Method for accurately selecting heavy metal polluted cultivated land remediation measures based on rhizosphere evaluation

Abstract

The invention relates to the technical field of ecological environment protection, and discloses a method for accurately selecting heavy metal polluted cultivated land remediation measures based on rhizosphere evaluation. According to the method for accurately selecting the remediation measures of the heavy metal polluted cultivated land based on rhizosphere evaluation, the heavy metal pollution condition in soil and agricultural products and the condition of soil microorganisms under heavy metal stress are comprehensively considered, the heavy metal pollution level of the cultivated land soil is comprehensively evaluated, and the remediation measures of the cultivated land are accurately selected. Proper soil remediation measures are selected by combining the soil pH and the heavy metal content in the irrigation water, so that the heavy metal polluted cultivated land can be accurately remedied, the heavy metal content is reduced, and the quality of agricultural products is guaranteed; compared with large-scale soil remediation, through accurate evaluation, partitioned remediation can be carried out on the cultivated land, the remediation effect is improved, the remediation cost is reduced, normal production of farmers is basically not affected, and remediation and production are carried out at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological environment protection, and in particular to a method for accurately selecting restoration measures for heavy metal polluted farmland based on rhizosphere assessment. Background Art

[0002] The quality of cultivated land soil is closely related to the growth of agricultural products. Heavy metal pollution in soil poses a serious threat to the quality and safety of agricultural products. The existing heavy metal contaminated cultivated land restoration technology, products and models are not yet mature, and the restoration technology is not systematic and complete. Its shortcomings are mainly manifested in:

[0003] (1) The restoration system of heavy metal-contaminated farmland is imperfect: There are many technologies for the restoration of heavy metal-contaminated farmland, including physiological barriers, soil passivation, deep tillage, and alternative planting, but the applicability of the technologies is not clear and systematic enough;

[0004] (2) The restoration technology for heavy metal contaminated farmland is not very targeted: For farmland contaminated by heavy metals, physiological barriers and soil passivation are currently commonly used for restoration. However, due to differences in pollutants, pollution levels, agricultural products, planting habits, etc., there are problems such as uneven restoration effects and waste of funds.

[0005] Therefore, building a comprehensive and complete evaluation system for heavy metal pollution in cultivated land soil is of great significance for the targeted selection of appropriate technologies, accurate restoration of cultivated land contaminated by heavy metals, and ensuring the quality of agricultural products. Summary of the invention

[0006] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, the purpose of the present invention is to provide a method for accurately selecting remediation measures for heavy metal-contaminated cultivated soil.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The present invention provides a method for accurately selecting restoration measures for heavy metal-contaminated farmland based on rhizosphere assessment, comprising the following steps:

[0009] S1. Obtain the measured values ​​of total content of single heavy metals and effective DTPA content in rhizosphere soil, abundance of bacterial OTUs in rhizosphere soil, and heavy metal content in agricultural products;

[0010] S2. Calculate the soil heavy metal single factor pollution index P based on the measured value i , soil heavy metal single factor effective state ratio L i , Heavy metal single factor pollution index E of agricultural products i and together with the rhizospheric soil bacterial OTUs abundance W, were used as evaluation factors for the risk level of cultivated soil pollution;

[0011] S3, dividing the evaluation factors into three levels: low, medium and high, determining the classification standard of each evaluation factor, and determining the heavy metal pollution risk level of the cultivated soil through weight distribution operation;

[0012] S4. Obtain the measured values ​​of rhizosphere soil pH and heavy metal content in irrigation water, and accurately select restoration measures for heavy metal-contaminated cultivated land based on the risk level of heavy metal pollution in the cultivated land soil.

[0013] In some embodiments of the present invention, the heavy metal includes at least one of cadmium, mercury, arsenic, chromium and lead.

[0014] In the present invention, when evaluating the degree of heavy metal pollution, a single factor evaluation method is adopted to detect the total content of a single heavy metal and the effective state content of DTPA, and calculate the soil heavy metal single factor pollution index and the soil heavy metal single factor effective state ratio.

[0015] In some embodiments of the present invention, the soil heavy metal single factor pollution index P i The calculation expression is:

[0016]

[0017] Where P i is the single factor pollution index of heavy metal i in rhizosphere soil;

[0018] C i is the measured total content of heavy metal i in rhizosphere soil, mg / kg;

[0019] S i It is the evaluation standard value of heavy metal i recorded in GB 15618 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard", mg / kg;

[0020] The soil heavy metal single factor pollution index is classified into: low 1≤P i <2, medium 2≤P i <3, high P i ≥3.

