Carbon budget of paddy ecosystems in China simulated by denitrification-decomposition model

Quantifying the carbon budget in rice paddy ecosystems is fundamental to understanding the role of paddy fields as carbon sinks or sources and to mitigating global climate change. This study used a process-based model of the denitrification-decomposition (DNDC) model to estimate greenhouse gas (GHG) emissions and carbon sinks in the paddy ecosystem across China. The simulation results showed that the GHG emissions were 0.147 Pg C-equivalent year⁻¹ and that the carbon sequestration in rice plants and soils reached 0.253 Pg C year⁻¹ in 2016, indicating high carbon sequestration potential of the Chinese paddy ecosystem. Land management had a great influence on carbon budgets, among which straw residue incorporation rate and nitrogen fertilizer applications had a stronger influence on carbon budgets, particularly for double cropping rice. These results indicate that appropriate tillage practices can reduce GHG emissions and increase carbon sequestration of rice ecosystems while ensuring rice yields.