Agricultural method for plant-microorganism combined remediation of cadmium-contaminated soil

Abstract

The invention discloses an agricultural method for plant-microorganism combined remediation of cadmium-contaminated soil. The method comprises the following steps: (1) conditioning soil by using biochar and humic acid; (2) soaking sedum alfredii hance seeds and sunflower seeds in the diluted bacterial liquid; (3) alternately planting sedum alfredii hance and sunflowers at equal line spacing; (4) controlling the moisture content of the soil, and regularly irrigating the diluted bacterial liquid to the roots of the sedum alfredii hance and the sunflower in the growth period; (5) regularly harvesting the sedum alfredii hance, and integrally removing the sunflower after the sunflower is mature. According to the method, sedum alfredii hance and sunflowers are intercropped, cadmium absorption is promoted, meanwhile, microorganisms are used for further activating cadmium, and the cadmium contaminated soil is further improved; the biochar and the humic acid are matched to condition the soil, so that the content of available cadmium can be reduced, and the risk of secondary pollution is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of cadmium-contaminated soil remediation, and in particular to an agronomic method for plant-microorganism combined remediation of cadmium-contaminated soil. Background Art

[0002] Currently, my country's soils are severely contaminated by heavy metals, particularly cadmium, which has attracted widespread attention due to its stability, high toxicity, and difficulty in removal. Currently, commonly used methods for remediating heavy metal-contaminated soils include biological, chemical, and physical methods. Physical methods primarily involve soil addition and deep tillage, which are labor-intensive and costly, and also involve the issue of secondary soil treatment. Chemical methods can reduce the toxicity of pollutants in the soil, but they cannot eradicate them. Factors such as rainfall and temperature fluctuations can cause pollutants to be re-released, leading to sudden soil problems. Biological methods are mainly divided into phytoremediation and microbial remediation. Traditional phytoremediation relies on a single hyperaccumulator, resulting in a long remediation cycle, typically 3-5 years, and limited effectiveness for remediating high-concentration cadmium (>5 mg / kg). Microbial remediation, however, is susceptible to inhibition by factors such as soil pH and organic matter content, resulting in poor stability and difficulty in large-scale application. Furthermore, soil conditioners (such as lime) can only fix cadmium in the short term; long-term use may cause soil compaction. Summary of the Invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, an embodiment of the present invention provides an agronomic method for plant-microorganism combined repair of cadmium-contaminated soil.

[0005] In a first aspect, the present invention provides an agronomic method for plant-microorganism combined remediation of cadmium-contaminated soil, comprising the following steps:

[0006] (1) Using biochar and humic acid to condition the soil;

[0007] (2) Soaking Sedum alfredii seeds and sunflower seeds in diluted bacterial solution;

[0008] (3) Plant Sedum australis and sunflower alternately with equal row spacing;

[0009] (4) controlling the soil moisture content and regularly applying the diluted bacterial solution to the roots of the Sedum alfredii and sunflower during the growing season;

[0010] (5) Harvest Sedum alfredii regularly and remove the sunflowers as a whole after they mature.

[0011] Furthermore, the step (1) includes mixing the biomass and the humic acid and then plowing to 20 to 25 cm, wherein the mass proportion of the biomass is 8%±0.2% and the mass proportion of the humic acid is 3%±0.2%.

[0012] Furthermore, the bacterial liquid is a composite bacteria composed of Bacillus subtilis and Rhizobium, wherein the Bacillus subtilis is ACCC 11060 and the Rhizobium is ATCC 39207.

[0013] Furthermore, the mass ratio of the Bacillus subtilis to the Rhizobium is 1:1.

[0014] Furthermore, the concentration of the bacterial solution is (1±0.2)×10 8 CFU / mL.

[0015] Furthermore, the row spacing of the Sedum alfredii and sunflower is 30±2 cm, and the plant spacing is 20±2 cm.

[0016] Furthermore, the planting density of the Sedum alfredii is 8 to 10 plants / m 2 The planting density of sunflower is 4 to 6 plants / m 2 .

[0017] Furthermore, in step (4), the soil moisture content is maintained at 60% to 70%.

[0018] Furthermore, in the step (4), the diluted bacterial solution is irrigated to the roots of Sedum alfredii and Helianthus annuus at intervals of 28 to 30 days during the growth period.

[0019] Furthermore, in the step (5), the Sedum alfredii is harvested once every 85 to 90 days.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention promotes cadmium absorption by intercropping Sedum alfredii and sunflower, and simultaneously utilizes microorganisms to further activate cadmium, thereby further improving cadmium-contaminated soil.

