续断菊与蚕豆间作下土壤部分化学特征与Cd形态分布状况研究

通过田间试验,研究间作和单作两种种植模式下植物根际土壤p H、有机质、碱解氮、速效钾、速效磷和不同形态Cd分布状况变化,考察综合因素对土壤重金属Cd形态分布状况与续断菊(Sonchus asper L.Hill)和蚕豆(Vicia faba L.)两种植物吸收Cd的影响。结果表明:随着植物的生长,单作蚕豆与单作续断菊土壤p H值没有显著变化,间作土壤p H值下降0.11个单位;间作土壤有机质比单作蚕豆和单作续断菊分别增加12.64%和20.13%;随着植物的生长,间作与单作蚕豆碱解氮含量分别显著增加139.87%、155.15%;间作与单作续断菊土壤速效钾含量接近,变幅在5%左右,单作蚕豆下降10.60%;不同种植模式土壤速效磷含量均呈现下降趋势,间作显著下降7%左右,单作蚕豆与续断菊下降量接近;各时期Cd各形态含量分布为可交换态碳酸盐结合态铁锰氧化物结合态有机物结合态;成熟期间作Cd可交换态含量比单作蚕豆与单作续断菊分别下降21.98%、22.13%,碳酸盐结合态、铁锰氧化物结合态和有机物结合态含量没有差异性;间作蚕豆生物量相比单作降低了24.77%,间作续断菊生物量相比单作增加15.29%;单作蚕豆根、叶、豆荚与籽粒Cd质量分数显著大于间作蚕豆,间作续断菊地上部Cd质量分数显著大于单作,根部无差异。总之,间作增强了续断菊对Cd的吸收,降低了蚕豆对Cd的吸收。

Soil chemical properties and Cd form distribution in Vicia faba and Sonchus asper intercropping system

Intercropping food crops with plants with high metal-accumulating ability may reduce the accumulation of metals in the food crops. In this study, a field plot experiment was conducted to examine soil chemical properties(pH value, organic matter, available nitrogen, available potassium, and available phosphorus), soil Cd form distribution, and plant Cd accumulation in monoculture and intercropping systems of Sonchus asper L. Hill and Vicia fabaL. Results indicated that:(1)During the experimental period, soil pH values in V. faba and S. asper monoculturing plots did not significantly change, but declined by 0.11 units in intercropping plot, compared with the initial soil.(2)Soil organic matter content in the intercropping plot was 12.64% and 20.13% higher than that in V. Faba monoculture and S. asper monoculture, respectively.(3)Compared with the initial soil, intercropping and monocropping V. faba increased soil available nitrogen by 139.87% and 155.15%, respectively; monocropping V. faba decreased available potassium by 10.6% while there was little difference in soil available potassium in other systems; soil available phosphorus content showed reduction in all systems.(4)Soil Cd forms were in order of exchangeable > carbonates bound > iron and manganese oxides bound > organic matter bound. Exchangeable Cd content was 21.98% and 22.13% higher in intercropping systems than in V. faba and S. asper monocultures at plant mature stage. However, no difference was observed in other Cd forms.(5)The biomass of S. asper increased by 15.29% in intercropping system, compared with its monoculture, whereas that of V. faba was 24.77% lower in intercropping than in monoculture system.(6)Content of Cd in roots, leaves, bean pods and beans was significantly lower in V. faba intercropping than in monoculturing systems. Cadmium content in shoot of S. asper was significantly higher in intercropping than in monoculture, but Cd content in S. asper roots was not different. In conclusion, intercropping V. faba with S. asper promotes Cd accumulation in S. asper but reduces Cd content in V. faba.