Functional fungi, soil conditioners, and their applications based on photovoltaic-based screening of saline-alkali land soil.

Abstract

This invention discloses a functional fungus, a soil conditioner, and their applications based on soil selected from photovoltaic saline-alkali land. The functional fungus selection process includes: selecting saline-alkali soil with pH ≥ 9 and salinity ≥ 4.5 g / kg below centralized photovoltaic power stations in arid and cold northern regions, and collecting soil samples from the top 0-20 cm layer; preparing the soil samples into a suspension, culturing at 28℃ for 5 days, picking single colonies of filamentous fungi, and obtaining pure cultures through multiple streak purifications; culturing and screening out salt-tolerant strains that can grow normally; inoculating the salt-tolerant strains onto a phosphate-solubilizing medium containing insoluble calcium phosphate, culturing at 28℃ for 7 days, and screening out phosphate-solubilizing strains that form a transparent phosphate-solubilizing zone around the colony to obtain the functional fungus. This invention utilizes highly efficient salt-tolerant functional fungi selected from photovoltaic saline-alkali land soil, combined with modified phosphogypsum, to form a soil conditioner, solving the problems of high cost, poor adaptability, short effective period, and potential secondary pollution of existing soil amendments.

Description

Technical Field

[0001] This invention belongs to the field of microbial and soil remediation technology, specifically relating to a functional fungus, soil conditioner, and its application based on photovoltaic saline-alkali land soil screening. Background Technology

[0002] Northwest China boasts abundant renewable resources and vast land, giving it a natural advantage in developing renewable energy. However, it also faces challenges such as a fragile ecological environment, frequent sandstorms, and severe salinization. The "salt-solar complementary" model, combining photovoltaic power generation with saline-alkali land remediation, is a crucial pathway to achieving a green and low-carbon energy transition and enhancing ecosystem services. Currently, methods for remediating saline-alkali soils mainly include irrigation, deep tillage, chemical injection, and the cultivation of salt-tolerant plants. Irrigation requires large amounts of water and is costly; deep tillage and chemical remediation can lead to soil nutrient loss or secondary pollution; while traditional bioremediation has environmental advantages, the introduced exogenous microorganisms often have poor adaptability to local extreme environments (high salinity, drought, and infertility), resulting in unstable remediation effects and short-lived benefits.

[0003] Studies have shown that fungi can effectively reduce soil pH, decrease total salt content, and increase soil organic matter content by secreting extracellular polymeric substances (EPS) and organic acids. However, the use of fungal agents alone has problems such as short survival time and high cost; while phosphate mineral phosphogypsum, as an industrial waste, will cause harm to soil and water bodies due to pollutants such as fluorine and heavy metals if left untreated.

[0004] Therefore, there is an urgent need for a functional microorganism that can adapt to the special habitat (high salinity, drought, low temperature, etc.) of northern photovoltaic saline-alkali land, and to combine it with the resource utilization of solid waste to develop a low-cost, environmentally friendly and long-lasting soil remediation product. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a functional fungus with high salt and alkali tolerance selected from photovoltaic saline-alkali land in northern China, and to provide a composition and its application based on the fungus, so as to solve the problems of high cost, poor adaptability, short duration of effect and possible secondary pollution of existing soil conditioners.

[0006] According to the first aspect of the present invention, the present invention provides a functional fungus screening process based on photovoltaic saline-alkali land soil, the functional fungus screening process including the following steps: Below centralized photovoltaic power stations in arid and cold northern regions, select saline-alkali soils with pH ≥ 9 and salinity ≥ 4.5 g / kg, and collect soil samples from the top 0-20 cm layer. Soil samples were prepared into suspensions, cultured at 28°C for 5 days, and single colonies of filamentous fungi were picked and purified by streak filtration multiple times to obtain pure cultures. After cultivation, salt- and alkali-tolerant strains that can grow normally were screened out. Salt-tolerant strains were inoculated onto a phosphorus-solubilizing medium containing insoluble calcium phosphate and cultured at 28°C for 7 days. Phosphorus-solubilizing strains that formed transparent phosphorus-solubilizing zones around their colonies were screened out to obtain functional fungi.