[0022] The present invention utilizes biochar and humic acid to condition the soil, which can reduce the effective cadmium content without the risk of secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0024] Figure 1 This is a flow chart of the agronomic method for plant-microorganism combined remediation of cadmium-contaminated soil according to the present invention;

[0025] Figure 2 This is a schematic diagram of the alternating planting method of equal row spacing of Sedum alfredii and sunflower in the present invention. DETAILED DESCRIPTION

[0026] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0027] The following describes the agronomic method of the present invention for the combined use of plants and microorganisms to repair cadmium-contaminated soil with reference to the accompanying drawings.

[0028] like Figure 1 As shown, the agronomic method of the present invention for plant-microorganism combined repair of cadmium-contaminated soil comprises the following steps:

[0029] (1) Using biochar and humic acid to condition the soil;

[0030] (2) Soaking Sedum alfredii seeds and sunflower seeds in diluted bacterial solution;

[0031] (3) Plant Sedum australis and sunflower alternately with equal row spacing;

[0032] (4) controlling the soil moisture content and regularly applying the diluted bacterial solution to the roots of the Sedum alfredii and sunflower during the growing season;

[0033] (5) Harvest Sedum alfredii regularly and remove the sunflowers as a whole after they mature.

[0034] Step (1) is a soil conditioning process, wherein the soil is conditioned using biochar and humic acid, the biomass and humic acid are mixed and then plowed to 20-25 cm, wherein the biochar is straw biochar, and the specific surface area of ​​the biochar is ≥300m 2 / g, the mass proportion of the biomass is 8%±0.2%, and biochar is used to adsorb cadmium and improve soil porosity; the humic acid is industrial-grade humic acid, the purity of humic acid is ≥90%, and the mass proportion of the humic acid is 3%±0.2%. The use of a biochar-humic acid composite conditioner can reduce the effective cadmium in the soil without secondary pollution.

[0035] Step (2) is the process of soaking the seeds of Sedum alfredii and sunflower seeds in a dilution of the bacterial solution, wherein the concentration of the bacterial solution is (1±0.2)×10 8CFU / mL, the bacterial solution is a composite bacteria composed of Bacillus subtilis and Rhizobium, the mass ratio of the Bacillus subtilis to the Rhizobium is 1:1, wherein the Bacillus subtilis is ACCC 11060 and the Rhizobium is ATCC 39207. That is, before sowing, the seeds of Sedum alfredii and sunflower seeds are soaked in a dilution of the bacterial solution, and the dilution of the bacterial solution is obtained by diluting the bacterial solution 10 to 12 times.

[0036] Step (3) is the seeding process, such as Figure 2 As shown, alternating Sedum alfredii and sunflower at equal spacing in cadmium-contaminated soil after soil conditioning. Sedum alfredii is a hyperaccumulator, accumulating cadmium up to 200-300 mg / kg (dry weight). Sunflower can activate soil cadmium through root secretions such as citric acid, thereby promoting cadmium absorption. Planting Sedum alfredii and sunflower at intervals can increase cadmium adsorption and thus improve soil remediation efficiency.

[0037] In some embodiments, the row spacing of the Sedum alfredii and sunflower is 30±2 cm, and the plant spacing is 20±2 cm. It can be understood that the row spacing and plant spacing of the Sedum alfredii and sunflower can be adjusted accordingly according to specific circumstances.

[0038] In some embodiments, the planting density of the Sedum alfredii is 8 to 10 plants / m 2 The planting density of sunflower is 4 to 6 plants / m 2 , it is understandable that the planting density of Southeast Sedum and Sunflower can be adjusted accordingly according to specific circumstances.

[0039] Step (4) is a field management process. After sowing, the soil moisture content is controlled within an appropriate range to avoid cadmium leaching. During the growing season, the diluted bacterial solution is regularly irrigated to the roots of the southeastern sedum and sunflower. The irrigated roots of the southeastern sedum and sunflower can further activate cadmium by microorganisms, thereby promoting cadmium absorption and improving soil remediation efficiency.

[0040] In some embodiments, the soil moisture content is controlled at 60% to 70%.

[0041] In some embodiments, the diluted bacterial solution is irrigated to the roots of Sedum alfredii and Sunflower every 28 to 30 days during the growth period at a rate of 450 to 500 mL / m 2 .

[0042] Step (5) is the plant management process. The Sedum alfredii is harvested regularly during its growth period, and the sunflowers are removed as a whole after they mature. The mature sunflower biomass can be used for energy production, such as biogas production, and the cadmium in the ashes after the sunflowers are burned can be recycled and smelted.

[0043] In some embodiments, the Sedum alfredii is harvested every 85-90 days during the growing season.

