Interactive effects of temperature and moisture on CO2 and CH4 production in a paddy soil under long-term different fertilization regimes

Abstract

Temperature and moisture effects on organic carbon (C) decomposition (i.e., CO2 and CH4 emissions) determine the feedback of soil organic carbon (SOC) stocks in rice (Oryza sativa L.) paddies to climate change. In the present study, soils from a long-term (initiated in 1981) fertilization experiment [unfertilized control, combined inorganic nitrogen, phosphorus, and potassium fertilization (NPK), inorganic NPK plus organic manure (NPKM)] were incubated at 20 and 30 °C under both aerobic and anaerobic conditions. Relative to aerobic conditions, anaerobic conditions significantly reduced CO2 and total C release, but led to CH4 production. On average, the temperature sensitivity (Q 10) of CH4 production was 7.4 times greater than that of CO2 production. Under anaerobic conditions, the contribution rates of CH4 production to total C release significantly increased from an average of 2.4 % at 20 °C to 14.5 % at 30 °C, and to the global warming potential (GWP) from 18.1 to 59.9 %, respectively. Anaerobic conditions significantly reduced the Q 10 of CO2 and total C release, but increased that of GWP. Manure-amended soils showed higher CO2 and CH4 production on a per gram soil C basis and lower Q 10 of CO2 and total C production, but higher Q 10 of CH4 production than those of the control and NPK soils. Therefore, our results suggest that there are significant interactive effects of temperature, moisture, and fertilization regimes on SOC decomposition in the paddy soil.