模拟酸雨对福州平原水稻田土壤碳库及碳库管理指数的影响

为阐明酸雨对水稻田土壤有机碳组分含量以及土壤碳库的影响,以福州平原水稻田为研究对象,在不同生长期早稻和晚稻中,设置对照(CK)、模拟pH 2.5、pH 3.5、pH 4.5酸雨处理,对酸雨影响下福州平原水稻田土壤有机碳组分含量进行了测定与分析。结果表明:酸雨处理对土壤总有机碳(SOC)存在不同程度的影响,在早稻整个生长期,酸雨对土壤SOC含量的影响不显著(P0.05),晚稻返青期和成熟期中,返青期依次高于CK处理24.70%,10.47%,9.97%,成熟期依次高于CK处理6.33%,8.75%,9.46%,酸雨显著提高土壤SOC含量(P0.05)。早稻成熟期,对照组溶解性有机碳(DOC)含量显著高于pH 3.5酸雨处理组;整个晚稻生长期,酸雨对土壤DOC含量的综合影响不显著(P0.05)。早晚稻酸雨的施加使土壤易氧化态碳(EOC)含量低于对照组(P0.05);早晚稻土壤微生物量碳(MBC)含量表现出明显的随时间变化的规律,早稻对照组土壤MBC含量低于酸雨处理(P0.05),晚稻则相反。早稻土壤SOC与TN、TP、电导和含水量存在极显著正相关关系(P0.01),晚稻土壤SOC与TP存在极显著正相关关系(P0.01)。将早晚稻的对照作参考土壤,早稻返青期以及晚稻拔节期和成熟期酸雨处理下碳库活度(A)及碳库活度指数(AI)低于对照处理,其他生长期差异性不大,且在一定范围内稻田土壤有机碳库维持一定的活跃度。早稻返青期、晚稻拔节期和成熟期酸雨处理下碳库指数(CPI)和碳库管理指数(CPMI)显著低于对照组(P0.05)。酸雨处理降低了土壤碳库管理指数将不利于水稻生长。

Effects of Simulated Acid Rain on Soil Carbon Pool and Soil Carbon Pool Management Index of Paddy Field in Fuzhou Plain

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.