Preparation method and application of artificial organic soil based on yellow phosphorus slag

Abstract

The present application relates to solid waste resource utilization technical field, the present application discloses a kind of preparation method and application of artificial organic soil based on yellow phosphorus slag, comprising the following steps: 1) modified yellow phosphorus slag, 2) modified humus, 3) compounding, the modified yellow phosphorus slag is mixed with modified humus, appropriate amount of water is added while mixing, stationary, obtain mixed material, drying, by pulverizer grinding and mixer stirring, obtain artificial organic soil;The present application solves the problem of soil resource deficiency and yellow phosphorus slag resource utilization, not only can improve the capacity of soil resources, but also can break through the bottleneck of yellow phosphorus slag resource utilization.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a method for preparing artificial organic soil based on yellow phosphorus slag and its application. Background Technology

[0002] Soil scarcity is a significant global environmental problem. With population growth and economic development, pressure on soil resources is constantly increasing, leading to a series of problems such as soil degradation, declining fertility, and reduced arable land. The Root World Report, "The State of Land and Water in the World's Food and Agriculture Sector 2021," states that soil resources, the foundation of agricultural food systems, are "on the verge of collapse" and will be insufficient to meet the food needs of nearly 10 billion people globally by 2050. Soil scarcity manifests itself primarily in two ways: soil degradation and arable land reduction. First, soil degradation refers to the deterioration of soil structure and function due to improper land use and management. The Food and Agriculture Organization of the United Nations (FAO) estimates that more than half of the world's agricultural land is affected by land degradation each year, leaving approximately one-third of the world's soil in a degraded state. Soil degradation includes soil erosion, salinization, and pollution. The scarcity of soil resources poses a serious threat to food production and ecosystem services.

[0003] Comprehensive resource utilization is an important aspect of implementing sustainable development. With a large stockpile of bulk solid waste and significant environmental impact, efficient resource utilization is one of the major challenges facing my country today. Taking yellow phosphorus slag as an example, it is a byproduct of yellow phosphorus electric furnace production. For every ton of yellow phosphorus produced, approximately 8-10 tons of phosphorus slag are generated. Currently, my country produces nearly 1 million tons of yellow phosphorus annually, generating nearly 9 million tons of phosphorus slag. The massive disposal and stockpiling of phosphorus slag not only occupies vast areas of land, but also causes the leaching of fluorine and phosphorus by rainwater, polluting land and water resources, affecting plant growth and human health, and is also a waste of resources. Finding a reasonable solution for phosphorus slag disposal, transforming it into a resource, turning waste into treasure, and turning harm into benefit is an important issue that yellow phosphorus enterprises urgently need to address and a direction for development.

[0004] Soil originates from the Earth's crust, which is composed of rocks. Rocks break down into particles of varying sizes, which mix with water and air to form the structure of soil. Most of the minerals in soil come from rocks, while organic matter primarily originates from carbon inputs from plants and microorganisms. When rocks are affected by weathering, chemical processes, and biological activity, they release nutrients, providing the necessary nutrients for plant growth. During phosphate rock processing, the ore is crushed into fine particles, resulting in yellow phosphorus slag that is not only diverse in particle size but also rich in phosphorus. With the addition of appropriate organic matter, it has the potential to be used to create artificial organic soil. Summary of the Invention

[0005] The purpose of this invention is to provide the manufacture and application of artificial organic soil based on yellow phosphorus slag, aiming to solve the problems of soil resource scarcity and the resource utilization of yellow phosphorus slag. This method can not only increase the capacity of soil resources, but also break through the bottleneck of yellow phosphorus slag resource utilization.

[0006] The solution of the present invention is:

[0007] A method for preparing artificial organic soil based on yellow phosphorus slag includes the following steps:

[0008] 1) Modified yellow phosphorus slag: The pH of the yellow phosphorus slag is adjusted to reach a pH value of 6-9. It is then mixed with phosphogypsum. The mixture is then soaked in water for ≥72 hours, with stirring for 30 minutes every 24 hours. After soaking, it is rinsed with clean water to obtain modified yellow phosphorus slag.

