CN105665439A - Practical method for farmland soil cadmium pollution remediationby planting Salix jiangsuensis J795 - Google Patents

Abstract

The invention discloses a practical method for farmland soil cadmium pollution remediationby planting Salix jiangsuensis J795 and belongs to the field of soil remediation. The practical method for farmland soil cadmium pollution remediationby planting Salix jiangsuensis J795 comprises the following steps: (1) after selecting a farmland with cadmium pollution, carrying out ploughing, soil smashing, ridge separating and designing on draining canal; (2) planting young branches of Salix jiangsuensis J795; and (3) performing agricultural management and protection to ensure that the survival rate of the willow is more than 90%, so that the Cd content of the originally polluted farmland soil is reduced by 30% in two years. According to the method, young branches of Salix jiangsuensis J795 can be planted in farmland soil with serious pollution of Cd, the Cd content in the polluted soil can be reduced by more than 20% in average in the first year; and by repeatedly planting and transplanting for 3-5 years, the farmland with the Cd content of the soil higher than 3.0mg/kg can be basically remediated to achieve an effect that the total Cd content of the farmland soil is less than 1.0mg/kg.

Description

Plant Su Liu 795 and repair the practical approach of agricultural land soil cadmium pollution

Technical field

The present invention relates to farming land Cadmium in Soil (Cd) pollution amelioration and Treatment process, it is specifically related to plant Su Liu 795 and repairs the practical approach of agricultural land soil cadmium pollution, it is that a kind of original position removes the mcroorganism amount phytoremediation technology of unnecessary Cd in agricultural land soil, compared with traditional over-accumulated plant recovery technique, the technology has popularizing application prospect widely, Salix seedlings can be cultivated and combine with agricultural land soil Cd pollution amelioration, can by ornamental plantation, the greenery constructions such as shelter-forest combine with heavy metal-polluted soil decontamination, it is fundamentally solve agricultural land soil Cd pollute and land resource can be made full use of, the effective ways of nursery stock resource.

Background technology

On April 17th, 2014 national environmental protection portion and Ministry of Land and Resources " whole nation Soil Pollution Investigation publication " issued point out: whole nation Farmland contamination accounting reaches 19.4%, especially prominent with heavy metal pollution problems such as cadmiums. 320 severe contamination district soil investigations of national 24 provinces, city were once found by the Ministry of Agriculture, heavy metal-polluted soil exceeding standard rate accounts for the 80% of contaminated soil and crops, about 1.3 ten thousand hectares of arable lands at present, the whole nation are subject to Cd and pollute, annual about 10,000,000 tons of the grain lost because of heavy metal pollution, economic loss is at least up to 20,000,000,000 yuan. Arable land Cd pollutes the production safety not only threatening grain, also directly relates to the future of health or even nationality, and preventing and treating is ploughed or agricultural land soil Cd pollutes and just becoming the epoch topic that national people show great attention to. Administer agricultural land soil Cd and pollute the recovery technique needing maturation, Cd Pollution in Soil phytoremediation technology is fundamentally to remove the method put things right once and for all of residual heavy metal in soil, there is the features such as ecological, sustainable, green, be also easiest to be accepted by common people, certain also the most challenging. Phytoremediation technology for heavy-metal contaminated soils such as Cd studies the extensive concern being just subject to the ambits such as agrology, environmentology, ecology, agronomy, geochemistry for many years, but the mature technology of the real popularization and application of energy at present is very not many.

