通过盆栽试验,研究了不同赤泥施用量对水稻产量、土壤中镉生物有效性及其形态和糙米镉含量的影响。结果表明,适宜的赤泥施用量能提高水稻有效穗数和促进水稻生长,实现水稻增产,与不施赤泥处理相比,0.75%(W/W)赤泥处理的水稻株高、有效穗数和产量分别提高了5.02%、1.12%和6.93%。随着赤泥施用量的增加,土壤pH值增加,土壤交换态Cd含量逐渐减少,碳酸盐结合态、铁锰氧化物结合态和残渣态Cd含量逐渐增加,但对有机结合态Cd含量的影响不明显,相比不施赤泥处理,1.25%(W/W)赤泥处理的土壤交换态Cd含量下降了31.6%(P〈0.01),碳酸盐结合态、铁锰氧化物结合态和残渣态Cd含量分别增加了16.3%、22.5%和8.7%(P〈0.01)。水稻糙米中Cd的含量随赤泥施用量的增加而降低,当赤泥施用量达到或高于0.5%(W/W)时,糙米Cd含量达到国家粮食卫生标准,综合考虑水稻产量、土壤修复效应和糙米品质,在本试验Cd污染程度的稻田土壤上赤泥的适宜施用量为0.75%(W/W)。
A pot experiment was conducted to study the effects of application of different amount of red mud on rice yield, bioavailability and forms of cadmium in soils as well as cadmium concentrations in brown rice. The results indicate that the appropriate application of red mud can apparently promote rice growth and increase effective panicle number and grain yield. Compared to the control (RM-0) without red mud application, plant height, effective panicle number and grain yield in the 0.75% red mud (W/W) treatment are increased by 5.02%, 1.12% and 6.93%, respectively. With increase of red mud application, soil pH is increased, the exchangeable cadmium concentration is decreased, while the concentrations of carbonate-bound, iron- and manganese-oxides- bound and residual cadmium are increased, and the organic bound cadmium is not changed obviously. Compared to the RM-0 treatment, the soil exchangeable cadmium in the 1.25% (W/W) red mud treatment is decreased by 31.6% (P 〈0.01), while the carbonate-bound, iron- and manganese-oxides-bound and residual cadmium are increased by 16.3%, 22. 5% and 8.7%, respectively (P 〈 0.01 ). The cadmium concentration in brown rice is decreased with increase of red mud application, and the cadmium concentration meets the national food hygiene standards when the application amount is greater than or equal to 0. 5% (W/W) red mud. Considering the grain yield, the effect of soil remediation and quality of brown rice comprehensively, the appropriate amount of red mud application is 0. 75% (W/W) in the studied cadmium contaminated paddy soil.