Modified biochar as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of tobacco seedling raising, and particularly relates to biochar modification and a preparation method and application thereof. The invention provides a preparation method of modified biochar (acid modified biochar), which comprises the following steps: mixing biochar with 0.015-0.025 mol / L phosphoric acid solution, carrying out shaking treatment on a shaking table at 25 + / -2 DEG C for 24 + / -1 h, carrying out solid-liquid separation, and air-drying the separated solid to obtain the modified biochar (acid modified biochar). The invention also provides an application of the acid-modified biochar, and the prepared tobacco soilless seedling substrate is composed of the following components in volume content: 0-80% of turf, 0-80% of acid-modified biochar, 15% of vermiculite and 5% of perlite.

Description

Technical Field

[0001] The invention belongs to the technical field of tobacco seedling cultivation, and in particular relates to biochar modification, a preparation method and application thereof. Background Art

[0002] As the main organic material in commercial floating seedling substrates, peat is widely used due to its consistently good physical properties and high nutrient exchange capacity. Peat, as a non-renewable resource, is also the main storage of soil carbon and a unique ecosystem that maintains biodiversity. In other words, peatlands play an important role in buffering water levels and filtering water pollutants. However, the continued large-scale extraction of peat as a plant growth medium is one of the main reasons for the continued deterioration of wetland ecosystems. In addition to destroying the ecological balance of wetlands, peat extraction also releases the originally stable and sequestered carbon into the carbon cycle, exacerbating the problem of climate change. The high cost of commonly used substrates due to fuel costs such as peat extraction, processing and transportation, the availability of substrate components, and the desire to use more sustainable substrates have made peat for commercial use more expensive. At present, the increasing demand for sustainable and low-cost peat substitutes is also an insurmountable challenge in flue-cured tobacco seedling production. Therefore, it is urgent to explore a new soilless seedling substrate that can replace peat in floating seedling substrates in large quantities.

[0003] Therefore, it is very necessary to develop a method to utilize modified biochar resources to replace peat.

[0004] The invention of CN117602983A, "Acid-modified biochar-based bacterial fertilizer for increasing the effective phosphorus content in soil and its preparation method", informs: put the biochar into a phosphoric acid solution with a phosphoric acid concentration of 30%, put it into a constant temperature oscillating agitator, and acidify it for 3 hours. The acidified biochar is washed with water several times and placed in a 105°C oven for drying. The acid-modified carbon-based bacterial fertilizer has a very significant effect on increasing the total phosphorus in the soil, can supplement the phosphorus in the soil, and is beneficial to the activity of soil microorganisms.

[0005] The invention of CN116874327A, "A soil loosening and root promoting agent and its preparation method", informs: FeCl is added to biochar. 3 6H 2 O and MgCl 2 6H 2 O, placed in a muffle furnace, heated to obtain metal-modified biochar, then added nitric acid solution (65%), magnetically stirred for 1-2h at a speed of 200rpm, filtered, and washed with deionized water until neutral to obtain acid-modified biochar. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a modified biochar and a preparation method and application thereof.

[0007] In order to solve the above technical problems, the present invention provides a method for preparing modified biochar (acid-modified biochar), comprising the following steps:

[0008] The biochar was mixed with 0.015-0.025 mol / L phosphoric acid solution at a solid-liquid ratio of 1 g: 23-27 ml, and the mixture was shaken at 25±2° C. for 24±1 h, followed by solid-liquid separation (filtration), and the separated solid was air-dried (air-dried to a moisture content of ≤3%) to obtain modified biochar (acid-modified biochar).

[0009] As an improvement to the preparation method of the modified biochar of the present invention: the shaking table speed is 100±20 rpm.

[0010] As a further improvement of the preparation method of the modified biochar of the present invention: the biochar is rice husk biochar.

[0011] As a further improvement of the preparation method of the modified biochar of the present invention: rice husk biochar is mixed with 0.02 mol / L phosphoric acid solution in a solid-liquid ratio of 1 g:25 ml.

[0012] The present invention also provides modified biochar prepared by any of the above methods.

[0013] The present invention also provides a tobacco soilless seedling substrate (tobacco floating seedling substrate), wherein the modified biochar prepared by any of the above methods is composed of the following components in volume content:

[0014] Peat 0-80%, acid-modified biochar 0-80%, vermiculite 15%, perlite 5%.

