模拟酸雨对福州平原水稻田土壤化学结合态有机碳含量的影响

为阐明酸雨对水稻田土壤化学结合态有机碳含量的影响,以福州平原水稻田为研究对象,在早稻和晚稻生长期中,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化学结合态有机碳含量进行了测定与分析.结果表明,酸雨作用下早、晚稻土壤有机碳(SOC)含量介于13.40～20.17 g·kg~(-1),与土壤全氮(TN)含量显著正相关(p0.01);各处理下早稻田SOC含量均低于晚稻田,且早稻田土壤各处理间SOC含量差异不显著(p0.05),其中,晚稻CK、pH=2.5和pH=3.5处理的SOC含量与早稻差异显著(p0.05),酸雨处理均高于CK(p0.05).早、晚稻土壤Ca-SOC含量介于0.31～0.42 g·kg~(-1),早稻期间pH=2.5处理中Ca-SOC含量与其他处理差异明显(p0.05).早、晚稻土壤Fe(Al)-SOC含量介于2.90～4.64 g·kg~(-1),早稻各处理间差异不显著(p0.05),而晚稻各处理间差异显著(p0.05).相比之下,晚稻残渣态-SOC含量显著高于早稻(p0.05),酸雨处理显著高于CK(p0.05),且pH=2.5处理含量最高,均值为(15.21±0.37) g·kg~(-1),而早稻各处理残渣态-SOC含量差异不显著(p0.05).此外,早、晚稻SOC与Fe(Al)-SOC、残渣态-SOC之间均具有显著正相关关系(p0.01),早稻残渣态-SOC、晚稻Fe(Al)-SOC与土壤TN显著正相关(p0.01).综上所述,酸雨通过提高晚稻SOC和Fe(Al)-SOC含量,进而增强土壤碳库稳定性,促进有机碳的积累.

Effect of simulated acid rain on soil chemical bonded organic carbon content in paddy of Fuzhou plain

In order to elucidate the effect of acid rain on the chemically bounded soil organic carbon content in paddy, different simulated acid rain treatments (CK, simulated pH=2.5, pH=3.5 and pH=4.5) were performed in the paddy of Fuzhou plain, and the effect of simulated acid rain on chemically bonded soil organic carbon content was determined in the growth stages of early rice and late rice. The results showed that the SOC content of early and late paddy under acid rain was between 13.40 and 20.17 g·kg^-1, which was significantly and positively correlated with soil TN (p<0.01). The SOC content of early paddyunder all treatments was lower than that of the late paddy, and there was no significant difference in SOC content among treatments in early paddy (p>0.05). The CK, pH=2.5 and pH=3.5 treatments in late paddy were significantly different from those of the early paddy (p<0.05), and acid rain treatment was significantly higher than that of the CK (p<0.05). The Ca-SOC content in early and late paddy was ranged from 0.31 to 0.42 g·kg^-1. The Ca-SOC content in early paddy during pH=2.5 treatment was significantly different from those of other treatments (p<0.05). The contents of Fe(Al)-SOC in early and late paddy was ranged from 2.90 to 4.64 g·kg^-1. There was no significant difference among treatments in early paddy(p>0.05), and the averaged values of the treatments were significantly difference among treatments in late paddy (p<0.05). In contrast, the residue-state SOC content of late paddy was significantly higher than that of early paddy (p<0.05), and acid rain treatment was significantly higher than that of CK (p<0.05), and was highest in pH=2.5, with a mean value of (15.21±0.37) g·kg^-1, while the residue status of early paddy processing-SOC were not significant differences (p>0.05). In addition, there was significantly positively correlation between soil SOC and Fe(Al)-SOC/residual-state SOC in early and late paddy (p<0.01). Residual residue-SOC in early paddy and Fe(Al)-SOC in late paddy were significantly and positively correlated with soil TN (p<0.01). In summary, soil SOC and Fe (Al)-SOC content was increased by acid rain in late paddy, thereby the stability of soil carbon pools was improved and accelerated the accumulation of organic carbon.