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

Abstract

The invention relates to the technical field of solid waste resource utilization, and discloses a yellow phosphorus slag-based artificial organic soil preparation method and application thereof, and the method comprises the following steps: 1) modifying yellow phosphorus slag, 2) modifying humus, and 3) compounding: mixing the modified yellow phosphorus slag with the modified humus, adding a proper amount of water while mixing, standing to obtain a mixture, and drying to obtain the artificial organic soil. Crushing by a crusher and stirring by a stirrer to obtain artificial organic soil; the method solves the problems of lack of soil resources and resource utilization of the yellow phosphorus slag, not only can improve the capacity of the soil resources, but also can break through the bottleneck of resource utilization of the yellow phosphorus slag.

Description

Technical Field

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

[0002] The scarcity of soil resources is an important environmental problem facing the world. With population growth and economic development, the pressure on soil resources continues to increase, leading to a series of problems such as soil degradation, decreased fertility and reduced arable land. According to the Rhizosphere "The State of Land and Water Resources in the World for Food and Agriculture 2021" report, soil resources, as the foundation of the agricultural food system, are "on the verge of limit" and will be difficult to meet the food needs of nearly 10 billion people worldwide by 2050. The scarcity of soil is mainly reflected in two aspects: soil degradation and reduction of arable land. 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, which makes about 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] Carrying out comprehensive resource utilization is an important part of implementing sustainable development. The stock of bulk solid waste is large and the environmental impact is prominent. How to efficiently utilize resources is one of the major challenges currently facing my country. Take yellow phosphorus slag as an example. Yellow phosphorus slag is a by-product of yellow phosphorus electric furnace production. This method produces about 8 to 10 tons of phosphorus slag for every 1 ton of yellow phosphorus produced. my country currently produces nearly 1 million tons of yellow phosphorus and nearly 9 million tons of phosphorus slag each year. The abandonment and stacking of huge amounts of phosphorus slag will not only occupy large tracts of land, but also cause the dissolution of fluorine and phosphorus after being washed by rainwater, pollute land and water resources, affect plant growth and human health, and is also a waste of resources. Reasonably solving the way out of phosphorus slag, turning it into resources, turning waste into treasure, and turning harm into benefit is an important problem and development direction that yellow phosphorus enterprises need to solve urgently.

[0004] Soil comes from the earth's crust, which is made up of rocks. Rocks are broken into particles of different sizes, which mix with water and air to form the structure of the soil. Most of the minerals in the soil come from rocks, while organic matter mainly comes from carbon input from plants and microorganisms. When rocks are affected by weathering, chemical action and biological action, they release nutrients that provide the nutrients needed for plant growth. During the processing of phosphate rock, the ore is crushed into fine particles, so yellow phosphorus slag not only has a variety of particle sizes, but is also rich in phosphorus. If appropriate organic matter is added, it has the potential to be used to make artificial organic soil. Summary of the invention

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

[0006] The scheme of the present invention is:

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

[0008] 1) Modifying yellow phosphorus slag, adjusting the pH value of the yellow phosphorus slag to 6-9, mixing the yellow phosphorus slag with phosphogypsum, and soaking the mixture in water for ≥72 hours, stirring for 30 minutes every 24 hours of soaking, and rinsing with clean water after soaking to obtain modified yellow phosphorus slag;

[0009] 2) Modified humus: dehydrate the humus for 1 hour by freeze drying to reduce the water content of the humus to 10-30%, then add a decomposing bacteria agent, add 0.05-0.1g of the decomposing bacteria agent per kilogram of humus, stir evenly, add an appropriate amount of water, sprinkle on the surface of the bedding, sprinkle with water, decompose for 7-10 days, the decomposition temperature is ≥50°C, and the decomposition is completed to obtain modified humus;

[0010] 3) Compounding: mixing the modified yellow phosphorus slag with the modified humus, adding a proper amount of water while mixing, standing for 25 hours to obtain a mixture, drying, crushing with a crusher and stirring with a mixer to obtain artificial organic soil.

[0011] As a preferred technical solution, the specific step of adjusting the pH of yellow phosphorus slag is 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, in the step 1), the mass ratio of yellow phosphorus slag to phosphogypsum is 100:40-60.