[0007] In some implementations, the arid and cold regions of the north refer to arid and cold regions in northern China above 39.9° north latitude.

[0008] According to the second aspect of the present invention, the present invention provides a soil conditioner based on functional fungi, the preparation method of which includes the following steps: Select phosphogypsum with a calcium mass fraction ≥10.0%, a sulfur mass fraction ≥2.0%, a water-soluble phosphorus content ≥75.0 mg / kg, and a pH ≤4.5. Crush it, add a cleansing agent and wash it with water, then add an activator for surface modification to obtain modified phosphogypsum. A soil conditioner was prepared by inoculating functional fungi into modified phosphogypsum at a mass ratio of (0.5-1):1000. The functional fungi are strains found beneath centralized photovoltaic power stations in arid and cold northern regions, capable of reducing soil salinity and regulating pH.

[0009] In some implementations, the functional fungal screening process includes the following steps: Below centralized photovoltaic power stations in arid and cold northern regions, select saline-alkali soils with pH ≥ 9 and salinity ≥ 4.5 g / kg, and collect soil samples from the top 0-20 cm layer. Soil samples were prepared into suspensions, cultured at 28°C for 5 days, and single colonies of filamentous fungi were picked and purified by streak filtration multiple times to obtain pure cultures. After cultivation, salt- and alkali-tolerant strains that can grow normally were screened out. Salt-tolerant strains were inoculated onto a phosphorus-solubilizing medium containing insoluble calcium phosphate and cultured at 28°C for 7 days. Phosphorus-solubilizing strains that formed transparent phosphorus-solubilizing zones around their colonies were screened out to obtain functional fungi.

[0010] In some implementations, the arid and cold regions of the north refer to arid and cold regions in northern China above 39.9° north latitude.

[0011] In some embodiments, functional fungi are inoculated into modified phosphogypsum and then subjected to solid-state fermentation at a temperature of 30°C-40°C and an aeration rate of 4 m³ / s. 3 / h-6m 3 / h, the time is 2-3 days.

[0012] In some embodiments, functional fungi are inoculated into modified phosphogypsum and then subjected to solid-state fermentation until the total number of spores is not less than 10⁹ / g.

[0013] In some embodiments, after impurities are removed from the phosphogypsum, the particle size is ground to below 400 mesh.

[0014] According to the third aspect of the technical solution of the present invention, the present invention provides an application of a soil conditioner based on functional fungi in the remediation of saline-alkali land under photovoltaic arrays. The remediation process includes: uniformly spreading soil conditioner particles on a saline-alkali soil layer under a photovoltaic array; the soil conditioner particles gradually decompose under the action of water; functional fungal strains rapidly germinate on a modified phosphogypsum matrix, producing a large amount of EPS; EPS forms a complex with salt ions, reducing the activity of salt ions and forming a microporous structure, thereby improving the soil's water retention capacity; the calcium ions provided by the modified phosphogypsum and the EPS produced by the functional fungi jointly construct a calcium-EPS composite network, which forms a stable colloidal bridge in the soil pores, improving the compressive strength and erosion resistance of the soil structure.

[0015] In some implementations, soil conditioner granules are evenly spread on the saline-alkali soil layer under the photovoltaic array, the soil conditioner is mixed with the soil, and the soil moisture content is maintained at 50%-80%, with a repair cycle of 30-90 days.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. Unique strain source: The target fungus was obtained by screening from the saline-alkali soil of photovoltaic power plants in northern China. This strain has a strong natural adaptability to the native environment, overcoming the problems of low survival rate and unstable effect of exogenous strains.

[0017] 2. Resource recycling: Industrial waste phosphogypsum is transformed into a high-value-added modifier, solving the pollution problem caused by phosphogypsum stockpiling.

[0018] 3. Chemical-biological synergistic repair mechanism: EPS and organic acids secreted by fungi work synergistically with calcium ions provided by phosphogypsum.

