Journal of Cleaner Production：南方稻田作物生命周期评价及施肥方案优化

浙江大学公共管理学院李艳教授团队通过测土配方施肥试验，确定了鄂州市稻田作物施肥的最佳方案，既能保证粮食产量，又能减少环境污染。相关成果发表于Journal of Cleaner Production（IF=9.297）。

该研究得到国家重点研发计划项目、国家自然科学基金项目、浙江省自然科学基金项目的资助。

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Highlights

·Soil testing and formulated fertilization field data were applied.

·Rapeseed production had higher environmental emissions than rice production.

·Eutrophication contributed the most to environment pollution for crop production.

·Optimal fertilization guaranteed food sufficiency and reduced environment pollution.

Abstract

Although the application of synthetic fertilizers remarkably improves crop yields, their excessive application can bring about serious environmental pollution. However, previous studies largely focused on life cycle assessment about environmental risk and impact through measuring environmental emissions, or fertilization scheme recommendation with single optimization goal based on field experiments. In this study, we used soil testing and formulated fertilization field data from the experimental region (Ezhou, South China) to acquire the optimal application scheme of synthetic fertilizers for paddy field crops. Based on four crops (i.e. rapeseed, early rice, middle rice and late rice) and two rotation systems (i.e. rapeseed-rice rotation and rice-rice rotation), we applied the life cycle assessment method to analyze life cycle inventories and assess environmental impacts. The fertilizer production and resource consumption were defined as the initial boundary, and the crop production and environmental emissions were defined as the terminal boundary. Four crops were assessed and compared under 1t crop grain functional unit and 1hm² cropland area functional unit, and two rotation systems were assessed and compared under 1hm² cropland area functional unit. The environmental impact categories assessed were energy consumption, climate change, eutrophication, environmental acidification, land use and water consumption. Based on three fertilization schemes (i.e. fertilization on benchmark value (Scheme_b), yield balance value (Scheme_yb) and threshold value (Scheme_t)), we subsequently simulated crop yields and environmental emissions of fertilization schemes. The results show that the estimated environmental impact category indicators assessed by life cycle per t of rapeseed were higher than rice, and that per hm² of rapeseed-rice rotation were lower than rice-rice rotation. Eutrophication contributed the most (over 80%) to the environmental impact of producing 1t crop, followed by environmental acidification. Ammonia (NH₃) emission accounted for a high contribution to eutrophication (about 30%) or environmental acidification (about 90%), and nitrate ion (NO₃^-) loss contributed the most to eutrophication (about 40%). The results also show that paddy field crops reached maximum yields but caused greatest environmental impact under the Scheme_yb. Whereas, the Scheme_t could guarantee paddy field crops to keep average yields but cause minimum environmental impact, which was the optimal fertilization scheme. Our study indicates that producing 1t rice and 1hm² rapeseed-rice rotation had higher environmental benefit than producing 1t rapeseed and 1hm² rice-rice rotation respectively. Eutrophication could lead to the biggest threat to ecological environment, and the key to alleviating this environmental impact was reducing NH₃ volatilization and NO₃^- loss. Our work implies that the optimal fertilization scheme can both guarantee food sufficiency and reduce environmental pollution, which is applicable combining with soil testing and formulated fertilization technology in Ezhou.

以南方典型农业区湖北省鄂州市为例，应用生命周期评价和施肥方案模拟方法确定稻田作物化肥施用的最佳方案，分析了不同作物（油菜、早稻、中稻和晚稻）和不同轮作制度（油菜-水稻轮作、水稻-水稻轮作）的生命周期评价，评估了其环境影响，并采用“基准施肥”方案（Scheme_b）、“产量平衡施肥”方案（Scheme_yb）和“阈值施肥”方案（Scheme_t）对作物产量和环境排放进行了模拟。

表1 油菜-水稻轮作和水稻-水稻轮作系统的生命周期评价

从生命周期评价结果来看，单位产量油菜的环境排放高于水稻，单位面积油菜-水稻轮作系统的环境效益高于水稻-水稻轮作系统。单位产量作物对环境影响最大的是富营养化，其贡献率超过80%，对生态环境的威胁最大。其次是环境酸化。由于NH₃排放对富营养化和环境酸化的贡献都很大，分别约为30%和90%，NO₃^-损失对富营养化的贡献最大，约为40%，缓解综合环境影响的关键是减少NH₃挥发和NO₃^-损失。

表2 研究区各城镇施肥方案模拟

注：B代表Scheme_b方案，作为基准值，为100%；YB表示Scheme_yb，T表示Scheme_t。

根据施肥方案模拟结果，在Scheme_yb下，稻田作物产量最大，但综合环境影响最大，NH₃、NO₃^-、PO₄^3-排放最严重。Scheme_t既能保证稻田作物的产量维持平均水平，又能降低综合环境影响，说明测土配方施肥技术适用于鄂州地区。

研究表明，DNDC模型的区域适用性对于施肥评价和模拟至关重要，未来的农业施肥方案需要考虑更多的田间试验数据和区域实际情况（如复种）。本研究为在保证产量的前提下减少生态环境破坏，保持农业可持续发展提供了理论和实践参考，也为区域尺度测土配方施肥技术的应用奠定了坚实的基础。

责任编辑：宋潇

校对和审核：张阳  王农