During phytoremediation technology is applicable to, low intensive large-scale pollution administer, can when not spoiled soil ecological environment keeps Soil structure, by root system of plant directly by plurality of heavy metal element absorption, environmental protection, the improvement effect of heavy metal contaminated soil has permanent. The research of modern soil the research of phytoremediation in heavy metal contaminated soils is started in developed country, once has some developed countries develop artificial wetland at discharge of industrial wastes mouth and plant aquatic macrophyte, is used for absorbing Heavy Metals in Waters etc. In North America, the state such as Europe and Southeast Asia have scholar to carry out the test with the super Heavy metal repairing polluted soil of plant. Marchiol etc. propose the desirable plants standard for plant extraction for 2004: one is able to the heavy metal in absorption soil and can be migrated to aboveground vegetation part;Two is pollute heavy metal in soil to have stronger patience; Three be fast growth and Biomass big; Four be strong adaptability and be prone to harvesting. Wherein xylophyta Biomass is big, and heavy metal patience is good, it is possible to produce higher extraction total amount. And willow is as the representative of xylophyta, it is utilized also relatively wider in phytoremediation technology is researched and developed. China is engaged in the heavy-metal contaminated soil phytoremediation technology researchs such as cadmium also one section of experience, but ripe practical phytoremediation technology is limited, how still in the exploratory stage, has, but without being formed, the technology that applicable large-scale promotion is worth. Phytoremediation technology research has two basic orientation, it is simply that finding mcroorganism amount plant and the over-accumulated plant that can absorb heavy metal-polluted soil, willow belongs to mcroorganism amount plant.

Over-accumulated plant is exactly the plant finding energy excess Enriching soil heavy metal, is the main flow of current phytoremediation technology research, how based on herbaceous plant. Herbaceous plant is of a great variety, strong stress resistance, has adaptability and indomitable vitality widely, and the patience of heavy metal is strong, is also widely used for the research and development of heavy-metal contaminated soil phytoremediation technology. The various heavy hyperaccumulative plant having now been found that broadly falls into herbaceous plant, for instance: arsenic over-accumulated plant Herba pteridis vittatae, zinc Cd hyperaccumulator are sky blue holds back blue dish, manganese hyperaccumulative plant Radix Phytolaccae etc. High concentration heavy metal is still had stronger adaptive capacity by the super enriching plant in herbaceous plant, it is possible to effectively protect surface soil, is enriched with high concentration metal. But herbal Biomass is less, the total amount extracting heavy metal-polluted soil might not be a lot. Compared with herbaceous plant, xylophyta well developed root system, heavy metal element in deep soil can be absorbed, the total amount extracting heavy metal-polluted soil is relatively higher, and after results, it is also used as fuel use or timber use, collecting Footwall drift material after flue gas and ash process further, this approach can avoid heavy metal to enter food chain. Therefore, the technical research also never pause of pedo relict heavy metal is extracted as xylophytas such as willows. The research work of phytoremediation is concentrated mainly on following 3 aspects:

(1) find, screen accumulation, over-accumulated plant in nature, cultivate domestication to meet actual repair engineer applied.

(2) plant heavy metal absorb, accumulation and removing toxic substances Mechanism Study, affect rhizosphere environment condition and the rhizosphere process study mechanism of plant absorption, to accurate instruction practical application and take Reasonable Regulation And Control technology to have important function.

(3) combined remediation technology exploitation and application. Chelating agen-phytoremediation technology, uses chelating agen in soil and improves the content of heavy metal in the soil liquid, the absorption of strengthening over-accumulated plant heavy metal.