[0019] 4. Environmentally friendly: It does not use synthetic chemical agents, avoids secondary soil and water pollution, and meets the requirements of green and sustainable development. Attached Figure Description

[0020] Figure 1 This is a flowchart of the preparation method of the soil conditioner of the present invention. Detailed Implementation

[0021] This invention provides a functional fungus, a soil conditioner, and its application based on soil selected from photovoltaic saline-alkali land. Specifically, it relates to a functional fungus selected from northern photovoltaic saline-alkali land, a soil conditioner containing this fungus, and its application in the remediation of saline-alkali land, particularly photovoltaic saline-alkali land. This invention utilizes a highly efficient salt-tolerant functional fungus selected from photovoltaic saline-alkali land soil, combined with modified phosphogypsum, to form a soil conditioner, solving the problems of high cost, poor adaptability, short effective period, and potential secondary pollution associated with existing soil conditioners.

[0022] Please see Figure 1 The technical solution of this invention comprises two main parts: functional fungi and phosphate minerals. The final soil conditioner is formed by combining screened functional fungi with modified phosphate minerals. The functional fungi used are preferably typical strains found below centralized photovoltaic power stations in arid and cold regions of northern China (above 39.9°N latitude), which can reduce soil salinity and regulate pH. The phosphate mineral used is phosphogypsum, which, after impurity removal, can be used to reduce the salinity of photovoltaic saline-alkali land. The soil conditioner is prepared by inoculating Penicillium mold at a mass ratio of (0.5-1):1000 onto the modified phosphogypsum.

[0023] The phosphate mineral phosphogypsum used is a byproduct of the phosphate chemical industry; the production of 1 ton of phosphoric acid generates 4-5 tons of phosphogypsum. Containing pollutants such as fluorine and heavy metals, long-term storage can cause harm to soil and water bodies through leaching. After modification, phosphogypsum can provide abundant calcium. 2+ Replace Na on soil colloids + It significantly reduces total salt content; at the same time, it provides a solid substrate for fungi, extending their survival time in the soil.

[0024] The functional fungus is a Penicillium species that can produce large amounts of EPS through fermentation. EPS can react with Na+ in the soil. + Cl - It forms complexes with salt ions, reducing salt activity and regulating pH. Simultaneously, it secretes organic acids to dissolve insoluble salts and promotes the release of nutrients such as calcium and phosphorus.

[0025] This soil conditioner not only addresses the salinization problem in photovoltaic saline-alkali land but also effectively solves the pollution problem caused by phosphogypsum accumulation. The conditioner granules are evenly spread in the saline-alkali soil layer (top 0-30cm) under the photovoltaic array, where they gradually decompose under the action of rainwater or irrigation water. Functional bacterial strains rapidly germinate on the phosphogypsum matrix, producing a large amount of EPS (extracellular polymeric substances). EPS forms complexes with salt ions, further reducing salt ion activity and forming a microporous structure, thus improving soil water retention. The calcium ions provided by phosphogypsum, together with the EPS produced by functional fungi, construct a calcium-EPS composite network. This network forms stable "colloidal bridges" in the soil pores, significantly improving the soil's compressive strength and erosion resistance.

[0026] Specifically, this invention provides a functional fungus screening method based on photovoltaic saline-alkali land soil. The functional fungus screening process includes the following steps: Step S11: Select saline-alkali soil with pH ≥ 9 and salinity ≥ 4.5 g / kg below centralized photovoltaic power stations in arid and cold northern regions, and collect soil samples from the top 0-20 cm layer. Step S12: Prepare a suspension of soil sample, incubate at 28°C for 5 days, pick single colonies of filamentous fungi, and obtain pure culture by streak purification multiple times. Step S13: After cultivation, salt-tolerant strains that can grow normally are screened out. Step S14: Inoculate the salt-tolerant strains onto a phosphorus-solubilizing medium containing insoluble calcium phosphate, and incubate at 28°C for 7 days. Screen out the phosphorus-solubilizing strains that form a transparent phosphorus-solubilizing zone around the colonies to obtain functional fungi.

[0027] In a specific embodiment, the functional fungus is Penicillium, which was screened from photovoltaic saline-alkali soil in northern China.

[0028] Preferably, in step S11, the arid and cold region in northern China refers to the arid and cold region above 39.9°N latitude in northern China. More preferably, the light resource abundance level of the arid and cold region in northern China is rich or above.

[0029] Preferably, in step S13, the culturing process specifically involves inoculating the pure culture (purified strain) obtained in step S12 onto a culture medium containing 5% NaCl and pH 9.0, and culturing it at 28°C for 7 days; thus, salt-tolerant strains are screened out.

