Die Stickstoffbedarfswerte der Dngeverordnung (DV) fr Winterraps und Winterweizen sind 15-20% zu hoch angesetzt - eine Replik auf Kage et al. (2022): Stickstoffdngung zu Winterraps und Winterweizen

Kage et al. (2022) have presented a comprehensive and considerable evaluation and analysis of multi -location and multi-year trials with increasing N fertilisation rates for both winter rape and winter wheat with the aim of 'evaluating the DuV', and deriving 'optimal N fertilisation intensities' for these crops. The authors conclude that the specifications of the DuV regarding the nitrogen requirement values lead to economic losses of 18-20% for these two crops compared to fertilisation at the level of the economic optimum and that a further reduction of the fertilisation level by 20% as specified in the so-called 'red areas' is not necessary, as other measures are available to avoid nutrient losses. This statement is contested in the present paper: Taking into account (i.) adequate mathematical functions to describe the yield response to increasing N fertilisation; (ii.) the standard yields for winter wheat and winter rape in the DuV; and (iii.) the relationships between nitrogen balances and N losses via drainage water, it is shown that according to the purpose of the Fertiliser Act (1, paragraph 4: to avoid nutrient losses into the environment as far as possible) a reduction of the required N supply for winter wheat and winter rape by 15-20% is required. The adjustment of the corresponding figures in the DuV on the part of the BMEL is thus essential. This reduction in fertiliser requirements ensures both sustainable preservation of soil fertility and minimises nutrient surpluses at high yield levels. In addition, this adjustment is a motivation to implement further measures of good practice outlined in the article on farms at a large scale and optimize their fertilizer management according to the EU Farm to Fork strategy.