Policy-Driven Shifts in Crop Choices – A Case Study on the German Implementation of the EU Nitrates Directive

This file is a discussion paper on "Policy-Driven Shifts in Crop Choices – A Case Study on the German Implementation of the EU Nitrates Directive", linked to WP 4 activities of the Brightspace project. Farmers’ crop choices are shaped by economic factors, natural conditions, and policy interventions. While some policies directly target cropping decisions, others can unintentionally influence farmers’ crop choices. Understanding these indirect effects is essential for preventing unintended environmental consequences and accurately assessing the economic implications. In Germany, the revised implementation of the EU Nitrates Directive introduced extensive management restrictions in areas with high nitrate pollution, such as additional restrictions on manure application and overall fertilizer use. However, its impact on farm-level decision-making, particularly cropping decisions, remains largely unexplored. This study investigates whether the revised implementation of the EU Nitrates Directive in Germany leads to short-term adjustments in crop choices, shedding light on how regulatory changes shape agricultural land use. We apply a differences-in-differences approach with staggered treatment timing to account for changes in the definition of nitrate-polluted areas. Estimations are performed within a Probabilistic Programming framework, providing a Bayesian representation of uncertainty. As a case study, we analyze the German federal state of North RhineWestphalia, where up to 30% of agricultural land is designated as nitrate-polluted. Our findings indicate that the short-term effects of nitratepolluted area designations on crop choices are modest, with all observed changes being smaller than 2% points. Overall, the policy has a reducing effect on the cultivation of maize and winter cereals other than winter wheat while an increasing effect on winter wheat, sugar beet, and rapeseed. However, these effects vary over time, suggesting that farmers adjust their adoption behavior as the policy remains in place longer and larger areas are classified as nitrate-polluted. From a policy perspective, we conclude that measures might be less limiting than suggested by the public debate and that missing knowledge might hinder the optimal adaption of crop choices. --------------- Funding acknowledgement Funded by the European Union. Grant Agreement No. 101060075. Views and opinions expressed are those of the authors only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the granting authority can be held responsible for them. UK Research and Innovation Project Code: 10047415 https://gtr.ukri.org/projects?ref=10047415 This work is further also funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy – EXC 2070 – 390732324 (PhenoRob). Citation Kuhn, T., Pahmeyer, C., Baumert, J., & Storm, H. (2026). Policy-Driven Shifts in Crop Choices – A Case Study on the German Implementation of the EU Nitrates Directive. Zenodo. https://doi.org/10.5281/zenodo.18754494 Legal notice This document was produced under the terms and conditions of Grant Agreement No. 101060075 for the European Commission. It does not necessary reflect the view of the European Union and in no way anticipates the Commission’s future policy in this area. The European Commission is not liable for any consequence stemming from the reuse of this publication. © BrightSpace, 2026 The reuse of this document is authorised under a Creative Commons Attribution 4.0 International (CCBY 4.0) licence (https://creativecommons.org/licenses/by/4.0/). This means that reuse is allowed provided appropriate credit is given and any changes are indicated. For any use or reproduction of elements that are not owned by the BrightSpace consortium, permission may need to be sought directly from the respective right holders. Project information BrightSpace Horizon Europe project Grant Agreement No. 101060075 https://cordis.europa.eu/project/id/101060075 CALL: Innovative governance, environmental observations and digital solutions in support of the Green Deal WORK PROGRAMME Topic ID: HORIZON-CL6-2021-GOVERNANCE-01-12 EU agriculture within a safe and just operating space and planetary boundaries BrightSpace Project coordination: Wageningen Economic Research, The Hague, NL Contact: brightspace.wser@wur.nl | Website: www.brightspace-project.eu Project duration: 1 November 2022 – 31 October 2027