水分状况对红壤水稻土中有机物料碳分解和分布的影响

EFFECTS OF SOIL MOISTURE REGIME ON DECOMPOSITION OF ORGANIC MATERIAL AND DISTRIBUTION OF ORGANIC MATERIAL-DERIVED CARBON IN PADDY RED SOIL IN SUBTROPICAL CHINA

以室内模拟的方法研究了好气、淹水和干湿交替3种水分条件下有机物料碳在红壤水稻土中分解和分布的差异。试验结果表明,干湿交替条件下有机物料的分解速率最高,好气条件下次之,淹水条件下较低。好气和淹水条件下添加物料促进土壤原有有机碳的矿化,产生正激发效应,而干湿交替条件显著抑制了土壤原有有机碳的矿化,呈负激发效应,随着培养时间的延长激发效应减弱。干湿交替条件下添加有机物料处理的土壤胡敏酸(Humic acid,HA)色调系数和E4/E6比值显著低于淹水和好气条件,淹水培养使土壤胡敏酸的结构简单化,干湿交替使胡敏酸芳构化和腐殖化程度增加,结构复杂化。有机物料碳在土壤腐殖质组分中的分配比例显示,干湿交替和好气条件促进了胡敏酸的形成,提高了土壤原有富里酸(Fulvic acid,FA)组分的转化和胡敏酸组分的分解;淹水条件下物料碳在富里酸组分中分布比例较高,且抑制了土壤原有胡敏酸组分的分解。有机物料碳在>0.053 mm粒级团聚体中分布比例较大,干湿交替和淹水条件下更为明显。

Decomposition and distribution of carbon derived from organic materials in paddy soils in the red soil region of subtropical China as affected by moisture regime （aerobic, flooding and wet-dry alternating） were investigated in laboratory through incubation experiments. Results indicate that organic material decomposition rate was the highest in the soil under wet –dry alternation and the lowest in the soil under flooding. Amendment of organic materials promoted mineralization of soil original carbon native in the soils under aerobic and flooding conditions, displaying a positive priming effect, but reversely in the soil under wet-dry alternation, showing a negative priming effect. The priming effects weakened with the incubation going on. ΔlogK and E4/E6 ratio of humic acid was significantly lower in the soil amended with organic material under wet-dry alternation than in the soils under flooding and aerobic conditions. Flooding made humic acid in the soil simple in structure, while wet-dry alternation made it complicated, with enhanced aromatization and humification. The distribution ratio of organic material-derived carbon in soil humus fractions showed that wet-dry alternation and aerobic condition promoted formation of humic acid, conversion of fulvic acid fraction and decomposition of humic acid fraction native in the soils. In the soil under flooding, the carbon derived from organic materials accounted for a high proportion in soil fulvic acid fraction and inhibited decomposition of soil native humic acid components. A high proportion of the carbon derived from organic materials was distributed in 〉 0.053 mm aggregates, which was especially obvious in the soil under wet-dry alternation and flooding.