[0030] This invention provides a soil conditioner based on functional fungi. The preparation process of the soil conditioner requires the functional fungi to be mixed in weight according to the ratio of nutrients required for growth. A preferred preparation method includes the following steps: Step S21: Select phosphogypsum with calcium mass fraction ≥10.0%, sulfur mass fraction ≥2.0%, water-soluble phosphorus (referring to all phosphorus elements that can be dissolved in water, expressed as mass fraction) ≥75.0 mg / kg, and pH ≤4.5. Crush it, add a purification agent and wash it with water, then add an activator for surface modification to obtain modified phosphogypsum. Step S22: The soil conditioner is prepared by inoculating the functional fungi into the modified phosphogypsum at a mass ratio of (0.5-1):1000. The functional fungi are strains found below centralized photovoltaic power stations in arid and cold regions of northern China, which can reduce soil salinity and regulate pH.

[0031] Preferably, the toxic and harmful substance content of the phosphogypsum selected in step S21 meets the limit requirements of GB38400.

[0032] Preferably, the functional fungi used in step S22 are the functional fungi of the foregoing embodiments of the present invention, obtained by the screening process of the foregoing embodiments.

[0033] Preferably, in step S22, after the functional fungi are inoculated into the modified phosphogypsum, solid-state fermentation is carried out at a temperature of 30℃-40℃ and an aeration rate of 4m³ / h. 3 / h-6m 3 / h, for 2-3 days. The suitable fermentation temperature for Penicillium was determined through small-scale experiments. The Penicillium used is an aerobic bacteria, and ensuring an appropriate aeration rate can guarantee the aerobic respiration of the bacteria.

[0034] Preferably, in step S22, after the functional fungi are inoculated into the modified phosphogypsum, solid-state fermentation is carried out until the total number of spores is not less than 10⁹ / g. At this time, the fungi are in the logarithmic growth phase, with the maximum growth rate, active enzyme system, and vigorous metabolism.

[0035] The phosphate mineral is phosphogypsum, which is modified by washing to remove impurities and activation treatment. Preferably, in step S21, after removing impurities, the phosphogypsum is ground to a particle size of less than 400 mesh.

[0036] Based on the soil conditioner of this invention, this invention provides its application in the remediation of photovoltaic saline-alkali land soil.

[0037] Specifically, the soil conditioner of the present invention is applied to the remediation of photovoltaic saline-alkali land. The remediation steps include: uniformly spreading soil conditioner particles on the saline-alkali soil layer under the photovoltaic array; the soil conditioner particles gradually decompose under the action of water; functional fungal strains rapidly germinate on the modified phosphogypsum matrix, producing a large amount of EPS; EPS forms a complex with salt ions, reducing the activity of salt ions and forming a microporous structure, thereby improving the soil's water retention capacity; the calcium ions provided by the modified phosphogypsum and the EPS produced by the functional fungi jointly construct a calcium-EPS composite network, which forms a stable colloidal bridge in the soil pores, improving the soil structure's compressive strength and erosion resistance.

[0038] Preferably, after evenly spreading the soil conditioner granules on the saline-alkali soil layer under the photovoltaic array, the soil conditioner is mixed with the soil, and the soil moisture content is maintained at 50%-80%. The remediation period is 30-90 days. Maintaining a certain moisture content is suitable for fungal growth and metabolism, and the appropriate remediation time allows the fungi to fully adapt to the polluted soil environment, achieving the best remediation effect.

[0039] In summary, the soil conditioner of this invention utilizes screened functional fungi combined with modified phosphogypsum to form a conditioner suitable for the salinization of photovoltaic saline-alkali land in northern China. This structure reduces salt activity and regulates pH. Experiments show that it can effectively reduce soil salinity.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; obviously, the described embodiments are some embodiments of the present invention, but 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; in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other; modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions for some of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A functional fungus screened based on photovoltaic saline-alkali soil, characterized in that, The screening process for functional fungi includes the following steps: Below centralized photovoltaic power stations in arid and cold northern regions, select saline-alkali soils with pH ≥ 9 and salinity ≥ 4.5 g / kg, and collect soil samples from the top 0-20 cm layer. Soil samples were prepared into suspensions, cultured at 28°C for 5 days, and single colonies of filamentous fungi were picked and purified by streak filtration multiple times to obtain pure cultures. After cultivation, salt- and alkali-tolerant strains that can grow normally were screened out. Salt-tolerant strains were inoculated onto a phosphorus-solubilizing medium containing insoluble calcium phosphate and cultured at 28°C for 7 days. Phosphorus-solubilizing strains that formed transparent phosphorus-solubilizing zones around their colonies were screened out to obtain functional fungi.

