A method for remediation of crop rotation soils using biochar

Abstract

The application relates to the technical field of soil remediation, and particularly discloses a method for remediation of crop rotation soil by using biochar, which comprises the following steps: S1, uniformly mixing plough soil and composite fillers according to a mass ratio of 6-10:1 to prepare initial mixture; the composite fillers are composed of carrier biochar particles, carrier cotton seed hulls and coated perilla meal according to a mass ratio of 1:0.5-0.8:0.2-0.5; S2, adding the initial mixture into the plough soil, wherein the composite fillers are 250-300 kg per mu of plough soil, and the soil can be remediated by ploughing and water spraying; the method has the advantages of efficient and rapid soil remediation and guarantee of crop growth.

Description

Technical Field

[0001] This application relates to the field of soil remediation technology, and more specifically, it relates to a method for remediating crop rotation soil using biochar. Background Technology

[0002] The yield of crops is closely related to people's lives. In order to ensure the annual crop yield, farmers continuously apply chemical fertilizers. Long-term use of chemical fertilizers will accelerate soil acidification, accelerate the loss of calcium and magnesium from the soil, reduce the content of beneficial microorganisms, and cause changes in soil flora, affecting the content of toxic and harmful substances in the soil. This not only easily reduces crop yield, but also easily increases the toxins in crops, thus affecting human health.

[0003] Soil remediation refers to technical measures to restore contaminated soil to its normal function. These include physical remediation, chemical remediation, and bioremediation. Physical remediation generally includes extraction, screening, infiltration, excavation, and covering methods. Extraction involves removing contaminants from the contaminated soil; screening involves sieving the contaminated soil; infiltration involves removing contaminants from the soil; excavation involves digging out the contaminated soil; and covering involves covering the contaminants to prevent overflow. However, physical remediation is not suitable for large-scale soil remediation in Northeast China due to its heavy workload, complex procedures, and limited operating time. Chemical remediation includes solidification-stabilization, leaching, and oxidation-reduction methods. Solidification-stabilization involves fixing contaminants in the contaminated medium; leaching involves injecting water or aqueous solutions containing rinsing aids, acid or alkali solutions, complexing agents, or surfactants into the contaminated soil or sediment. Among the various methods of soil remediation, the process of washing away and cleaning pollutants from the soil is called oxidation-reduction. This method involves adding chemical oxidants to the soil and using their reaction with pollutants to purify the soil. However, while the addition of chemical reagents can treat heavy metal pollution, residual metal pollution can easily remain, affecting the health of crops. Bioremediation includes phytoremediation, microbial remediation, and combined bioremediation. Phytoremediation utilizes the hyperaccumulation or accumulation functions of plants to absorb and repair pollutants, and uses plant roots to control the spread of pollution and restore ecological functions. However, for agricultural land, crops are generally planted instead of other plants, so it is not suitable for agricultural soil remediation. Microbial remediation refers to the use of microorganisms to decompose organic matter, transform nutrients, increase soil porosity and permeability, while inhibiting the growth and reproduction of pathogens in the soil. It has a wide range of applications and can be used for agricultural soil remediation.

[0004] Because winters are long in Northeast China, the activity of microorganisms is easily inhibited in the cold environment, so the time available for microorganisms to repair the soil is short. Furthermore, it takes time for microorganisms to decompose and come into contact with organic matter in the soil, and it takes a long time to completely decompose the organic matter. However, replanting is required in the summer, and crop yields must be guaranteed.

[0005] Therefore, how to quickly and efficiently restore soils used in crop rotation to ensure crop growth is a problem that needs to be solved. Summary of the Invention

[0006] In order to quickly and efficiently remediate crop rotation soils and thus ensure crop growth, this application provides a method for remediating crop rotation soils using biochar.

[0007] This application provides a method for remediating crop rotation soil using biochar, which employs the following technical solution:

[0008] A method for remediating crop rotation soil using biochar includes the following steps:

[0009] S1. Weigh the cultivated soil and mix it evenly with the composite filler at a mass ratio of 6-10:1 to obtain the initial mixture; the composite filler is composed of biochar particles, cottonseed hulls and coated perilla meal with a mass ratio of 1:0.5-0.8:0.2-0.5.

[0010] S2. Add the initial mixture to the soil of the cultivated land. The amount of composite filler is 250-300 kg per acre of cultivated land. It can be prepared by plowing and watering.