[0015] The improvement of the tobacco soilless seedling substrate of the present invention is composed of the following components in volume content: 24-64% of peat, 16-56% of acid-modified biochar, 15% of vermiculite and 5% of perlite.

[0016] As a further improvement of the tobacco soilless seedling substrate of the present invention, it is composed of the following components in volume content: 32-48% of peat, 32-48% of acid-modified biochar, 15% of vermiculite and 5% of perlite.

[0017] As a further improvement of the tobacco soilless seedling substrate of the present invention, it is composed of the following components in volume content: 40% peat, 40% acid-modified biochar, 15% vermiculite and 5% perlite.

[0018] The present invention has the following technical advantages:

[0019] 1. Resource Recycling and Ecological Protection

[0020] Waste resource utilization: Modified biochar uses organic materials such as agricultural waste as raw materials, realizing the resource utilization of waste and reducing environmental pollution.

[0021] Protecting non-renewable resources: By replacing non-renewable resources such as peat, modified biochar helps protect wetland ecosystems and maintain ecological balance.

[0022] 2. Significant economic benefits

[0023] Reduce production costs: Compared with traditional peat substrates, modified biochar has lower preparation costs, which helps reduce seedling production costs.

[0024] Improve crop yield and quality: Modified biochar has good physical and chemical properties, which can promote crop growth and improve yield and quality.

[0025] 3. Wide range of applications

[0026] Tobacco seedling cultivation and other crop cultivation: Modified biochar is not only suitable for tobacco seedling cultivation, but can also be widely used in soilless cultivation and soil improvement of other crops.

[0027] Environmental remediation field: It has strong adsorption properties and can be used for water and soil remediation, removing pollutants and promoting environmental recovery.

[0028] In summary, the tobacco soilless seedling substrate prepared by the modified biochar of the present invention has strong growth potential (early growth period, good agronomic traits), agronomic traits (stem thickness, leaf length, leaf width, etc.) are more coordinated with physiological indicators, and all root morphology parameters are better than commercial substrates. It shows that acid-modified biochar can partially replace peat substrate to cultivate high-quality tobacco seedlings, meet the requirements of tobacco production for strong seedlings, and has great application potential in flue-cured tobacco seedling cultivation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0030] Figure 1 This is a comparison chart of the effects of different acid-modified biochar matrices on tobacco seedling emergence rates;

[0031] Figure 2 Comparison of tobacco seedling morphology after treatment with different acid-modified biochar ratios;

[0032] Figure 3 This is a comparison chart of the effects of different acid-modified biochar matrices on the SPAD value of tobacco seedling chlorophyll;

[0033] Figure 4 This is a comparison of the root morphology of tobacco seedlings with different acid-modified biochar ratios;

[0034] Figure 5 This is a comparison chart of the effects of different acid-modified biochar matrices on the total length of roots of tobacco seedlings of different diameters;

[0035] Figure 6 This is a comparison chart of the effects of different acid-modified biochar matrices on the root activity of tobacco seedlings;

[0036] Figure 7 This is a comparison chart of the effects of different acid-modified biochar matrices on protective enzymes in tobacco seedling leaves. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0038] 1. Materials and Methods

[0039] 1.1 Test location and materials

[0040] The experiment was conducted in the greenhouse of Yunnan Agricultural University from June to August, with the monthly average minimum temperature of 15-16°C and the monthly average maximum temperature of 25-26°C. Rice husk biochar is commercially available, for example, from Henan Lize Environmental Protection Technology Co., Ltd.; the flue-cured tobacco variety tested is K326, which is supplied by Yuxi Zhongyan Seed Co., Ltd. The floating seedling tray (160 small trays) has specifications of 525mm×335mm×60mm, and the inner diameter of the seedling hole is 24mm×24mm. Before sowing, the floating tray is sterilized and disinfected as usual, and 1 seed is sown in each hole; special fertilizer for tobacco seedlings (N:P 2 O 5 :K 2 O=18:12:13), provided by Honghe Henglin Chemical Co., Ltd., 25g of tobacco seedling fertilizer was added to about 14L of water to prepare a nutrient solution.