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

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

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

[0016] As a preferred technical solution, the decomposing bacteria agent in step 2) is a probiotic or a decomposing bacteria with extracellular enzymes, wherein the effective live bacteria count is >20 billion / g; and the probiotic is a Bacillus, a yeast, or a filamentous fungus.

[0017] As a preferred technical solution, the pH value of the modified humus is 6-8, the number of fecal coliform bacteria is ≤100 / g, and the mortality rate of ascaris eggs is ≥95%.

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

[0019] As a preferred technical solution, the drying conditions of the mixed material in step 3) are 65°C, 48h, and dried to a moisture content of <5%; the particle size after pulverization by the pulverizer is <1mm, and the stirring of the mixer is 200 rpm, 30min.

[0020] As a preferred technical solution, the standard for adding an appropriate amount of water in the step 2) and the step 3) is that the ball can be formed by hand, water can be seen between fingers but does not drip, and it will fall apart when the hand is released and the ball falls to the ground.

[0021] The present invention also discloses an application of artificial organic soil manufactured by a preparation method of artificial organic soil based on yellow phosphorus slag in soil materials. The application method of artificial organic soil of yellow phosphorus slag needs to be adjusted according to the target soil, crop type and expected effect, wherein the application method includes: 1) Use as soil, directly use the artificial organic soil of yellow phosphorus slag as soil; 2) Base application, before sowing or transplanting, evenly spread the artificial organic soil of yellow phosphorus slag on the soil surface, then plow into the soil and fully mix with the soil; 3) Topdressing, during the growth period of crops, apply the artificial organic soil of yellow phosphorus slag around the roots of crops by trenching or hole application, and then cover with soil; 4) Seedling medium, mix the artificial organic soil of yellow phosphorus slag with peat, perlite, etc. in a certain proportion,

[0022] Made into seedling medium for growing seedlings of vegetables, flowers and other crops; 5) Organic fertilizer auxiliary material, the artificial organic soil made from yellow phosphorus slag is mixed and fermented with organic waste such as livestock and poultry manure and straw to produce organic fertilizer. Application scenarios include: 1) Reconstruction of the tillage layer. The artificial organic soil made from yellow phosphorus slag can be directly used to construct the tillage layer. 2) Afforestation of barren hills. The artificial organic soil made from yellow phosphorus slag can improve the soil fertility of afforestation on barren hills. 3) Improvement of saline-alkali land. The artificial organic soil made from yellow phosphorus slag can balance the ion composition in saline-alkali soil, improve soil structure, and increase soil fertility. 4) Improvement of acidic soil. The artificial organic soil made from yellow phosphorus slag can neutralize soil acidity, increase soil pH, improve soil microbial environment, and promote crop growth. 5) Remediation of heavy metal-contaminated soil. The calcium and sulfur in the artificial organic soil made from yellow phosphorus slag can react with heavy metal ions to precipitate, reduce the effectiveness of heavy metals, and reduce the absorption of heavy metals by crops. 6) Improvement of facility agriculture soil. The artificial organic soil made from yellow phosphorus slag can improve the physical and chemical properties of facility agriculture soil, improve soil water and fertilizer retention capacity, and promote crop growth. 7) Improvement of gardening soil. The artificial organic soil made from yellow phosphorus slag can improve the structure and fertility of gardening soil, promote plant growth, and improve greening effects.

[0023] Advantages of the present invention:

[0024] 1. The present invention transforms yellow phosphorus slag, a large solid waste, into valuables through modification. By modifying humus, a natural organic matter, yellow phosphorus slag is quickly converted into organic soil, which can better support mung bean planting than physical soil.

[0025] 2. The artificial soil of the present invention is suitable for promotion and large-scale use. It can not only effectively solve the problem of large-scale open-air storage of yellow phosphorus slag, but also provide ideal soil materials for the transformation of barren hillsides. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The microstructure and element composition diagram of the artificial organic soil in the test experiment of the present invention;

[0027] Figure 2 A comparison diagram of changes in pore water environment between artificial organic soil and farmland soil in the test experiment of the present invention;

[0028] Figure 3 A comparison chart of the effectiveness of typical heavy metals in pore water of artificial organic soil and farmland soil in the test experiment of the present invention;

[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 the present invention;

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

[0031] Figure 6 This is a comparison diagram of the aggregate structures of artificial organic soil and farmland soil after planting mung beans in the test experiment of the present invention;

[0032] Figure 7 This is a comparison of heavy metal contents in mung beans grown in artificial organic soil and farmland soil in the test experiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments.

