有机肥施用下水稻不同生育期土壤水稻系统中微量元素与Cd的关系

On relation between trace elements and Cd content in soil-rice system at different rice stages under organic fertilizer application

为了研究Cd污染稻田中施加有机肥在土壤分解释放的微量元素与Cd的相互关系,通过水稻田间试验,测定施用有机肥(0、7.5 g/kg、15 g/kg、30 g/kg)后水稻3个生育期(分蘖盛期、灌浆期、成熟期)土壤微量元素、Cd的酸可提取态质量比及成熟期水稻各部位(根系、茎、叶、谷壳、糙米)中Ca、Fe、K、Mg、Mn、P、Zn元素质量比,并分析它们在水稻不同生育期土壤-水稻系统中的变化规律和相关关系。结果表明:有机肥的施用显著降低了3个水稻生育期土壤酸可提取态Cd质量比,不同程度增加了土壤酸可提取态Ca、K、Mg、P质量比。除Fe质量比有明显上升的趋势外,随水稻生育期延长,土壤Cd和其他微量元素酸可提取态质量比均无明显变化。施用有机肥显著增加了水稻根系中Cd、Fe、K、Mg、P质量比,茎中P质量比,叶中K、Mg、P、Zn质量比和谷壳中K、P、Zn质量比。水稻茎和叶中Ca质量比、糙米中Mn质量比在有机肥处理下出现显著下降。水稻3个生育期土壤酸可提取态Cd质量比与酸可提取态P、Mg质量比均存在不同程度的负相关关系,施加有机肥后土壤中P与Mg质量比的增加均有利于抑制土壤中Cd活性。除水稻糙米外,水稻各部位Cd与Zn质量比均呈现显著或极显著正相关关系,这表明Zn与Cd在水稻各部位均存在一定的协同关系。总之,施用有机肥增加了水稻对微量元素的摄取,能通过各元素与Cd之间的竞争、协同、拮抗等过程,有利于降低Cd在土壤-水稻系统中的迁移转运。

In this paper,we have made a detailed analysis of the relation between Cd and the related trace elements in the soilrice system at different rice growing stages so as to trace and register the changes of the acid extractable rates of Cd and the trace elements known as Ca,Fe,K,Mg,Mn,P,Zn in soil. The investigation and analysis has been done by analyzing the trace elements concentrations,the Cd concentration rates in the soil at three rice growing stages( i. e. the tillering stage,the filling stage,and the maturity stage) under the organic fertilizer application( 0,7. 5 g/kg,15 g/kg,30 g/kg) and those elements accumulation in the rice tissues( roots,straws,leaves,husks,and brown rice) by means of on-spot experiment. The results of our investigation show that:( a) The application of the organic fertilizer since significantly reduced acid extractable of the Cd concentration in the soil,and in turn increased its soil acid extractable of Ca,K,Mg and P concentrations at the three rice growth stages. Except for Fe,the acid extractable of Cd concentration rate and the concentration rates of the other trace elements in the soil fail to show significant difference or effect with the extension of the rice growing period;( b) The application of the organic fertilizer has since significantly increased its concentration rates of Cd,Fe,K,Mg,P in the rice roots,its concentration rates of P in the stems,its concentration rates of K,Mg,P,Zn in leaves and those of K,P,Zn in husks would also have increased positively. On the other hand,a significant reduction of Ca concentration rate in the stems and the leaves and Mn concentration rate in the brown rice would also be observed and determined in treating the organic fertilizer;( c) There would be found some negative correlations between the acid extractable Cd concentration rate and P and Mg acid extractable concentration rates during the three growth stages of rice. The concentration rates of P and Mg in the soil should be beneficial to the inhibition of the activity of Cd when the organic fertilizer was used. Furthermore,except in the brown rice,Cd and Zn concentration rates in the rice plants would show significantly positive correlation,all of which indicate that there exists a certain synergistic correlation between Zn and Cd in the rice,especially in the rice roots,stems,and leaves. Thus,it can be concluded that,in general,the application of organic fertilizer could help to increase the uptake of the trace elements by rice,which is beneficial for reducing the accumulation and translocation of Cd in the soil rice-system through various interactive processes between the trace elements and Cd,such as competition,synergism,antagonism,and so on.