[0021] In some embodiments of the present invention, the soil heavy metal single factor effective state ratio L i The calculation expression is:

[0022]

[0023] Where, L i is the single factor effective state ratio of heavy metal i in rhizosphere soil, %;

[0024] T i1is the total content of exchangeable and carbonate forms of heavy metal i in rhizosphere soil, mg / kg;

[0025] T i2 is the total content of heavy metals i iron and manganese in oxidized, organically bound and residual forms in rhizosphere soil, mg / kg;

[0026] The single factor effective state ratio of soil heavy metals is classified into: low 15% ≤ L i <30%, medium 30%≤L i <50%, high L i ≥50%.

[0027] In some embodiments of the present invention, the calculation expression of the agricultural product heavy metal single factor pollution index is:

[0028]

[0029] In the formula, E i is the single factor pollution index of heavy metal i in agricultural products, %;

[0030] A i is the total measured content of heavy metal i in agricultural products, mg / kg;

[0031] R is the standard error of the measured concentration of heavy metal i in agricultural products;

[0032] S i It is the limit standard of heavy metal i in agricultural products recorded in GB 2762 "National Food Safety Standard Limits of Contaminants in Food", mg / kg;

[0033] The heavy metal single factor pollution index of agricultural products is classified into: low E i <75%, medium 75%≤E i <100%, high E i ≥100%.

[0034] In some embodiments of the present invention, the limit values ​​recorded in the latest standard of GB 2762 "National Food Safety Standard Limits of Contaminants in Food" are used as the limit standards for the content of heavy metal i in agricultural products.

[0035] In some embodiments of the present invention, the rhizosphere soil bacterial OTUs abundance W is graded as follows: low W>3000, medium 1000<W≤3000, and high W≤1000.

[0036] In some embodiments of the present invention, the expression of the weight distribution operation is:

[0037]

[0038] Where: Y is the weighted sum of the scores of various evaluation factors of cultivated land soil;

[0039] a j is the score of the evaluation factor j, where the low, medium and high score values ​​are 1, 2 and 3 points respectively;

[0040] b j To evaluate the weight of factor j, the weights of agricultural product heavy metal single factor pollution index, soil heavy metal single factor pollution index, soil heavy metal single factor effective state ratio and bacterial OTUs abundance are 0.3, 0.3, 0.2 and 0.2 respectively;

[0041] The heavy metal pollution risk levels of the cultivated soil are classified as follows: Level I Y<1.5, Level II 1.5≤Y≤2, Level III 2<Y≤2.5, Level IV 2.5<Y<3, and Level V Y≥3.

[0042] In some embodiments of the present invention, when the heavy metal pollution risk level of the cultivated soil is Level I, it indicates that the agricultural products are relatively safe, the degree of soil heavy metal pollution is moderate or below, the effective content of heavy metals is low, the soil microbial community is good, and the pollution of agricultural products is not easy to worsen.

[0043] In some embodiments of the present invention, when the heavy metal pollution risk level of the cultivated soil is Level II, it indicates that the agricultural products are relatively safe, the degree of soil heavy metal pollution is moderate or below, the effective content of heavy metals is relatively high, the soil microbial community is relatively good, and the pollution of agricultural products may be aggravated.

[0044] In some embodiments of the present invention, when the heavy metal pollution risk level of the cultivated soil is Level III, it indicates that the heavy metal content of agricultural products is on the verge of exceeding the standard, the degree of soil heavy metal pollution is severe or below, the effective content of heavy metals is low, the soil microbial community is under a certain threat, and the pollution of agricultural products may worsen.

[0045] In some embodiments of the present invention, when the heavy metal pollution risk level of the cultivated soil is Level IV, it indicates that the heavy metal content of agricultural products exceeds the standard, the degree of soil heavy metal pollution is severe or below, the effective content of heavy metals is high, the soil microbial community is under a certain threat, and the pollution of agricultural products is likely to worsen.

[0046] In some embodiments of the present invention, when the heavy metal pollution risk level of the cultivated soil is Level V, it indicates that the heavy metal content of agricultural products exceeds the standard, the degree of heavy metal pollution in the soil is severe, the effective content of heavy metals is high, the soil microbial community is threatened, and it is not suitable for growing edible agricultural products.

