A Study of Paddy CO2 Emissions under Long-Term Fertilizations and Associated Impact Factors

摘要

A field experiment was made using static chamber-GC theory to observe CO2 emissions from rice paddy that have been fertilized for 25 consecutive years. Impact factors derived from the experiment were also studied. Seasonal variations of CO2 flux presented a similar pattern, though they were different in treatment. CO2 flux peaks appeared in the flooding season, with the bottom in the drainage. Seasonal trends of CO2 flux went along with the air temperature near the ground. Chemical fertilizer applications produced more CO2 flux, compared with other treatments, though there was no significant correlation between other treatments and the treatment with only chemical fertilizer. NPKS had the largest CO2 flux, or 502.58mg·m-2·h-1, and CK the lowest flux, or 249.16mg·m-2·h-1.There was a significant negative correlation between CO2 flux and water depth (p<0.01). Water is a most important factor that controls paddy CO2 flux. Temperature is another most important factor that controls CO2 flux from rice-involved plots, in a range of 13.33℃～38.59℃. There is a significant exponential relationship between CO2 flux and temperature, or F=20.1365e0.088838T (p<0.01). Temperature coefficient (Q10) was 2.43. Both soil pH and Eh values were correlated with CO2 flux (p<0.01), though further study is needed to clarify the mechanism.