Evaluation of DNDC Modelling Approaches for Predicting a Long-Term Effect of Rice Straw Incorporation on Soil Organic Carbon Changes and Rice Yield in a Korean Paddy Soil.

Soil organic carbon (SOC) dynamic in crop fields is crucial for qualifying soil health and crop productivity. Recently, rice straw incorporation could be considered the backbone of maintaining SOC contents in paddy soils. In South Korea, a long-term field experiment (35 years) was conducted with the annual incorporation of rice straw to evaluate an impact on rice production and SOC contents. Three levels of rice straw incorporation: no rice straw (control), rice straw (RS), and rice straw compost (RSC) as a main plot; five levels of nitrogen (N) fertilizer application: N 0 kg ha^-1, N 100 kg ha^-1, N 150 kg ha^-1, N 200 kg ha^-1, and N 250 kg ha^-1 as a sub-plot were carried out on Iksan experimental station of National Institute of Crop Science, RDA, South Korea. The denitrification-decomposition (DNDC) model was employed to predict on rice yields and SOC contents. The DNDC model also simulated further scenarios on SOC contents under different methods of continuous and discontinuous rice straw incorporation in paddy soils. Results revealed that rice straw incorporation into soils presented higher grain yields by 9 % (RS) and 11 % (RSC) increase compared with control. The DNDC model estimated a period to attaining a steady state of SOC contents in the scenarios. The DNDC model recommended that maintaining SOC content must be imperative for sustaining rice production, and the model showed that a robust tool for the prediction of rice yield and SOC contents under different management practices in Korean paddy field. However, further researches are required on greenhouse gas emission affected by the incorporated rice straw in paddy soils.