[0009] 2) Modified humus: The humus is dehydrated by freeze drying for 1 hour to reduce the moisture content to 10-30%. Then, 0.05-0.1g of the composting agent is added per kilogram of humus. After stirring evenly, an appropriate amount of water is added and sprinkled on the surface of the bedding material. The mixture is allowed to compost for 7-10 days at a temperature ≥50℃. Once the composting process is complete, modified humus is obtained.

[0010] 3) Compounding: The modified yellow phosphorus slag is mixed with the modified humic material, and an appropriate amount of water is added while mixing. The mixture is left to stand for 25 hours to obtain a mixture. The mixture is then dried, crushed by a pulverizer and stirred by a mixer to obtain artificial organic soil.

[0011] As a preferred technical solution, the specific steps for adjusting the pH of yellow phosphorus slag are to mix slag acid, phosphogypsum, agricultural waste straw or biochar, humic acid and yellow phosphorus slag in a mass ratio of 1:1.5:1:1:4-5.

[0012] As a preferred technical solution, the mass ratio of yellow phosphorus slag to phosphogypsum in step 1) is 100:40-60.

[0013] As a preferred technical solution, in step 1), the mixture is soaked with water at a ratio of 1:1 v / w.

[0014] As a preferred technical solution, the modified yellow phosphorus slag contains arsenic ≤100mg / kg, cadmium ≤1.5mg / kg, chromium ≤800mg / kg, lead ≤400mg / kg, and mercury ≤2.0mg / kg.

[0015] As a preferred technical solution, the humus in step 2) is lake bottom humus, and the freeze-drying temperature is -65℃.

[0016] As a preferred technical solution, in step 2), the composting agent is one of probiotics or extracellular enzyme composting bacteria, wherein the effective viable count is >20 billion / g; the probiotic is one of Bacillus, yeast, or filamentous fungi.

[0017] As a preferred technical solution, the modified humus has a pH value of 6-8, a fecal coliform count of ≤100 CFU / g, and a roundworm egg mortality rate of ≥95%.

[0018] As a preferred technical solution, in step 3), the modified yellow phosphorus slag and the modified humic material are mixed at a mass ratio of 7:2.

[0019] As a preferred technical solution, the drying conditions of the mixture in step 3) are 65°C for 48 hours, until the moisture content is <5%; the particle size after being crushed by the pulverizer is <1mm, and the stirring of the mixer is 200 rpm for 30 minutes.

[0020] As a preferred technical solution, the standard for adding an appropriate amount of water in steps 2) and 3) is that when the ball is squeezed into a ball, water can be seen between the fingers but does not drip, and when the ball is released and falls to the ground, it disperses.

[0021] This invention also discloses the application of artificial organic soil prepared by a method for preparing artificial organic soil based on yellow phosphorus slag in soil materials. The application method of the yellow phosphorus slag artificial organic soil needs to be adjusted according to the target soil, crop type, and expected results. The application methods include: 1) as soil: using the yellow phosphorus slag artificial organic soil directly as soil; 2) basal application: before sowing or transplanting, evenly spreading the yellow phosphorus slag artificial organic soil on the soil surface, then tilling it into the soil and mixing it thoroughly; 3) top dressing: during crop growth, applying the yellow phosphorus slag artificial organic soil in furrows or holes around the crop roots, then covering with soil; 4) seedling substrate: mixing the yellow phosphorus slag artificial organic soil with peat moss, perlite, etc., in a certain proportion.

[0022] 5) Organic fertilizer additives: The artificial organic soil made from yellow phosphorus slag is mixed with organic waste such as livestock and poultry manure and straw for fermentation to produce organic fertilizer. Application scenarios include: 1) Topsoil reconstruction: Yellow phosphorus slag artificial organic soil can be directly used to construct the topsoil; 2) Afforestation of barren hills: Yellow phosphorus slag artificial organic soil can improve soil fertility in afforestation of barren hills; 3) Saline-alkali land improvement: Yellow phosphorus slag artificial organic soil can balance the ionic composition in saline-alkali soil, improve soil structure, and increase soil fertility; 4) Acidic soil improvement: Yellow phosphorus slag artificial organic soil can neutralize soil acidity, increase soil pH value, improve the soil microbial environment, and promote crop growth; 5) Heavy metal contaminated soil remediation: Calcium and sulfur in yellow phosphorus slag artificial organic soil can react with heavy metal ions to reduce the effectiveness of heavy metals and reduce the absorption of heavy metals by crops; 6) Facility agriculture soil improvement: Yellow phosphorus slag artificial organic soil can improve the physical and chemical properties of facility agriculture soil, improve soil water and fertilizer retention capacity, and promote crop growth; 7) Landscaping soil improvement: Yellow phosphorus slag artificial organic soil can improve the structure and fertility of landscaping soil, promote plant growth, and improve the greening effect.