[0011] By adopting the above technical solution, soil and composite filler are first mixed. The number of beneficial bacteria in the initial mixture gradually increases. Moreover, the biochar particles, cottonseed hulls, and coated perilla meal are evenly dispersed in the initial mixture. The bacteria in the initial mixture adapt to the soil environment in advance, which facilitates better growth and reproduction in arable soil, thereby inhibiting the growth and reproduction of harmful bacteria and pests. At the same time, biochar particles, cottonseed hulls, and perilla meal can loosen the soil structure, neutralize the soil pH, provide nutrients for beneficial bacteria, increase the content of organic matter such as carbon and nitrogen in the soil, and also adsorb heavy metals and other harmful substances, thus achieving the effect of rapid remediation of subgraded soil.

[0012] Preferably, the biochar-loaded particles are prepared by the following method:

[0013] Weigh out biochar granules and disperse them in water. Then add Bacillus subtilis powder at a mass ratio of 1:0.01-0.03. Continue dispersing and then filter out the biochar granules to obtain a semi-finished product. Spray the surface of the semi-finished product with a binder and fiber filaments at a mass ratio of 1:0.2-0.4:0.1-0.3. After drying and dispersion, obtain the finished biochar granules.

[0014] By adopting the above technical solution, the high porosity and good loading effect of biochar particles make it easy to load Bacillus subtilis powder, and then the viscosity of the binder makes it easy to adhere the fibers to the surface of the biochar particles.

[0015] When biochar granules are added to the soil, their high porosity increases the soil's porosity. The presence of fibers allows the biochar granules to remain on the soil surface. The permeability of the fibers, the air permeability of the pore structure between them, and the permeability of the pores within the biochar granules ensure that Bacillus subtilis can contact oxygen. Since Bacillus subtilis grows aerobicly, its growth and reproduction are ensured within the biochar granules. Simultaneously, Bacillus subtilis can decompose and utilize the binder and fibers, further providing nutrients for its growth and reproduction. As the fibers and binder are gradually decomposed by Bacillus subtilis within the biochar granules and by the bacteria in the soil, Bacillus subtilis is gradually released. It emerges from the biochar pores and acts on the soil, regulating soil permeability, pH, granulation effect, and adsorbing heavy metal pollution to remediate the soil.

[0016] Biochar particles, binder, and fiber filaments work together, with the fiber filaments acting as grafts and exhibiting a dispersed structure on the surface of the biochar. This not only loosens the soil but also promotes the adhesion of heavy metals to the surface of the fiber filaments, enabling the biochar particles to aggregate and load heavy metals, thereby reducing heavy metals in the soil and ensuring crop growth.

[0017] Preferably, the adhesive liquid is composed of a sodium alginate solution and a fucoidan solution in a mass ratio of 1:1-2.

[0018] By adopting the above technical solution, the combination of sodium alginate solution and fucoidan solution not only has a high bonding effect, but also easily forms a breathable bonding layer, which not only ensures the contact between Bacillus subtilis and oxygen, but also ensures that the fibers adhere relatively stably to the surface of biochar particles.

[0019] By utilizing the polysaccharide properties of fucoidan, it can be gradually decomposed and utilized by Bacillus subtilis to supply the growth and reproduction of the bacteria. The gradual destruction of the binding layer makes it easier for the reproduced Bacillus subtilis to migrate towards the surface of the biochar particles, thereby acting on the soil at the interface with the surface of the biochar particles, loosening the soil and improving soil permeability. Combined with the alkalinity of sodium alginate, it neutralizes the soil pH, thereby further realizing soil remediation.

[0020] Preferably, the fiber filament is composed of bamboo fiber, cotton fiber, starch solution and casein in a mass ratio of 1:1-2:0.2-0.5:0.1-0.3.

[0021] By adopting the above technical solution, bamboo fiber, cotton fiber, starch liquid, and casein are combined. The particle dispersion effect of starch liquid and casein facilitates adhesion and filling between the pores of bamboo fiber and cotton fiber. Both bamboo fiber and cotton fiber have high porosity, which can loosen the soil and improve soil permeability. The filling of starch and casein, combined with the permeability effect of the binder, further improves the soil permeability. Starch liquid and casein can cross-link with the binder, and casein acts as a filling bridge, further ensuring the permeability effect and facilitating the relatively stable bonding of bamboo fiber and cotton fiber to the surface of biochar particles.

