秸秆和猪粪的施用对土壤镉有效性的影响和机理研究

AVAILABILITY AND THE RELATED MECHANISMS OF CADMIUM IN SOILS AS INFLUENCED BY THE APPLICATION OF STRAW OR PIG MANURE

用盆栽试验研究作物秸秆和腐熟猪粪对土壤镉(Cd)有效性的影响及机理。结果表明,施用秸秆促进油麦菜对Cd的吸收,而施用猪粪降低油麦菜对Cd的吸收,这主要是由于秸秆显著地增加了交换态Cd含量,而猪粪则显著降低交换态Cd含量。秸秆或猪粪对交换态Cd含量的影响则主要与土壤胡敏酸(HA)和富里酸(FA)的变化有关。施用秸秆对土壤中FA增加幅度大于对HA的增加幅度,即HA/FA比值降低。而施用猪粪则增加了HA/FA比值。相关分析表明,施用秸秆和猪粪情况下土壤HA/FA与交换态Cd含量之间呈显著负相关关系(P<0.05)。结果还表明,秸秆和猪粪对土壤交换态Cd含量的影响还与其对腐殖酸芳构化程度的影响有关,添加猪粪比添加秸秆的土壤腐殖酸芳构化程度大。因此,有机物质对土壤Cd有效性的影响与土壤有机质组成的变化密切相关。

A pot experiment was conducted to study the effects of straw or composted pig manure application on availability of cadmium （Cd） in soil and the related mechanisms. Results showed that application of straw increased Cd uptake and pig manure decreased Cd uptake of leafused lettuce. It was mainly because that straw increased exchangeable Cd and pig manure decreased exchangeable Cd. The effect of straw or pig manure on exchangeable Cd was related to the changes of humic acid （HA） and fulvie acid （FA）. When straw was applied the increase of FA in the soil was more than HA and HA/FA ratio decreased, while application of pig manure increased HA/FA. Statistical analysis showed that soil HA/FA ratio was negatively correlated with soil exchangeable Cd （ P 〈 0.05）. Results also showed that the aromatization of humic substance was higher in soil applied with pig manure than the soil amended with straw. It was concluded that the availability of Cd in soil could be influenced by the changes of organic fractions after application of organic materials.