understood. In the U.S. Midwest, corn (Zea mays L.) stover removal combined with no‐till practices may increase or decrease soil N2O emissions by influencing soil moisture, temperature, and nutrient dynamics, yet empirical evidence from long‐term field experiments is inconsistent. We investigated the effects of residue management (residue retained or removed) and tillage (chisel‐till or no‐till) on cumulative soil nitrous oxide (N2O) emissions, grain yield, and yield‐scaled N2O emissions in a 3‐year study initiated 10 years after treatment implementation in a long‐term, continuous corn experiment in Illinois, United States. Crop yields were affected by treatment in only one of three study years, with the combination of residue removal and no‐till reducing yields compared to both chisel‐till treatments. Cumulative N2O emissions, soil inorganic N concentrations, and yield‐scaled N2O emissions differed over the 3‐year period and were significantly affected by tillage, with no response to residue management. In 2 years, no‐till decreased cumulative N2O emissions and yield‐scaled N2O emissions by an average of 64% and 60%, respectively. Correlations between daily N2O fluxes and soil moisture, temperature, and inorganic N concentrations suggested that the relative importance of these variables changed depending on year and treatment. While more research across a range of sites and management practices is needed, our findings support previous studies which have challenged IPCC methodology assumptions regarding the effects of residue removal on N2O emissions. We conclude there is inherent difficulty in predicting the impacts of residue removal due to the complexity of soil processes underlying N2O emissions coupled with inter‐annual weather variability in this rainfed continuous corn system. Future efforts to evaluate the net greenhouse gas emissions of cellulosic biofuel production may benefit from accounting for this uncertainty.

Factors That Influence Nitrous Oxide Emissions from Agricultural Soils as Well as Their Representation in Simulation Models: A Review

“…Applying crop residues to the soil generally increases N 2 O production mainly because the increased available organic C can be used in the N mineralization processes [108,136,137]. In addition, crop residues decomposition requires aerobic conditions, following which the drawdown of soil oxygen activates denitrification [44].…”

The broad impacts of corn stover and wheat straw removal for biofuel production on crop productivity, soil health and greenhouse gas emissions: A review

“…Incorporation of crop residues resulted in mixed effects on N 2 O emissions, and responses are mostly strongly influenced by soil texture, feedstock quality and climate variability (Yuan et al, 2018). Gentile et al (2008) measured a reduction of fertilizer-derived N 2 O emissions when urea (120 kg N/ha) was applied with a low-quality corn feedstock (42% C, 1.3% N, C:N ratio of 31, 3.1% lignin, 1.1% polyphenols) at ~9.5 Mg/ha in two coarse textured soils in Zimbabwe, likely explained by an increased in the N immobilization from the fertilizer.…”

“…Incorporation of crop residues resulted in mixed effects on N 2 O emissions, and responses are mostly strongly influenced by soil texture, feedstock quality and climate variability (Yuan et al, 2018). Gentile et al.…”

Impacts of corn stover removal on carbon dioxide and nitrous oxide emissions

“…In an Iowa residue removal study, N 2 O emissions were greater with CT than NT at the 0 and 50% removal rates, but they were similar at the 100% removal rates (Guzman et al, 2015). Yuan, Greer, Nafziger, Villamil, and Pittelkow (2018) reported lower N 2 O emissions under NT compared with CT in 2 out of 3 yr in a recent corn study. Elevated N 2 O emissions under CT were observed in a study on the same soil type under a winter wheat-corn-soybean rotation, whereby 3-yr N 2 O emissions with CT were on average 4.19 kg N ha −1 compared with 3.50 kg N ha −1 under NT (Drury et al, 2012).…”