## 3 Results and Discussion
### Distribution of National Differences  
As shown in this comparison of the different national/regional implementations of the USLE, it is hardly possible to derive reasonable standardized soil conservation rules on a larger scale. This is especially problematic as the different methods do not simply lead to a bias of modelled erosion of all fields, but also change the catchment internal arrangement of fields with low to high erosion rates (Figure 4B,C,E,G,I,J). In BY and AT, the most pronounced differences between modelled field-specific erosion from different methods were found for small fields with low erosion, which regarding soil conservation is more or less unproblematic. However, in some cases, there seemed to be a tendency that the relative differences between methods increase with increasing erosion (\(>5\,\mathrm{t\,ha^{-1}}\) a\({}^{-1}\)) (Figure 4B,E,G), which might lead to wrong decisions with respect to allocating soil conservation measures. In practice, this study underlines that soil erosion assessment, as well as erosion control, highly depends on the region or nation. There are very different approaches, requirements, and lists of soil control measures and technologies, which are applied within individual countries. The same methods of determination of the necessity of the implementation measures and critical values differ from country to country. While in Austria, farmers are required to follow GAEC (Good Agricultural and Environmental Conditions) standards to fulfil requirements of Cross Compliance policy, which do not include any soil erosion control measures, in CZ, eight standards of GAEC are implemented, where two of them deal with soil erosion control (and are based on the above-introduced methodology of soil erosion risk quantification). The list of measures applicable to fulfil requirements varies in time, according to political discussion of individual professional clusters within the agricultural chamber--i.e., removing stones is accepted as a soil erosion control measure within potato production to fulfil the GAEC 5 requirements in CZ. In BY, different initiatives exist using erosion modelling to encourage farmers to adopt soil conservation measures. These are mostly orientated towards the reduction of off-site effects and meet the targets of the Water Framework Directive [11]. The same is true concerning of determination of fields where measures are required to apply. Different approaches, input values, and detailed methodologies (as documented in previous paragraphs) are implemented at state level within the three countries compared within the paper. If standards were applied across borders, high inequity would be introduced for individual countries in the sense of what measures are required to be respected/implemented by individual farmers.  
Furthermore, the process of seeking optimum methods and input data, updated tolerable soil losses, and critical values to determine soil conservation measures in individual countries is very dynamic. Since the beginning of 2020, for example, a new approach for soil erosion protection has been planned by the Ministry of Agriculture in CZ. In BY, the administration of the Bavarian State Research Centre for Agriculture is discussing the use of rainfall radar data to derive yearly and seasonal rainfall erosivity data in a 1 km \(\times\) 1 km grid [54]. Last but not least, the AT results presented in this paper have to be considered as intermediate, since the computation methods of the \(LS\) and \(C\) factors were adapted from a periodic report of an ongoing project. Final results with revised \(LS\) and \(C\) factor computations have become available only after termination of this work [55]. The updated information demonstrates an overall reduction of erosion by approximately 20% but a similar spatial distribution of soil loss compared to the methodology used in this study.