Because although the concentration that over-accumulated plant absorbs the heavy metals such as pedo relict Cd is higher, but because by the restriction of Biomass, remove the high concentrations of Cd difficulty after all of residual in soil in a short time and see actual effect, certain limitation is had plus the cost of over-accumulated plant reparation, management, Technique Popularizing etc., so people pursue the exploitation of over-accumulated plant in phytoremediation for soil technical research, but do not ignore another one direction, it is simply that manage to be removed the heavy metals such as soil Cd by suitable mcroorganism amount plant yet. Willow is the mcroorganism amount plant easily survived, and can grow up again in Cd contaminated soil, naturally also becomes one of alternative plant of reparation Cd contaminated soil.In disclosed patent application document in the recent period, have and utilize willow as rehabilitation plant, absorb heavy metal-polluted soil by planting willow, it is possible to avoid the defect that the Cd Pollution Plants such as plant is short and small, the speed of growth is slow, Aboveground Biomass of Young is little are repaired. application documents if application number is 200910024586.4 (publication number is CN101486041A) disclose a kind of name and are called the technical scheme of " plant restoration method of a kind of soil polluted by heavy metal cadmium ", this technical scheme is to insert kind of a willow in Cd contaminated soil, apply ethyl lactate and the chemical enhancer of ethylenediaminetetraacetic acid composition after two months, strengthening extraction absorption efficiency, after processing 60 days, remediation efficiency is about 10%-20%, but in this patent of invention, in order to test needs, artificially with the addition of Cd solution and be prepared for Cd contaminated soil, certain gap may be there is with Cd polluted agricultural land in reality. it addition, the normal use ploughed can not be affected by the crops such as rice cultivation, Semen Tritici aestivi while plantation willow. willow can absorb top layer arable layer nutrient in a large number, reduces farm land quality. and for example, application number is that the application documents of 200910184526.9 (publication number is CN101642769A) disclose a kind of name and are called the technical scheme of " the chemical enhanced plant restoration method of polycyclic aromatic hydrocarbon-cadmium pollution soil ", golden silk willow (one of willow) is used in combination with chemical enhancer (ethyl lactate and ethylenediamine tetraacetate composition), has repaired the combined contamination soils such as polycyclic aromatic hydrocarbon and cadmium. plantation over-accumulated plant is also had to reach to repair Cd polluted agricultural land purpose, the application documents that application number is 200710020380.5 (publication number is CN100518970C) disclose a kind of technical scheme being called " plant restoration method of soil of zinc-cadmium combined pollution ", it is through plantation Cd over-accumulated plant companion ore deposit Herba hylotelephii erythrosticti with elsholtzia splendens to administer soil of zinc-cadmium combined pollution, regularly gather in plant, thus removing Cd in soil. the method repairing efficiency is long, it is necessary to put into the subsequent treatment of manpower management and plant. the grain amaranth field experiment Partial Proof feasibility of the method, certain natural organic fertilizer activator is applied in soil, it is obviously promoted the grain amaranth absorption efficiency to heavy metal in soil Cd, remediation efficiency improves 9.51～94.8%, and the facilitation of high concentrations of Cd contaminated soil remediation efficiency is better than low concentration Cd pollution. the super enriching plant that plantation is suitable, it is possible to significantly more efficient restoration of soil polluted by heavy metal.

Additionally, Xu Aichun etc. (2007), Wang Youliang etc. (2011) all reported that willow can absorb the data of heavy metal Cd, but do not provide the evidence of relevant field experiment. In the phytoremediation technology of forefathers' research and development, the heavy metals the such as totally result with lab simulation is on the high side, the Cd remained in soil also more is not from farmland. Heavy-metal contaminated soil phytoremediation technology research domestic at present still has many problems not capture, and substantially shows:

(1) inclined lab simulation, seldom carries out for the cadmium pollution of agricultural land soil and specializes in;

(2) continuity of technical research is inadequate, and for willow, the comparison of report willow energy cadmium pollution soil repair is many, has lacking of indoor complete result of the test to land for growing field crops;

(3) for the polluted agricultural lands such as cadmium, plantation willow obtain field experiment success illustration almost without;

(4) successful examples filtering out concrete willow kind is rare.

Include Jiangsu, the recovery technique of the anxious scarce practicalities of heavy metal pollution such as China's many grain-producing area preventing and treatings cadmium.The research of phytoremediation in heavy metal contaminated soils such as research and development relatively economical is practical, the cadmium of low cost are very necessary, willow is as the mcroorganism amount plant being expected, there is the potential quality that can absorb heavy metal-polluted soil, form to plant willow completes the heavy metals such as the Cd of agricultural land soil and removes, and the technological break-through of this respect more has application prospect. Willow is various in style, the willow kind also more than one that can absorb heavy metal Cd reported at present, how by strict experiment sieving, select suitable willow kind to remove the pollutant such as Cd of agricultural land soil residual, be the Key technique problem being currently needed for capturing. Otherwise, willow can be repaired Cd contaminated soil and mostly can only be rested on the aspect of possible in theory.

