Effect of diatomite application on rice yield, methane emission and temperature sensitivity of methane emission under the ratoon rice

Understanding the effect of nitrogen (N) fertilizer and diatomite application on methane (CH₄) emissions and the temperature sensitivity (Q₁₀) of CH₄ emissions under the ratoon rice system is crucial for optimizing greenhouse gas emissions from paddy ecosystems. A two-year field experiment was conducted from 2022 to 2023 in Jingzhou city, Hubei Provice. Three treatments were set up on this study site: N fertilizer application (N), N fertilizer combined with diatomite application (N+Si), and no N fertilizer application (CK). The CH₄ fluxes were measured by using a closed-chamber method. The rice yield and soil properties were observed. Results showed that compare to CK treatment, both N and N+Si treatment could significantly increase the rice yield of main season and ratoon season(P<0.05). And N+Si treatment significantly increased the rice yield of main season by 3.75%−3.85%(P<0.05), compare with N treatment. The cumulative CH₄ emissions of the entire growth period (main season and ratoon season) in both N and N+Si treatments were significantly higher than CK treatment(P<0.05). But, N+Si treatment significantly reduced the cumulative CH₄ emissions by 23.73%−41.36% in the main season, 17.13%−37.49% in the ratoon season, and 25.99%−36.66% in the entire growth season, respectively (P<0.05) compare with N treatment. Consequently, N+Si treatment significantly reduced CH₄ emissions of per unit yield in both the main season and ratoon season by 26.52%−43.51%, and 18.65%−41.14% (P <0.05), respectively, compare with N treatment. Correlation analysis revealed that the influences of soil properties on CH₄ fluxes were quite differences among treatments and period of rice growing season. The CH₄ fluxes was significantly decreased with the soil Eh (P<0.05) in the main season (P <0.05). But in the ratoon season, the CH₄ fluxes were significantly increased with soil temperature and soil NH₄⁺-N (P<0.05). The CH₄ emission was also significantly positively influenced by the soil temperature during the period of conventional irrigation in the main season. The N+Si treatment had the highest Q₁₀ of CH₄ fluxes with the value of 8.8640, indicating that the addition of diatomite made CH₄ fluxes more sensitive to temperature changes. In conclusion, as a sustainable fertilizer management, combined application of nitrogen fertilizer and diatomite not only increase the yield of ratoon rice but also effectively reduces the CH₄ emissions from ratoon rice system.