生物炭对水稻根际微域土壤Cd生物有效性及水稻Cd含量的影响

采用根际箱培养的方式,研究了在Cd污染土壤中施用生物炭对根际和非根际土壤pH值、Cd生物有效性及Cd在水稻植株不同部位累积量的影响。结果表明:土壤pH值随着输入生物炭比例增加有上升趋势。在不同用量生物炭添加下,根际和非根际土壤Cd有效态含量均有下降,其中,根际土壤在中用量(50 g·kg~(-1))生物炭处理下降幅最大,达13.9%;非根际第一、二层土壤在高用量(100 g·kg~(-1))生物炭处理下达显著差异(P0.05),分别下降了27.4%和22.9%,而第三层土壤Cd有效态含量在中用量(50 g·kg~(-1))处理下效果最明显,下降了29.2%。施加生物炭均降低水稻各部位Cd含量,且与对照相比,水稻根和糙米中Cd的含量在中用量(50g·kg~(-1))生物炭处理下达显著性差异(P0.05),分别下降了49.8%和81.2%;茎叶和稻壳分别在高用量(100 g·kg~(-1))和中用量(50 g·kg~(-1))处理下降幅最大,分别下降了28.2%和47.1%。由此可见,在Cd污染土壤中添加一定量的生物炭能提高土壤的pH值,降低土壤中Cd的生物有效性并抑制水稻对Cd的吸收。

Effects of biochar on Cd bioavailability in rhizosphere microenvironment of cadmium-polluted paddy and Cd content in rice

Rhizobox training experiments were performed to investigate the role of biochar on the pH, Cd bioavailability in rhizosphere and non-rhizosphere soil and the accumulation of Cd in different parts of rice plants. Results showed that the soil pH value has a rising trend with the increasing proportion of biochar. The available forms of Cd were declined under different dosages of biochar in rhizosphere and non-rhizosphere soil, with the maximum reduction of 13.9% under the treatment of 50 g·kg^-1 biochar in rhizosphere soil. Cd concentrations in the first and second layer in non-rhizosphere soil were significant decreased under the dosage of 100 g·kg^-1 biochar, resulting in 27.4% and 22.9% reduction, respectively in contrast to the control, but for available Cd concentration in the third layer of non-rhizosphere soil, it was significantly declined under the middle dosage of 50 g·kg^-1 biochar, and decreased by 29.2 compared with CK. The application of biochar reduced Cd accumulation in different parts of rice. There was a significant difference(P<0.05) in root and rice under the content of 50 g·kg^-1 biochar compared with control treatments, and dropped by 49.8% and 81.2% respectively. The maximum reduction of 28.2% and 47.1% in Cd concentrations in the leaf and rice husk was got under the dosage of 100 g·kg^-1 and 50 g·kg^-1, respectively. It was observed that application of a certain amount of biochar can improve pH value of soil, and reduce the bioavailability of Cd in soil and Cd absorption in rice.