Summary of the invention

1, the problem to solve

The present invention is directed to soil Cd to repair and governing problem, specifically be aiming at farmland or arable soil Cd content reach severe contamination degree after be not suitable for continuing to cultivate and the urgent issue of the pollutant such as the heavy metal cadmium that remains in native soil must be removed, present invention offer plants Su Liu 795 and repairs the practical approach of agricultural land soil cadmium pollution, the heavy metal of residual in soil is extracted by planting mcroorganism amount Su Liu 795, reduce the cadmium concentration of former agricultural land soil and progressively recover the basic ecological functions in farmland, belong to one of heavy metal pollution of soil phytoremediation technology, in polluted agricultural land, new long willow also has biological sequestration, Radix Saposhnikoviae, the functions such as greenery patches protection, have and have a extensive future, simple to operate, the advantages such as instant effect.

2, technical scheme

Principles of the invention: Su Liu 795 is a kind of fast-growing willow, belongs to a kind of in the willow series cultivated on soil, Jiangsu, and willow woods that is big and that grow up to has Radix Saposhnikoviae, biological sequestration, supplies several functions such as viewing and admiring Biomass. Su Liu 795 can absorb the heavy metals such as the Cd in soil, and scavenging effect is better than the many over-accumulated plant reported at present according to mass balance calculation. Cd in agricultural land soil run up to will necessarily threaten after to a certain degree agricultural product safely, even result in agricultural land soil and lose and basic cultivate function or other ecological functions, it is necessary to find suitable Method means and remove in agricultural land soil the pollutant such as the Cd of residual. it is exactly one of Method means therein that plantation willow removes unnecessary Cd in agricultural land soil. hands section is managed and protected in different Planting patterns and plant growing, different soil texture difference etc. all determine plantation willow and repair the agricultural land soil Cd difference on effect polluted, willow extracts the speed of (or absorption) soil Cd in growth course, effects etc. are required for strict observation experiment and could obtain, how Cd in agricultural land soil carries out internal distribution, it is relevant that the willow of different cultivars absorbs the disposal options after the difference on effect etc. of soil Cd grows up to willow, everything also all relies on strict scientific observation test, and the summary of correlation test result is refined. have based on Su Liu 795 and quickly draw the characteristic of Cd in soil, choose typical case's Cd polluted agricultural land and carry out system and plant willow scrubbing test, sum up a practicality based on planting Su Liu 795 method successfully repairing agricultural land soil Cd pollution.

Plant Su Liu 795 and repair the practical approach of agricultural land soil cadmium pollution, the steps include:

(1), after selected Cd-polluted farmland, carry out turning over, hack, Fen Long, designing and arranging Box Drain;

(2) Su Liu 795 young shoots is planted;

(3) managed and protected by agronomy and guarantee that willow survives more than 90%, within 2 years, make the soil Cd content of original polluted agricultural land decline 30%;Namely Su Liu 795 growth of plantation completely connects root for 1 year from farmland and all removes, and again plants Su Liu 795, treats that year and a day is removed again; Repeat 3-5, substantially agricultural land soil Cd content can be repaired all less than 1.0mg/kg in the soil Cd content farmland more than 1.0mg/kg.

In step (1) cadmium pollution soil Cd content all greater than 2.0mg/kg, soil pH value all less than 6.5.

Preferably, in step (2), Su Liu 795 young shoots is 15 centimetres high, diameter is less than 1 centimetre of young shoots.

Preferably, step (2) plants upper Su Liu 795 young shoots according to 40 × 30 centimetres of spacing.