[0022] The combination of bamboo fiber, cotton fiber, starch solution, casein, and binder utilizes the insulating properties of bamboo and cotton fibers to reduce the impact of low temperatures on bacterial activity during cold winters. The fibers also provide space for ice crystal expansion, minimizing the impact of ice crystal growth on bacterial activity. Simultaneously, the bamboo and cotton fibers shrink in winter but partially expand and absorb moisture in the spring when temperatures rise, rapidly breaking down their structure and facilitating rapid bacterial decomposition. This not only enables rapid bacterial release but also promotes bacterial growth and reproduction, while simultaneously enriching the soil's organic matter content, thus quickly repairing the soil and promoting crop growth.

[0023] Preferably, the cottonseed hulls used as the loading material are prepared by the following method:

[0024] Weigh cottonseed hulls and disperse them in water. Then add lactic acid bacteria powder and disperse and stir. The mass ratio of cottonseed hulls to lactic acid bacteria powder is 1:0.005-0.015. Filter out the cottonseed hulls and then spray a coating liquid evenly. The mass ratio of cottonseed hulls to coating liquid is 1:0.2-0.5. After drying and dispersion, the finished cottonseed hulls are obtained.

[0025] By adopting the above technical solution, cottonseed hulls are loaded with lactic acid bacteria powder and then coated. The oxygen barrier effect of the membrane layer is used to ensure the growth of anaerobic lactic acid bacteria. Cottonseed hulls are rich in cellulose and protein, which can be gradually decomposed and utilized by lactic acid bacteria and microorganisms in the soil, thereby increasing the organic matter content in the soil and also increasing the microbial content in the soil.

[0026] Preferably, the coating solution is an ethyl cellulose solution.

[0027] By adopting the above technical solution, the ethyl cellulose solution has a good oxygen barrier effect after film formation, which enables the anaerobic lactic acid bacteria to maintain their activity. The lactic acid bacteria can gradually decompose cellulose, and the ethyl cellulose is gradually decomposed by other bacteria in the soil, which not only supplies the growth of bacteria, but also increases the organic matter content in the soil.

[0028] Preferably, the ethyl cellulose solution is composed of an ethyl cellulose ethanol solution, shell powder, and lauric acid in a mass ratio of 10:0.5-1:1-2.

[0029] By adopting the above technical solution, ethyl cellulose ethanol solution, shell powder, and lauric acid are combined. Utilizing the filling effect of shell powder, the membrane layer at the location where ethyl cellulose is loaded with shell powder is thinner and more easily decomposed by bacteria, thereby promoting contact between lactic acid bacteria and the soil. Simultaneously, the porosity of shell powder improves soil looseness and permeability. Furthermore, the calcium carbonate in shell powder can combine with lauric acid. The adsorption of heavy metals by lauric acid, combined with the adsorption of heavy metals by calcium carbonate and lauric acid, reduces the mobility of heavy metals in the soil, thus achieving soil remediation.

[0030] Preferably, the coated perilla meal is prepared by the following method:

[0031] Weigh out perilla meal and soak and disperse it in glucono-delta-lactone solution. Then add Bacillus licheniformis powder. The mass ratio of perilla meal to Bacillus licheniformis is 1:0.01-0.035. After dispersion treatment, filter out perilla meal to obtain loaded perilla meal.

[0032] Bacillus licheniformis powder was evenly sprayed onto the surface of the perilla meal at a mass ratio of 1:0.001-0.003, followed by an evenly sprayed polylactic acid solution. The mass ratio of the perilla meal to the polylactic acid solution was 1:1-2. After drying, the finished coated perilla meal was obtained.

[0033] By adopting the above technical solution, perilla meal, glucono-delta-lactone, Bacillus licheniformis, and polylactic acid solution are combined. The ester groups in glucono-delta-lactone attract and connect with the lipid groups in perilla meal, making the hydrophilic groups of glucono-delta-lactone face outward and promoting the loading of Bacillus licheniformis onto the perilla meal. The hydroxyl groups in polylactic acid and glucono-delta-lactone facilitate adsorption and connection, forming a polylactic acid film layer coating the surface of the perilla meal, which partially blocks oxygen and ensures the activity of facultative anaerobic Bacillus licheniformis. At the same time, the sugars contained in the glucose further ensure the growth activity of Bacillus licheniformis.

