The Inlfuence Of Perennial Ryegrass, Kochia Scoparia,thlaapi Arensa On CD Contaminated Soil With Different Agronomic Measures

The measures of controlling heavy metal pollution in soil become a major concern in today’s world, ofwhich, phytoremediation is deemed as the most promising means, plus various methods of improvingefficiency of phytoremediation. In this paper, the impact of three Cd accumulators, i.e. Lolium perenne L.,Kochia scoparia L. and Thlaspi arvense L. were studied for their influence on restoring Cd-contaminatedsoil with different agronomic measures (intercropping maize, adding earthworm, cow dung, stalk, urea etc.)in a greenhouse. The restoring efficiency of those three plants and variation characters was studied withfive agronomic measures respectively in transverse and longitudinal ways. In the transverse way, based onstudying the variation of restoring efficiency of single plant (one of Lolium perenne L., Kochia scoparia L.and Thlaspi arvense L.) with five agronomic measures respectively, the agronomic measure maximizingthe restoring efficiency of the plant was determined; in the longitudinal way, based on studying the impactof an agronomic measure (intercropping maize, adding earthworm, cow dung, stalk, urea) on the said plants,the differences in impact of one agronomic measure on the restoring efficiency of various plants weredetermined.The result indicate that:(1) Among Lolium perenne L., Kochia scoparia L. and Thlaspi arvense L., Thlaspi arvense L. is thebest Cd accumulator and its Cd content was up to28.34mg/kg, while the highest Cd content of Loliumperenne L.16.49mg/kg and Kochia scoparia L.13.80mg/kg. Thlaspi arvense L., however, was of smallbiomass and grew slowly, which led to low restoring efficiency and the highest restoring efficiency reached0.1423%; Kochia scoparia L.0.1987%and Lolium perenne L.0.1583%. Since Lolium perenne L. could bemowed3-4times every year, which made biomass increased and soil cadmium content decreased.Therefore, Lolium perenne L. was selected for further study with interactive agronomic measures.(2) The restoring efficiency of Lolium perenne L. with interactive agronomic measures was bettersignificantly than that with single agronomic measure, which proved that interactive agronomic measures were correct and feasible. Moreover, for choosing interactive agronomic measures, interaction of inorganicand organic fertilizers shall be considered first since the findings showed that interaction of inorganic andorganic fertilizers increased the restoring efficiency of Lolium perenne L. significantly.(3) Intercropping maize, as an agronomic measure, helps Lolium perenne L., Kochia scoparia L. andThlaspi arvense L. improve their Cd-accumulating capacity; comparing with non-intercropped maize,intercropped maize saw significantly-declined Cd content, i.e. the intercropping of maize withCd-accumulating plants not only increased restoring capacity of Cd accumulator plants, but inhibited Cdflow from soil to maize, which decreased Cd content of maize and improved security of maize to certainextent for serving two ends. Such findings offer scientific rationale for establishing and operating safeproduction system in urban-fringe area effectively.