3, beneficial effect

Compared to prior art, the invention have the benefit that

(1) in the with serious pollution agricultural land soil of Cd, plantation this kind of Arbor willow branch of Su Liu 795, wicker can be made in 1 year to grow to 3 meters high, big tree about thick about 3 cm diameters from 15 centimeter length, thick about 0.5 cm diameter, by willow growth course is drawn the Cd of residual in soil, Cd in soil can be made to reduce year by year, the Cd content in contaminated soil in First Year, can be made on average to decline more than 20%.

(2) under the premise breaking off agricultural land soil Cd pollution source, by big potted plant kind of Su Liu 795, First Year can make soil Cd content drop to 5.02mg/kg from average 6.03, mean reduction reaches 16.75%, in 2 years can soil Cd content from average 6.03 dropping to 4.45mg/kg, mean reduction reaches 26.2%.

(3) under the premise that cannot block agricultural land soil Cd pollution source, Su Liu 795 cutting is transplanted on the spot by land for growing field crops, Su Liu 795 can be made over 1.5 years to grow up to the big willow of 5 meters high from small stems 15 centimetres high, single willow quality is on average more than 4.5kg, trunk is straight and upright, flourishing, has sight and gos deep into value. Absorbed by Su Liu 795, make the Cd content entire lowering about 32% of agricultural land soil, the part heavy metal Zn in agricultural land soil can also be absorbed simultaneously.

(4) pot experiment and field experiment all show, plant Su Liu 795 branch and can quickly draw Cd unnecessary in soil, but the ability of each site absorption soil Cd of willow tissue has marked difference, the Cd content distribution of different willow tissues is uneven, the strongest with the absorbability of tree root, leaves, its Folium Pterocaryae absorbs bio-concentration factor (BCF) maximum of soil Cd more than 10.0.

(5) degree of depth that agricultural land soil Cd pollutes on the spot is usually no more than 40 centimetres, in Su Liu 795 growth course, root system is extremely strong to deep penetration capacity, willow all takes root in the deep soil of less than 50 centimetres after growing 1.5 years in soil, soil does not now have the Cd supply of abundance, has caused that transplanting Su Liu 795 shoot growth absorbs soil Cd effect after 1.5 years is remarkably decreased. It is exactly annual transplanting 1 time that plantation Su Liu 795 absorbs the best way of agricultural land soil Cd, and the content of soil Cd declines again.

(6) Su Liu 795 draws the ability of soil Cd and is better than Salix babylonica L., red maple etc. and views and admires class nursery stock, and the Soviet Union also superior to another numbering Su Liu 172 produces the repairing effect of willow kind.

Accompanying drawing explanation

Fig. 1 is that Su Liu 795 potted plant repairing test soil Cd content changes over comparison diagram, (pot experiment soil picks up from polluted agricultural land, plants Liu Xiufu and has been turned off polluter);

Fig. 2 is pot experiment plant (Su Liu 795) organization internal Cd content and BCF value comparison diagram thereof, (in figure, max represents variable maximum, and min represents variable minima, and BCF is the bio-concentration factor of plant absorption soil element);

Fig. 3 is the constituent content variation diagrams (trial zone is positioned at E Hu town, Wuxi City Xishan District) such as plantation Su Liu 795 trial zone different depth soil Cd;

Fig. 4 changes over comparison diagram (in figure, max represents soil Cd content maximum, and min represents soil Cd content minima) for plantation Su Liu 795 field experiment soil Cd content;

Fig. 5 changes over figure for plantation Su Liu 795 field experiment leaves Cd content and BCF value thereof, (in figure, Cd content and BCF value are all meansigma methods);

Fig. 6 is plantation Su Liu 795 field experiment inside plant tissues Cd content and BCF value comparison diagram (in figure, Cd content and BCF value are all meansigma methods) thereof.

