Biochar-based composite material as well as preparation method and application thereof

Abstract

The invention discloses a charcoal-based composite material as well as a preparation method and application thereof, and belongs to the technical field of soil improvement. The preparation method comprises the following steps: modifying rice straw with calcium lignosulphonate, carbonizing to obtain biochar, and co-fermenting with calcium lignosulphonate, rice straw, EM engineering bacteria and urea to obtain the biochar-based composite material. When in use, the charcoal-based composite material is uniformly spread on the surface of acidified soil, ploughing and mixing are performed, irrigation and mulching film covering are performed, and crops can be planted 30-120 days later. When the biochar-based composite material is used for soil improvement, the pH value of acidified soil can be remarkably increased, the non-uniform acidification characteristic of the soil is improved, the physical property and the soil fertility are improved, and the biochar-based composite material has the advantages of being low in remediation cost and free of chemical components and can provide technical support for guaranteeing cultivated land health and promoting ecological agriculture development.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, specifically relating to a biochar-based composite material, its preparation method, and its application. Background Technology

[0002] Soil is the foundation of agricultural production, and its health directly affects crop yield, agricultural product quality, and the sustainability of the ecological environment. However, globally, irrational land use practices, particularly the long-term excessive or unbalanced application of chemical fertilizers and pesticides, industrial pollutants and acid rain deposition, and continuous cropping obstacles, have led to increasingly prominent problems of soil acidification in large areas of farmland. Soil acidification manifests as a continuous decline in soil pH, which in turn triggers a series of deteriorations in soil physicochemical and biological properties. For example, soil acidification can lead to the loss of beneficial basic ions (CaO, Ca2+ ... 2+ Mg 2+ Significant loss of nutrients reduces the soil's ability to retain fertilizer. Simultaneously, the solubility and bioavailability of heavy metals such as aluminum and manganese in the soil increase significantly, toxicizing crop roots and inhibiting their growth and development. Soil aggregate structure is also easily damaged, leading to soil compaction and reduced aeration and permeability. Furthermore, acidification significantly alters the community structure and activity of soil microorganisms, inhibiting the growth and reproduction of beneficial microorganisms (such as nitrogen-fixing and phosphorus-solubilizing bacteria), reducing soil enzyme activity, and affecting the decomposition of organic matter and nutrient cycling. Ultimately, this leads to soil fertility decline, reduced crop yields, and even crop failure, seriously threatening food security and sustainable agricultural development.

[0003] Current technologies for improving acidified soils mainly include physical, chemical, and biological methods. Physical methods (such as deep tillage and topsoil application) can improve soil permeability, but their effectiveness in neutralizing acidity is limited, and they are costly and difficult to promote. Chemical methods (primarily using calcareous substances) are commonly used, offering quick results and lower costs, but they suffer from drawbacks such as difficulty in controlling dosage, the potential for excessively high pH levels leading to new nutrient imbalances, the possibility of long-term application worsening soil physical properties, and insufficient depth and persistence of improvement. Biological methods (such as increasing the application of organic fertilizers, planting acid-tolerant green manure, and using microbial agents) are considered more environmentally friendly and sustainable. Organic fertilizers can improve soil structure and increase buffering capacity, while microbial agents can activate nutrients and promote growth. However, traditional organic fertilizers are slow to take effect and require large dosages, and single microbial agents have unstable effects in complex soils and weak ability to rapidly regulate pH in severely acidified soils. In recent years, biochar, as a novel soil conditioner, has shown great potential in improving acidified soils, enhancing soil fertility, and reducing carbon emissions due to its porous structure, high specific surface area, abundant surface functional groups, and generally alkaline nature. However, ordinary biochar also suffers from problems such as low nutrient content and limited effectiveness in improving certain soil properties. Therefore, existing acidified soil improvement technologies still suffer from incomplete improvement effects, short-lasting effects, insufficient environmental friendliness, or low cost-effectiveness. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a biochar-based composite material, its preparation method, and its application, which can efficiently, stably, environmentally friendly, and economically improve the physical, chemical, and biological properties of acidified soils, restore and enhance soil productivity, and ensure the sustainable development of agricultural production.