[0023] Advantages of this invention:

[0024] 1. This invention transforms yellow phosphorus slag, a major solid waste, into a valuable resource through modification. By modifying humus, a natural organic matter, the yellow phosphorus slag is rapidly converted into organic soil, which, compared to solid soil, can better support mung bean cultivation.

[0025] 2. The artificial soil of the present invention is suitable for large-scale application. It can not only effectively solve the problem of large-scale open-air storage of yellow phosphorus slag, but also provide an ideal soil material for the transformation of barren hillsides. Attached Figure Description

[0026] Figure 1 This is a diagram showing the microstructure and elemental composition of the artificial organic soil used in the test experiments of this invention.

[0027] Figure 2 This is a comparison diagram of the changes in pore water environment based on artificial organic soil and farmland soil in the test experiment of this invention;

[0028] Figure 3 This is a comparison chart of the effectiveness of testing experiments of artificial organic soil and farmland soil in detecting typical heavy metals in pore water.

[0029] Figure 4 This is a comparison diagram of the effects of planting mung beans in artificial organic soil and farmland soil in the test experiment of this invention;

[0030] Figure 5 This is a comparison diagram of enzyme activity after planting mung beans in artificial organic soil and farmland soil in the test experiment of this invention;

[0031] Figure 6 This is a comparison diagram of the aggregate structure of mung beans grown in artificial organic soil and farmland soil in the test experiment of this invention.

[0032] Figure 7 This invention compares the heavy metal content of mung beans grown in artificial organic soil and farmland soil during the test experiments. Detailed Implementation

[0033] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0034] Unless otherwise specified, the experimental methods in the following examples are conventional methods; the materials used are conventional materials; and the chemical reagents used are of analytical grade.

[0035] The materials used in this embodiment of the invention are sourced from the following sources:

[0036] Yellow phosphorus slag: provided by Yunnan Yuntianhua Co., Ltd., collected from the waste residue of the company's yellow phosphorus production.

[0037] Lake bottom humus: provided by Yunnan Yuntianhua Co., Ltd., collected from the bottom of Yilong Lake in Shiping County, Honghe Prefecture, Yunnan Province.

[0038] Artificial organic soil: developed by Yunnan Yuntianhua Co., Ltd., it is a compound of modified yellow phosphorus slag and modified lake bottom humus.

[0039] Soil: Collected from farmland in Xiangshan, Zhejiang.

[0040] Example 1:

[0041] 1) Modified yellow phosphorus slag: The pH of the yellow phosphorus slag is adjusted (by mixing the slag acid, phosphogypsum, agricultural waste straw, humic acid and yellow phosphorus slag in the wet process of phosphoric acid production at a mass ratio of 1:1.5:1:1:4) to reach a pH value of 6-7. The mixture is then mixed with phosphogypsum, and the mixture is soaked in water for 72 hours, with stirring for 30 minutes every 24 hours. After soaking, the water is filtered out, and the solid is rinsed with twice the volume of clean water to obtain modified yellow phosphorus slag.

[0042] 2) Modified humus: The humus is dehydrated by freeze drying for 1 hour to reduce the moisture content to 15%. Then, 0.08g of the composting agent is added per kilogram of humus. After stirring evenly, an appropriate amount of water is added and sprinkled on the surface of the bedding material. After composting for 9 days at a temperature ≥50℃, the modified humus is obtained.

[0043] 3) Compounding: The modified yellow phosphorus slag is mixed with the modified humic material, and an appropriate amount of water is added while mixing. The mixture is left to stand for 25 hours to obtain a mixture. The mixture is then dried, crushed by a pulverizer and stirred by a mixer to obtain artificial organic soil.

[0044] In step 1), the mass ratio of yellow phosphorus slag to phosphogypsum is 100:50.

[0045] In step 1), the mixture is soaked with water at a ratio of 1:1 v / w.

