Cultivated peatlands are widespread in temperate and boreal climate zones. For example, in Europe about 15% of the pristine peatland area have been lost through drainage for agricultural use. When drained, these organic soils are a significant source of greenhouse gas (GHG) emissions. To reach climate goals, the agricultural sector must reduce its GHG emissions, and one measure that has been discussed is changing land use from cropland to ley production or perennial green fallow. This management change leads to lower reported emissions, at least when using the IPCC default emission factors (EF) for croplands and grasslands on organic soils (IPCC 2014). However, there was a limited background dataset available for developing the EFs, and other variables than management affect the comparison of the land use options when the data originates from varying sites and years. Thus, the implications for future policies remain uncertain. This protocol describes the methodology to conduct a systematic review to answer the question of whether ley production or perennial green fallow can be suggested as a valid alternative to annual cropping to decrease GHG emissions on organic soils in temperate and boreal climate. Publications will be searched in different databases and bibliographies of relevant review articles. The comprehensiveness of the search will be tested through a list of benchmark articles identified by the protocol development team. The screening will be performed at title and abstract level and at full text level, including repeatability tests. Eligible populations are organic agricultural soils in temperate and boreal climate regions. Interventions are grasslands without tillage for at least 3 years, and comparators are annual cropping systems within the same study as the intervention. The outcome must be gas fluxes of either carbon dioxide (CO2), nitrous oxide (N2O), or methane (CH4), or any combination of these gases. Studies will go through critical appraisal, checking for internal and external validity, and finally data extraction. If possible, a meta-analysis about the climate impact of perennial green fallow compared to annual cropping on organic soils will be performed.

中文翻译：

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莱地或多年生休耕地的温室气体通量是否低于耕地有机土壤？系统审查协议

耕种泥炭地广泛分布于温带和寒带气候区。例如，在欧洲，大约 15% 的原始泥炭地面积因农业用途的排水而消失。当排水时，这些有机土壤是温室气体（GHG）排放的重要来源。为了实现气候目标，农业部门必须减少温室气体排放，而已讨论的一项措施是将土地用途从耕地改为利地生产或多年生绿色休耕。这种管理变化导致报告的排放量降低，至少在使用 IPCC 默认排放因子（EF）用于有机土壤上的农田和草地时是如此（IPCC 2014）。然而，可用于开发 EF 的背景数据集有限，当数据来自不同地点和年份时，管理以外的其他变量会影响土地利用方案的比较。因此，对未来政策的影响仍不确定。本议定书描述了进行系统审查的方法，以回答以下问题：是否可以建议将雷生产或多年生绿色休耕作为一年生作物的有效替代方案，以减少温带和寒带气候下有机土壤的温室气体排放。出版物将在不同的数据库和相关评论文章的参考书目中进行检索。搜索的全面性将通过协议开发团队确定的基准文章列表进行测试。筛选将在标题和摘要级别以及全文级别进行，包括可重复性测试。符合条件的人群是温带和寒带气候地区的有机农业土壤。干预措施是至少 3 年没有耕种的草原，比较对象是与干预措施相同的研究中的一年生种植系统。结果必须是二氧化碳 (CO2)、一氧化二氮 (N2O) 或甲烷 (CH4) 或这些气体的任意组合的气体通量。研究将经过严格评估、检查内部和外部有效性，最后提取数据。如果可能的话，将对多年生绿色休耕与有机土壤上一年生作物的气候影响进行荟萃分析。和比较对象是与干预措施相同的研究中的一年生种植系统。结果必须是二氧化碳 (CO2)、一氧化二氮 (N2O) 或甲烷 (CH4) 或这些气体的任意组合的气体通量。研究将经过严格评估、检查内部和外部有效性，最后提取数据。如果可能的话，将对多年生绿色休耕与有机土壤上一年生作物的气候影响进行荟萃分析。和比较对象是与干预措施相同的研究中的一年生种植系统。结果必须是二氧化碳 (CO2)、一氧化二氮 (N2O) 或甲烷 (CH4) 或这些气体的任意组合的气体通量。研究将经过严格评估、检查内部和外部有效性，最后提取数据。如果可能的话，将对多年生绿色休耕与有机土壤上一年生作物的气候影响进行荟萃分析。