[0005] This invention is achieved through the following technical solution:

[0006] A method for preparing a biochar-based composite material includes the following steps:

[0007] Step 1) After removing impurities from the rice straw, wash it with deionized water, dry it to constant weight, and crush it into straw particles with a length of 1-3 cm and uniform particle size for later use.

[0008] Step 2) Dissolve calcium lignosulfonate in deionized water to prepare a calcium lignosulfonate solution with a mass concentration of 5%~10%; add the crushed rice straw from step 1) to the solution and shake it at room temperature to ensure that the calcium lignosulfonate is fully loaded onto the straw; then perform solid-liquid separation and dry the loaded straw to obtain calcium lignosulfonate loaded straw raw material.

[0009] Step 3) The lignosulfonate-loaded straw raw material obtained in step 2) is pyrolyzed and carbonized under a nitrogen protective atmosphere; after carbonization, it is naturally cooled to room temperature in a nitrogen atmosphere, the carbonized product is taken out, ground and sieved to obtain lignosulfonate-modified biochar.

[0010] Step 4) Calcium lignosulfonate, rice straw crushed in Step 1), EM engineered bacteria and urea are mixed and fermented together, and the fermentation product is obtained after being piled up and fermented under natural environmental conditions for 15 to 30 days.

[0011] Step 5) Mix the fermentation product obtained in step 4) with the calcium lignosulfonate modified biochar obtained in step 3) and carry out a second fermentation for 15-30 days to obtain the final product.

[0012] Preferably, the cleaning time in step 1) is 20-30 minutes; the drying temperature is 100-110°C.

[0013] Preferably, the vibration treatment time in step 2) is 24~48 h; the drying temperature is 60~70℃.

[0014] Preferably, the specific steps of the pyrolysis carbonization in step 3) are as follows: the nitrogen flow rate is controlled at 200~300 mL / min, the pyrolysis temperature is set at 500~550℃, the heating rate is 10℃ / min, and the carbonization is carried out at a constant temperature for 2 h after reaching the set temperature.

[0015] Preferably, the carbon-nitrogen ratio of the mixture in step 4) is (25~30):1.

[0016] Preferably, the mass ratio of the fermentation product to the calcium lignosulfonate modified biochar in step 5) is (5~10):1.

[0017] The biochar-based composite material prepared by the above method.

[0018] The above-mentioned biochar-based composite materials are used in the improvement of acidified soil.

[0019] Preferably, it includes the following steps:

[0020] Step A) Spread the biochar-based composite material evenly on the surface of the acidified soil, and then till it to a depth of 10-20 cm to fully mix the biochar-based composite material and the acidified soil.

[0021] Step B) Implement irrigation treatment, using 30% to 60% of the field capacity as the irrigation quota, and replenish water to the 0 to 10 to 20 cm soil layer;

[0022] Step C) Cover the soil surface with polyethylene film and maintain it for 30-120 days. When white mycelium grows on the soil surface, the soil acidification improvement is complete and crops can be planted.

[0023] The beneficial effects of this invention are as follows:

[0024] (1) This invention utilizes rice straw loaded with calcium lignosulfonate, followed by pyrolysis and carbonization to form modified biochar. This modified biochar is then co-fermented with EM engineered bacteria, calcium lignosulfonate, straw, and urea to obtain a biochar-based composite material modifier. This multi-stage, multi-component preparation method allows for the organic combination of various effective components (such as the specific functions of calcium lignosulfonate, the stable porous structure of biochar, and the bioactivity of EM fermentation products), laying a material foundation for its synergistic effect in soil.

[0025] (2) The biochar-based composite material prepared by the present invention can effectively neutralize soil acidity, significantly increase soil pH value, and effectively improve soil structure and reduce bulk density, thereby improving aeration and water permeability and alleviating soil compaction problem. This is due to the porosity of biochar and the promoting effect of organic fermentation products on aggregates.

[0026] (3) The biochar-based composite material prepared by the present invention can significantly increase the total organic carbon (TOC) content of soil, supplement and activate soil nutrients, and improve the supply capacity of nutrients such as available nitrogen (AN) and available phosphorus (AP). This is due to the carbon input of biochar, the addition of organic matter and the transformation effect of microorganisms.