[0041] 1.2 Preparation of acid-modified biochar

[0042] The rice husk biochar and 0.02 mol / L phosphoric acid solution were shaken at 25±2°C and 100 rpm on a rotary shaker for 24 hours at a solid-liquid ratio of 1 g / 25 ml (1 g biochar corresponds to 25 ml phosphoric acid solution), and then the supernatant and the extracted biochar were filtered to achieve separation. The extracted biochar was placed indoors to air dry naturally (air dried to a moisture content of ≤3%), named acid-modified biochar, and set aside.

[0043] 1.3 Experimental Design

[0044] The experiment designed 10 kinds of acid-modified biochar to replace peat ratios, including 0% (commercial substrate CK), 20% (T1), 30% (T2), 40% (T3), 50% (T4), 60% (T5), 70% (T6), 80% (T7), 90% (T8) and 100% (T9) of new seedling substrates (Table 1). Randomized block arrangement, 3 replicates per treatment, each replicate was 1 tray.

[0045] Description: The commercial matrix (CK) is composed of 80% peat + 15% vermiculite + 5% perlite.

[0046] Table 1 Treatments of acid-modified biochar replacing peat (volume %)

[0047]

[0048] Specifically:

[0049] One tobacco seed is sown in each hole of a sterilized floating tray, and each hole of the floating tray is filled with any of the novel seedling substrates (CK, T1-T9) described in Table 1 above; the floating seedling tray is placed on a nutrient solution (14 L); seedlings are raised under conventional seedling raising conditions; fertilizers are applied twice during the seedling raising period, the first application when the seedlings are about 75% emerged, and the second application when the tobacco seedling leaves close the tray.

[0050] The conventional seedling raising conditions are as follows: after sowing, the temperature in the greenhouse is preferably maintained at 22°C to 24°C, which is conducive to improving the emergence rate; from emergence to the cross stage, the temperature is preferably controlled at 25°C to 28°C. The maximum temperature in the greenhouse cannot exceed 30°C, and the minimum temperature should not be lower than 15°C.

[0051] Note: When about 75% of the seedlings have emerged, it is about 7 days after sowing. When the tobacco seedling leaves cover the tray, it means that the tobacco seedling leaves cover the surface of the tray and the tray cannot be seen when looking down; it is about 25 to 30 days after sowing.

[0052] Each time you apply fertilizer, pour out the original nutrient solution and replace it with a newly prepared nutrient solution made by adding 25g of tobacco seedling-specific fertilizer to 14L of water.

[0053] During the seedling raising process, maintain the nutrient solution water level at 14 liters. When the water level drops, add distilled water to 14 liters and maintain the same water level every day.

[0054] 1.4. Measurement items and methods

[0055] Determination of physical and chemical properties of substrate: refer to the relevant provisions of YC / T 310-2009 "Tobacco floating seedling substrate";

[0056] Determination of tobacco seedling growth period and agronomic traits: refer to the industry standard YC / T 142-2010 Survey of Tobacco Agronomic Traits; follow the measurement method, the fresh and dry weights of tobacco seedlings are weighed using a balance with an accuracy of 1 / 10000; the emergence rate is investigated 20 days after sowing.

[0057] The following items were measured 45 days after sowing:

[0058] Determination of root architecture: Epson Perfection V800 photo99 was used to measure root morphological parameters such as total root length, total root surface area, root volume, average diameter, number of root tips, number of branches, and three root diameter grades (0<L≤1.0mm small fine roots, 1.0mm<L≤2.0mm medium roots, and L≥2.00mm coarse roots), and WinRHIZO analysis system was used for calculation and analysis.

[0059] Chlorophyll (SPAD) determination: The relative content of leaf chlorophyll was determined using a Nissan portable SPAD502 chlorophyll content meter; root activity determination: red tetrazolium (TTC) colorimetric method was used.

[0060] Determination of protective enzyme activities (SOD, POD, NR): superoxide dismutase activity was determined by the nitroblue tetrazolium method; peroxidase activity was determined by the guaiacol method; nitrate reductase activity was determined by the sulfonamide-naphthylamine colorimetric method.

