Method for repairing molybdenum pollution of soil by combining arbuscular mycorrhizal fungi with sunflower and sedum bulbiferum intercropping

Abstract

The invention relates to a method for remedying molybdenum pollution of soil by combining arbuscular mycorrhizal fungi with sunflower and sedum bulbiferum intercropping, which comprises the following steps: ploughing molybdenum pollution soil, applying a composite modifier, ploughing, uniformly mixing, spraying water until the water content of the soil reaches 60-70% of the field moisture capacity, and standing for 7-10 days; sunflowers are inoculated in a seed dressing mode, sedum rugossypii are inoculated in a seedling root dipping mode, strip type interplanting and regular irrigation are conducted according to the mode that three sunflowers and five sedum rugossypii are planted, the water content of soil is kept to be 50%-60% of the field moisture capacity, decomposed organic fertilizer is dressed 1-2 times in the growing period, and after the sunflowers are harvested, the overground part of the sedum rugossypii is harvested and moved out of a polluted area. According to the method, the molybdenum-contaminated soil is remedied by combining the mycorrhizal fungi with the sunflower and sedum bulbiferum intercropping, the physicochemical properties of the soil are improved through the composite modifier, efficient remediation of the molybdenum-contaminated soil and safe production of the sunflower are achieved through the synergistic effect of the three, and the contradiction between remediation and utilization of the molybdenum tailing soil is solved.

Description

Technical Field

[0001] This invention belongs to the field of plant-microbe combined soil remediation technology, specifically involving a method for remediating molybdenum contamination in soil by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum. Background Technology

[0002] With the large-scale development of mining in recent years, soil molybdenum pollution caused by molybdenum tailings accumulation has become increasingly prominent. High concentrations of molybdenum in molybdenum tailings migrate to surrounding soils through leaching and dust, leading to the deterioration of arable land and ecological land quality. Although molybdenum is an essential micronutrient for plants, excessive molybdenum can inhibit photosynthesis and nutrient absorption, resulting in reduced crop yields or even crop failure. Furthermore, it can accumulate through the food chain and harm human health. Therefore, how to achieve efficient remediation and safe utilization of soil contaminated by molybdenum tailings has become a core challenge for ecological restoration in molybdenum mining areas.

[0003] Existing technologies for remediating molybdenum-contaminated soil mainly include physical soil replacement, chemical leaching, and bioremediation. Physical soil replacement requires large-scale replacement with clean soil, which is costly and prone to causing secondary ecological damage. Chemical leaching activates molybdenum in the soil with chemical reagents, providing rapid short-term results, but it easily damages soil aggregate structure, leading to decreased soil fertility and secondary pollution of the leachate. Phytoremediation within bioremediation methods has attracted much attention due to its low cost and environmental friendliness; however, the remediation cycle for single hyperaccumulating plants is long, and their growth is limited in barren molybdenum tailings soils. Monoculture carries the risk of excessive molybdenum absorption, making it difficult to balance remediation effectiveness with production needs.

[0004] Arbuscular mycorrhizal fungi, as a highly efficient microbial resource, can form a symbiotic system with plant roots, enhancing the plant's absorption of nutrients and tolerance to heavy metals. However, there is still no mature technology to combine them with plant intercropping systems for the remediation of soil contaminated by molybdenum tailings. Summary of the Invention

[0005] To address the above problems, this invention provides a method for remediating molybdenum-contaminated soil by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum. This method solves the technical problems of molybdenum pollution, soil infertility, low remediation efficiency, and difficulty in balancing production and remediation in molybdenum tailings areas, thereby achieving efficient remediation and sustainable utilization of molybdenum-contaminated soil.

