钝化剂-锌肥降低烟草镉含量长期效果研究

采用田间小区试验,通过外源添加1.5 mg kg-1镉(Cd)模拟轻度Cd污染土壤,研究赤泥、油菜秸秆、玉米秸秆及其组合并配施硫酸锌降低土壤Cd有效性和烟草各部位Cd含量的长期效果。结果表明,施用钝化剂后,烟叶产量增加了7.0%~32.1%,中上等烟叶比例提高了2.9%~20.2%,烟草经济效益提高了6.6%~31.3%。钝化剂处理土壤有效态Cd含量降低显著,2012年和2013年降幅分别为18.6%~47.4%、16.0%~27.0%。烟草各部位Cd含量排序为下部叶中部叶、上部叶茎秆,且均与土壤有效态Cd含量呈极显著正相关关系。2011—2013年钝化剂处理烟草叶片Cd平均含量较对照分别降低了28.3%、28.1%、15.2%,烟草各部位Cd含量年变化幅度下部叶最大,茎秆最小,叶位间Cd含量差异随钝化时间延长逐渐缩小。钝化剂降低土壤-烟草系统Cd生物有效性效果稳定持久,其中油菜秸秆优于玉米秸秆,有机无机复合钝化剂效果最好。配施锌肥后,2011—2013年烟草叶片Cd含量较对照分别降低了19.1%、23.3%、17.9%,且下部和中部叶片降低效果达到显著水平;中部和上部叶Cd、Zn含量呈显著负相关关系。因此,在轻度Cd污染土壤上,赤泥油菜秸秆复合钝化剂配施锌肥是降低烟叶镉含量兼顾高产的最佳生产措施。

Effects of long-term amendment with passivant and zinc fertilizeron cadmium reduction in tobacco growing in a Cd contaminated field

To find a best way of reducing cadmium content concentration in tobacco in contaminated soils, long-term effects of five amendments (red mud, rape straw, corn straw, red mud plus rape straw, and red mud plus corn straw) with zinc fertilizer on cadmium phytoavailability of soil-tobacco system were investigated using a three-year field plot experiment with 1.5 mg?kg-1 Cd added to soil. The results showed that tobacco leaf yield of amendments treatment was significantly increased by 2.6% ~ 32.3%, and . the ratio of mid-high grade leaves were enhanced by 2.9% ~ 20.2% due to the biomass of middle and upper leaves raised, so The the economic benefit were shapely increased by 6.6% ~ 31.3%. The highest yield and economic benefit wereas found in the treatment of red mud plus rape straw. Applying amendments stably decreased soil available cadmium concentration by 18.6%~47.4% (2012), 16.0%~27.0% (2013). Cadmium content concentration in tobacco was directly influenced by soil available cadmium concentration, therefore cadmium content concentration in tobacco leaves at different seasons (2011-2013) were lowered by 28.3%, 28.1%, 15.2% on average with amendments added. The maximum reduce range among the years was found in bottom leaves and minimum was found in stem. Interestingly, With the decrease of soil available cadmium concentration, the difference of cadmium content concentration in three parts of tobacco leaves was shrunk down with the decrease of soil available cadmium concentration. For In terms of cadmium reduction effect, rape straw full of thiols was better than corn straw, and inorganic-organic amendment with plenty of heavy metal combination sites was the most effective and stable method. Combined with amendments, applying zinc fertilizer can further much more significantly lower cadmium concentration in different parts of tobacco leaves at different seasons. In all treatmentsAbove all, red mud plus rape straw with zinc fertilizer was the most effective to decrease cadmium phytoavailability in soil-tobacco system. Therefore it can be an efficient and cost-effective measure to reduce cadmium content concentration in tobacco leaves in cadmium contaminated soils.