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<p>Cover crop residues can affect nitrous oxide (N<sub>2</sub>O) emissions when incorporated. This case study investigated the magnitude and temporal dynamics of N<sub>2</sub>O emissions as influenced by tillage practice and cover crop composition. Perennial ryegrass (RG<i>, Lolium perenne</i>), plantain (PL, <i>Plantago lanceolata</i>), RG-PL, and RG-PL-red clover mix (RG-PL-RC, <i>Trifolium pratense</i>) were either terminated by shallow rotovation followed by moldboard ploughing (ro + plou), or directly by ploughing (plou), whereafter spring barley (<i>Hordeum vulgare</i>) was established. The N<sub>2</sub>O flux was monitored continuously with eight automated chambers from mid-March until mid-June 2021 (DOY 72–166). The ro + plou treatments had on average 11% of cumulative N<sub>2</sub>O emissions after rotovation but before ploughing, while in plou treatments only 2% of cumulative N<sub>2</sub>O emissions occurred before ploughing. Across treatments, 92% of emissions occurred after ploughing, but only after rainfall in May. The plou treatments generated more, high-magnitude and short-duration N<sub>2</sub>O peaks than ro + plou. RG, PL, and RG-PL had predominantly daytime maximum N<sub>2</sub>O emissions, while RG-PL-RC had more nighttime maximum N<sub>2</sub>O emissions. Cumulative N<sub>2</sub>O-N emissions were higher for plou (3.6–7.0&#xa0;kg&#xa0;ha<sup>−1</sup>) than for ro + plou (1.2–3.8&#xa0;kg&#xa0;ha<sup>−1</sup>). This was also true for yield-scaled N<sub>2</sub>O emissions. N<sub>2</sub>O emissions were directly related to soil water-filled pore space in plou treatments, whereas there was a time lag of up to 5&#xa0;days for ro + plou treatments which was explained by a more advanced degradation of residues when soil conditions became conducive to N<sub>2</sub>O emissions. Rotovation prior to ploughing could thus mitigate N<sub>2</sub>O emissions compared to ploughing but this may require a period with well-drained soil conditions.</p>

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Nitrous oxide emissions as influenced by tillage practice for cover crop termination

  • 期刊论文

  • 发表日期：

    2025年12月15日

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  • Christian Dold,
  • Chiara De Notaris,
  • Esben Øster Mortensen,
  • Jim Rasmussen,
  • Søren O. Petersen

摘要

Cover crop residues can affect nitrous oxide (N2O) emissions when incorporated. This case study investigated the magnitude and temporal dynamics of N2O emissions as influenced by tillage practice and cover crop composition. Perennial ryegrass (RG, Lolium perenne), plantain (PL, Plantago lanceolata), RG-PL, and RG-PL-red clover mix (RG-PL-RC, Trifolium pratense) were either terminated by shallow rotovation followed by moldboard ploughing (ro + plou), or directly by ploughing (plou), whereafter spring barley (Hordeum vulgare) was established. The N2O flux was monitored continuously with eight automated chambers from mid-March until mid-June 2021 (DOY 72–166). The ro + plou treatments had on average 11% of cumulative N2O emissions after rotovation but before ploughing, while in plou treatments only 2% of cumulative N2O emissions occurred before ploughing. Across treatments, 92% of emissions occurred after ploughing, but only after rainfall in May. The plou treatments generated more, high-magnitude and short-duration N2O peaks than ro + plou. RG, PL, and RG-PL had predominantly daytime maximum N2O emissions, while RG-PL-RC had more nighttime maximum N2O emissions. Cumulative N2O-N emissions were higher for plou (3.6–7.0 kg ha−1) than for ro + plou (1.2–3.8 kg ha−1). This was also true for yield-scaled N2O emissions. N2O emissions were directly related to soil water-filled pore space in plou treatments, whereas there was a time lag of up to 5 days for ro + plou treatments which was explained by a more advanced degradation of residues when soil conditions became conducive to N2O emissions. Rotovation prior to ploughing could thus mitigate N2O emissions compared to ploughing but this may require a period with well-drained soil conditions.