[0046] The modified yellow phosphorus slag contains arsenic ≤100mg / kg, cadmium ≤1.5mg / kg, chromium ≤800mg / kg, lead ≤400mg / kg, and mercury ≤2.0mg / kg.

[0047] In step 2), the humus is lake bottom humus, and the freeze-drying temperature is -65℃.

[0048] In step 2), the composting agent is a probiotic, wherein the effective live bacteria count is >20 billion / g; the probiotic is Bacillus.

[0049] The modified humus has a pH of 6-8, a fecal coliform count ≤100 CFU / g, and a roundworm egg mortality rate ≥95%.

[0050] In step 3), the modified yellow phosphorus slag and modified humic material are mixed at a mass ratio of 7:2.

[0051] The drying conditions for the mixture in step 3) are 65°C for 48 hours, until the moisture content is <5%; the particle size after being crushed by the pulverizer is <1mm, and the stirring is carried out at 200 rpm for 30 minutes.

[0052] The standard for adding an appropriate amount of water in steps 2) and 3) is that when the ball is squeezed in the hand, water can be seen between the fingers but not dripping, and when the ball is released and falls to the ground, it will crumble.

[0053] The artificial organic soil was tested and found to be loose in texture, free of lumps, odorless, free of visible impurities, and with uniform particles. Its basic properties conform to Table 1 below.

[0054] Table 1:

[0055]

[0056] Example 2:

[0057] 1) Modified yellow phosphorus slag: The pH of the yellow phosphorus slag is adjusted (by mixing the slag acid, phosphogypsum, biochar, humic acid and yellow phosphorus slag from the wet process of phosphoric acid production at a mass ratio of 1:1.5:1:1:4.5) to achieve a pH value of 6.5-8. The mixture is then mixed with phosphogypsum, and the mixture is soaked in water for 72 hours, with stirring for 30 minutes every 24 hours. After soaking, the mixture is rinsed with twice the volume of clean water to obtain modified yellow phosphorus slag.

[0058] 2) Modified humus: The humus is dehydrated by freeze drying for 1 hour to reduce the moisture content to 10%. Then, 0.05g of the composting agent is added per kilogram of humus. After stirring evenly, an appropriate amount of water is added and sprinkled on the surface of the bedding material. The mixture is allowed to compost for 7 days at a temperature ≥50℃. Once the composting process is complete, modified humus is obtained.

[0059] 3) Compounding: The modified yellow phosphorus slag is mixed with the modified humic material, and an appropriate amount of water is added while mixing. The mixture is left to stand for 25 hours to obtain a mixture. The mixture is then dried, crushed by a pulverizer and stirred by a mixer to obtain artificial organic soil.

[0060] In step 1), the mass ratio of yellow phosphorus slag to phosphogypsum is 100:40.

[0061] In step 1), the mixture is soaked with water at a ratio of 1:1 v / w.

[0062] The modified yellow phosphorus slag contains arsenic ≤100mg / kg, cadmium ≤1.5mg / kg, chromium ≤800mg / kg, lead ≤400mg / kg, and mercury ≤2.0mg / kg.

[0063] In step 2), the humus is lake bottom humus, and the freeze-drying temperature is -65℃.

[0064] In step 2), the composting agent is an extracellular enzyme composting agent.

[0065] The modified humus has a pH of 6-8, a fecal coliform count ≤100 CFU / g, and a roundworm egg mortality rate ≥95%.

[0066] In step 3), the modified yellow phosphorus slag and modified humic material are mixed at a mass ratio of 7:2.

[0067] The drying conditions for the mixture in step 3) are 65°C for 48 hours, until the moisture content is <5%; the particle size after being crushed by the pulverizer is <1mm, and the stirring is carried out at 200 rpm for 30 minutes.

[0068] The standard for adding an appropriate amount of water in steps 2) and 3) is that when the ball is squeezed in the hand, water can be seen between the fingers but not dripping, and when the ball is released and falls to the ground, it will crumble.