[0027] (4) The biochar-based composite material prepared in this invention can optimize soil cation balance and significantly increase exchangeable calcium (Ca). 2+ ), magnesium (Mg) 2+ The content of basic ions such as aluminum (Al) is reduced, while the exchangeable active aluminum (Al) content is significantly decreased. 3+ The concentration of aluminum effectively mitigates the harm of aluminum toxicity to crops, which is related to the combined effects of pH increase, organic complexation, and ion exchange.

[0028] (5) The biochar-based composite material prepared by this invention can optimize the soil micro-ecological environment. This is due to the introduction of EM engineered bacteria and the subsequent co-fermentation process, which is rich in a large number of beneficial microorganisms and their metabolites. After being applied to the soil, these microorganisms can quickly colonize and play a role, significantly increasing the number of beneficial microorganisms and enzyme activity in the soil, and promoting the decomposition of organic matter and nutrient cycling.

[0029] (6) The improved method proposed in this invention includes steps such as fully mixing the biochar-based composite material (amendant) with the topsoil, controlling the irrigation amount, and subsequent mulching and static cultivation, which creates favorable hydrothermal and aeration conditions for the microbial activity in the amendant, the further maturation of organic materials, and the full interaction between the material and the soil, thereby maximizing the remediation potential of the amendant and ensuring the stability and efficiency of the acidified soil remediation effect.

[0030] (7) The present invention uses rice straw as a biochar raw material, which helps to recycle agricultural waste resources and reduce the negative impact of agricultural production on the environment. In addition, calcium lignosulfonate is inexpensive and is an organic amendment that will not pollute the soil. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments.

[0032] Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art, and the experimental methods without specific conditions are all conventional methods in the art.

[0033] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0034] A method for preparing a biochar-based composite material, the specific steps of which are as follows:

[0035] (1) After removing impurities from rice straw, wash it with deionized water for 20-30 min, place it in an oven at 100-110℃ and dry it to constant weight, and then crush it into straw particles with a uniform particle size of 1-3 cm for later use.

[0036] (2) Dissolve calcium lignosulfonate in deionized water to prepare a calcium lignosulfonate solution with a mass concentration of 5%~10%; add crushed rice straw to the solution and shake at room temperature for 24~48 h to allow calcium lignosulfonate to be fully loaded onto the straw; then perform solid-liquid separation and dry the loaded straw at 60~70℃ to obtain calcium lignosulfonate loaded straw raw material.

[0037] (3) The prepared calcium lignosulfonate-loaded straw raw material was placed in a crucible and then placed in a muffle furnace for pyrolysis and carbonization under a nitrogen protective atmosphere. The nitrogen flow rate was controlled at 200~300 mL / min, the pyrolysis temperature was set at 500~550℃, the heating rate was 10℃ / min, and the carbonization was carried out at a constant temperature for 2 h after reaching the set temperature. After carbonization, the carbonized product was naturally cooled to room temperature in a nitrogen atmosphere, ground, and sieved through a 2 mm sieve to obtain calcium lignosulfonate-modified biochar.

[0038] (4) Ferment calcium lignosulfonate, rice straw crushed to 1-3 cm, EM engineered bacteria (commercially available) and urea together, adjust the carbon-nitrogen ratio (C / N) of the mixture to (25-30):1, and ferment it under natural environmental conditions for 15-30 days to obtain the fermentation product.

[0039] (5) The fermentation product and calcium lignosulfonate modified biochar are mixed at a mass ratio of (5~10):1 and then fermented for 15~30 days to obtain the biochar-based composite material.

[0040] The specific steps of the method for improving acidified soil based on the above-mentioned biochar-based composite materials are as follows:

[0041] (1) Spread the biochar-based composite material evenly on the surface of acidified soil, and then till it to a depth of 10-20cm to fully mix the biochar-based composite material and acidified soil.

[0042] (2) Implement irrigation treatment, with an irrigation quota of 30% to 60% of the field water holding capacity, to replenish the soil layer from 0 to 10 to 20 cm.

[0043] (3) Cover the soil surface with polyethylene film and maintain it for 30 to 120 days. When white mycelium grows on the soil surface, the soil acidification improvement is completed and crops can be planted.

[0044] Example 1

[0045] A method for preparing a biochar-based composite material, the specific steps of which are as follows:

[0046] (1) After removing impurities from rice straw, wash it with deionized water for 25 min, place it in an oven at 105℃ and dry it to constant weight, then crush it to a length of 1~3 cm to obtain straw particles with uniform particle size for later use.