Detailed description of the invention

Below in conjunction with relevant process of the test, chart and enforcement illustration, the present invention will be further described:

Embodiment 1

Carry out potted plant Su Liu 795 for Cd polluted farmland soil to test:

From before the found heavy metal pollution of soil clue of Jiangsu the whole province eco-geochemical investigation and evaluation, it is preferable that going out the heavy metal severe contamination farmlands such as 5 representational Cd, the Cd content of selected agricultural land soil is 2.6 10.8mg/kg, soil pH=5.6 6.5. From farmland, fetch 1000kg soil (every polluted agricultural land fetch earth 200kg), be divided in 10 pottery basins, basin is high 60 centimetres, basin mouth diameter more than 60 centimetres, every basin contains soil more than thickness of soil in 60kg, basin be more than or equal to 50cm. Soil in basin is carried out in small, broken bits, remove impurity (grass, sand, stone etc.), floating, lightly compacting, wet water, then before the Ching Ming Festival, plug willow branch, 3 wickers equidistantly plugged by every basin, every basin ensures to survive at least 1, the seedling point-of-sale purchasing that the branch of Su Liu 795 kind planted is developed in Jiangsu Provincial Forest Science Research Inst.. After the willow planted survives, regularly water (tap water watered flowers), employ internal institution gardener willow in basin is kept an eye on. Allow willow free growth Cd (dry branches and fallen leaves in basin give in time remove) of absorbing in soil in basin, till willow no longer grows. From slotting willow, in the period taken at regular intervals basins such as 0.5 year, 1 year, 2 years, soil is chemically examined, and and blank. This test continues 2 years (during because of full 2 years willow not regrowth substantially in basin) altogether, finally willow is removed, carry out the chemical examination unified with pedotheque of willow sample, the Cd content of soil in the Cd content of mensuration willow difference plant tissue and corresponding basin thereof. This test, tests the plant samples 32 such as pedotheque 75, leaves altogether, and also the special tap water to pouring willow detects but finds that the Cd content of the water sample detected is entirely below detection limit.

Fig. 1 is shown in the Cd content statistical result over time of above-mentioned 10 basin soil, from planting Su Liu 795 branch, the Cd content of every basin soil all presents the trend of being decreased obviously, in First Year the biggest drop person reach 32.29%, its soil Cd content drop to slotting willow 1 year from 5.45 before planting trees after 3.69mg/kg, willow First Year absorb soil Cd at most, Second Year assimilation effect is decreased obviously. Willow organization internal Cd skewness, with tree root, bark, leaves absorb soil Cd ability relatively higher, tree root absorbs the bio-concentration factor (BCF value) of soil Cd can reach 6.8, bark absorbs the BCF value of soil Cd and is 7.7 to the maximum, leaves absorbs the BCF value of soil Cd and is 3.7 to the maximum, as shown in Figure 2. Su Liu 795 absorbs the ability of soil Cd and is better than Su Liu 172, and above-mentioned results from pot experiment test can clearly confirm this point.

It addition, also in pot experiment, Su Liu 795 grows also better in Cd contaminated soil, and trunk is straight and upright, branch and leaf are luxuriant, and leaves is denseer.

Embodiment 2

Choose typical case scene, Cd severe contamination farmland and plant Su Liu 795 branch

From the Cd-polluted farmland that Jiangsu Province had previously found, choose a Typical Areas carry out the land for growing field crops repairing test of plantation Su Liu 795 branch. This is experimental field positioned at, 100 meters of west side of E Hu town, Wuxi City Xishan District Battery Plant, take up an area 2.4 mu, by wheatland one piece independent, thing be about 80 meters, north and south wide about 20 meters, its surface soil Cd average content is more than 3.2mg/kg, soil pH=5.6, the heavy metal contaminants such as Cd are mainly gathered in the above deep soil of earth's surface 20cm, but its Hg pollution depth extends to below the 50cm degree of depth, soil deposit post evaluation also finds that experimental field soil exists certain acidifying and topsoil Zn slight enrichments (as shown in Figure 3). Experimental field north side is orchard (vineyard), west side is nursery for large stretch of paddy field, southern side for this.