[0061] 2. Results

[0062] 2.1. Physical and chemical properties of seedling medium

[0063] As shown in Table 2, the physical and chemical indicators of the substrates treated with different acid-modified biochar ratios all met the standard requirements of the floating seedling substrate in the tobacco industry, and as the proportion of acid-modified biochar increased, the pH value of the mixed substrate increased and tended to be neutral; in addition, the bulk density and EC of the mixed substrate with the addition of acid-modified biochar were significantly lower than those of the control, which indicates that different acid-modified biochar ratios have different effects on the physical and chemical properties of the tobacco seedling growth medium.

[0064] Table 2: Physical and chemical indicators of biochar matrix modified by different acid ratios

[0065]

[0066]

[0067] 2.2 Effects of different substrate treatments on tobacco seedling emergence rate

[0068] Compared with the commercial substrate, the emergence rate of tobacco seedlings (investigated 20 days after sowing) showed an overall trend of increasing first and then decreasing with the increase of the replacement ratio of acid-modified biochar ( Figure 1), the tobacco seedling emergence rate in T4 treatment was the highest, reaching 97.78%, 10.00 percentage points higher than CK, and there was a significant difference; while the tobacco seedling emergence rate in T9 treatment decreased to only 85.56%, 2.22 percentage points lower than the control. This shows that the preparation of a suitable acid-modified biochar mixed matrix has a promoting effect on the tobacco seedling emergence rate.

[0069] 2.3 Effects of different substrate treatments on tobacco seedling growth period and growth potential

[0070] As shown in Table 3, the emergence period of each treatment was consistent, all 9 days; 16-19 days after sowing, the small cross period was entered, of which the T7 treatment and the control used the same number of days, the T8 and T9 treatments were later than the control, and the other treatments were earlier than the control; 23-33 days after sowing, the large cross period was entered, the T7, T8, and T9 treatments were later than the control, and the other treatments were consistent with the control; 31-39 days after sowing, the cat ear period was entered, the T2, T3, T4, T5, and T6 treatments were 1-2 days earlier than the CK, and the other treatments were 2-6 days later than the CK; 45 days after sowing, the transplanting period was entered, and the T7, T8, and T9 treatments were green and yellowish, and the growth potential was medium to weak, which did not meet the transplanting requirements. The seedlings of other treatments were dark green and had strong growth potential, all meeting the standard requirements for the tobacco seedling transplanting period. After the ratio of more than 70% of acid-modified biochar to replace peat, the growth of tobacco seedlings showed a stagnation phenomenon as a whole.

[0071] Table 3 Effects of different ratios of acid-modified biochar substrate on the growth period and growth potential of tobacco seedlings

[0072]

[0073]

[0074] Note: “—” means “not measured”.

[0075] 2.4 Effects of different substrate treatments on tobacco seedling growth and development

[0076] Compared with the commercial substrate, with the increase of the acid-modified biochar content, the stem height, leaf number, stem girth, leaf length, leaf width, and maximum leaf area of ​​tobacco seedlings at different stages showed a trend of first increasing and then decreasing (Table 4, Figure 2 ), 45 days after sowing, the acid-modified biochar reached its maximum value when it replaced (40-60%) peat treatment, which were 19.13cm, 5.33 pieces, 16.83mm, 22.72cm, 10.17cm and 146.44cm2, respectively, which were 33.78%, 14.13%, 14.33%, 11.10%, 10.78% and 22.80% higher than the control, respectively; while the high dosage (80-100%) of acid-modified biochar treatment had an inhibitory effect on various indicators of agronomic traits of tobacco seedlings.

[0077] Table 4 Effects of different ratios of acid-modified biochar substrate on agronomic traits of tobacco seedlings

[0078]

[0079]

[0080] 2.5 Effects of different substrate treatments on photosynthetic characteristics of tobacco seedling leaves

[0081] Plant height and stem thickness reflect to a certain extent the plant's ability to absorb light, leaf length and width reflect the size of the leaf area that absorbs light, and chlorophyll content is a key indicator that directly reflects the photosynthetic capacity of plant leaves and the health status of the plant.

[0082] The results are as follows Figure 3 shown.