[0047] (2) Dissolve calcium lignosulfonate in deionized water to prepare an aqueous solution with a mass concentration of 10%. Add the aforementioned crushed straw to the solution and treat it by shaking at room temperature for 24 h to ensure that the calcium lignosulfonate is fully loaded onto the straw. After loading is completed, perform solid-liquid separation and dry the wet loaded straw at 65°C to obtain calcium lignosulfonate loaded straw raw material.

[0048] (3) Place the lignosulfonate-loaded straw raw material in a crucible and put it into a muffle furnace. Pyrolysis and carbonization are carried out under a nitrogen protective atmosphere. The nitrogen flow rate is controlled at 300 mL / min, the pyrolysis temperature is set at 500℃, the heating rate is 10℃ / min, and the carbonization is maintained at the set temperature for 2 h. After the carbonization process is completed, the carbonization product is naturally cooled to room temperature in a nitrogen atmosphere, the carbonization product is taken out, ground, and sieved through a 2 mm sieve to obtain lignosulfonate-modified biochar.

[0049] (4) Mix EM inoculant, brown sugar and water in a weight ratio of 1:1:10 evenly, seal and ferment at an ambient temperature of not less than 25°C for at least 5 days to obtain EM fermentation liquid. Then, mix calcium lignosulfonate, the aforementioned crushed rice straw (1~3cm particles), brown sugar and urea with EM fermentation liquid, adjust the carbon-nitrogen ratio (C / N) of the mixture to the range of 25~30, and pile and ferment under natural environmental conditions for 25 days to obtain fermentation product.

[0050] (5) The fermentation product and the prepared calcium lignosulfonate modified biochar were mixed at a mass ratio of 10:1 and then piled up under natural environmental conditions for secondary fermentation. The fermentation time was 25 days. During the fermentation, necessary turning and humidity adjustment were carried out according to the actual fermentation situation. Finally, biochar-based composite material was obtained.

[0051] Example 2

[0052] This embodiment conducted five sets of experiments, including one experimental group and four control groups. The experimental group used the biochar-based composite material prepared in Example 1 as a soil conditioner to carry out planting experiments in acidified soil in a greenhouse in Nanjing, Jiangsu Province. Control group 1 was directly planted in acidified soil in the same greenhouse. Control groups 2, 3, and 4 were planted in acidified soil in the same greenhouse using EM organic fertilizer, calcium lignosulfonate, and biochar, respectively.

[0053] The specific procedures for the experimental group are as follows:

[0054] Apply the soil conditioner (biochar-based composite material) evenly to the soil surface at a rate of 3% of the soil weight at a depth of 0-15 cm. Till the soil to a depth of 15 cm to ensure thorough mixing with the soil. Calculate the irrigation amount based on 45% of the field water holding capacity. Cover the soil surface with polyethylene film. After 50 days, white mycelium will grow on the soil surface. Then, plant green peppers.

[0055] The specific procedures for control groups 2-4 are as follows:

[0056] EM organic fertilizer (control group 2), calcium lignosulfonate (control group 3), and biochar (control group 4) were evenly spread on the soil surface at a rate of 3% of the soil weight at a depth of 0-15 cm. After tilling to a depth of 15 cm to ensure thorough mixing with the soil, green peppers were planted.

[0057] During the experiment, routine management practices such as irrigation (using pH-neutral irrigation water), weeding, and pest and disease control were implemented according to the crop's growth needs to ensure that all conditions were consistent except for the soil conditioner treatment. Detailed soil types and experimental results before and after using the soil conditioner (biochar-based composite material) of this invention are shown in Tables 1-4 below.

[0058] Table 1 Effects of different soil amendments on soil pH

[0059]

[0060] Note in Table 1: Different lowercase letters in the same column indicate significant differences between treatments (P < 0.05).