[0047] In some embodiments of the present invention, when obtaining the measured values ​​of the total content of single heavy metals in rhizosphere soil and the effective content of DTPA, the abundance of rhizosphere soil bacteria OTUs, and the heavy metal content of agricultural products, a plum blossom sampling method or a snake sampling method is used to arrange sampling sites in heavy metal contaminated farmland. For every 15 mu of heavy metal contaminated farmland, the number of sampling sites is greater than or equal to 5, and the samples collected from each sampling site are mixed into one sample as the detection sample of the rhizosphere soil or agricultural products of the heavy metal contaminated farmland.

[0048] In some embodiments of the present invention, the rhizosphere soil sample is the surface soil of 0-20 cm in the rhizosphere of the agricultural product.

[0049] In some embodiments of the present invention, the agricultural product sample is an edible portion of the agricultural product.

[0050] In some embodiments of the present invention, the soil is divided into acidic pH≤5.5, neutral 5.5<pH≤7.5 and alkaline pH>7.5 according to the measured pH value of the rhizosphere soil.

[0051] In some embodiments of the present invention, the heavy metal content of the irrigation water is limited by GB 5084 "Farmland Irrigation Water Quality Standard".

[0052] In some embodiments of the present invention, the limit values ​​recorded in the latest standard GB 5084 "Farmland Irrigation Water Quality Standard" are used as the limit standards for heavy metal content in irrigation water.

[0053] In the present invention, irrigation water is included in the evaluation system based on the fact that irrigation water will have a significant impact on cultivated soil and agricultural product quality. When the heavy metal content in irrigation water is lower than the limit standard recorded in GB 5084 "Agricultural Irrigation Water Quality Standard", irrigation water is considered to be safe water.

[0054] In some embodiments of the present invention, the restoration measures are selected from at least one of water control, fertilizer control, soil passivation, biological agent control, plant replacement planting, and intercropping.

[0055] In some embodiments of the present invention, the water regulation is applicable to paddy fields, specifically including: deep water (3-5 cm water depth) after rice transplanting to activate the stump, shallow water (2-3 cm water depth) to cover the field to promote tillering from the green stage to the panicle differentiation stage, and promote the development and rooting of rice roots, control ineffective tillering and reduce nutrient consumption, which is beneficial to rice panicle formation; long-term flooding (3-5 cm water depth) from the heading stage to the maturity stage to reduce the root zone and field temperature, improve the fruit setting rate, and increase the number of filled grains, drain and air the field 10 days before harvest, and harvest in time.

[0056] In some embodiments of the invention, the fertilizer regulation includes applying organic fertilizer or inorganic fertilizer.

[0057] In some embodiments of the present invention, the organic fertilizer includes decomposed manure, peat, and sawdust.

[0058] In some embodiments of the present invention, the inorganic fertilizer includes ferrous sulfate, ammonium sulfate, superphosphate, potassium dihydrogen phosphate, and potassium sulfate.

[0059] In some embodiments of the present invention, the application amount of the inorganic acidic fertilizer is regulated according to the soil pH value.

[0060] In some embodiments of the present invention, the soil passivation includes applying a soil passivator; the soil passivator is selected from a base material, an acid-based material or a modified biochar material.

[0061] In some embodiments of the present invention, the base material is an organic passivator or an inorganic passivator modified with an alkaline material; the alkaline material includes ammonium nitrogen and nitrate nitrogen.

[0062] In some embodiments of the present invention, the acid-based material is an organic passivating agent modified by an acidic material; the alkaline material includes sulfuric acid, humic acid, and citric acid.

[0063] In some specific embodiments of the present invention, the soil passivator includes a magnesium-based passivator, a silicon-based passivator, an iron-based passivator, a humic acid-modified calcium-based passivator, a citric acid-modified calcium-based passivator, and an organic passivator.

[0064] In some specific embodiments of the present invention, when the cultivated soil is contaminated by cadmium, a magnesium-based passivator, a silicon-based passivator or an organic passivator is applied.

[0065] In some specific embodiments of the present invention, when the cultivated soil is contaminated with arsenic and / or lead, an iron-based passivator or an organic passivator is applied.

[0066] In some specific embodiments of the present invention, when the cultivated soil is contaminated by mercury and / or chromium, a humic acid-modified calcium-based passivator or a citric acid-modified calcium-based passivator is applied.

