Interannual variability and legacy impacts of climate change and nitrogen fertilization on corn yield and soil nitrous oxide emissions: a modeling approach

Climate change and nitrogen application significantly influence agricultural productivity and soil greenhouse gas emissions. However, the impacts of interannual climate variability and the legacy effects of nitrogen application on corn yield and soil nitrous oxide (N₂O) emissions remain poorly understood. In this study, we utilized the DeNitrification-DeComposition (DNDC) model to simulate corn yield and soil N₂O emissions over a 40-year period (1981~2020). We designed a series of experiments by shifting climate year data and altering nitrogen application rates to quantify interannual variability in corn yield and soil N₂O emissions, as well as to disentangle the contributions of climate variability and nitrogen legacy effects. The results showed large interannual variability in both corn yield and soil N₂O emissions. Corn yield was primarily driven by changes in growing season precipitation, while soil N₂O emissions were influenced by precipitation, exchangeable NH₄⁺, nitrification-denitrification processes. Severe drought strongly reduced corn yield, while soil N₂O emissions exhibited a gradual yet pronounced legacy effect of nitrogen application, increasing from 2 kg N ha^-1 to approximately 5 kg N ha^-1 over the 40-year period. High nitrogen application rates amplified the interannual variability of both corn yield and soil N₂O emission. This study highlights the relatively weak influence of interannual climate variability compared to the stronger legacy effects of nitrogen application on crop yield and soil N₂O emissions, providing valuable insights for sustainable agricultural and environmental management.