[0006] This invention is specifically achieved through the following technical solution: a method for remediating soil molybdenum pollution by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum, according to this invention, includes the following steps: (1) Soil pretreatment: The contaminated soil around the molybdenum tailings is tilled to a depth of 20-30cm, then a compound soil conditioner is applied and tilled again to mix it evenly. The soil is then watered until the soil moisture content reaches 60-70% of the field water holding capacity and left to stand for 7-10 days. The compound soil conditioner includes, by weight, 30-40 parts of decomposed straw, 20-30 parts of peat soil, 5-10 parts of phosphate rock powder, and 8-12 parts of humic acid. (2) Inoculation with fungal agents and intercropping: Sunflowers are inoculated by seed dressing, that is, sunflower seeds are mixed with arbuscular mycorrhizal fungal agents before sowing; Sedum bulbils are inoculated by root dipping of seedlings, and the roots of Sedum bulbils seedlings are soaked in arbuscular mycorrhizal fungal agent suspension for 10-15 minutes; intercropping is carried out in strips with 3 sunflowers and 5 Sedum bulbils, with the horizontal and vertical spacing between two adjacent sunflowers being 15-25cm and 35-45cm respectively, the horizontal and vertical spacing between two adjacent Sedum bulbils being 15-25cm, and the horizontal spacing between two adjacent Sedum bulbils and sunflowers being 15-25cm; (3) Field management: Irrigate regularly to maintain soil moisture content at 50-60% of field capacity. Apply well-rotted organic fertilizer 1-2 times during the growing season. After the sunflowers are harvested, harvest the above-ground part of the bulbils and remove it from the polluted area.

[0007] The aforementioned method for remediating soil molybdenum pollution by combining arbuscular mycorrhizal fungi with intercropping sunflower and bulbil sedum, wherein the amount of compound amendment applied in step (1) is 1500-2000 kg / mu.

[0008] The aforementioned method for remediating soil molybdenum pollution by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum, wherein the arbuscular mycorrhizal fungicide in step (2) is a mixed fungicide of Rhizocystis ulmoides and Sedum juvenileum, with a mass ratio of Rhizocystis ulmoides to Sedum juvenileum of 2:1, an effective spore content of arbuscular mycorrhizal fungicide ≥100 spores / g, and an inoculation amount of 2-8 kg / mu.

[0009] The aforementioned method for remediating soil molybdenum pollution by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum involves the following steps: in step (2), the amount of sunflower seeds used is 1 kg / mu, and the sunflower seeds and arbuscular mycorrhizal fungi are mixed at a mass ratio of 1:(2-5).

[0010] Furthermore, in step (2), the concentration of the arbuscular mycorrhizal fungal suspension is 7-15 g / L.

[0011] Preferably, in step (2), the horizontal and vertical spacing between two adjacent sunflower plants is 20cm and 40cm respectively, the horizontal and vertical spacing between two adjacent Sedum bulbiferum plants is 20cm, and the horizontal spacing between two adjacent Sedum bulbiferum plants and sunflower plants is 20cm.

[0012] The aforementioned method of remediating soil molybdenum pollution by combining arbuscular mycorrhizal fungi with intercropping sunflower and bulbil sedum, wherein the decomposed organic fertilizer mentioned in step (3) is a mixture of chicken manure and sheep manure with a mass ratio of 1:1.

[0013] Ideally, the first application of well-rotted organic fertilizer should be 30 days after planting, at a rate of 200 kg / mu; the second application should be 60 days after planting, at a rate of 150 kg / mu.

[0014] Further, in step (3), the above-ground parts of the bulbils are harvested, then incinerated and landfilled, or molybdenum is extracted and recovered.

[0015] Compared with existing technologies, this invention has significant advantages and beneficial effects. Through the above technical solution, this invention achieves considerable technological advancement and practicality, and has broad application value, possessing at least the following advantages: (1) Synergistic Remediation: Sedum bulbiferum, as a molybdenum hyperaccumulator, can efficiently absorb molybdenum from the soil and accumulate it in its above-ground parts. Sunflower has a large biomass and a well-developed root system, which can absorb molybdenum from deep soil layers. Intercropping sunflower and Sedum bulbiferum forms a three-dimensional absorption system, expanding the absorption range of molybdenum. Inoculation with arbuscular mycorrhizal fungi further promotes the growth of both plants and molybdenum absorption. After symbiosis with the roots of the two plants, the fungi can increase the absorption area of ​​the plant roots through the hyphal network, secrete organic acids to activate the insoluble molybdenum in the soil, making it into molybdenum that is easily absorbed by the plants, while improving the antioxidant capacity of the plants, alleviating molybdenum toxicity, and promoting plant growth and molybdenum absorption efficiency.