[0034] Bacillus licheniformis and the microorganisms in the soil can decompose polylactic acid, which not only promotes the growth and reproduction of the microorganisms, but also allows the microorganisms to come into contact with the soil, thereby improving the uniformity of the microorganisms in the soil and rapidly repairing the soil. The decomposed polylactic acid, sugars, and perilla meal can also increase the organic matter content in the soil. Before decomposition, perilla meal, due to its porous and hydrophobic properties, is not prone to forming soil aggregates, thus ensuring the porosity of the soil structure and improving soil aeration.

[0035] Preferably, the polylactic acid solution is made from a polylactic acid aqueous solution, polycaprolactone, and fructose in a mass ratio of 10:0.1-0.4:0.1-0.2.

[0036] By adopting the above technical solution, polylactic acid aqueous solution, polycaprolactone, and fructose are combined. Polycaprolactone and fructose are not easily soluble in aqueous solution. Through the filling effect, they promote the rapid decomposition of the membrane layer by bacteria, provide energy for the growth and reproduction of bacteria, and increase the organic matter content in the soil. Polycaprolactone contains ester groups, which facilitate mutual attraction and connection with the lipophilic groups remaining on the surface of perilla meal, thereby further ensuring the adhesion stability of the polylactic acid membrane layer on the surface of perilla meal. This ensures that Bacillus licheniformis can be evenly and in high concentration dispersed in the soil, achieving the effect of rapid soil remediation.

[0037] Preferably, the gluconolactone solution has a mass fraction of 0.5-2%.

[0038] By adopting the above technical solution, Bacillus licheniformis is loaded onto perilla meal.

[0039] In summary, this application has the following beneficial effects:

[0040] 1. First, mix the soil with the composite filler. The number of beneficial bacteria in the initial mixture gradually increases. The biochar particles, cottonseed hulls, and coated perilla meal are evenly dispersed in the initial mixture. The bacteria in the initial mixture adapt to the soil environment in advance, which facilitates their better growth and reproduction in the cultivated soil, thereby inhibiting the growth and reproduction of harmful bacteria and pests. At the same time, the biochar particles, cottonseed hulls, and perilla meal can loosen the soil structure, neutralize the soil pH, provide nutrients for beneficial bacteria, increase the content of carbon-based, nitrogen-based, and other organic matter in the soil, and also adsorb heavy metals and other harmful substances, thus achieving the effect of rapid remediation of subgraded soil.

[0041] 2. If Bacillus subtilis powder, lactic acid bacteria powder, and Bacillus licheniformis powder are added directly to the soil, it is difficult to achieve uniform contact between the powder and the soil because the soil is also tilled in blocks. Biochar granules, as granular structures, are not likely to have a higher density than the powder, and they are easy to mix while not easily floating on the surface. Due to their light weight, the powder is not only difficult to mix evenly but also tends to float on the soil surface, affecting the uniformity of the powder in the soil, thus affecting the uniformity and efficiency of the powder in soil remediation.

[0042] 3. After the autumn harvest in Northeast China, temperatures drop rapidly, and the soil becomes cold. Adding loaded biochar granules utilizes the lightweight properties of bamboo and cotton fibers, allowing them to disperse easily near the soil surface, the coldest part of the soil. The insulating properties of bamboo and cotton fibers alleviate the chill, and combined with the bonding layer and the porosity of the biochar granules, further insulate against the cold and protect Bacillus subtilis. With the arrival of spring and increasing humidity, the water in the bamboo and cotton fibers forms ice crystals that expand and alter the fiber structure. As the ice crystals melt, the fiber pores are destroyed, further increasing the porosity. This allows the bamboo and cotton fibers to be rapidly decomposed by microorganisms. The decomposed bamboo and cotton fibers, along with starch, casein, and fucoidan, not only provide nutrients for microbial growth but also increase the soil's organic matter content and bind heavy metals, promoting rapid soil remediation.

[0043] 4. The membrane layer on the surface of cottonseed hulls and the membrane layer on the surface of perilla meal can partially block ice crystals in the cold winter, minimizing the impact of expanding ice crystals on the activity of lactic acid bacteria and Bacillus licheniformis. In spring, the membrane structure damaged by ice crystals, combined with the hydrophilic effect of polylactic acid on the surface of perilla meal, can quickly promote the disintegration of the membrane layer, which can be decomposed, absorbed, and utilized by the soil and the bacteria loaded inside. This increases the content of beneficial bacteria and allows the soil to be quickly repaired to meet the needs of summer cultivation. Detailed Implementation

[0044] The present application will be further described in detail below with reference to the embodiments.

