种植杞柳对根际土壤中重金属镉形态、养分质量分数及微生物数量的影响

Effects of Sailx integra Planting on Cd Fractionations,Soil Nutrient and Microbial Quantity

为揭示杞柳(sali xintegra)在镉污染下根际行为对镉形态、土壤养分质量分数及微生物数量的影响,在棚内进行盆栽试验。试验设置4个镉质量分数处理(0、50、100及150mg·kg-1),每个处理同时设置种苗组和未种植组。对根际、非根际及未种植组土壤的阳离子交换量、pH值、有机质质量分数、速效养分质量分数等进行测定分析;采用BCR逐级提取技术对根际、非根际及未种植组土壤的镉形态进行分析;采用稀释涂布平板法,计算微生物菌落数量。结果表明:随着镉质量分数的增加,根际土壤pH值降低,速效钾与碱解氮质量分数升高,种植组土壤阳离子交换量显著小于未种植组。50mg·kg-1处理组对根际速效磷呈现出一定的抑制作用。土壤中镉各形态质量分数由大到小的大体顺序为弱酸提取态、可还原态、残渣态、可氧化态,对生物有效性高的弱酸提取态质量分数由小到大排序为根际、非根际、未种植组。微生物数量随着污染程度增加而减少,根际微生物数量大于非根际微生物数量。重金属对微生物数量影响较大。

We studied the effect of rhizosphere behavior on the Cd fractionations, soil nutrients and microbial quantity of Salix integra under Cd pollution. We set the four Cd concentration gradient treatments (0, 50, 100 and 150 mg·kg -1 ), and planted group and un-planted group set in each treatment. And we analyzed the cation exchange capacity, pH, organic matter, available nutrients of soil in rhizosphere, non-rhizosphere and unplanted group. Cd fractionations of the rhizosphere, non-rhizosphere and unplanted group soil were analyzed by BCR technique. The numbers of microbial was calculated by the method of medium counting. The pH of rhizosphere soil was decreased, and the contents of AK and AN were increased with the increase of Cd fractionations. The CEC value of planting group was significantly lower than that un-planted group. The 50 mg·kg -1 group showed an inhibitory effect on the content of AP in rhizosphere. The content of Cd fractionations forms showed descending order of EX, OXI, RES, and ORG. The content of EX form showed ascending order of rhizosphere, non-rhizosphere, and un-planted. The numbers of microbes were decreased as pollution was increased, and the numbers of rhizosphere microbes were higher than those of non-rhizosphere microbes. Cd has a greater impact on the numbers of microbes.