[0083] After 45 days of sowing, the highest SPAD value of tobacco seedling chlorophyll was found in the T4 treatment, followed by the T6 treatment, which were significantly higher than the control, reaching 33.37 and 31.50 respectively; the lowest SPAD values ​​of the T8 and T9 treatments were 24.15 and 24.92. The above shows that the appropriate proportion of acid-modified biochar in the seedling medium can increase the chlorophyll content of tobacco seedlings, and the best treatment is the 50% replacement.

[0084] 2.6 Effects of different substrate treatments on tobacco seedling biomass

[0085] The comprehensive comparison of the biomass of different parts of tobacco seedlings under different treatments is shown in Table 5. At 35d and 45d after sowing, the aboveground dry weight of the T4 treatment was 33.10% and 48.47% higher than that of the control, respectively, both reaching significant levels. The root dry weight and total biomass of the tobacco seedlings under the T4 treatment were also the best, significantly higher than the control. The results show that acid-modified biochar can replace peat to improve the biological traits and biomass of tobacco seedlings.

[0086] Table 5 Effects of different ratios of acid-modified biochar matrix on tobacco seedling biomass

[0087]

[0088]

[0089] 2.7 Effects of different substrate treatments on root architecture of tobacco seedlings

[0090] 2.7.1 Effects of different substrate treatments on root morphology

[0091] On the 45th day after sowing, the root morphological parameters of tobacco seedlings are shown in Table 6 and Figure 4The total root length, total surface area, root volume and number of branches were the highest in T5 treatment, reaching 497.44cm, 67.79cm2, 0.74cm3 and 3380.00 respectively, which increased by 93.92%, 59.66%, 32.14% and 56.63% compared with the commercial substrate, and the effect was obvious; the number of root tips was the largest in T6 (70%) treatment, which was 2714.33, significantly higher than the control. Except for the average diameter parameter, the T3, T4 and T5 treatments had different increases in the root system configuration parameters compared with CK. Comprehensive comparison showed that the root morphological characteristics of tobacco seedlings treated with T3, T4, T5 and T6 were better, significantly better than the control.

[0092] Table 6 Effects of different ratios of acid-modified biochar matrix on the root architecture of tobacco seedlings

[0093]

[0094] 2.7.2 Effects of different substrate treatments on the total length of roots of tobacco seedlings of different diameters

[0095] Analysis of total root length of different diameter classes Figure 5 With the increase of the replacement ratio of acid-modified biochar, the total length of different root diameters showed an overall trend of first increasing and then decreasing. In the total length of fine roots with L≤0.5mm, 0.5mm≤L≤1.0mm and medium roots with 1.0mm<L≤2.0mm, the T5 treatment had the largest increase, which was 110.52%, 46.04% and 85.33% higher than the control, and there was a significant difference; the total length of coarse roots with diameter L>2.0mm reached the maximum in the T3 treatment, which increased by 29.90% compared with CK; while the total length of roots of different diameters in the T8 and T9 treatments was significantly lower than that of the commercial substrate, indicating that the acid-modified biochar replacing the peat seedling substrate had different increasing effects on the total length of roots of different diameters of tobacco seedlings when the replacement ratio was less than 70%, especially the total length of fine roots with L≤0.5mm and medium roots with 1.0mm<L≤2.0mm had the largest increase.

[0096] 2.8 Effects of different substrate treatments on root activity of tobacco seedlings

[0097] Effects of different acid-modified biochar ratios on root activity of tobacco seedlings Figure 6 The root activity of T4 treatment was the highest, followed by T6 treatment, which was 65.86% and 48.91% higher than the commercial substrate, respectively, and reached a significant level. T7 treatment had the lowest. This shows that acid-modified biochar replacing a certain amount of peat can improve the root activity of flue-cured tobacco seedlings and promote root growth, but high dosage or complete replacement of peat has a significant inhibitory effect on root activity. Among them, the root activity of T8 treatment was abnormal, which may be due to the fact that the leaves of T8 were too small, and the marginal effect of root activity occurred when selecting the leaves of seedlings.

[0098] 2.9 Effects of different substrate treatments on protective enzymes in tobacco seedling leaves

[0099] Different treatments have different effects on SOD activity in tobacco seedling leaves Figure 7 a. With the increase of the proportion of acid-modified biochar, the SOD activity of tobacco seedlings showed an overall trend of first increasing and then decreasing. When the replacement ratio was 40%, the SOD activity of tobacco seedlings reached the maximum, which increased by 49.94% compared with the control. There was no significant difference between other treatments and the control.