[0061] Table 1 shows that the experimental group treatment significantly increased the pH of the top 0–20 cm soil layer to 6.65, outperforming all control treatments and demonstrating its strong surface acidity neutralization and buffering capacity. More importantly, the improvement effect of the experimental group penetrated downwards significantly, with the pH still reaching 5.88 in the 20–40 cm soil layer, significantly higher than control group 1 and each single-component treatment (control groups 2–4), indicating its excellent potential for improving deep soil acidification. This may be attributed to the leaching of water-soluble alkaline components in the amendment, the deep-penetration activity of EM microorganisms, and the improved soil structure from biochar and organic matter promoting the transmission of the improvement effect. This ability to alleviate deep acidification is of great significance for improving the deep root growth environment of crops and enhancing the overall remediation effect, far superior to single amendments that mainly act on the surface.

[0062] Table 2 Effects of different soil amendments on soil fertility

[0063]

[0064] Table 2 Note: Different lowercase letters in the same column indicate significant differences between treatments (P < 0.05).

[0065] As shown in Table 2, the experimental group treatments exhibited the best performance in reducing redox potential, increasing available nitrogen, available phosphorus, and total organic carbon, significantly outperforming the blank control group 1 and each single-component treatment (control groups 2-4). This fully demonstrates that the biochar-based composite material of the present invention, through the synergistic effect of calcium lignosulfonate, EM microbial organic fertilizer, and biochar, has outstanding comprehensive advantages in rapidly neutralizing soil acidity, improving the soil redox environment, and enhancing soil nutrient availability and organic matter content, providing an efficient solution for the rapid improvement and restoration of soil fertility in acidified soils.

[0066] Table 3 Effects of different soil amendments on soil ion balance

[0067]

[0068] Table 3 Note: Different lowercase letters in the same column indicate significant differences between treatments (P < 0.05).

[0069] Table 3 shows that the experimental treatments significantly improved the ion balance and reduced aluminum toxicity in acidified soil. After the experimental treatments, the exchangeable Ca in the soil... 2+ and Mg 2+ The content of all components reached the highest level, far exceeding that of control group 1 and each single component treatment (control groups 2-4), effectively replenishing soil basic ions. Simultaneously, exchangeable Al... 3+ The aluminum content plummeted from 3.05 cmol / kg in control group 1 to 0.28 cmol / kg, a reduction of 90.8%, almost completely eliminating aluminum toxicity. Its superiority stems from a significant increase in pH, strong complexation and adsorption of organic matter, and the exchange and substitution of base ions. In contrast, while control group 4 showed good results, it was not as comprehensive as the experimental group, and the effects of control groups 2 and 3 were even more limited. This demonstrates that the biochar-based composite material of this invention, through multiple synergistic mechanisms, can efficiently restore soil ion balance and passivate aluminum toxicity, creating a favorable chemical environment for healthy crop growth.

[0070] Table 4 Effects of different soil amendments on soil physical properties

[0071]

[0072] Note in Table 4: Different lowercase letters in the same column indicate significant differences between treatments (P < 0.05).

[0073] Table 4 shows that the experimental group treatments showed the most significant improvement in soil physical properties. After applying the biochar-based composite material amendment of this invention, the content of water-stable aggregates >0.25 mm (R0.25) in the soil reached 65.8%, and the mean weight diameter (MWD) and geometric mean diameter (GMD) also increased to 1.85 mm and 1.22 mm, respectively, all significantly better than control group 1 and each single-component treatment (control groups 2-4). Simultaneously, the soil bulk density significantly decreased to 1.15 g / cm³. 3 The total porosity increased accordingly to 56.60%. This is attributed to the physical framework of biochar in the amendment, the bio-cementitious substances produced by EM organic fertilizer, and the potential cementing effect of calcium lignosulfonate, which jointly promoted the formation of stable large aggregates and optimized the soil structure. In comparison, although control groups 4 and 2 showed some improvement, their overall effect was not as good as the experimental group, with control group 3 showing the weakest effect. The biochar-based composite material of this invention creates an optimal physical environment for crop root growth and soil water-air coordination by comprehensively improving soil aggregation, reducing compaction, and increasing porosity.

