镉铅污染的玉米秸秆还田对蚕豆生长、养分和镉铅含量的影响

通过盆栽试验,模拟铅锌矿区镉铅污染的玉米秸秆还田,研究玉米秸秆的不同部分(根茬、茎秆、叶片和整株)还田对土壤速效养分、蚕豆生长、养分(N、P和K)、Cd含量、Pb含量的影响,结果表明:玉米秸秆还田增加土壤的碱解N和速效K的含量,增幅分别为14%~58%和36%~134%,但对土壤速效P的含量影响不显著。玉米秸秆还田显著增加蚕豆地上部养分的含量,其中叶片还田使N、P和K含量分别增加28%、40%和102%,根茬还田使P含量增加42%,茎秆和整株还田使K含量增加61%和98%;但对蚕豆地下部养分含量没有显著影响(仅叶片还田增加蚕豆地下部的P含量)。玉米秸秆还田导致蚕豆叶片叶绿素a和叶绿素b的含量显著下降,对蚕豆株高和生物量的影响小,仅叶片还田增加蚕豆的株高、茎秆还田增加蚕豆地上部的生物量。污染玉米秸秆还田极显著增加蚕豆地上部的Cd和Pb、地下部的Cd含量,分别提高了56%~76%、50%~133%和204%~507%,叶片和整株还田的蚕豆地上部Pb和地下部Cd的含量增幅较大。综上可知,镉铅污染的玉米秸秆还田在提高土壤肥力、改善后茬作物矿质营养的同时,会增加后茬作物对Cd、Pb的吸收,降低叶片叶绿素含量,有一定的环境危害风险,且秸秆不同部位的影响存在差异。

Effects of applying Cd/Pb contaminated maize stalks on growth and nutrient and Cd and Pb content of faba bean

In this experiment, Cd-Pb contaminated maize stalks grown in a Pb-Zn mining area was applied to soil, and biomass of roots, stems, leaves and whole plants of, and N, P, K, Cd and Pb content of faba bean plants and soil available nutrients were examined. Application of maize stalks enhanced soil available N and K by 14%~58% and 36%~134%, respectively; but had no significant effect on soil available P. Applying maize leaves increased faba bean N, P and K by 28%, 40% and 102%, respectively, while adding maize roots only enhanced P by 42%. Applications of stems and whole plants promoted the faba bean K content by 61% and 98%, respectively. No significant effects of maize stalk applications on nutrient content in the underground part of faba bean were observed, except an increase in P content caused by maize leaves. However, maize stalk applications caused significant decreases in chlorophyll a and b in the faba bean leaves. The height and biomass of faba bean were little affected by maize stalk applications, but applying leaves and stems increased the height and aboveground biomass of the bean. Applications of maize leaves enhanced the Cd and Pb content in the aboveground part, and Cd content in the belowground part of faba bean by 56%~76% and 50%~133%, and 204%~507%, respectively. These results indicate that applying maize stalks contaminated with Cd/Pb shows beneficial roles in enhancing soil fertility and improving mineral nutrition of the following crop, while may cause environmental risks induced by Cd/Pb contamination to soils including increased plant Cd and Pb uptake by and decreased chlorophyll content in leaves of the following crops.