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

[0035] The sources of materials in the embodiments of the present invention are as follows:

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

[0037] Lake bottom humus: provided by Yunnan Yuntianhua Co., Ltd. and collected from the bottom of Yilóng 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] Embodiment 1:

[0041] 1) Modifying yellow phosphorus slag, adjusting the pH of the yellow phosphorus slag (mixing slag acid in the wet phosphoric acid production process, phosphogypsum, agricultural waste straw, humic acid and yellow phosphorus slag in a mass ratio of 1:1.5:1:1:4) to a pH value of 6-7, mixing it with phosphogypsum, and soaking the mixed mixture in water for 72 hours, stirring for 30 minutes every 24 hours of soaking, filtering out water after soaking, and eluting the solid with 2 times the volume of clean water to obtain modified yellow phosphorus slag;

[0042] 2) Modified humus: dehydrate the humus for 1 hour by freeze drying to reduce the water content of the humus to 15%, then add a decomposing bacteria agent, add 0.08g of the decomposing bacteria agent per kilogram of humus, stir evenly, add an appropriate amount of water, sprinkle on the surface of the bedding, sprinkle water, decompose for 9 days, the decomposition temperature is ≥50°C, and the decomposition is completed to obtain modified humus;

[0043] 3) Compounding: mixing the modified yellow phosphorus slag with the modified humus, adding a proper amount of water while mixing, standing for 25 hours to obtain a mixture, drying, crushing with a crusher and stirring with a mixer to obtain artificial organic soil.

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

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

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

[0047] The humus in step 2) is lake bottom humus, and the freeze-drying temperature is -65°C.

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

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

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

[0051] The drying conditions of the mixed material in step 3) are 65° C. for 48 hours, until the moisture content is less than 5%; the particle size after being crushed by the pulverizer is less than 1 mm, and the stirring of the mixer is 200 rpm for 30 minutes.

[0052] The standard for adding an appropriate amount of water in step 2) and step 3) is that the dough can be formed by hand, water can be seen between fingers but does not drip, and it falls apart when the hands are released.

[0053] The artificial organic soil was tested to be loose in texture, free of lumps, odor, and obvious debris, and the particles were uniform. The basic properties were in accordance with the following Table 1.

[0054] Table 1:

[0055]

[0056] Embodiment 2:

[0057] 1) Modifying yellow phosphorus slag, adjusting the pH value of the yellow phosphorus slag (mixing slag acid, phosphogypsum, biochar, humic acid and yellow phosphorus slag in a wet phosphoric acid production process according to a mass ratio of 1:1.5:1:1:4.5) to a pH value of 6.5-8, mixing the yellow phosphorus slag with phosphogypsum, adding the mixed mixture into water for immersion for 72 hours, stirring for 30 minutes every 24 hours of immersion, and rinsing with 2 times the volume of clean water after immersion to obtain modified yellow phosphorus slag;

[0058] 2) Modified humus: dehydrate the humus for 1 hour by freeze drying to reduce the water content of the humus to 10%, then add a decomposing bacteria agent, add 0.05g of the decomposing bacteria agent per kilogram of humus, stir evenly, add an appropriate amount of water, sprinkle on the surface of the bedding, sprinkle water, decompose for 7 days, and the decomposition temperature is ≥50°C. After the decomposition is completed, the modified humus is obtained;

[0059] 3) Compounding: mixing the modified yellow phosphorus slag with the modified humus, adding a proper amount of water while mixing, standing for 25 hours to obtain a mixture, drying, crushing with a crusher and stirring with a mixer to obtain artificial organic soil.

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

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

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

[0063] The humus in step 2) is lake bottom humus, and the freeze-drying temperature is -65°C.

[0064] In the step 2), the decomposing bacteria agent is a decomposing bacteria with extracellular enzymes.