[0045] The fucoidan in the following raw materials was purchased from Fufeng Sinote Biotechnology Co., Ltd., which produces fully water-soluble fucoidan; the Bacillus subtilis powder was purchased from Shandong Haifeng Bioengineering Co., Ltd.; and the other raw materials and equipment were all commercially available.

[0046] Preparation Example 1: The loaded biochar particles were prepared using the following method:

[0047] Weigh 1 kg of sodium alginate solution and 1.5 kg of fucoidan solution, mix and stir evenly to prepare a binder; the sodium alginate solution is a 1% sodium alginate aqueous solution; the fucoidan is a 1% fucoidan aqueous solution.

[0048] Weigh 2 kg of starch and place it in 98 kg of water, heat it to 65°C, and stir it into a paste to obtain starch solution.

[0049] 0.4 kg of starch solution was evenly sprayed onto the surface of 1 kg of bamboo fiber and 1.5 kg of cotton fiber, and then 0.2 kg of casein was evenly sprayed onto the surface. The casein was passed through a 200-mesh sieve, dried, and dispersed to obtain fiber filaments. The average length of the fiber filaments was 3 mm.

[0050] 1 kg of biochar granules with an average particle size of 1 mm were placed in 99 kg of water and dispersed and stirred at a speed of 1000 rpm. Then, 0.02 kg of Bacillus subtilis powder with an effective viable count of ≥100 billion / g was added. The dispersion was continued for 20 min, and the biochar granules were filtered out to obtain a semi-finished product. 0.3 kg of binder liquid was evenly sprayed onto the surface of 1 kg of semi-finished product, and then 0.2 kg of fiber filaments were evenly sprayed onto it. After drying and dispersion, the finished loaded biochar granules were obtained.

[0051] Preparation Example 2: The difference between this preparation example and Preparation Example 1 is that:

[0052] Weigh 1 kg of sodium alginate solution and 1 kg of fucoidan solution, mix and stir evenly to obtain the adhesive liquid;

[0053] 0.2 kg of starch solution was evenly sprayed onto the surface of 1 kg of bamboo fiber and 1 kg of cotton fiber, and then 0.1 kg of casein was evenly sprayed onto the surface. After drying and dispersion, fiber filaments were obtained.

[0054] 1 kg of biochar granules with an average particle size of 1 mm were placed in 99 kg of water and dispersed and stirred at a speed of 1000 rpm. Then, 0.01 kg of Bacillus subtilis powder with an effective viable count of ≥100 billion / g was added. The dispersion was continued for 20 min, and the biochar granules were filtered out to obtain a semi-finished product. 0.2 kg of binder liquid was evenly sprayed onto the surface of 1 kg of semi-finished product, and then 0.1 kg of fiber filaments were evenly sprayed onto it. After drying and dispersion, the finished loaded biochar granules were obtained.

[0055] Preparation Example 3: The difference between this preparation example and Preparation Example 1 is that:

[0056] Weigh 1 kg of sodium alginate solution and 2 kg of fucoidan solution, mix and stir evenly to obtain the adhesive liquid;

[0057] 0.5 kg of starch solution was evenly sprayed onto the surface of 1 kg of bamboo fiber and 2 kg of cotton fiber, followed by 0.3 kg of casein. After drying and dispersion, fiber filaments were obtained.

[0058] 1 kg of biochar granules with an average particle size of 1 mm were placed in 99 kg of water and dispersed and stirred at a speed of 1000 rpm. Then, 0.03 kg of Bacillus subtilis powder with an effective viable count of ≥100 billion / g was added. The dispersion was continued for 20 min, and the biochar granules were filtered out to obtain a semi-finished product. 0.4 kg of binder liquid was evenly sprayed onto the surface of 1 kg of semi-finished product, and then 0.3 kg of fiber filaments were evenly sprayed onto it. After drying and dispersion, the finished loaded biochar granules were obtained.

[0059] The lactic acid bacteria powder in the following raw materials was purchased from Jiangsu Caiwei Biotechnology Co., Ltd.; other raw materials and equipment are commercially available.