[0069] Example 3:

[0070] 1) Modified yellow phosphorus slag: The pH of the yellow phosphorus slag is adjusted (by mixing the slag acid, phosphogypsum, agricultural waste straw, humic acid and yellow phosphorus slag in the wet process of phosphoric acid production at a mass ratio of 1:1.5:1:1:5) to achieve a pH value of 7-8.5. The mixture is then mixed with phosphogypsum, and the mixture is soaked in water for ≥72 hours. The mixture is stirred for 30 minutes every 24 hours and then rinsed to obtain modified yellow phosphorus slag.

[0071] 2) Modified humus: The humus is dehydrated by freeze drying for 1 hour to reduce the moisture content to 30%. Then, 0.1 g of the composting agent is added per kilogram of humus. After stirring evenly, an appropriate amount of water is added and sprinkled on the surface of the bedding material. The mixture is allowed to compost for 10 days at a temperature ≥50℃. Once the composting process is complete, modified humus is obtained.

[0072] 3) Compounding: The modified yellow phosphorus slag is mixed with the modified humic material, and an appropriate amount of water is added while mixing. The mixture is left to stand for 25 hours to obtain a mixture. The mixture is then dried, crushed by a pulverizer and stirred by a mixer to obtain artificial organic soil.

[0073] In step 1), the mass ratio of yellow phosphorus slag to phosphogypsum is 100:60.

[0074] In step 1), the mixture is soaked with water at a ratio of 1:1 v / w.

[0075] The modified yellow phosphorus slag contains arsenic ≤100mg / kg, cadmium ≤1.5mg / kg, chromium ≤800mg / kg, lead ≤400mg / kg, and mercury ≤2.0mg / kg.

[0076] In step 2), the humus is lake bottom humus, and the freeze-drying temperature is -65℃.

[0077] In step 2), the composting agent is a probiotic with an effective live bacteria count >20 billion / g; the probiotic is yeast.

[0078] The modified humus has a pH of 6-8, a fecal coliform count ≤100 CFU / g, and a roundworm egg mortality rate ≥95%.

[0079] In step 3), the modified yellow phosphorus slag and modified humic material are mixed at a mass ratio of 7:2.

[0080] The drying conditions for the mixture in step 3) are 65°C for 48 hours, until the moisture content is <5%; the particle size after being crushed by the pulverizer is <1mm, and the stirring is carried out at 200 rpm for 30 minutes.

[0081] The standard for adding an appropriate amount of water in steps 2) and 3) is that when the ball is squeezed in the hand, water can be seen between the fingers but not dripping, and when the ball is released and falls to the ground, it will crumble.

[0082] The corresponding components of Example 1 were subjected to the following experimental tests.

[0083] 1. Microstructure and elemental composition analysis of yellow phosphorus slag modified materials

[0084] Scanning electron microscopy analysis showed that the modified yellow phosphorus slag particles were uniformly distributed and had smooth surfaces. It contained elements such as C (1.95%), O (47.73%), Mg (0.33%), Al (0.23%), Si (1.21%), S (17.07%), K (0.11%), Ca (26.79%), and Fe (0.12%). The modified material, when mixed with humus at a ratio of 100:40, contained more fine particles, and the elemental composition of the material changed significantly. This artificial organic soil contained C (2.52%), O (45.12%), Mg (2.08%), Al (1.89%), Si (14.95%), S (0.29%), K (0.40%), Ca (28.13%), and Fe (0.05%). Figure 1 The carbon content increased by about 30%, which is because humus is rich in organic carbon. Humus in the field can significantly increase the organic carbon content in the modified material, which will create favorable conditions for improving the water retention of the material and normal plant growth.

[0085] 2. Changes in the pore water environment of artificial organic soil and actual soil

[0086] This study employed a pot experiment, weighing 1 kg each of artificial organic soil and actual farmland soil into black culture pots (15 cm in diameter and 10 cm in height). Two treatments were established: artificial organic soil and actual soil, with three replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, with regular watering to maintain soil moisture content >60%. During the 60-day cultivation period, soil pore water was collected periodically (0, 30, and 60 days) using a Rhizon sampler (0.1 μm sampling head). The pH and redox potential of the pore water were measured using a portable pH and redox potentiometer, and changes in the organic matter structure within the pore water were analyzed using three-dimensional fluorescence spectroscopy.