[0016] (2) Balancing soil improvement and production: The decomposed straw and peat in the compound amendment can improve the aeration and water and fertilizer retention capacity of polluted soil, while phosphate rock powder and humic acid can regulate the soil pH value, providing a good growth environment for plants and microorganisms. The synergistic effect of arbuscular mycorrhizal fungi combined with intercropping sunflower and bulbil sedum and the compound amendment has achieved efficient remediation of molybdenum-contaminated soil and safe production of sunflowers, keeping the molybdenum content in sunflower seeds within a safe range, thus resolving the contradiction between soil remediation and utilization of molybdenum tailings.

[0017] (3) Low cost and sustainability: The sunflower and bulbils used in this invention are both highly adaptable and easy-to-propagate plants. The arbuscular mycorrhizal fungi agent has a low preparation cost, and the composite amendment can be prepared using agricultural waste straw and inexpensive raw materials. The entire technical process is simple to operate, requires no large-scale equipment, and is suitable for large-scale application in the ecological restoration and agricultural utilization of soil pollution in molybdenum tailings areas. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the intercropping pattern of 3 sunflowers and 5 bulbils of Sedum in a strip, combined with arbuscular mycorrhizal fungi inoculation, according to the present invention.

[0019] Figure 2 This is an image of sunflower root sections stained with arbuscular mycorrhizal fungi under a 400x microscope, showing the infection process.

[0020] Figure 3 This is an image of the infection observation under a 400x microscope on stained sections of Sedum bulbils after inoculation with arbuscular mycorrhizal fungi. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The present invention will be described in detail below with specific embodiments. Unless otherwise specified, all conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Raw materials and reagents whose manufacturers are not specified are all commercially available products. The *Rhizocarpium radicans* and *Gyrocarpium juvenilee* used in the following embodiments were provided by China Agricultural University. These two strains are deposited in the Germplasm Bank of Arbuscular Mycorrhizal Fungi (BGC) in China, with accession numbers BGC HEB07D (*Rhizocarpium radicans*, ...). Rhizophagusintraradices ), BGC HEB04 (Young Glomerulosa), Claroideoglomusetunicatum ).

[0023] Example 1 A method for remediating soil molybdenum contamination by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum includes the following steps: (1) Soil pretreatment: Select the contaminated soil around the molybdenum tailings with a molybdenum content of 85 mg / kg, plow the soil to a depth of 25cm, apply a compound soil conditioner (by weight, the compound soil conditioner includes 35 parts of decomposed straw, 25 parts of peat soil, 8 parts of phosphate rock powder and 10 parts of humic acid), the amount of compound soil conditioner is 1800 kg / mu, plow the soil again evenly and then water it so that the soil moisture content reaches 65% of the field water holding capacity, and let it stand for 8 days; (2) Inoculation with fungal agent and intercropping: The arbuscular mycorrhizal fungal agent (hereinafter referred to as "fungal agent") is a mixture of Rhizospora radiata and Rhizospora juvenilee in a mass ratio of 2:1. The effective spore content of the fungal agent is 120 spores / g. The inoculation amount is 5 kg / mu, of which 3 kg is used for sunflower seed treatment and 2 kg is used to prepare Sedum bulbiferum root-dipping suspension. The amount of sunflower seeds is 1 kg / mu, which is mixed with 3 kg of fungal agent in a mass ratio of 1:3 before sowing. 2 kg of fungal agent is added to water to prepare a 10 g / L fungal agent suspension. The roots of Sedum bulbiferum seedlings are soaked in the fungal agent suspension for 12 minutes before transplanting. Intercropping is done in strips with 3 sunflowers and 5 Sedum bulbiferums. The horizontal and vertical spacing between two adjacent Sedum bulbiferum plants is 20 cm, the horizontal and vertical spacing between two adjacent sunflowers is 20 cm and 40 cm, respectively, and the horizontal spacing between two adjacent Sedum bulbiferum and sunflower plants is 20 cm. (3) Field management: Irrigate regularly to maintain soil moisture content at about 55% of field capacity. Apply well-rotted chicken manure-sheep manure mixed fertilizer (chicken manure and sheep manure in a 1:1 ratio) 30 days after planting, at a rate of 200 kg / mu. Apply well-rotted chicken manure-sheep manure mixed fertilizer (chicken manure and sheep manure in a 1:1 ratio) again 60 days after planting, at a rate of 150 kg / mu. Harvest the seeds after the sunflower matures, and return the straw to the field to improve soil structure (choose whether to return it to the field based on the measured molybdenum content). Harvest the above-ground parts of Sedum bulbiferum and burn them in a concentrated manner before landfilling, or carry out subsequent molybdenum extraction and recovery. Leave the underground parts of Sedum bulbiferum in the farmland for the next season to sprout new plants. Sedum bulbiferum can be planted for two consecutive seasons. After two seasons, the underground parts of Sedum bulbiferum can be returned to the field to improve the soil.

