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ABSTRACT
The long-term effects of rice straw incorporation on soil organic carbon (SOC) content and rice yield were evaluated from rice cultivation with different treatments: no rice straw (control), rice straw (RS), and rice straw compost (RSC) as a main-plots; five levels of nitrogen (N) fertilizer application: 0, 100, 150, 200, and 250 of N (kg ha−1) as a sub-plots. The denitrification and decomposition (DNDC) model was employed to simulate changes in SOC content and rice grain yield over 35 years. Additionally, scenario analysis on continuous or discontinuous RS incorporation in rice fields was conducted using the DNDC model. The long-term results indicated that RS and RSC treatments played a crucial role in increasing grain yields by 9% and 11% due to the increased SOC contents compared to control treatment. The validated DNDC model on SOC contents and yields showed a good agreement between the observed and simulated values based on the normalized root mean square errors. The model predicted a rapid decline of SOC contents without RS incorporation. Results suggested that incorporating rice straw or amending manure to paddy soils is a preferred practice for maintaining SOC contents.
Acknowledgments
The authors would like to thank Dr. Chang Hyu Yang and former faculty and staff members of National Institute of Crop Science (NICS), Rural Development Administration (RDA), South Korea for their continuous contribution on the long-term field research. The study was funded by RDA (project No.: PJ00930204), the key project of NICS, RDA during the 35 years and USDA NIFA Hatch (Project #: LAB94285 for Dr. Changyoon Jeong).
Disclosure statement
No potential conflict of interest was reported by the authors.