## 4 Discussion  
### Comprehensive Analysis of Evaluation Results  
We adopted a scientific theoretical framework and an evaluation index system. Previous studies evaluating cultivated land quality considered soil health, \"functional management\", soil stress, and the \"short board effect\" [54; 55]. Based on these foundations, we constructed an evaluation framework of \"Cultivated Land Quality-Function/Degradation Risk-Evaluation Indicators.\" The evaluation index system is divided into two parts: cultivated land function and degradation risk. This approach has not been previously used in the evaluation of cultivated land quality in China. Traditional evaluations have mainly focused on cultivated land resources and production functions, without assessing the multi-functionality and sustainable protection and utilization of cultivated land. When choosing indicators, [PERSON] [20] pointed out that climatic factors are usually not included in cultivated land quality evaluation. Our study addresses this by incorporating indicators such as annual precipitation and accumulated temperature into the evaluation. Moreover, for different degradation risks, we referred to the European Union soil environmental quality system. This study also introduced soil biological indicators to improve the evaluation accuracy [56]. In summary, through a comprehensive evaluation from multiple perspectives and indicators, this study significantly enhances the evaluation grade of cultivated land quality in black soil regions. Comparing the results of this study with the \"Bulletin on the quality grades of cultivated land in China in 2019\" (hereinafter referred to as the \"Bulletin\"), significant differences are found. The \"Bulletin\", based on the national standard \"Cultivated Land Quality Grade\"  
Figure 6: Spatial distribution of comprehensive cultivated land quality assessment results in the black soil of Northeast China (BSNC) region. The right-hand side of the figure presents the proportional area of each evaluation grade across different regional types, providing a clear comparison of cultivated land quality levels in various areas. (GB/T 33469-2016) [57], divides cultivated land quality into ten grades, with Grades 1 to 4 accounting for 67.29% of the total cultivated land area in Northeast China. We divide cultivated land quality into five grades, assuming that Grade I corresponds to Grades 1 and 2 in the \"Bulletin\". Our results show that Grades 1 to 4 account for 28.46% of the total cultivated land area, which is significantly lower than the \"Bulletin\" results. [PERSON] [4] evaluated 320 counties in the BSNC, showing that the overall quality of cultivated land is relatively good, with an average grade of 3, indicating a high grade. In contrast, our study shows that Grades 5 and 6 account for 48.61% of the total area, suggesting that most of the cultivated land is of moderate quality [47]. This discrepancy may be due to our study considering the impact of degradation risk on cultivated land quality and incorporating it as a limiting factor in the evaluation system, emphasizing the sustainable utilization of cultivated land. Therefore, the evaluation results of this study are more conservative yet somewhat more progressive compared to previous studies, but they are also more comprehensive and scientific. To analyze the coupling between cultivated land functions and degradation risks, we employed a bivariate analysis method to examine the spatial distribution of different levels of cultivated land functions and degradation risks. As shown in Figure 7, most regions exhibit high-high or low-low distributions of cultivated land functions and degradation risks. In the SNP and SJP regions, both cultivated land functions and degradation risks are at higher levels. In the CBMEL, WS, and DXXXL regions, both cultivated land functions and degradation risks are at lower levels. However, in the LHP, low-level cultivated land functions and high-level degradation risks coexist.