Effect Of Film Mulching On Soil Aggregates,Cd Availability And Plant Remediation Potential Of Heavy Metal Contaminated-farmland

With the rapid development of industry and agriculture,soil heavy metal pollution has become a research hotspot at home and abroad.Compared with physical and chemical remediation techniques,phytoremediation is an environmentally friendly,low economic cost,safe and sustainable in-situ remediation method for heavy metal pollution.The situation of heavy metal pollution in farmland soil in Hunan Province is severe,and simple mulching treatment and multi-season crop rotation of oil crops have the possibility of realizing the remediation of polluted soil while producing.This experiment took Cd-contaminated farmland in Jiaoxi Town,Liuyang City as the research object,through the composite mode of mulching-crop rotation:(1)film mulching/non-film mulching oil sunflower-rape;(2)film mulching/non-film mulching soybean-flax;(3)Field experiments were carried out with film mulching/non-film mulching Southeast Sedum-Peanut,etc.to explore the effects of film mulching on the basic physical and chemical properties of soil,soil Cd bioavailability,crop biomass,heavy metal content in various parts of crops,and soil heavy metal accumulation and concentration.The effect of removal rate.The purpose is to screen crops that are tolerant to cadmium and have the ability to enrich;to explore the remediation potential of six crop rotation modes on heavy metals;to find suitable plant rotation modes to remediate heavy metal-contaminated farmland.Experimental results show that:(1)Film mulching significantly increased the biomass of oil sunflower,soybean and flax,and increased the Cd concentration,Cd extraction amount and soil Cd restoration efficiency in different parts of the crop.(2)Compared with CK,film mulching g significantly reduced soil pH,OM and CEC contents of oil sunflower,soybean and Southeast Sedum.The mulching treatment significantly decreased the pH and OM of oil sunflower and soybean soils compared with the non-film mulching treatment.In addition,film mulching significantly increased the MWD and GMD values of oil sunflower,soybean and Southeast Sedum soils,decreased D and PAD values<0.25,and promoted the water stability of soil aggregates.(3)Film mulching significantly increased the biomass,Cd concentration,BCF,TF,total Cd extraction and total restoration efficiency of the subsequent rape and flax.Compared with the non-film mulching treatment,the soil pH of rape and flax was significantly decreased after the film-covered treatment.In addition,film mulching significantly increased the soil CaCl2-Cd content of rapeseed,flax and peanut,and significantly decreased the total soil Cd content after two-season crop rotation.(4)The total restoration efficiency of oil sunflower,soybean,sedum,rape,flax and peanut under the single planting and non-film mulching treatment modes ranged from(0.4%)to(3.72%)sedum sedum;The total restoration efficiency of different crops ranged from flax(0.66%)-(10.47%)to Sedum southeast under the planting and film mulching treatment modes;while the total restoration efficiency ranged from soybean-flax(1.47%)-(5.98%)Sedum sedum-Peanut;the total restoration efficiency of the composite mode of film mulching rotation pattern ranged from soybean-linen(2.58%-12.13%)Sedum sedum-Peanut.(5)The composite mode of film mulching and crop rotation can effectively promote the remediation potential of heavy metal-Cd polluted farmland soil of subsequent crops.This study provides new ideas and insights for the subsequent mulching-crop rotation composite remediation of heavy metal-contaminated farmland soil and remediation during production.