不同钝化剂配施硫酸锌对石灰性土壤中镉生物有效性的影响研究

为了降低轻度镉（Cd）污染土壤中Cd的生物有效性以确保农产品安全,以低吸收豆类蔬菜（豇豆）作为供试植物,通过田间试验研究了在轻度Cd污染（Cd1.5mg·kg-1）石灰性土壤中施加赤泥、油菜秸秆、玉米秸秆、赤泥＋油菜秸秆等钝化处理并配施硫酸锌肥料对土壤中Cd的生物有效性的影响。结果表明,与对照相比,不同钝化处理可显著（P〈0.05）降低豇豆豆角中Cd浓度和土壤中可溶态Cd浓度;钝化处理条件下豇豆豆角中Cd浓度降低了27%（玉米秸秆）~83%（赤泥＋油菜秸秆）。在施加钝化剂的基础上,配施硫酸锌肥料可进一步降低豇豆对Cd的吸收,各钝化处理在配施锌肥后,豇豆豆角中Cd平均浓度与未施锌肥相比降低了27%。对不同作物秸秆而言,富含巯基的油菜秸秆比富含纤维素的玉米秸秆钝化效果好。由此可见,在轻度Cd污染的石灰性土壤中,无机钝化剂赤泥和富含巯基的油菜秸秆复合使用是一种高效且环境友好的钝化手段。同时,合理施用锌肥可能会进一步降低作物对Cd的吸收。

Cadmium Phytoavailability to Cowpea Decreased by Rape Straw and Red Mud with Zinc Sulphate in a Calcareous Soil

To reduce Cd phytoavailability in calcareous soils, the effects of soil amendments of red mud, rape straw, corn straw and red mud plus rape straw in combination with zinc fertilization on Cd extractability and phytoavailability to cowpea were investigated in a calcareous soil with added Cd at 1.5 mg·kg-1. The results showed that water soluble and exchangeable Cd in soils was significantly decreased by the a- mendments, which resulted in significant decrease by about 27%（corn straw）-83%（red mud plus rape straw） in Cd concentration in cowpea. Combined with amendments, Zn fertilization further decreased the Cd concentration in cowpea. Compared with amendments only, the con- centrations of Cd in the edible parts of cowpea treated with the Zn fertilization plus amendments decreased by 27% on average. Also crucifer- ous rape straw was more effective than gramineous corn straw. In all treatments, rape straw plus red mud combined with Zn fertilization was most effective in decreasing Cd phytoavailability to cowpea in soils, and it is potential to be an efficient, cost-effective and environmentally friendly measure to ensure food safety for crop production in mildly Cd-contaminated and calcareous soils.