[0024] Example 2 A method for remediating soil molybdenum contamination by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum includes the following steps: (1) Soil pretreatment: Select the contaminated soil around the molybdenum tailings with a molybdenum content of 72 mg / kg, plow the soil to a depth of 20cm, apply the compound soil conditioner (by weight, the compound soil conditioner includes 30 parts of decomposed straw, 20 parts of peat soil, 5 parts of phosphate rock powder and 8 parts of humic acid), the amount of compound soil conditioner is 1500 kg / mu, plow the soil again evenly and then water it so that the soil moisture content reaches 60% of the field water holding capacity, and let it stand for 7 days; (2) Inoculation with fungal agents and intercropping: The arbuscular mycorrhizal fungal agent (hereinafter referred to as "fungal agent") is a mixture of Rhizocystis ulmoides and Rhizocystis juvenilee in a mass ratio of 2:1. The effective spore content of the arbuscular mycorrhizal fungal agent is 100 spores / g, and the inoculation amount is 4 kg / mu. Among them, 2.5 kg is used for sunflower seed treatment, and 1.5 kg is used to prepare Sedum bulbiferum root-dipping suspension. The amount of sunflower seeds is 1 kg / mu, which is mixed with 2.5 kg of fungal agent in a mass ratio of 1:2.5 before sowing. 1.5 kg of fungal agent is added to water to prepare a 7.5 g / L fungal agent suspension. The roots of Sedum bulbiferum seedlings are soaked in the fungal agent suspension for 10 minutes before transplanting. Intercropping is done in strips with 3 sunflowers and 5 Sedum bulbiferums. The horizontal and vertical spacing between two adjacent Sedum bulbiferum plants is 20 cm, the horizontal and vertical spacing between two adjacent sunflowers is 20 cm and 40 cm, respectively, and the horizontal spacing between two adjacent Sedum bulbiferum and sunflower plants is 20 cm. (3) Field management: Irrigate regularly to maintain soil moisture content at about 50% of field capacity. Apply well-rotted chicken manure-sheep manure mixed fertilizer (chicken manure and sheep manure in a 1:1 ratio) 30 days after planting, at a rate of 200 kg / mu. Apply well-rotted chicken manure-sheep manure mixed fertilizer (chicken manure and sheep manure in a 1:1 ratio) again 60 days after planting, at a rate of 150 kg / mu. Harvest the seeds after the sunflower matures, and return the straw to the field to improve soil structure (choose whether to return it to the field based on the measured molybdenum content). Harvest the above-ground parts of Sedum bulbiferum and burn them in a concentrated manner before landfilling, or carry out subsequent molybdenum extraction and recovery. Leave the underground parts of Sedum bulbiferum in the farmland for the next season to sprout new plants. Sedum bulbiferum can be planted for two consecutive seasons. After two seasons, the underground parts of Sedum bulbiferum can be returned to the field to improve the soil.