[0087] The results showed that the pH of the artificial organic soil decreased with increasing cultivation time, slowly increasing to 6.89±0.053 after 30 days, while the pH of the actual soil remained relatively stable (7.91±0.042). The pH of the artificial organic soil was significantly lower than that of the actual farmland soil, and closer to neutral, thus being more conducive to crop growth. Figure 2A); The electrical conductivity (Ec) of the two types of soil showed the same trend. With the increase of incubation time, the Ec of the artificial organic soil decreased from 6873±555.0 μS / cm to 2475±15.4 μS / cm, while the Ec of the actual soil decreased from 2771.6±155.1 μS / cm to 555.1±74.3 μS / cm. The Ec of the artificial organic soil was significantly higher than that of the actual soil, which may be due to the higher content of primary minerals in the artificial organic soil. Figure 2 B). One-way ANOVA showed that the pH of the artificial organic soil was significantly decreased (p<0.01), while Ec was significantly increased (p<0.01). Figure 2 C). Three-dimensional fluorescence analysis ( Figure 2 D) indicates that the composition of soluble organic carbon in artificial organic soil is highly similar to that of actual soil, suggesting that the fertility of artificial soil is good.

[0088] 3. Comparison of the availability of typical heavy metals in the pore water of artificial organic soil and farmland soil

[0089] This study employed a pot experiment. 1 kg of artificial organic soil and actual farmland soil were weighed into black culture pots (15 cm in diameter, 10 cm in height). Two treatments were established: artificial organic soil and actual soil, with three replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, and watered regularly to maintain soil moisture content >60%. During the 60-day cultivation period, soil pore water was collected periodically (0, 30, and 60 days) using a Rhizon sampler (0.1 μm sampling head aperture). The collected pore water was acidified with 1M hydrochloric acid to pH <2. The levels of heavy metals such as arsenic (As), cadmium (Cd), chromium (Cr), and zinc (Zn) in the pore water were tested using ICP-MS (NexION 1000G, PerkinElmer, Inc., Shelton, CT USA) to characterize changes in the bioavailability of these heavy metals.

[0090] The results showed that the concentrations of heavy metals in both the artificial organic soil and the actual soil were very low, indicating no heavy metal pollution. With prolonged incubation time, the contents of available As and Cr in the artificial organic soil showed a decreasing trend.

[0091] The available As content decreased from 33.9±2.85 μg / L to 8.77±0.82 μg / L. The available Cr content decreased from 0.70±0.08 μg / L to nearly 0 μg / L. In contrast, the As content in the actual soil initially increased from 11.93±5.16 μg / L to 28.90±3.10 μg / L, then gradually decreased to 7.83±1.33 μg / L after 30 days. At the end of the incubation period, the available arsenic content in the artificial organic soil and the actual soil were consistent. The Cr content in the actual soil remained near the detection limit. The trends in Cd and Zn content in the artificial organic soil and the actual soil were similar, with Cd content remaining stable and Zn content gradually increasing. Figure 3 A and B). ANOVA analysis showed significant differences in Cd and Cr levels between artificial organic soil and actual soil (p < 0.05). Figure 3 C), but the relative contents were all low, and there was no phenomenon of heavy metal exceeding the standard.

[0092] 4. Comparison of the effects of planting mung beans in artificial organic soil and farmland soil

[0093] This study employed a pot experiment. 1 kg of artificial organic soil and actual farmland soil were weighed into black culture pots (15 cm in diameter, 10 cm in height). Two treatments were established: one using artificial organic soil and the other using actual soil, with three replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, with regular watering to maintain soil moisture content >60%. After 60 days of cultivation, five growth indicators were measured: plant height, SPAD (spider plant diameter), number of root nodules, fresh weight of root nodules, and dry weight of the plant.

[0094] The results showed that mung beans grew similarly in both artificial organic soil and actual soil, and both grew quite well. Figure 4 The plant height of mung beans in artificial organic soil and actual soil were 12.67±0.95cm and 12.55±1.10cm, respectively; the SPAD values ​​of mung bean leaves in artificial organic soil and actual soil were 30.87±3.73 and 29.85±2.34, respectively; the number of root nodules of mung beans in artificial organic soil and actual soil were 24.67±13.22 / plant and 16.67±4.11 / plant, respectively; the root nodule weight of mung beans in artificial organic soil and actual soil were 0.98±0.48 / plant and 0.38±0.13 / plant, respectively; and the dry weight of mung beans in artificial organic soil and actual soil were 3.60±0.54 / plant and 2.98±0.60 / plant, respectively. Overall, the plant height, SPAD value, number of root nodules, root nodule weight, and dry weight of mung beans grown in artificial soil were 0.93%, 3.41%, 48.0%, 158%, and 20.56% higher than those in actual soil, respectively. While the differences in these indicators were not statistically significant due to their large variability, mung beans generally grew better in artificial organic soil.