According to the practical approach planting Su Liu 795 and repairing agricultural land soil cadmium pollution, first selected field is first arranged, rent machinery and the artificial wheat seedling removed in original field, by in small, broken bits for about more than 20cm deep soil, leveling, trench digging point ridge, be divided into 5 ridges according to field natural length, to be 80m length × 3.6 meter to every ridge wide, stays gutter to hold concurrently personnel's walking passageway between ridge and ridge, and field surrounding is dug more than 80cm zanjon and surrounding isolation, is used simultaneously as experimental field gutter; Preprepared Su Liu 795 branch is planted according to 40cm × 30cm spacing, disposable 12000, wicker is planted on April 11st, 2012, survive about more than 90%, survive situation according to willow after 1 month and carry out suitable thinning or interpolation, finally survive about 11000, willow; From plugging willow branch, namely employ special messenger in locality to experimental field carrying out maintenance management, including regularly watering, weeding, control worm, transplant seedlings and thinning, winter deadwood leaf reclaim and burn with fixed point, bury and fill out. This experimental field side stay a fritter blank ground, for carrying out blank with kind of a willow soil. This test has carried out 3 years altogether, in willow grows, within each 0.5 year, chemically examined 1 time by professional's regular sampling analysis, gather 20, fixing soil sample, 20, Folium Pterocaryae sample every time, when test proceeds to 1.5 years (mid-term) take whole willow and enter System Partition sampling in plant. 180, the plant samples such as cumulative analysis testing experiment field soil-like 160, leaves, also tree water sample 5 is watered in analysis, all water samples all do not detect the heavy metals such as Cd.

Above-mentioned field experiment result shows, plants Su Liu 795 branch Cd to quickly removing in above-mentioned agricultural land soil and obtains positive effect. Fig. 4 illustrates above-mentioned polluted farmland soil Cd changes of contents after planting willow, and in 1 year year, soil Cd average content drops to 2.2mg/kg from 3.31, decreases by 33.5%. Fig. 5 compared for the Cd changes of contents of the grown willow different times Folium Pterocaryae of above-mentioned field, can be seen that the Cd content of Folium Pterocaryae in 1.5 years and BCF value thereof are all substantially higher, when willow grows 0.5 year, 1 year, 1.5 years, the bio-concentration factor BCF value of its leaves absorption soil Cd respectively reaches 6.5,13.3,2.4, and the BCF value of the soil Cd of willow absorption afterwards drops to less than 2.0 and tends towards stability. When willow grows into 1.5 years, it absorbs Cd from soil and tends to saturated, now in willow plant tissue system, still absorb soil Cd relatively at most (as shown in Figure 6) with tree root, leaves, illustrating that willow absorbs soil Cd and relies primarily on leaves, tree root, this is consistent with above-mentioned results from pot experiment test.

Su Liu 795 branch is planted in the normal soil over experimental field 300 meters of west side (its soil Cd content is lower than 0.3mg/kg, pH=6.0), find that in the willow that grows, the Cd content such as leaves, bark is all not high, consistent with the Cd content of the normal willow such as Salix babylonica L.. Chemically examine after Folium Pterocaryae experimental field is collected burning, find that the Cd content of leaves ashes is up to 300mg/kg, suitable with the Cd content of the over-accumulated plant ashes such as winter indigo plant Herba hylotelephii erythrosticti, but with more than 5 times that the ashes growing Folium Pterocaryae on homalographic soil are growth winter indigo plant Herba hylotelephii erythrostictis, its efficiency of Cd severe contamination that instruction plantation Su Liu 795 goes out in agricultural land soil to exceed a lot.

