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

A field experiment was made using static chamber-GC theory to observe CO
₂
emissions from rice paddy that have been fertilized for 25 consecutive years. Impact factors derived from the experiment were also studied. Seasonal variations of CO
₂
flux presented a similar pattern, though they were different in treatment. CO
₂
flux peaks appeared in the flooding season, with the bottom in the drainage. Seasonal trends of CO
₂
flux went along with the air temperature near the ground. Chemical fertilizer applications produced more CO
₂
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 CO
₂
flux, or 502.58 mgldrm
^-2
h
^-1
, and CK the lowest flux, or 249.16 mgldrm
^-2
h
^-1
. There was a significant negative correlation between CO
₂
flux and water depth (p<0.01). Water is a most important factor that controls paddy CO
₂
flux. Temperature is another most important factor that controls CO
₂
flux from rice-involved plots, in a range of 13.33degC~38.59degC. There is a significant exponential relationship between CO
₂
flux and temperature, or F=20.1365e
^0.088838T
(p<0.01). Temperature coefficient (Q10) was 2.43. Both soil pH and Eh values were correlated with CO
₂
flux (p<0.01), though further study is needed to clarify the mechanism.