[0095] 5. Comparison of enzyme activity after planting mung beans in artificial organic soil and farmland soil

[0096] This study employed a pot experiment. 1 kg of artificial organic soil and actual farmland soil were weighed into black culture pots (15 cm in diameter, 10 cm in height). Two treatments were established: one using artificial organic soil and the other using actual soil, with three replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, with regular watering to maintain soil moisture content >60%. After 60 days of cultivation, once the mung beans were harvested, the pH of the fresh soil and the activities of five enzymes (β-1,4-glucosidase (BG), cellobiase (CB), β-1,4-N-acetylglucosidase (NAG), β-xylosidase (XYL), and acid phosphatase (PHOS)) were measured.

[0097] The results showed that the activities of all five enzymes were high in both artificial organic soil and actual soil, with most enzymes exhibiting higher activity in actual soil. The soil pH and pore water pH results after mung bean harvest were consistent; the pH of the artificial organic soil was near neutral (6.94±0.04), while the pH of the actual soil was higher (8.62±0.35). The activities of BG, CB, XYL, and PHOS enzymes in the actual soil were 8.12±2.90 μmol h⁻¹, respectively. -1 g -1 1.99±0.58μmol h -1 g -1 1.89±0.22μmol h -1 g -1 76.91±20.78μmol h -1 g -1 Both were significantly higher than those of artificial organic soil (3.10 ± 0.99 μmol h⁻¹). -1 g -1 0.66±0.26μmol h -1 g -1 0.65±0.21μmol h -1 g -1 5.60±2.89μmol h -1 g -1 The NAG enzyme in artificial organic soil (4.86±0.59 μmol h) -1 g -1 The concentration was significantly higher than that of actual soil (1.89 ± 0.22 μmol h). -1 g -1 ()( Figure 5 In general, real soils have higher enzyme activity due to longer reclamation time and more thorough maturation; while artificial soils have lower enzyme activity due to shorter maturation time. Crop planting is expected to rapidly improve the enzyme activity of artificial soils.

[0098] 6. Comparison of aggregate structure after planting mung beans in artificial organic soil and farmland soil

[0099] This study employed a pot experiment. 1 kg of artificial organic soil and actual farmland soil were weighed into black culture pots (15 cm in diameter, 10 cm in height). Two treatments were established: one using artificial organic soil and the other using actual soil, with three replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, with regular watering to maintain soil moisture content >60%. After 60 days of cultivation, the aggregate structure of the fresh soil was measured after mung bean harvest.

[0100] The results showed that the aggregate structure of artificial organic soil differed significantly from that of actual soil. The content of large aggregates in actual soil was significantly higher (19.17±3.87%) than that in artificial organic soil (3.10±1.12%). The contents of aggregates with particle sizes of 0.053–0.25 mm and 0.25–2 mm were comparable between artificial organic soil and actual soil (28.57±14.58% vs 31.90±0.78% and 34.53±16.95% vs 32.43±1.07%), with no significant differences. Figure 6 The clay and silt content of artificial organic soil (<0.053 mm; 33.80±10.49%) was significantly higher than that of actual soil (16.53±2.33%). It is known that the finer the soil particles, the greater their binding force, which is more conducive to the formation of compound particles. Therefore, artificial organic soil possesses the prerequisites for developing into high-quality soil.

[0101] 7. Comparison of heavy metal content in mung beans grown in artificial organic soil and farmland soil

[0102] The results showed that the study used a pot experiment. 1 kg of artificial organic soil and actual farmland soil were weighed into black culture pots (15 cm in diameter and 10 cm in height). Two treatments were set up: artificial organic soil and actual soil, with three replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, and watered regularly to maintain soil moisture content >60%. After 60 days of cultivation, and upon harvesting the mung beans, the contents of heavy metals such as chromium (Cr), manganese (Mn), copper (Cu), arsenic (As), cadmium (Cd), and lead (Pb) in the mung bean plants were measured.