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

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

[0067] The drying conditions of the mixed material in step 3) are 65° C. for 48 hours, until the moisture content is less than 5%; the particle size after being crushed by the pulverizer is less than 1 mm, and the stirring of the mixer is 200 rpm for 30 minutes.

[0068] The standard for adding an appropriate amount of water in step 2) and step 3) is that the dough can be formed by hand, water can be seen between fingers but does not drip, and it falls apart when the hands are released.

[0069] Embodiment 3:

[0070] 1) Modifying yellow phosphorus slag, adjusting the pH value of the yellow phosphorus slag (mixing slag acid in the wet phosphoric acid production process, phosphogypsum, agricultural waste straw, humic acid and yellow phosphorus slag in a mass ratio of 1:1.5:1:1:5) to reach a pH value of 7-8.5, mixing it with phosphogypsum, and soaking the mixed mixture in water for ≥72 hours, stirring for 30 minutes every 24 hours of soaking, eluting, and obtaining modified yellow phosphorus slag;

[0071] 2) Modified humus: dehydrate the humus for 1 hour by freeze drying to reduce the water content of the humus to 30%, then add a decomposing bacteria agent, add 0.1g of the decomposing bacteria agent per kilogram of humus, stir evenly, add an appropriate amount of water, sprinkle on the surface of the bedding, sprinkle with water, decompose for 10 days, the decomposition temperature is ≥50°C, and the decomposition is completed to obtain modified humus;

[0072] 3) Compounding: mixing the modified yellow phosphorus slag with the modified humus, adding a proper amount of water while mixing, standing for 25 hours to obtain a mixture, drying, crushing with a crusher and stirring with a mixer to obtain artificial organic soil.

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

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

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

[0076] The humus in step 2) is lake bottom humus, and the freeze-drying temperature is -65°C.

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

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

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

[0080] The drying conditions of the mixed material in step 3) are 65° C. for 48 hours, until the moisture content is less than 5%; the particle size after being crushed by the pulverizer is less than 1 mm, and the stirring of the mixer is 200 rpm for 30 minutes.

[0081] The standard for adding an appropriate amount of water in step 2) and step 3) is that the dough can be formed by hand, water can be seen between fingers but does not drip, and it falls apart when the hands are released.

[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] The results of scanning electron microscopy analysis show that the modified yellow phosphorus slag has uniform particle distribution and smooth surface, and contains 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 mixed with humus in a ratio of 100:40 has more fine particles, and the elemental composition of the material has also changed significantly. The artificial organic soil contains 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 is increased by about 30%. This is because humus is rich in organic carbon. The humus field can greatly increase the organic carbon content in the modified material, which will create favorable conditions for improving the water retention of the material and the normal growth of plants.

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

[0086] The study used a pot experiment, weighing 1 kg of artificial organic soil and actual farmland soil into a black culture pot (15 cm in diameter, 10 cm in height). The experiment set up two treatments of artificial organic soil and actual soil, with 3 replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, and watered regularly during the period to keep the soil moisture content >60%. During the 60-day cultivation process, soil pore water was collected regularly (0, 30, and 60 days) using a soil pore water sampler (Rhizon sampler, sampling head aperture: 0.1μm), and the pH and redox potential of the pore water were tested using a portable pH and redox potentiometer. The changes in the organic matter structure in the soil pore water were tested using a three-dimensional fluorescence spectrum.

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

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

[0089] The study used a pot experiment, weighing 1 kg of artificial organic soil and actual farmland soil into a black culture pot (15 cm in diameter, 10 cm in height). The experiment set up two treatments of artificial organic soil and actual soil, with 3 replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, and water was regularly irrigated during the period to maintain the soil moisture content>60%. During the 60-day cultivation process, soil pore water was collected regularly (0, 30, 60 days) using a soil pore water sampler (Rhizon sampler, sampling head aperture: 0.1μm), and the collected pore water was acidified to pH<2 with 1M hydrochloric acid. The contents 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 the changes in the bioavailability of related heavy metals.

