## 4 Discussion  
The measurement of crop NPP relies on well-established principles and methods, primarily utilizing model estimations based on remote sensing data. However, these estimates can be affected by weather conditions. The accuracy of these measurements can introduce inaccuracies in crop NPP estimation, and variations in meteorological data interpolation methods can lead to errors. Consequently, the results revealed that the cumulative corn NPP in the Fen River Basin from May to October 2020 reached a total of 368.65 gC/m\({}^{2}\). Notably, corn NPP exhibited a positive association with air temperature and precipitation but displayed a negative correlation with solar radiation. [PERSON] et al. [44] highlighted precipitation as the primary factor controlling NPP variations in semi-arid and arid regions, while temperature exerted greater influence in semi-humid and humid regions. Additionally, [PERSON] et al. [45] reported precipitation as the key driver of NPP variability in Shaanxi Province. Given the similar climates of Shanxi and Shaanxi provinces, these findings resonate with the results of this study. The inter-annual fluctuations in corn NPP observed in this study may stem from the combined influence of natural environmental factors and human activities. [PERSON] et al. [46] observed an increase in mean annual precipitation and mean annual temperature in Shanxi Province by 99.20 mm and 1.2 \({}^{\circ}\)C, respectively, between 1959 and 2008, indicating an improved natural environment and enhanced crop growth. Moreover, Shanxi Province has implemented various ecological conservation and construction projects in recent years, such as land-to-forest conversion and watershed management, thereby fostering NPP growth. A similar investigation conducted by [PERSON] et al. [26] on winter wheat and summer corn in the Huang-Huai-Hai Plain indicated that the lowest average NPP for summer corn was observed in the plains of the northern Jiangsu Province, measuring at 482.10 gC/m\({}^{2}\). NPP was positively linked to solar radiation and inversely related to temperature and precipitation. Comparing these findings, the NPP values of summer corn in the Fen River Basin were notably lower than those in the Huang-Huai-Hai Plain. This discrepancy can be attributed to various factors such as climate, soil, and topography, affecting corn growth. The Huang-Huai-Hai Plain, located in the southern region of China, benefits from relatively flat terrain and more favorable climatic conditions conducive to crop growth. However, the Fen River Basin has a more intricate topography and encounters a greater variety of climatic conditions, which may impede the growth of corn. When examining the relationship between NPP and climatic factors, distinctions emerged between the Fen River Basin and Huang-Huai-Hai Plain. This distinction resulted from the fact that the corn growing season is in summer, a period characterized by solar radiation as the limiting factor. In the southern region, there were more rainy days, necessitating higher levels of solar radiation for crop growth, whereas, in the northern region, rainfall decreased, constraining the crop growth. Consequently, in the northern area, NPP was negatively correlated with solar radiation and positively correlated with rainfall and temperature. Conversely, this relationship was reversed in the southern region. [PERSON] et al. [18] investigated corn NPP in Iowa and Illinois, USA, reporting an estimated value of 384.00 gC/m\({}^{2}\). The key reason for this is the similarity between the climate conditions, topography, and landscape of the Fen River Basin and those of Iowa and Illinois in the USA. These results are consistent with the findings presented in this study, establishing a scientific reference value for the simulation results. Given the linear relationship between aboveground biomass and carbon sequestration in corn and NPP, the results and distribution were similar to those for NPP.