[0067] In some embodiments of the present invention, the microbial agent includes a Bacillus agent, a Burkholderia agent, a saprophytic Staphylococcus agent, a fluorescein Pseudomonas agent, and a Pseudomonas aeruginosa agent.

[0068] In some specific embodiments of the present invention, when the cultivated soil is contaminated by cadmium, a Bacillus agent or a Burkholderia agent is applied.

[0069] In some specific embodiments of the present invention, when the cultivated soil is contaminated by arsenic and / or lead, a Bacillus, Burkholderia or Staphylococcus saprophyticus agent is applied.

[0070] In some specific embodiments of the present invention, when the cultivated soil is contaminated by mercury, a Pseudomonas fluorescens inoculant is applied.

[0071] In some specific embodiments of the present invention, when the cultivated soil is contaminated by chromium, a Pseudomonas aeruginosa bacterial agent is applied.

[0072] In some embodiments of the present invention, the plant replacement planting and intercropping planting include planting non-food plants with high heavy metal enrichment, including Sedum australis, Phytolacca americana, Solanum nigrum, Centipede grass, Pink fern, sunflower, ramie, Chinese mustard, Artemisia selengensis, Euphorbia lathyris, Ligustrum lucidum, Ricinus communis, Psoralea corylifolia, King bamboo grass, Giant fungus grass, alfalfa, Astragalus membranaceus, and mulberry.

[0073] In some specific embodiments of the present invention, when the cultivated soil is contaminated by cadmium, Sedum alfredii, Phytolacca americana or Solanum nigrum is planted.

[0074] In some specific embodiments of the present invention, when the cultivated soil is contaminated by arsenic, Sedum austriatum, mulberry, centipede grass or pink fern is planted.

[0075] In some specific embodiments of the present invention, when the arable soil is contaminated by lead, sunflower, ramie or Chinese mustard is planted.

[0076] In some specific embodiments of the present invention, when the cultivated soil is contaminated by mercury, Artemisia annua or Euphorbia pulex is planted.

[0077] In some specific embodiments of the present invention, when the cultivated soil is contaminated by chromium, Ligustrum lucidum, Ricinus communis or Ligusticum chuanxiong are planted.

[0078] In some specific embodiments of the present invention, the farmland soil pollution remediation technology is:

[0079]

[0080]

[0081] Compared with the prior art, the present invention has the following beneficial effects:

[0082] The method provided by the present invention for accurately selecting restoration measures for heavy metal-contaminated farmland based on rhizosphere assessment comprehensively considers the heavy metal pollution in soil and agricultural products, as well as the conditions of soil microorganisms under heavy metal stress, comprehensively evaluates the heavy metal pollution level of farmland soil, and then selects appropriate soil restoration measures in combination with soil pH and heavy metal content in irrigation water, so as to accurately carry out restoration of farmland contaminated by heavy metals, reduce heavy metal content, and ensure the quality of agricultural products.

[0083] Compared with large-scale soil remediation, through precise assessment, we can carry out zoned remediation of cultivated land, improve the remediation effect, reduce remediation costs, and basically not affect the normal production of farmers, thus achieving production while remediation. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 This is a photo of the on-site restoration of Plot 1 in the embodiment;

[0085] Figure 2 This is a photo of the on-site restoration of Plot 6 in the embodiment;

[0086] Figure 3 This is a photo of the on-site restoration of the water control plot in the embodiment;

[0087] Figure 4 The photos are of the on-site plots of water regulation and composite restoration of attapulgite and lime mixed passivation agent in the examples;

[0088] Figure 5 This is a photo of the on-site replacement planting of mulberry trees in Plot 3 of the embodiment. DETAILED DESCRIPTION

[0089] The present invention is further described in detail below by specific examples. The raw materials, reagents or devices used in the examples can be obtained from conventional commercial sources or by prior art methods unless otherwise specified. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0090] Example

[0091] 1. 150 mu of arsenic-contaminated farmland in a county of Shaoguan City, Guangdong Province was repaired. The farmland was divided into 10 areas and numbered as plots 1-10. Five soil sample sampling sites (plum blossom sampling method) were set up in each area, and the soil samples (0-20 cm surface soil in the rice rhizosphere) collected from the five sampling sites in each area were mixed to obtain rice rhizosphere soil samples in 10 areas (1 in each area) for the detection of total arsenic content in rhizosphere soil, DTPA effective content in rhizosphere soil, and abundance of bacterial OTUs in rhizosphere soil in each area; referring to the soil sample acquisition method, rice samples (edible parts) in each area were collected for the detection of total arsenic content in rice; according to the test results, the soil arsenic pollution index P was calculated respectively. i , soil arsenic available state ratio L i and rice arsenic contamination index E i , the calculation formula is:

[0092] 1) Soil arsenic pollution index:

[0093] Where P iis the arsenic pollution index of rice rhizosphere soil;

[0094] C i is the measured total content of arsenic in rice rhizosphere soil, mg / kg;

[0095] S i It is the evaluation standard value of arsenic recorded in GB 15618-2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard", mg / kg;

[0096] 2) Ratio of available arsenic in soil:

[0097] Where, L i is the ratio of available arsenic in rice rhizosphere soil, %;

[0098] T i1 is the total content of exchangeable and carbonate arsenic in rice rhizosphere soil, mg / kg;

[0099] T i2 is the total content of arsenic, iron and manganese in oxidation, organic binding and residual forms in rice rhizosphere soil, mg / kg;

[0100] 3) Rice arsenic pollution index:

[0101] In the formula, E i is the rice arsenic pollution index, %;

[0102] A i is the total measured content of arsenic in rice, mg / kg;

[0103] R is the standard error of the measured concentration of arsenic in rice;

[0104] S i The limit standard for arsenic in rice recorded in GB 2762-2022 "National Food Safety Standard Limits of Contaminants in Food", mg / kg;

[0105] The calculation results are averaged to represent the calculation results of the evaluation factors of each block, as shown in Table 1:

[0106] Table 1 Evaluation factor calculation results in the embodiment

[0107]

[0108]

[0109] 2. According to the evaluation factor grading standard, each evaluation factor is divided into three levels: low, medium and high, and the score of each level is recorded. The results are shown in Table 2:

[0110] Table 2 Evaluation factor levels and scores in the examples

[0111]

[0112] 3. According to the formula Calculate the weighted sum of the scores of various soil evaluation factors:

[0113] Where: Y is the weighted sum of the scores of various soil evaluation factors;

[0114] a j is the score value of the evaluation factor j, as shown in Table 2;

[0115] b j To evaluate the weight of factor j, the weights of the rice arsenic pollution index, soil arsenic pollution index, soil arsenic effective state ratio and bacterial OTUs abundance were 0.3, 0.3, 0.2 and 0.2, respectively. The calculation results are shown in Table 3:

[0116] Table 3 Weighted sum of scores of various evaluation factors and pollution risk level of cultivated land soil in the embodiment

[0117] Plot Number Weighted scores of various evaluation factors of cultivated land soil Risk level of soil pollution in cultivated land 1 3 Level V 2 2 Level II 3 3 Level V 4 2.5 Grade III 5 1 Level I 6 2.8 Level IV 7 1.3 Level I 8 1.3 Level I 9 2 Level II 10 1.9 Level II

[0118] 4. The pH of cultivated land soil was monitored, and the average pH of the soil was 5.13, which was acidic soil. The current irrigation water quality was sampled and analyzed. The contents of heavy metals As and Pb in the three irrigation water samples collected were 4.7μg / L and 7.2μg / L respectively, and Cd, Hg and Cr were not detected. According to the standard values ​​of farmland irrigation water quality in GB 5084-2021 "Farmland Irrigation Water Quality Standards": As ≤ 50μg / L, Pb ≤ 20μg / L, confirming that the irrigation water source is a safe water source.

[0119] Pollution remediation was carried out on farmland in different areas, and the remediation technologies are shown in Table 4:

[0120] Table 4: Cultivated soil remediation technology in the examples

[0121]

[0122]

[0123] Figure 1 This is a photo of the on-site restoration of Plot 1 in the embodiment. Figure 2 This is a photo of the on-site restoration of Plot 6 in the embodiment. Figure 3 This is a photo of the on-site restoration of the water control plot in the embodiment. Figure 4 The photos are of the on-site plots of water regulation and composite restoration of attapulgite and lime mixed passivation agent in the examples. Figure 5This is a photo of the mulberry tree replacement planting site in Plot 3 of the Example. After two years of restoration, the rice safety compliance rate in each plot was over 95%, and the concentration of heavy metals in the soil decreased by 20%-70%. The regional precise restoration effect was good, and compared with the large-scale physiological barrier or soil passivation method, the restoration cost was greatly reduced.