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

[0091] The available As decreased from 33.9±2.85μg / L to 8.77±0.82μg / L. The available Cr decreased from 0.70±0.08μg / L to nearly 0μg / L. The As content in the actual soil first increased from 11.93±5.16μg / L to 28.90±3.10μg / L, and then gradually decreased to 7.83±1.33μg / L after 30 days. At the end of the incubation, the available arsenic state of the artificial organic soil and the actual soil was consistent. The Cr content in the actual soil remained near the detection limit. The changing trends of Cd and Zn contents in artificial organic soil and actual soil were relatively consistent, both showing that the Cd content remained stable and the Zn content gradually increased ( Figure 3 A and B). ANOVA test showed that there were significant differences in Cd and Cr between artificial organic soil and actual soil (p<0.05) ( Figure 3 C), but the relative content is low and there is no excessive heavy metal content.

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

[0093] The study used a pot experiment, weighing 1 kg of artificial organic soil and actual farmland soil into a black culture pot (15 cm in diameter, 10 cm in height). The experiment set up two treatments of artificial organic soil and actual soil, with 3 replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, and watered regularly during the period to keep the soil moisture content >60%. After 60 days of cultivation, five growth indicators of mung beans were measured: plant height, SPAD, number of nodules, fresh weight of nodules, and dry weight of plants.

[0094] The results showed that the growth of mung bean in artificial organic soil and real soil was comparable and good ( Figure 4 ). The plant height of mung bean in artificial organic soil and actual soil was 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 mung bean nodules in artificial organic soil and actual soil were 24.67±13.22 / plant and 16.67±4.11 / plant, respectively; the nodule weight of mung bean in artificial organic soil and actual soil were 0.98±0.48 / plant and 0.38±0.13 / plant, respectively; the dry weight of mung bean in artificial organic soil and actual soil were 3.60±0.54 / plant and 2.98±0.60 / plant, respectively. In general, the plant height, SPAD value, nodule number, nodule weight and dry weight of mung bean planted in artificial soil were 0.93%, 3.41%, 48.0%, 158% and 20.56% higher than those in actual soil, respectively. Due to the large variation of related indicators, the differences in related indicators were not significant, but overall, mung bean grew better in artificial organic soil.

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

[0096] 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). The experiment set up two treatments of artificial organic soil and actual soil, with 3 replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, and watered regularly during the period to keep the soil moisture content>60%. After 60 days of cultivation and harvesting of mung beans, the pH of fresh soil and the activities of five enzymes (β-1,4-glucosidase (BG), cellobiohydrolase (CB), β-1,4-N-acetylglucosaminidase (NAG), β-xylosidase (XYL) and acid phosphatase (PHOS)) were measured.

[0097] The results showed that the activities of the five enzymes were high in both artificial organic soil and real soil, and most of them were more active in real soil. The test results of soil pH after harvesting mung beans were consistent with the test results of pore water pH. The pH of artificial organic soil was nearly neutral (6.94±0.04), while the pH of real soil was higher (8.62±0.35). The activities of BG, CB, XYL, and PHOS enzymes in real soil were 8.12±2.90μmol h -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 ) were significantly higher than those of artificial organic soil (3.10±0.99 μmol h -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 ), while NAGase in artificial organic soil (4.86±0.59 μmol h -1 g -1 ) was significantly higher than that of the actual soil (1.89±0.22μmol h -1 g -1 )( Figure 5 ). In general, the actual soil has a high enzyme activity due to its long reclamation time and sufficient soil maturation; while the artificial soil has a low enzyme activity due to its short maturation time. It is expected that the enzyme activity of the artificial soil will be rapidly improved through crop planting.

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

[0099] The study used a pot experiment, weighing 1 kg of artificial organic soil and actual farmland soil into a black culture pot (15 cm in diameter, 10 cm in height). The experiment set up two treatments of artificial organic soil and actual soil, with 3 replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, and watered regularly during the period to keep the soil moisture content >60%. After 60 days of cultivation, the aggregate structure of fresh soil was measured after the mung beans were harvested.

