Liu K, Machado P V F, Lin S, Drury C F, Lemke R L
Agriculture and Agri-Food Canada, 1 Airport Road, Swift Current, SK, S9H 3X2, Canada.
Agriculture and Agri-Food Canada, 1 Airport Road, Swift Current, SK, S9H 3X2, Canada.
J Environ Manage. 2024 Nov;370:122830. doi: 10.1016/j.jenvman.2024.122830. Epub 2024 Oct 5.
Production of agricultural crops with a low greenhouse gas (GHG) footprint is essential to mitigate the adverse effects of climate change. The inclusion of pulse crops in cereal-based rotations can enhance environmental quality by providing biologically fixed N and thereby reducing the amount of synthetic N fertilizer required for the crop rotation. The inclusion of pulse crop has the potential to reduce NO emissions from the agricultural system in both the legume phase and the subsequent wheat phase of the rotation. However, long-term studies are necessary to thoroughly investigate NO emissions from rotations with pulse crops, particularly in the semiarid region where pulse crops are frequently grown. In the present study, we evaluated cumulative NO emissions and emission intensity during the rotation cycle. The assessment was conducted over 4 years, during two complete 2-yr cycles of an established rotation (years 9-12), under the climatological conditions of 2018-2021. Four rotations including wheat-wheat, pea-wheat, lentil-wheat, and chickpea-wheat were selected from a trial in Swift Current, Saskatchewan (semiarid prairies/Brown Chernozem). Our experiment was subjected to below normal precipitation, with interannual variations in climate and the last 2 years (2020-21) were drier than the first two years (2018-2019). Under such climate, PW and LW demonstrated to be environmentally sustainable, always exporting the highest N in grains (133 kg N ha averaged across PW and LW and cycles) and consistently achieving the lowest NO intensity (2.8 g NO-N per kg exported N averaged across PW and LW and cycles). Continuous wheat presented inconsistent results, with a significant reduction in exported N from years 9-10 to 11-12 (the driest cycle). Because WW also promoted the highest cumulative NO emissions, NO intensity over the 2-yr was always the highest for WW. The CW consistently promoted the lowest N exports and was not resilient to dry soil conditions, with 23% lower exported N in years 11-12 than in years 9-10. Hence including pulse crops with pea or lentil in the rotation reduced NO emissions and enhanced wheat yield resiliency.
种植温室气体（GHG）足迹低的农作物对于减轻气候变化的不利影响至关重要。在以谷物为主的轮作中纳入豆类作物可以通过提供生物固氮来提高环境质量，从而减少轮作所需的合成氮肥量。纳入豆类作物有可能减少农业系统在豆类阶段和轮作后续小麦阶段的一氧化氮排放。然而，需要进行长期研究以彻底调查豆类作物轮作中的一氧化氮排放，特别是在经常种植豆类作物的半干旱地区。在本研究中，我们评估了轮作周期内的一氧化氮累积排放量和排放强度。评估在4年期间进行，处于一个既定轮作的两个完整的2年周期（第9 - 12年），在2018 - 2021年的气候条件下。从萨斯喀彻温省斯威夫特卡伦特（半干旱草原/棕色黑钙土）的一个试验中选择了四种轮作，包括小麦 - 小麦、豌豆 - 小麦、小扁豆 - 小麦和鹰嘴豆 - 小麦。我们的实验降水低于正常水平，气候存在年际变化，最后两年（2020 - 21年）比前两年（2018 - 2019年）更干燥。在这种气候条件下，豌豆 - 小麦和小扁豆 - 小麦被证明在环境上是可持续的，始终在谷物中输出最高的氮（豌豆 - 小麦和小扁豆 - 小麦以及各周期平均为133千克氮/公顷），并且始终实现最低的一氧化氮排放强度（豌豆 - 小麦和小扁豆 - 小麦以及各周期平均每千克输出氮排放2.8克一氧化氮 - 氮）。连作小麦的结果不一致，从第9 - 10年到11 - 12年（最干旱的周期）输出氮显著减少。因为连作小麦也促进了最高的一氧化氮累积排放量，所以在两年期间连作小麦的一氧化氮排放强度始终是最高的。鹰嘴豆 - 小麦始终促进最低的氮输出，并且对干旱土壤条件没有恢复力，在11 - 12年的输出氮比9 - 10年低23%。因此，在轮作中纳入豌豆或小扁豆等豆类作物可减少一氧化氮排放并提高小麦产量恢复力。