[0025] Example 3 (1) Soil pretreatment: Select the contaminated soil around the molybdenum tailings with a molybdenum content of 98 mg / kg, plow the soil to a depth of 30cm, apply a compound soil conditioner (by weight, the compound soil conditioner includes 40 parts of decomposed straw, 30 parts of peat soil, 10 parts of phosphate rock powder and 12 parts of humic acid), the amount of compound soil conditioner is 2000 kg / mu, plow again evenly and then water it so that the soil moisture content reaches 70% of the field water holding capacity, and let it stand for 10 days; (2) Inoculation with fungal agents and intercropping: The arbuscular mycorrhizal fungal agent (hereinafter referred to as "fungal agent") is a mixture of Rhizocystis ulmoides and Rhizocystis juvenilee in a mass ratio of 2:1. The effective spore content of the arbuscular mycorrhizal fungal agent is 150 spores / g, and the inoculation amount is 7 kg / mu. Among them, 4 kg is used for sunflower seed treatment, and 3 kg is used to prepare Sedum bulbiferum root-dipping suspension. The amount of sunflower seeds used is 1 kg / mu, which is mixed with 4 kg of fungal agent in a mass ratio of 1:4 before sowing. 3 kg of fungal agent is added to water to prepare a 15 g / L fungal agent suspension. The roots of Sedum bulbiferum seedlings are soaked in the fungal agent suspension for 10 minutes before transplanting. Intercropping is done in strips with 3 sunflowers and 5 Sedum bulbiferums. The horizontal and vertical spacing between two adjacent Sedum bulbiferum plants is 20 cm, the horizontal and vertical spacing between two adjacent sunflowers is 20 cm and 40 cm, respectively, and the horizontal spacing between two adjacent Sedum bulbiferum and sunflower plants is 20 cm. (3) Field management: Irrigate regularly to maintain soil moisture content at about 60% of field capacity. Apply well-rotted chicken manure-sheep manure mixed fertilizer (chicken manure and sheep manure in a 1:1 ratio) 30 days after planting, at a rate of 200 kg / mu. Apply well-rotted chicken manure-sheep manure mixed fertilizer (chicken manure and sheep manure in a 1:1 ratio) again 60 days after planting, at a rate of 150 kg / mu. Harvest the seeds after the sunflower matures, and return the straw to the field to improve soil structure (choose whether to return it to the field based on the measured molybdenum content). Harvest the above-ground parts of Sedum bulbiferum and burn them in a concentrated manner before landfilling, or carry out subsequent molybdenum extraction and recovery. Leave the underground parts of Sedum bulbiferum in the farmland for the next season to sprout new plants. Sedum bulbiferum can be planted for two consecutive seasons. After two seasons, the underground parts of Sedum bulbiferum can be returned to the field to improve the soil.

[0026] Comparative Example 1 Step (2) in Example 1 is changed to: interplanting in strips with one sunflower and one bulbil sedum, with a horizontal spacing of 20cm between two adjacent sunflowers and bulbil sedums, a vertical spacing of 20cm between two adjacent sunflowers and a vertical spacing of 20cm between two adjacent bulbil sedums, and without inoculating with arbuscular mycorrhizal fungi. The remaining steps are the same as in Example 1.

[0027] Comparative Example 2 The compound modifier was removed from step (1) of Example 1, and the remaining steps were the same as in Example 1.

[0028] Comparative Example 3 Plant only Sedum bulbil (monocytic), do not plant sunflowers and do not inoculate with arbuscular mycorrhizal fungi, and the remaining steps are the same as in Example 1.

[0029] Comparative Example 4 Following the method of Example 1, only sunflowers are planted (sunflower monoculture), and the remaining steps are the same as in Example 1.

[0030] Comparative Example 5 Following the method of Example 1, only Sedum bulbiferum is planted (Sedum bulbiferum is planted alone), and the remaining steps are the same as in Example 1.

[0031] Plant biomass, molybdenum uptake, and soil molybdenum content were measured under the planting patterns of Example 1, Comparative Examples 1-5, and the measurement methods are as follows: Biomass determination (unit: g / plant): The aboveground and underground parts of sunflowers were harvested separately. The aboveground and underground parts were washed and dried to constant weight. The dry weight of the aboveground and underground parts of each sunflower was weighed separately, and divided by the number of plants to obtain the biomass of the aboveground and underground parts per plant. The two were then added together to obtain the biomass of a single sunflower plant (g / plant). The biomass of the aboveground and underground parts of Sedum bulbiferum and the biomass of a single Sedum bulbiferum plant (g / plant) were determined using the same method.

[0032] Determination of molybdenum content (unit: mg / kg): Pretreatment was performed first: the harvested plant samples were rinsed with ultrapure water to remove surface soil and impurities, blanched at 105℃, dried at 80℃ to constant weight, pulverized, sieved, and sealed for storage. A certain amount of the pretreated sample was weighed into a PTFE digestion vessel, and nitric acid was added for digestion. After digestion, the sample was allowed to cool naturally to room temperature. The digestion solution was transferred to a volumetric flask, and the digestion vessel was washed three times with ultrapure water. The washings were added to the volumetric flask, and the solution was diluted to the mark and shaken well. A blank experiment was performed simultaneously (without sample, all other steps were the same). The molybdenum content of the plant samples was determined by graphite furnace atomic absorption spectrometry according to the National Food Safety Standard for Determination of Molybdenum in Food (GB5009.297-2023).