Embodiment 3

Different xylophytas absorb the contrast of agricultural land soil Cd repairing effect

The on-the-spot side of field experiment is carried out at above-described embodiment 2, utilize small pieces to carry out the contrast test of plantation Su Liu 795, Salix babylonica L. and other sight nursery stock blankly, result is shown on the Cd contaminated land in same location, find that agricultural land soil Cd skewness continues to be verified, but there is significant difference in the ability of different plant absorption soil Cd, for plant growing 1 term leaves, the ability that the leaves of Su Liu 795 absorbs soil Cd is the strongest, Su Liu 172 takes second place, and the plant leaves such as Salix babylonica L., red maple, southern magnolia does not absorb the Cd of excess in soil substantially. The comparison of test results of the different plant leaves absorption soil Cd including Su Liu 795 is shown in following table (table 1).

Table 1 field experiment Su Liu 795, other relevant sight nursery stock leaves analyze result with pedotheque Cd content (mg/kg)

Su Liu 795 leaves volume of production in growth course is maximum, absorb the ability remaining Cd in soil the strongest, in First Year, leaves absorbs the bio-concentration factor BCF of soil Cd generally more than 5.0, and the repairing effect than Su Liu 172 is better, be the nursery stocks such as Salix babylonica L., red maple, southern magnolia incomparable. but because experimental field agricultural land soil Cd pollution depth is very less more than 30 centimetres of degree of depth, but its root system penetration depth has already exceeded this depth of soil after Su Liu 795 plants 1 year, cause that Su Liu 795 is difficult to after planting 1 year drawing Cd unnecessary in soil again through Root Absorption, although the ability of plant absorption soil Cd is likely to also unsaturation, and for repairing effect, after should planting 1 year, adult even whole of root is removed, again planting new has immature willow branch, repeat 3-5, so move in circles better for acquirement repairing effect, substantially agricultural land soil Cd content can be repaired all less than 1.0mg/kg in the soil Cd content farmland more than 1.0mg/kg.

Claims (7)

1. plant Su Liu 795 and repair the practical approach of agricultural land soil cadmium pollution, the steps include:

(1), after selected Cd-polluted farmland, carry out turning over, hack, Fen Long, designing and arranging Box Drain;

(2) Su Liu 795 young shoots is planted;

(3) managed and protected by agronomy and guarantee that willow survives more than 90%, within 2 years, make the soil Cd content of original polluted agricultural land decline 30%.

2. the Su Liu of planting 795 according to claim 1 repairs the practical approach of agricultural land soil cadmium pollution, it is characterized in that, in described step (3), namely Su Liu 795 growth of plantation completely connects root for 1 year from farmland and all removes, again plant Su Liu 795, treat that year and a day is removed again.

3. the Su Liu of planting 795 according to claim 2 repairs the practical approach of agricultural land soil cadmium pollution, it is characterized in that, plantation Su Liu 795 growth completely connects root for 1 year from farmland and all removes, again Su Liu 795 is planted, treat that year and a day is removed again, repeat 3-5, substantially agricultural land soil Cd content can be repaired all less than 1.0mg/kg in the soil Cd content farmland more than 1.0mg/kg.

4. the Su Liu of planting 795 according to claim 1 repairs the practical approach of agricultural land soil cadmium pollution, it is characterised in that in described step (1) cadmium pollution soil Cd content all greater than 2.0mg/kg, soil pH value all less than 6.5.

5. the Su Liu of planting 795 according to claim 1 repairs the practical approach of agricultural land soil cadmium pollution, it is characterised in that in described step (2), Su Liu 795 young shoots is 15 centimetres high, diameter is less than 1 centimetre of young shoots.

6. the Su Liu of planting 795 according to claim 1 repairs the practical approach of agricultural land soil cadmium pollution, it is characterised in that described step (2) plants upper Su Liu 795 young shoots according to 40 × 30 centimetres of spacing.

7. the Su Liu of planting 795 according to claim 1 repairs the practical approach of agricultural land soil cadmium pollution, it is characterised in that by small, broken bits for more than 20cm deep soil, leveling a point ridge of ditching in described step (1).