The overuse of fertilizers in agriculture and their entry into freshwater has many negative impacts on biodiversity and poses problems for drinking water resources in Germany. In response to exceeding levels of nitrate concentrations in groundwater in parts of the country, an intense public dispute evolved and a significant policy change in fertilizer regulation occurred in 2020. Based on the German case of agricultural water pollution, this study demonstrates in an innovative way how discourse network analysis is a fruitful method for the integrated study of actor coalitions and their use of narrative strategies in public debate. Theoretically, the study draws on the narrative policy framework (NPF) to explain how actor coalitions use narrative strategies to attempt to influence policymaking on water pollution by agricultural activities. The empirical analysis builds on newspaper articles and press releases disseminated between 2010 and 2020. The results demonstrate how two opposing actor coalitions with congruent policy beliefs formed in the struggle over fertilizer regulation. These not only diverged in their policy beliefs but also differed in their use of narrative strategies to try to expand or contain the policy issue. More precisely, the coalitions adapted their narratives over time in response to changes in the likelihood to win or lose. Furthermore, the results suggest the coalition in favor of stricter fertilizer regulation was more sophisticated in its effort to mobilize specific target groups. Overall, the article provides a valuable contribution to the literature on the NPF by combining research on coalition formation and policy narratives.

农业中过度使用化肥及其进入淡水对生物多样性产生了许多负面影响，并给德国的饮用水资源带来了问题。为应对该国部分地区地下水中硝酸盐浓度超标的问题，引发了激烈的公众争议，2020 年化肥监管政策发生重大变化。本研究以德国农业水污染案例为基础，以创新的方式论证话语网络分析如何成为综合研究行动者联盟及其在公共辩论中使用叙事策略的富有成效的方法。从理论上讲，该研究利用叙事政策框架 (NPF) 来解释行动者联盟如何使用叙事策略来试图影响农业活动对水污染的决策。实证分析建立在 2010 年至 2020 年间传播的报纸文章和新闻稿的基础上。结果表明，两个具有一致政策信念的对立行动者联盟是如何在肥料监管的斗争中形成的。他们不仅在政策信念上存在分歧，而且在使用叙事策略试图扩大或遏制政策问题方面也存在差异。更准确地说，联盟随着时间的推移调整了他们的叙述，以应对输赢可能性的变化。此外，结果表明，支持更严格的肥料监管的联盟在动员特定目标群体方面更加复杂。总体而言，本文通过结合对联盟形成和政策叙述的研究，为 NPF 文献提供了宝贵的贡献。