[0074] Based on the analysis of the above physicochemical properties, including the main nutrient status of the soil surface layer, ion balance, and pH changes at different soil depths, the biochar-based composite material of this invention exhibits significant and comprehensive advantages in improving acidified soils. Compared with the blank control (control group 1) and the single-component application of EM organic fertilizer (control group 2), calcium lignosulfonate (control group 3), and biochar (control group 4), the experimental group treatment not only more effectively increased the pH value at different soil depths, reduced the redox potential, and significantly increased the content of available nitrogen, available phosphorus, and total organic carbon in the soil, but also significantly increased the content of exchangeable calcium and magnesium in the soil, while greatly reducing the content of exchangeable active aluminum, effectively detoxifying aluminum toxicity. In terms of improving soil physical properties, the experimental group treatment significantly increased R0.25, MWD, and GMD, greatly reduced soil bulk density, and significantly increased total soil porosity, indicating that it has excellent effects on improving soil structure and enhancing soil aeration, water permeability, and fertilizer retention capacity. These results fully demonstrate that there is a significant synergistic effect among the three components of the biochar-based composite material of the present invention: calcium lignosulfonate, EM microbial organic fertilizer, and biochar. This gives the composite material superior performance and application prospects in terms of the breadth, depth, and durability of its effects in the remediation of acidified soils, providing a promising technical solution for the efficient and sustainable remediation of acidified soils.

[0075] The embodiments described above are only some, not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. The scope of protection of the present invention is determined by the scope claimed in the claims. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a biochar-based composite material, characterized in that, Includes the following steps: Step 1) After removing impurities from the rice straw, wash it with deionized water, dry it to constant weight, and crush it into straw particles with a length of 1-3cm and uniform particle size for later use. Step 2) Dissolve calcium lignosulfonate in deionized water to prepare a calcium lignosulfonate solution with a mass concentration of 5%~10%; add the crushed rice straw from step 1) to the solution and shake it at room temperature to ensure that the calcium lignosulfonate is fully loaded onto the straw; then perform solid-liquid separation and dry the loaded straw to obtain calcium lignosulfonate loaded straw raw material. Step 3) The lignosulfonate-loaded straw raw material obtained in step 2) is pyrolyzed and carbonized under a nitrogen protective atmosphere; after carbonization, it is naturally cooled to room temperature in a nitrogen atmosphere, the carbonized product is taken out, ground and sieved to obtain lignosulfonate-modified biochar. Step 4) Calcium lignosulfonate, rice straw crushed in Step 1), EM engineered bacteria and urea are mixed and fermented together, and the fermentation product is obtained after being piled up and fermented under natural environmental conditions for 15 to 30 days. Step 5) Mix the fermentation product obtained in step 4) with the calcium lignosulfonate modified biochar obtained in step 3) and carry out a second fermentation for 15-30 days to obtain the final product.

2. The method for preparing a biochar-based composite material according to claim 1, characterized in that, Step 1) The cleaning time is 20~30 min; the drying temperature is 100~110℃.

3. The method for preparing a biochar-based composite material according to claim 1, characterized in that, Step 2) The vibration treatment time is 24~48 h; the drying temperature is 60~70℃.

4. The method for preparing a biochar-based composite material according to claim 1, characterized in that, Step 3) The specific steps of the pyrolysis carbonization are as follows: the nitrogen flow rate is controlled at 200~300 mL / min, the pyrolysis temperature is set at 500~550℃, the heating rate is 10℃ / min, and the carbonization is carried out at a constant temperature for 2 hours after reaching the set temperature.

5. The method for preparing a biochar-based composite material according to claim 1, characterized in that, Step 4) The carbon-to-nitrogen ratio of the mixture is (25~30):

1.

6. The method for preparing a biochar-based composite material according to claim 1, characterized in that, Step 5) The mass ratio of the fermentation product to the calcium lignosulfonate modified biochar is (5~10):

1.

7. The biochar-based composite material prepared by the preparation method according to any one of claims 1-6.

8. The application of the biochar-based composite material as described in claim 7 in the improvement of acidified soil.

9. The application according to claim 8, characterized in that, Includes the following steps: Step A) Spread the biochar-based composite material evenly on the surface of the acidified soil, and then till it to a depth of 10-20cm to fully mix the biochar-based composite material and the acidified soil. Step B) Implement irrigation treatment, using 30% to 60% of the field capacity as the irrigation quota, and replenish water to the 0 to 10 to 20 cm soil layer; Step C) Cover the soil surface with polyethylene film and maintain it for 30-120 days. When white mycelium grows on the soil surface, the soil acidification improvement is complete and crops can be planted.

Images