2. The functional fungi screened based on photovoltaic saline-alkali soil according to claim 1, characterized in that, The arid and cold regions of northern China refer to the arid and cold regions above 39.9° north latitude in northern China.

3. A soil conditioner based on functional fungi, characterized in that, The preparation method includes the following steps: Select phosphogypsum with a calcium mass fraction ≥10.0%, a sulfur mass fraction ≥2.0%, a water-soluble phosphorus content ≥75.0 mg / kg, and a pH ≤4.

5. Crush it, add a cleansing agent and wash it with water, then add an activator for surface modification to obtain modified phosphogypsum. A soil conditioner was prepared by inoculating functional fungi into modified phosphogypsum at a mass ratio of (0.5-1):1000. The functional fungi are strains found beneath centralized photovoltaic power stations in arid and cold northern regions, capable of reducing soil salinity and regulating pH.

4. The soil conditioner based on functional fungi according to claim 3, characterized in that, The screening process for functional fungi includes the following steps: Below centralized photovoltaic power stations in arid and cold northern regions, select saline-alkali soils with pH ≥ 9 and salinity ≥ 4.5 g / kg, and collect soil samples from the top 0-20 cm layer. Soil samples were prepared into suspensions, cultured at 28°C for 5 days, and single colonies of filamentous fungi were picked and purified by streak filtration multiple times to obtain pure cultures. After cultivation, salt- and alkali-tolerant strains that can grow normally were screened out. Salt-tolerant strains were inoculated onto a phosphorus-solubilizing medium containing insoluble calcium phosphate and cultured at 28°C for 7 days. Phosphorus-solubilizing strains that formed transparent phosphorus-solubilizing zones around their colonies were screened out to obtain functional fungi.

5. The soil conditioner based on functional fungi according to claim 4, characterized in that, The arid and cold regions of northern China refer to the arid and cold regions above 39.9° north latitude in northern China.

6. The soil conditioner based on functional fungi according to claim 3, characterized in that, Functional fungi were inoculated into modified phosphogypsum and then subjected to solid-state fermentation at a temperature of 30℃-40℃ and an aeration rate of 4m³ / h. 3 / h-6m 3 / h, the time is 2-3 days.

7. The soil conditioner based on functional fungi according to claim 3, characterized in that, Functional fungi were inoculated into modified phosphogypsum and then subjected to solid-state fermentation until the total number of spores was not less than 10⁹ / g.

8. The soil conditioner based on functional fungi according to claim 3, characterized in that, After impurities are removed from the phosphogypsum, the particle size is ground to below 400 mesh.

9. The application of the soil conditioner based on functional fungi according to claim 3 in the remediation of photovoltaic saline-alkali land soil, characterized in that, The repair process includes: Soil conditioner granules are evenly spread on the saline-alkali soil layer under the photovoltaic array; the soil conditioner granules gradually decompose under the action of water; functional fungal strains germinate rapidly on the modified phosphogypsum matrix, producing a large amount of EPS; EPS forms complexes with salt ions, reducing the activity of salt ions and forming a microporous structure, thereby improving the soil's water retention capacity; the calcium ions provided by the modified phosphogypsum and the EPS produced by the functional fungi jointly construct a calcium-EPS composite network, which forms a stable colloidal bridge in the soil pores, improving the soil structure's compressive strength and erosion resistance.

10. The application according to claim 9, characterized in that, After evenly spreading the soil conditioner granules on the saline-alkali soil layer under the photovoltaic array, the soil conditioner is mixed with the soil, and the soil moisture content is maintained at 50%-80%. The repair cycle is 30-90 days.

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