Rice Genomics and Genetics 2024, Vol.15, No.4, 203-211 http://cropscipublisher.com/index.php/rgg 209 incorporation and proper fertilization practices can enhance soil nitrogen content and improve soil health (Ku et al., 2019). The observed decline in grain yield due to nitrogen bonded to aromatic compounds in soil organic matter is also supported by earlier research, which highlights the importance of managing soil nitrogen availability for sustainable crop production (Schmidt-Rohr et al., 2004). Long-term rice cultivation has both positive and negative effects on soil organic nitrogen dynamics. While it can enhance soil nitrogen accumulation and improve soil health through proper management practices, it can also lead to challenges such as soil acidification and reduced nitrogen availability. Understanding the driving factors, including climatic conditions and agricultural practices, is essential for optimizing soil nitrogen dynamics and ensuring sustainable rice production. 5 Concluding Remarks The long-term effects of rice cultivation on soil organic nitrogen (SON) dynamics have been extensively studied, revealing several key findings. Firstly, rice cultivation significantly increases soil total nitrogen (TN) and SON fractions, such as amino acid N, ammonium N, amino sugar N, and hydrolyzable unknown N, which stabilize within approximately 100 years of cultivation. The application of organic materials, such as milk vetch, rice straw, and poultry manure, has been shown to enhance soil aggregate mass and improve the concentration of organic carbon (C) and nitrogen (N) in both light and heavy soil fractions. Additionally, long-term organic fertilizer substitution not only increases rice yield but also improves soil properties and regulates soil bacterial communities, which are crucial for maintaining soil health and fertility. However, intensive rice cropping can lead to a decline in grain yield due to the decreased availability of soil nitrogen, particularly nitrogen bonded to aromatic compounds in soil organic matter. To sustain and improve soil fertility and rice yield, several agricultural practices are recommended. The continuous application of organic materials, such as compost, rice straw, and green manure, is highly effective in increasing soil organic carbon and nitrogen fractions, thereby enhancing soil structure and fertility. Combining organic and inorganic fertilizers can also sustain high rice yields and improve soil chemical and bacterial properties, which are essential for long-term soil health. Additionally, incorporating rice straw or amending manure to paddy soils is a preferred practice for maintaining soil organic carbon content and ensuring sustainable rice production. These practices not only improve soil fertility but also contribute to the stabilization and fixation of carbon and nitrogen in rice fields. Future research should focus on understanding the long-term impacts of different organic and inorganic fertilizer combinations on soil health and crop productivity. Studies should investigate the specific mechanisms through which organic materials influence soil microbial communities and their role in nutrient cycling and soil fertility. Additionally, research should explore the effects of different rice cultivation practices on the formation and stabilization of nitrogen-bonded aromatics in soil organic matter, which have been linked to yield declines in intensive rice cropping systems. Long-term field experiments and modeling studies are needed to evaluate the sustainability of various agricultural practices and their impact on soil organic carbon and nitrogen dynamics over extended periods. Finally, the development of innovative soil management strategies that integrate organic and inorganic inputs to optimize soil health and crop yield should be a priority for future research. Acknowledgments The authors extend sincere thanks to two anonymous peer reviewers for their invaluable feedback on the initial manuscript. Conflict of Interest Disclosure The authors affirm that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest. References Chen A., Zhang W., Sheng R., Liu Y., Hou H., Liu F., Ma G., Wei W., and Qin H., 2021, Long-term partial replacement of mineral fertilizer with in situ crop residues ensures continued rice yields and soil fertility: a case study of a 27-year field experiment in subtropical China., The Science of the Total Environment, 787: 147523. https://doi.org/10.1016/j.scitotenv.2021.147523
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