The release of environmental pollutants, which partly emanates from the application of chemical inputs, is a major global concern. Attempt to determine the methods to reduce environmental risk of rice cultivation are required. Selecting the best cover crop in rice rotation is necessary. The novelty of this research versus current knowledge is that life cycle assessment (LCA) has not been applied to assess the environmental impacts of crop rotation systems in paddy fields in Iran. Hence, the life cycle of rice cultivars in different crop rotations was assessed in Neka region, northern Iran from 2017 to 2018. All the management practices/inputs of local (‘Tarom Hashemi’) and improved (‘Shiroodi’) rice cultivars were monitored. After recording the data of 100 selected paddy fields for each cultivar, nine cover crop-rice rotations (fallow-rice, clover-rice, rape seed-rice, wheat-rice, barley-rice, faba bean-rice, garlic-rice, lettuce-rice and cabbage-rice) were identified. Functional unit of LCA was 1-ton rice yield. The results demonstrated that the maximum and minimum amount of nitrogen, phosphorus and potassium were applied in fallow-rice and clover-rice rotations, respectively. The highest paddy yield for local (4856 kg ha −1 ) and improved (7745 kg ha −1 ) cultivars was produced in clover-rice rotation. Fossil CO 2 eq, biogenic CO 2 eq, global warming potential (GWP) 100a, terrestrial acidification (TA) and fossil depletion (FD) of local cultivar were 11.79%, 34.76%, 13.35%, 15.48%, and 20.13% greater than improved cultivar. The most cumulative energy demand (CED) in both cultivars was obtained for fallow-rice rotation followed by rape seed-rice rotation. The highest emission of biogenic CO 2 eq for both cultivar was observed in rape seed-rice and fallow-rice rotations. The lowest amount of GWP 100a was calculated in clover-rice rotation for local and improved cultivars (248.08 and 240.5 kg CO 2 eq). In both cultivars, the most and lowest amount of TA, freshwater eutrophication (FEU), ozone depletion (OD) and FD was emitted in fallow-rice and clover-rice rotations. Among the crop rotations, clover-rice and fallow-rice had significantly lowest and most emission of heavy metals in the air, water and soil, respectively. As a matter of fact, the environmental emissions of the study is straightly linked to the application of inputs and field management practices. According to this, the lowest amount of environmental emissions for both cultivars was observed in clover-rice rotation. The emissions released from environmental pollutants are positively correlated with the application of inputs and field management practices for crop species in rotation system. In conclusion, clover-rice rotation showed the potential to save non-renewable energies (fuel, nitrogen, and etc.) with higher paddy yield which is considered to be environmentally friendly crop in rotation with respect to reduce emissions of GHG.

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伊朗北部水稻品种轮作系统的生命周期评估

环境污染物的释放，部分源自化学投入物的应用，是全球关注的主要问题。需要尝试确定降低水稻种植环境风险的方法。在水稻轮作中选择最好的覆盖作物是必要的。与当前知识相比，这项研究的新颖之处在于，生命周期评估 (LCA) 尚未应用于评估伊朗稻田作物轮作系统的环境影响。因此，对 2017 年至 2018 年伊朗北部 Neka 地区不同轮作水稻品种的生命周期进行了评估。 监测了当地（“Tarom Hashemi”）和改良（“Shiroodi”）水稻品种的所有管理实践/投入. 在记录每个品种的 100 个选定稻田的数据后，九次覆盖作物 - 水稻轮作（休耕 - 水稻，三叶草水稻、油菜籽水稻、小麦水稻、大麦水稻、蚕豆水稻、大蒜水稻、生菜水稻和卷心菜水稻）。LCA 的功能单位是 1 吨水稻产量。结果表明，在休耕稻和三叶稻轮作中，氮、磷和钾的施用量分别为最大和最小量。本地（4856 kg ha -1 ）和改良（7745 kg ha -1 ）栽培品种的最高水稻产量是在三叶草-水稻轮作中生产的。化石CO 2 eq、生物CO 2 eq、全球变暖潜能值(GWP) 100a、陆地酸化(TA)和化石耗竭(FD)分别比当地品种高11.79%、34.76%、13.35%、15.48%和20.13%改良品种。休耕-水稻轮作其次是油菜种子-水稻轮作，获得了两个品种中最大的累积能量需求（CED）。在油菜种子水稻和休耕水稻轮作中观察到两种栽培品种的生物源 CO 2 eq 排放量最高。对于本地和改良品种（248.08 和 240.5 kg CO 2 当量），在三叶草-水稻轮作中计算出最低的 GWP 100a 量。在这两个品种中，在休耕稻和三叶草轮作中排放的 TA、淡水富营养化 (FEU)、臭氧消耗 (OD) 和 FD 量最高和最低。在轮作中，三叶草和休闲稻分别在空气、水和土壤中的重金属排放量显着最低和最高。事实上，研究的环境排放与投入和现场管理实践的应用直接相关。据此，在三叶草-水稻轮作中观察到两个品种的环境排放量最低。环境污染物释放的排放与轮作系统中作物物种的投入和田间管理实践的应用呈正相关。总之，三叶草-水稻轮作显示了节省不可再生能源（燃料、氮等）的潜力，水稻产量更高，在减少温室气体排放方面，轮作被认为是对环境友好的作物。