[0033] Determination of total molybdenum absorption (unit: g / mu): Following the aforementioned method for determining molybdenum content, the molybdenum content (mg / kg) of the above-ground parts, underground parts, and seeds of sunflower, and the molybdenum content (mg / kg) of the above-ground and underground parts of Sedum bulbiferum, were determined. The molybdenum absorption per sunflower plant (g / plant) and the molybdenum absorption per Sedum bulbiferum plant (g / plant) were calculated using the following formulas, and the total molybdenum absorption per mu of land (g / mu) was also calculated. Note that the units must be converted consistently.

[0034] Molybdenum uptake per sunflower plant (g / plant) = aboveground biomass of sunflower × aboveground molybdenum content of sunflower + underground biomass of sunflower × underground molybdenum content of sunflower; Molybdenum uptake per bulbil (g / plant) = aboveground biomass of bulbil × molybdenum content of aboveground part of bulbil + underground biomass of bulbil × molybdenum content of underground part of bulbil. Total molybdenum uptake by plants (g / mu) = molybdenum uptake per sunflower plant (g / plant) × number of sunflower plants (plants / mu) + molybdenum uptake per Sedum bulbil plant (g / plant) × number of Sedum bulbil plants (plants / mu).

[0035] The measurement results are shown in Tables 1 and 2: Table 1. Plant biomass and molybdenum uptake in different treatment groups Table 2. Changes in soil molybdenum content (mg / kg) in different treatment groups As shown in Tables 1 and 2, the remediation effect of Example 1 was significantly better than that of the other treatment groups. In Example 1, the sunflower biomass increased by 8.4% compared to sunflower monoculture (Comparative Example 4), and the molybdenum content in the seeds decreased by 73.4%. The Sedum bulbiferum biomass in Example 1 increased by 19.9% ​​compared to Sedum bulbiferum monoculture (Comparative Example 5), and the aboveground molybdenum content increased by 21.7%. The total molybdenum uptake in Example 1 increased by 195.1% and 70.9% compared to sunflower monoculture (Comparative Example 4) and Sedum bulbiferum monoculture (Comparative Example 5), respectively. The soil molybdenum removal rate reached 46.8%, which was 58.1%, 91.8%, 143.7%, 214.1%, and 76.6% higher than that of Comparative Examples 1, 2, 3, 4, and 5, respectively. The remediation effects of Examples 2 and 3 are consistent with the trend of Example 1, with soil molybdenum removal rates reaching 38.2% and 41.5%, respectively, and sunflower seed molybdenum content of 5.6±0.6 mg / kg and 6.5±0.7 mg / kg, respectively, all of which can achieve effective remediation and safe production.

[0036] Figure 1 This is a schematic diagram of the intercropping pattern of 3 sunflowers and 5 bulbils of Sedum inoculated with arbuscular mycorrhizal fungi according to the present invention. This pattern optimizes the planting density and spacing of the two plants, ensuring the growth space of the sunflowers while providing sufficient light and nutrients for the bulbils of Sedum, thus avoiding interspecific competition.

[0037] Figure 2 This is an image of sunflower root sections stained with arbuscular mycorrhizal fungi under a 400x microscope, showing the infection process. Figure 3 This is an image of the infection observation under a 400x microscope on stained sections of Sedum bulbils after inoculation with arbuscular mycorrhizal fungi. Figure 2 and Figure 3 Spores / vesicles and hyphae of arbuscular mycorrhizal fungi can be observed in both.