[0100] Leaf POD enzyme activity Figure 7 As shown in b, when the replacement rate was less than 70%, the POD activity of tobacco seedlings was stronger than that of the control, and the order of activity was T2>T5>T4>T6>T1. When the replacement rate was greater than 70%, the POD activity of tobacco seedlings was significantly lower than that of CK.

[0101] The significant difference analysis of NR enzyme activity is shown in Figure 7 c. Different replacement ratios of acid-modified biochar significantly affected the NR enzyme activity of tobacco seedlings. The NR activity of tobacco seedlings treated with T4 was the highest, which was 394.22 percentage points higher than that of CK.

[0102] In summary, acid-modified biochar can replace peat at a high mixing ratio of less than 70%, and the physical and chemical indicators of the mixed matrix are suitable. The tobacco seedlings grown are strong, the agronomic traits and physiological indicators are relatively coordinated, and the root morphology parameters are better than the commercial matrix. It shows that acid-modified biochar can partially replace peat matrix to cultivate high-quality tobacco seedlings, meet the requirements of tobacco production for strong seedlings, and has great application potential in flue-cured tobacco seedling cultivation.

[0103] The best solution of the present invention is T4 (ie, the ratio of acid-modified biochar replacing peat is 50%).

[0104] Comparative Example 1: The concentration of the phosphoric acid solution was changed from "0.02 mol / L" to that described in Table 7 below, and the acid-modified biochar obtained by "1.2, Preparation of acid-modified biochar" was replaced with the acid-modified biochar obtained by "1.2, Preparation of acid-modified biochar", and the rest was the same as the above-mentioned Scheme T4.

[0105] The comparison of the results obtained in this comparative example 1 with the results obtained in scheme T4 of the present invention is shown in Table 7 below.

[0106] Table 7

[0107]

[0108]

[0109] According to Table 7, the concentration of the phosphoric acid solution is too high, resulting in the acid-modified biochar being unable to be used as a matrix.

[0110] In addition, the inventors also used corn straw biochar or wheat straw biochar to replace rice husk biochar to prepare the corresponding acid-modified biochar, and then used it to replace the acid-modified biochar obtained in "1.2, Preparation of Acid-Modified Biochar", and the rest was the same as the above scheme T4. The emergence rate was about 93%.

[0111] Finally, it should be noted that the above examples are only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A method for preparing modified biochar, characterized in that The following steps are involved: The biochar was mixed with 0.015-0.025 mol / L phosphoric acid solution at a solid-liquid ratio of 1 g:23-27 ml, and then shaken at 25±2° C. for 24±1 h, followed by solid-liquid separation. The separated solid was air-dried to obtain modified biochar.

2. The method for preparing modified biochar according to claim 1, characterized in that: The shaking speed is 100±20rpm.

3. The method for preparing modified biochar according to claim 2, characterized in that: The biochar is rice husk biochar.

4. The method for preparing modified biochar according to claim 3, characterized in that: Rice husk biochar was mixed with 0.02 mol / L phosphoric acid solution at a solid-liquid ratio of 1 g:25 ml.

5. Modified biochar prepared by any one of the methods of claims 1 to 4.

6. A tobacco soilless seedling substrate, characterized in that: The modified biochar prepared by any of the methods of claims 1 to 4 is composed of the following components by volume: Peat 0-80%, acid-modified biochar 0-80%, vermiculite 15%, perlite 5%.

7. The tobacco soilless seedling raising substrate according to claim 6, characterized in that It is composed of the following components by volume: Peat 24-64%, acid-modified biochar 16-56%, vermiculite 15%, perlite 5%.

8. The tobacco soilless seedling raising substrate according to claim 7, characterized in that It is composed of the following components by volume: Peat 32-48%, acid-modified biochar 32-48%, vermiculite 15%, perlite 5%.

9. The tobacco soilless seedling raising substrate according to claim 8, characterized in that It is composed of the following components by volume: Peat 40%, acid-modified biochar 40%, vermiculite 15%, perlite 5%.

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