Evaluation of long-term organic carbon dynamics and organic matter stability in a cultivated paddy soil using a carbon and nitrogen stable isotopes-based model

Summary

Understanding soil organic matter (SOM) stability and carbon storage under long-term intensive land management systems is vital for estimating the C sequestration potentials of agricultural lands. Available methods currently used for measuring the stability of SOM, such as radiocarbon dating, are expensive. However, a cost-effective and reliable stable isotope-based model was developed for grasslands which utilizes the C/N ratio and δ15N of soils to determine the stability of SOM. We applied this model to test for the first time its usefulness for evaluating SOM stability in the top and subsoils of a subtropical paddy field cultivated for 37 years. We also compared paddy soil's SOM stability and carbon storage under different fertilizer treatments. Treatments evaluated were a control (CK),