[0044] Example 1

[0045] For a cadmium-contaminated farmland (pH 6.2, cadmium content 3.2 mg / kg), biochar obtained by burning corn straw was mixed with industrial-grade humic acid to condition the soil. The mass proportion of biochar was 8% and the mass proportion of industrial-grade humic acid was 3%. During the soil conditioning process, the biochar and humic acid were mixed and plowed to a depth of 20 cm.

[0046] After diluting the bacterial solution 10 times, use it to soak the seeds of Sedum alfredii and sunflower for 2 hours. After the soaking is completed, the Sedum alfredii and sunflower are planted alternately with equal row spacing. 8 CFU / mL, the bacterial solution is a mixture of Bacillus subtilis and Rhizobium in a mass ratio of 1:1. The row spacing between Sedum alfredii and sunflower is 30 cm, and the plant spacing is 20 cm.

[0047] After sowing, the soil moisture content was controlled at 60%, and the diluted bacterial solution was irrigated to the roots of Sedum australense and sunflower every 30 days during the growing season at a rate of 500 mL / m 2 .

[0048] During the growth period, Sedum austriatum was harvested every 90 days, and the cadmium enrichment of Sedum austriatum was tested every harvest. After the sunflowers matured, they were removed as a whole, and the cadmium enrichment of the sunflower roots was tested. The mature sunflowers were used for biogas production.

[0049] Six months after implementation, the cadmium content in the farmland soil was tested and the above steps were repeated for the second soil remediation.

[0050] Example 2

[0051] For a cadmium-contaminated farmland (pH 6.1, cadmium content 5.2 mg / kg), biochar obtained from burning corn straw was mixed with industrial-grade humic acid to condition the soil. The mass proportion of biochar was 8% and the mass proportion of industrial-grade humic acid was 3%. During the soil conditioning process, the biochar and humic acid were mixed and plowed to a depth of 23 cm.

[0052] After diluting the bacterial solution 10 times, use it to soak the seeds of Sedum alfredii and sunflower for 2 hours. After the soaking is completed, the Sedum alfredii and sunflower are planted alternately with equal row spacing. 8 CFU / mL, the bacterial solution is a mixture of Bacillus subtilis and Rhizobium in a mass ratio of 1:1. The row spacing between Sedum alfredii and sunflower is 30 cm, and the plant spacing is 20 cm.

[0053] After sowing, the soil moisture content was controlled at 60%, and the diluted bacterial solution was irrigated to the roots of Sedum australense and sunflower every 30 days during the growing season at a rate of 500 mL / m 2 .

[0054] During the growth period, Sedum austriatum was harvested every 90 days, and the cadmium enrichment of Sedum austriatum was tested every harvest. After the sunflowers matured, they were removed as a whole, and the cadmium enrichment of the sunflower roots was tested. The mature sunflowers were used for biogas production.

[0055] The cadmium content in farmland soil was tested 6 months after implementation.

[0056] Example 3

[0057] For a cadmium-contaminated farmland (pH 6.0, cadmium content 4.1 mg / kg), biochar obtained by burning corn straw was mixed with industrial-grade humic acid to condition the soil. The mass proportion of biochar was 8.1%, and the mass proportion of industrial-grade humic acid was 3.2%. During the soil conditioning process, the biochar and humic acid were mixed and then plowed to a depth of 20 cm.

[0058] After diluting the bacterial solution 10 times, use it to soak the seeds of Sedum alfredii and sunflower for 2 hours. After the soaking is completed, the Sedum alfredii and sunflower are planted alternately with equal row spacing. 8 CFU / mL, the bacterial solution is a mixture of Bacillus subtilis and Rhizobium in a mass ratio of 1:1. The row spacing between Sedum alfredii and sunflower is 30 cm, and the plant spacing is 20 cm.

[0059] After sowing, the soil moisture content was controlled at 70%, and the diluted bacterial solution was irrigated to the roots of Sedum australasia and sunflower every 30 days during the growing season at a rate of 460 mL / m 2 .

[0060] During the growth period, Sedum austriatum was harvested every 90 days, and the cadmium enrichment of Sedum austriatum was tested every harvest. After the sunflowers matured, they were removed as a whole, and the cadmium enrichment of the sunflower roots was tested. The mature sunflowers were used for biogas production.

[0061] The cadmium content in farmland soil was tested 6 months after implementation.

[0062] Comparative Example 1

[0063] For a cadmium-contaminated farmland (pH 6.2, cadmium content 3.2 mg / kg), biochar obtained by burning corn straw was mixed with industrial-grade humic acid to condition the soil. The mass proportion of biochar was 8% and the mass proportion of industrial-grade humic acid was 3%. During the soil conditioning process, the biochar and humic acid were mixed and plowed to a depth of 20 cm.