Claims

1. A method for accurately selecting restoration measures for heavy metal-contaminated farmland based on rhizosphere assessment, characterized in that: The following steps are involved: S1. Obtain the measured values ​​of total content of single heavy metals and effective DTPA content in rhizosphere soil, abundance of bacterial OTUs in rhizosphere soil, and heavy metal content in agricultural products; S2. Calculate the soil heavy metal single factor pollution index P based on the measured value i , soil heavy metal single factor effective state ratio L i , Heavy metal single factor pollution index E of agricultural products i and together with the rhizospheric soil bacterial OTUs abundance W, were used as evaluation factors for the risk level of cultivated soil pollution; S3, dividing the evaluation factors into three levels: low, medium and high, determining the classification standard of each evaluation factor, and determining the heavy metal pollution risk level of the cultivated soil through weight distribution operation; S4. Obtain the measured values ​​of rhizosphere soil pH and heavy metal content in irrigation water, and accurately select restoration measures for heavy metal-contaminated cultivated land based on the risk level of heavy metal pollution in the cultivated land soil.

2. The method according to claim 1, characterized in that The heavy metal includes at least one of cadmium, mercury, arsenic, chromium and lead.

3. The method according to claim 1, characterized in that: The soil heavy metal single factor pollution index P i The calculation expression is: Where P i is the single factor pollution index of heavy metal i in rhizosphere soil; C i is the measured total content of heavy metal i in rhizosphere soil, mg / kg; S i It is the evaluation standard value of heavy metal i recorded in GB 15618 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard", mg / kg; The soil heavy metal single factor pollution index is classified into: low 1≤P i <2, medium 2≤P i <3, high P i ≥3.

4. The method according to claim 1, characterized in that The single factor effective state ratio of soil heavy metals L i The calculation expression is: Where, L i is the single factor effective state ratio of heavy metal i in rhizosphere soil, %; T i1 is the total content of exchangeable and carbonate forms of heavy metal i in rhizosphere soil, mg / kg; T i2 is the total content of heavy metals i iron and manganese in oxidized, organically bound and residual forms in rhizosphere soil, mg / kg; The single factor effective state ratio of soil heavy metals is classified into: low 15% ≤ L i <30%, medium 30%≤L i <50%, high L i ≥50%.

5. The method according to claim 1, characterized in that The single factor pollution index of agricultural products heavy metals E i The calculation expression is: In the formula, E i is the single factor pollution index of heavy metal i in agricultural products, %; A i is the total measured content of heavy metal i in agricultural products, mg / kg; R is the standard error of the measured concentration of heavy metal i in agricultural products; S i It is the limit standard of heavy metal i in agricultural products recorded in GB 2762 "National Food Safety Standard Limits of Contaminants in Food", mg / kg; The heavy metal single factor pollution index of agricultural products is classified into: low E i <75%, medium 75%≤E i <100%, high E i ≥100%.

6. The method according to claim 1, characterized in that The rhizosphere soil bacterial OTUs abundance W was graded as follows: low W>3000, medium 1000<W≤3000, and high W≤1000.

7. The method according to claim 1, characterized in that The expression of the weight distribution operation is: Where: Y is the weighted sum of the scores of various evaluation factors of cultivated land soil; a j is the score of the evaluation factor j, where the low, medium and high score values ​​are 1, 2 and 3 points respectively; b j To evaluate the weight of factor j, the weights of agricultural product heavy metal single factor pollution index, soil heavy metal single factor pollution index, soil heavy metal single factor effective state ratio and bacterial OTUs abundance are 0.3, 0.3, 0.2 and 0.2 respectively; The heavy metal pollution risk levels of the cultivated soil are classified as follows: Level I Y < 1.5, Level II 1.5 ≤ Y ≤ 2, Level III 2 < Y ≤ 2.5, Level IV 2.5<Y<3, Level V Y≥3.

8. The method according to claim 1, characterized in that: According to the measured pH value of the rhizosphere soil, the soil is divided into acidic pH≤5.5, neutral 5.5<pH≤7.5 and alkaline pH>7.

5.

9. The method according to claim 1, characterized in that: The heavy metal content of the irrigation water is limited according to GB 5084 "Agricultural Irrigation Water Quality Standard".

10. The method according to claim 1, characterized in that The restoration measures are selected from at least one of water control, fertilizer control, soil passivation, microbial agent control, plant replacement planting, and intercropping.

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