[0100] The results showed that the aggregate structure of artificial organic soil was significantly different from that of actual soil. The content of large aggregates in actual soil was higher (19.17±3.87%), significantly higher than that in artificial organic soil (3.10±1.12%). The content of 0.053-0.25 mm and 0.25-2 mm aggregates in artificial organic soil and actual soil was similar (28.57±14.58% vs 31.90±0.78% and 34.53±16.95% vs 32.43±1.07%), with no significant difference ( Figure 6 The clay particles of artificial organic soil (<0.053mm; 33.80±10.49%) are significantly higher than those of actual soil (16.53±2.33%). It is known that the finer the soil particles, the greater their cohesive force and the more conducive to the formation of complex particles. Therefore, artificial organic soil has the prerequisite 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 potted experiment, weighing 1kg of artificial organic soil and actual farmland soil into a black culture pot (15cm in diameter, 10cm in height). The experiment set up two treatments of artificial organic soil and actual soil, with 3 replicates for each treatment. Mung beans (3 plants / pot) were planted under natural light, and watered regularly during the period to keep the soil moisture content >60%. After 60 days of cultivation, when the mung beans were harvested, 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 determined.

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

[0104] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing artificial organic soil based on yellow phosphorus slag, characterized in that: The following steps are involved: 1) Modifying yellow phosphorus slag, adjusting the pH value of the yellow phosphorus slag to 6-9, adding the mixed mixture into water for soaking, the soaking time is ≥72h, stirring for 30min every 24h soaking, and rinsing with clean water after soaking to obtain modified yellow phosphorus slag; 2) Modified humus: dehydrate the humus for 1 hour by freeze drying to reduce the water content of the humus to 10-30%, then add a decomposing bacteria agent, add 0.05-0.1g of the decomposing bacteria agent per kilogram of humus, stir evenly, add an appropriate amount of water, sprinkle on the surface of the bedding, sprinkle with water, decompose for 7-10 days, the decomposition temperature is ≥50°C, and the decomposition is completed to obtain modified humus; 3) Compounding: mixing the modified yellow phosphorus slag with the modified humus, adding a proper amount of water while mixing, standing for 25 hours to obtain a mixture, drying, crushing with a crusher and stirring with a mixer to obtain artificial organic soil.

2. The method for preparing artificial organic soil based on yellow phosphorus slag according to claim 1, characterized in that: In the step 1), the mass ratio of yellow phosphorus slag to phosphogypsum is 100:40-60.

3. The method for preparing artificial organic soil based on yellow phosphorus slag according to claim 1, characterized in that: In the step 1), the mixture and water are soaked at a ratio of 1:1 v / w.

4. The method for preparing artificial organic soil based on yellow phosphorus slag according to claim 1, characterized in that: The modified yellow phosphorus slag contains arsenic ≤100 mg / kg, cadmium ≤1.5 mg / kg, chromium ≤800 mg / kg, lead ≤400 mg / kg, and mercury ≤2.0 mg / kg.

5. The method for preparing artificial organic soil based on yellow phosphorus slag according to claim 1, characterized in that: The humus in step 2) is lake bottom humus, and the freeze-drying temperature is -65°C.

6. The method for preparing artificial organic soil based on yellow phosphorus slag according to claim 1, characterized in that: In the step 2), the decomposing bacteria agent is a probiotic or a decomposing bacteria with extracellular enzymes, wherein the effective live bacteria count is >20 billion / g; and the probiotic is a Bacillus, a yeast, or a filamentous fungus.

7. The method for preparing artificial organic soil based on yellow phosphorus slag according to claim 1, characterized in that: The pH value of the modified humus is 6-8, the number of fecal coliform bacteria is ≤100 / g, and the mortality rate of roundworm eggs is ≥95%.

8. The method for preparing artificial organic soil based on yellow phosphorus slag according to claim 1, characterized in that: In the step 3), the modified yellow phosphorus slag and the modified humus are mixed in a mass ratio of 7:2; the drying conditions of the mixture are 65° C., 48 hours, and the mixture is dried to a moisture content of <5%; the particle size after being crushed by the crusher is <1 mm, and the stirring of the mixer is 200 rpm, 30 minutes.

9. The method for preparing artificial organic soil based on yellow phosphorus slag according to claim 1, characterized in that: The standard for adding an appropriate amount of water in step 2) and step 3) is that the dough can be formed by hand, water can be seen between fingers but does not drip, and it falls apart when the hands are released.

10. Use of the method for preparing artificial organic soil based on yellow phosphorus slag as claimed in any one of claims 1 to 9 in soil materials.

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