[0064] Plant Sedum sedum and sunflower alternately with equal spacing. The row spacing between Sedum sedum and sunflower is 30 cm, and the plant spacing is 20 cm.

[0065] After sowing, the soil moisture content is controlled at 60%. 2 During the growth period, Sedum alfredii was harvested every 90 days, and the cadmium accumulation of Sedum alfredii was tested every harvest. After the sunflowers matured, they were removed as a whole, and the cadmium accumulation in the roots of the sunflowers was tested. The mature sunflowers were used for biogas production.

[0066] Six months after implementation, the cadmium content in the farmland soil was tested and the above steps were repeated for the second soil remediation.

[0067] Comparative Example 2

[0068] For a cadmium-contaminated farmland (pH 6.2, cadmium content 3.2 mg / kg), biochar obtained by burning corn straw was mixed with industrial-grade humic acid to condition the soil. The mass proportion of biochar was 8% and the mass proportion of industrial-grade humic acid was 3%. During the soil conditioning process, the biochar and humic acid were mixed and plowed to a depth of 20 cm.

[0069] After diluting the bacterial solution 10 times, use it to soak the seeds of Sedum australis for 2 hours. After the soaking is completed, plant the seeds of Sedum australis at equal row spacing. The concentration of the bacterial solution is 1×10 8 CFU / mL, the bacterial solution is a mixture of Bacillus subtilis and Rhizobium in a mass ratio of 1:1. The row spacing of Sedum alfredii is 30 cm and the plant spacing is 20 cm.

[0070] After sowing, the soil moisture content was controlled at 60%, and the diluted bacterial solution was irrigated to the roots of the southeastern sedum every 30 days during the growing season at a rate of 500mL / m 2 .

[0071] During the growth period, Sedum alfredii was harvested every 90 days, and the cadmium accumulation of Sedum alfredii was tested every time it was harvested.

[0072] Six months after implementation, the cadmium content in the farmland soil was tested and the above steps were repeated for the second soil remediation.

[0073] Test example

[0074] The cadmium content (dry weight) of the harvested Sedum alfredii and sunflower in Examples 1 to 3 and the cadmium content of the farmland after one restoration were tested. The test results are shown in Table 1 below.

[0075] Table 1:

[0076]

[0077] According to Table 1, Examples 1 to 3 have good repair capabilities for cadmium-contaminated soil, and the method of the present invention is suitable for the repair of farmland contaminated with high concentrations of cadmium.

[0078] According to Example 1, Comparative Example 1 and Comparative Example 2, when microbial remediation technology is not used or sunflower and Sedum alfredii intercropping are not used, the remediation effect on cadmium-contaminated soil decreases.

[0079] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms may be directed to different embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually inconsistent.

[0080] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0081] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A plant-microorganism combined agronomic method for remediating cadmium-contaminated soil, characterized in that: The following steps are involved: (1) Using biochar and humic acid to condition the soil; (2) Soaking Sedum alfredii seeds and sunflower seeds in diluted bacterial solution; (3) Plant Sedum australis and sunflower alternately with equal row spacing; (4) controlling the soil moisture content and regularly applying the diluted bacterial solution to the roots of the Sedum alfredii and sunflower during the growing season; (5) Harvest Sedum alfredii regularly and remove the sunflowers as a whole after they mature.

2. The method according to claim 1, wherein The step (1) comprises mixing the biomass and the humic acid and then plowing the mixture to a depth of 20 to 25 cm, wherein the mass proportion of the biomass is 8%±0.2% and the mass proportion of the humic acid is 3%±0.2%.

3. The method according to claim 1, wherein The bacterial liquid is a composite bacteria composed of Bacillus subtilis and Rhizobium, wherein the Bacillus subtilis is ACCC 11060 and the Rhizobium is ATCC 39207.

4. The method according to claim 3, wherein The mass ratio of the Bacillus subtilis to the Rhizobium is 1:

1.

5. The method according to claim 1, wherein The concentration of the bacterial solution is (1±0.2)×10 8 CFU / mL.

6. The method according to claim 1, wherein The row spacing of the Sedum alfredii and sunflower is 30±2 cm, and the plant spacing is 20±2 cm.

7. The method according to claim 1, wherein The planting density of the Sedum alfredii is 8 to 10 plants / m 2 The planting density of sunflower is 4 to 6 plants / m 2 .

8. The method according to claim 1, wherein In the step (4), the soil moisture content is maintained at 60% to 70%.

9. The method according to claim 1, wherein In the step (4), the diluted bacterial solution is irrigated to the roots of Sedum alfredii and Helianthus annuus at intervals of 28 to 30 days during the growth period.

10. The method according to claim 1, wherein In the step (5), the Sedum alfredii is harvested once every 85 to 90 days.

Images