The Federal Administrative Court (BVerwG) has declared the Bavarian Implementing Ordinance to the Fertiliser Ordinance invalid because it is not based on an effective authorisation. The four judicial review proceedings brought by affected farmers were therefore successful (Ref.: 10 CN 1.25, 10 CN 2.25, 10 CN 3.25 and 10 CN 4.25 of 24 October 2025). However, the error can be traced back to the basis of authorisation under federal law for the Bavarian implementing ordinance: Section 13a (1) of the Fertiliser Ordinance (DüV) does not specify exactly which areas are to be designated as polluted and are therefore subject to stricter fertiliser restrictions, the Federal Administrative Court found. A general administrative regulation on the designation of nitrate-polluted areas (AVV GeA 2022) is not sufficient; rather, a law is required. In addition, requirements for the density of measuring points and the type of procedures used to delimit polluted from unpolluted areas must be defined and it must be clarified whether and to what extent peripheral areas should be included.