[0103] The results showed that the heavy metal content in mung bean plants was low. The contents of chromium (Cr), manganese (Mn), copper (Cu), arsenic (As), cadmium (Cd), and lead (Pb) in mung bean plants grown in artificial organic soil were 10.37±0.75 mg / kg, 127±19 mg / kg, 9.73±4.93 mg / kg, 3.08±0.65 mg / kg, 0.39±0.13 mg / kg, and 15.38±8.82 mg / kg, respectively; the corresponding heavy metal contents in mung bean plants grown in actual soil were 11.07±2.62 mg / kg, 219±22 mg / kg, 14.66±5.29 mg / kg, 3.11±0.40 mg / kg, 0.13±0.03 mg / kg, and 4.26±0.95 mg / kg, respectively. Figure 7 The levels of Cr, Mn, Cu, and As in mung bean plants grown in artificial organic soil were lower than those in actual soil, while the levels of Cd and Pb in mung bean plants grown in artificial organic soil were higher than those in actual soil. Overall, the heavy metal content in mung bean plants grown in both artificial organic soil and farmland soil was low.

[0104] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing artificial organic soil based on yellow phosphorus slag, characterized in that, Includes the following steps: 1) Modified yellow phosphorus slag: The pH of the yellow phosphorus slag is adjusted to a value of 6-9. It is then mixed with phosphogypsum, and the mixture is soaked in water for ≥72 hours, stirring for 30 minutes every 24 hours. After soaking, it is rinsed with clean water to obtain modified yellow phosphorus slag. The specific steps for adjusting the pH of the yellow phosphorus slag are as follows: slag acid, phosphogypsum, agricultural waste straw or biochar, humic acid, and yellow phosphorus slag are mixed at a mass ratio of 1:1.5:1:1:4-5; the mass ratio of yellow phosphorus slag to phosphogypsum is 100:40-60; the mixture is soaked in water at a ratio of 1:1 v / w; the modified yellow phosphorus slag contains arsenic ≤100mg / kg, cadmium ≤1.5mg / kg, chromium ≤800mg / kg, lead ≤400mg / kg, and mercury ≤2.0mg / kg. 2) Modified humus: Humus is dehydrated for 1 hour using freeze-drying to reduce its moisture content to 10-30%. Then, a composting agent is added at a rate of 0.05-0.1g per kilogram of humus. After thorough mixing, an appropriate amount of water is added and sprinkled onto the surface of the bedding material. The mixture is allowed to compost for 7-10 days at a temperature ≥50℃. Once composting is complete, modified humus is obtained. The humus is lake bottom humus, and the freeze-drying temperature is -65℃. The modified humus has a pH of 6-8, a fecal coliform count ≤100 CFU / g, and a roundworm egg mortality rate ≥95%. The composting agent is one of probiotics or extracellular enzyme composting bacteria, with an effective viable count >20 billion / g. The probiotic is one of Bacillus, yeast, or filamentous fungi. 3) Compounding: The modified yellow phosphorus slag and modified humic material are mixed, and an appropriate amount of water is added while mixing. The mixture is left to stand for 25 hours to obtain a mixture. The mixture is then dried, pulverized by a pulverizer, and stirred by a mixer to obtain artificial organic soil. The modified yellow phosphorus slag and modified humic material are mixed at a mass ratio of 7:

2. The drying conditions for the mixture are 65℃ for 48 hours, until the moisture content is <5%. The particle size after pulverization is <1mm, and the stirring speed is 200 rpm for 30 minutes. The artificial organic soil meets the following requirements: organic matter ≥ 50 g / kg, non-capillary porosity ≥ 8%, and seed germination index ≥ 75%.

2. The method for preparing artificial organic soil based on yellow phosphorus slag as described in claim 1, characterized in that: The standard for adding an appropriate amount of water in steps 2) and 3) is that when the ball is squeezed in the hand, water can be seen between the fingers but not dripping, and when the ball is released and falls to the ground, it will crumble.

3. The application of a method for preparing artificial organic soil based on yellow phosphorus slag as described in any one of claims 1-2 in soil materials.

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