Abstract:In order to clarify the effects of acid rain on soil organic carbon content and soil carbon pool in paddy fields, the paddy field in Fuzhou Plain was taken as the research object, and the control (CK), simulated pH 2.5, pH 3.5, pH 4.5 acid rain treatments were set up in early and late rice at different growth stages to determine and analyze organic carbon component content of Paddy soil under the simulated acid rain. The results showed that acid rain had different effects on soil total organic carbon (SOC). During the whole growing season of early rice, the effect of acid rain on soil SOC content was not significant (P>0.05). For the late rice, the soil SOC contents of the acid rain treatments were 24.70%, 10.47% and 9.97% higher than that of CK during the greening period, and during the maturity period, the soil SOC contents were 6.33%, 8.75% and 9.46% higher than that of CK. Acid rain significantly increased soil SOC content (P<0.05). During maturation period of early rice, the dissolved organic carbon (DOC) content of the CK was significantly higher than that of the pH 3.5 acid rain treatment. The comprehensive effect of acid rain on soil DOC content was not significant during the whole growth period of late rice (P>0.05). The application of acid rain made the soil oxidizable carbon (EOC) content lower than that of the CK (P<0.05). The soil microbial biomass carbon (MBC) content of early and late rice showed obvious change with time. The MBC content of the early rice in the CK was lower than those in the acid rain treatments (P<0.05), while that of the late rice was the opposite. There was a significant positive correlation between soil SOC and TN, TP, conductivity and water content in early rice (P<0.01). There was a significant positive correlation between soil SOC and TP in late rice (P<0.01). Taking the CK of the early and late rice as the reference soil, the carbon storage activity (A) and carbon storage activity index (AI) of the early rice during greening period and late rice during jointing and mature periods in the acid rain treatment were lower than those of the CK, and there was no significant difference at other growth stages, and within a certain range, the paddy soil organic carbon pool maintained a certain degree of activity. The carbon pool index (CPI) and carbon pool management index (CPMI) of the early rice during greening period, late rice during jointing and mature periods in the acid rain treatments were significantly lower than those of the CK (P<0.05). Acid rain treatment reduced the CPMI, which would be detrimental to rice growth.