[0038] This invention remediates molybdenum-contaminated soil through intercropping of sunflower and Sedum bulbiferum with arbuscular mycorrhizal fungi. Sedum bulbiferum, a molybdenum hyperaccumulator, efficiently absorbs molybdenum from the soil and accumulates it in its above-ground parts. Sunflower, with its large biomass and extensive root system, can absorb molybdenum from deeper soil layers. The intercropping of the two plants forms a three-dimensional absorption system, expanding the absorption range of molybdenum. By optimizing the planting density and spacing of the two plants, sufficient growing space for sunflowers is ensured while providing ample light and nutrients for Sedum bulbiferum, avoiding interspecific competition. Inoculation with arbuscular mycorrhizal fungi further promotes the growth of both plants and molybdenum absorption. A composite amendment improves the physicochemical properties of the molybdenum tailings soil, providing a favorable environment for plant and microbial growth. The synergistic effect of these three factors achieves efficient remediation of molybdenum-contaminated soil and safe sunflower production, resolving the contradiction between the remediation and utilization of molybdenum tailings soil.

[0039] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for remediating soil molybdenum contamination by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum, characterized in that, Includes the following steps: (1) Soil pretreatment: The molybdenum contaminated soil is plowed to a depth of 20-30cm, then a compound amendment is applied and plowed again to mix it evenly. Water is applied until the soil moisture content reaches 60-70% of the field water holding capacity, and then left to stand for 7-10 days. According to the weight proportions, the composite amendment includes: 30-40 parts of decomposed straw, 20-30 parts of peat moss, 5-10 parts of phosphate rock powder, and 8-12 parts of humic acid. (2) Inoculation with fungal agents and intercropping: Sunflowers are inoculated by seed dressing, that is, sunflower seeds are mixed with arbuscular mycorrhizal fungal agents before sowing; Sedum bulbils are inoculated by root dipping of seedlings, and the seedling roots are soaked in arbuscular mycorrhizal fungal agent suspension for 10-15 minutes; intercropping is carried out in strips with 3 sunflowers and 5 Sedum bulbils, with the horizontal and vertical spacing between two adjacent sunflowers being 15-25cm and 35-45cm respectively, the horizontal and vertical spacing between two adjacent Sedum bulbils being 15-25cm, and the horizontal spacing between two adjacent Sedum bulbils and sunflowers being 15-25cm; (3) Field management: Irrigate regularly to maintain soil moisture content at 50-60% of field capacity. Apply well-rotted organic fertilizer 1-2 times during the growing season. After the sunflowers are harvested, harvest the above-ground part of the bulbils and remove it from the polluted area.

2. The method for remediating soil molybdenum pollution by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum as described in claim 1, characterized in that, The application rate of the compound amendment in step (1) is 1500-2000 kg / mu.

3. The method for remediating soil molybdenum contamination by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum as described in claim 1, characterized in that, The arbuscular mycorrhizal fungicide mentioned in step (2) is a mixed fungicide of Rhizocystis ulmoides and Gyrocystis juvenileis, with a mass ratio of Rhizocystis ulmoides to Gyrocystis juvenileis of 2:

1. The effective spore content of the arbuscular mycorrhizal fungicide is ≥100 spores / g, and the inoculation amount is 2-8 kg / mu.

4. The method for remediating soil molybdenum contamination by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum as described in claim 1 or 3, characterized in that, In step (2), the amount of sunflower seeds used is 1 kg / mu, and the sunflower seeds and arbuscular mycorrhizal fungi are mixed and stirred at a mass ratio of 1:(2-5).

5. The method for remediating soil molybdenum contamination by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum as described in claim 1 or 3, characterized in that, In step (2), the concentration of the arbuscular mycorrhizal fungal suspension is 7-15 g / L.

6. The method for remediating soil molybdenum contamination by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum as described in claim 1, characterized in that, In step (2), the horizontal and vertical spacing between two adjacent sunflower plants is 20cm and 40cm respectively, the horizontal and vertical spacing between two adjacent Sedum bulbiferum plants is 20cm, and the horizontal spacing between two adjacent Sedum bulbiferum plants and sunflower plants is 20cm.

7. The method for remediating soil molybdenum contamination by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum as described in claim 1, characterized in that, The composted organic fertilizer mentioned in step (3) is a mixture of chicken manure and sheep manure, with a mass ratio of chicken manure to sheep manure of 1:

1.

8. The method for remediating soil molybdenum contamination by combining arbuscular mycorrhizal fungi with intercropping sunflower and Sedum bulbiferum as described in claim 1 or 7, characterized in that, The first application of well-rotted organic fertilizer should be 30 days after planting, at a rate of 200 kg / mu; the second application should be 60 days after planting, at a rate of 150 kg / mu.

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