[0060] Preparation Example 4: The cottonseed hulls loaded with the material were prepared by the following method:

[0061] Weigh 10 kg of ethyl cellulose ethanol solution, mix it with 0.8 kg of shell powder and 1.5 kg of lauric acid until homogeneous to obtain ethyl cellulose solution, which is the coating solution; the mass fraction of ethyl cellulose ethanol solution is 5%, the mass fraction of ethanol is 75%, and the average particle size of shell powder is 80 μm;

[0062] Weigh 1 kg of cottonseed hulls and place them in 99 kg of water. The average particle size of the cottonseed hulls is 0.5 mm. Stir at 1000 r / min for 10 min. Then add 0.01 kg of lactic acid bacteria powder, which has passed through a 300-mesh sieve and has an effective live bacteria count ≥10 billion / g. Continue stirring for 20 min, filter out the cottonseed hulls, and then spray with 0.35 kg of coating liquid. After drying and dispersion, the finished cottonseed hulls are obtained.

[0063] Preparation Example 5: The difference between this preparation example and Preparation Example 4 is that:

[0064] Weigh 10 kg of ethyl cellulose ethanol solution, mix it with 0.5 kg of shell powder and 1 kg of lauric acid until homogeneous to obtain ethyl cellulose solution, which is the coating solution;

[0065] Weigh 1 kg of cottonseed hulls and place them in 99 kg of water. Stir at 1000 r / min for 10 min, then add 0.005 kg of lactic acid bacteria powder and continue stirring for 20 min. Filter out the cottonseed hulls, then spray with 0.2 kg of coating liquid, and after drying and dispersion, obtain the finished cottonseed hulls.

[0066] Preparation Example 6: The difference between this preparation example and Preparation Example 4 is that:

[0067] Weigh 10 kg of ethyl cellulose ethanol solution, mix it with 1 kg of shell powder and 2 kg of lauric acid until homogeneous to obtain ethyl cellulose solution, which is the coating solution;

[0068] Weigh 1 kg of cottonseed hulls and place them in 99 kg of water. Stir at 1000 r / min for 10 min, then add 0.015 kg of lactic acid bacteria powder and continue stirring for 20 min. Filter out the cottonseed hulls, then spray with 0.5 kg of coating liquid, and after drying and dispersion, obtain the finished cottonseed hulls.

[0069] The Bacillus licheniformis in the following raw materials was purchased from Hebei Hongtao Bioengineering Co., Ltd.; other raw materials and equipment were commercially available.

[0070] Preparation Example 7: Coated perilla meal was prepared using the following method:

[0071] Weigh 10 kg of polylactic acid aqueous solution, mix it with 0.3 kg of polycaprolactone and 0.15 kg of fructose until homogeneous to obtain a polylactic acid solution; the mass fraction of the polylactic acid aqueous solution is 10%.

[0072] Weigh 1 kg of perilla meal and soak it in 20 kg of glucono-delta-lactone solution (1% by mass). Disperse the mixture at 1000 r / min for 10 min, then add 0.02 kg of Bacillus licheniformis powder (with an effective viable count ≥ 20 billion / g) and continue dispersing for 20 min. Filter out the perilla meal, evenly spray 0.002 kg of Bacillus licheniformis powder onto the surface, and then evenly spray 1.5 kg of polylactic acid solution. After drying and dispersing, the finished coated perilla meal is obtained.

[0073] Preparation Example 8: The difference between this preparation example and Preparation Example 7 is that:

[0074] Weigh 10 kg of polylactic acid aqueous solution, mix it with 0.1 kg of polycaprolactone and 0.1 kg of fructose until homogeneous to obtain a polylactic acid solution; the mass fraction of the polylactic acid aqueous solution is 10%.

[0075] Weigh 1 kg of perilla meal and soak it in 20 kg of glucono-delta-lactone solution (0.5% by mass). Disperse it at 1000 r / min for 10 min, then add 0.01 kg of Bacillus licheniformis powder (with an effective viable count ≥ 20 billion / g) and continue dispersing for 20 min. Filter out the perilla meal, evenly spray 0.001 kg of Bacillus licheniformis powder onto the surface, and then evenly spray 1 kg of polylactic acid solution. After drying and dispersing, the finished coated perilla meal is obtained.

[0076] Preparation Example 9: The difference between this preparation example and Preparation Example 7 is that:

[0077] Weigh 10 kg of polylactic acid aqueous solution, mix it with 0.4 kg of polycaprolactone and 0.2 kg of fructose until homogeneous to obtain a polylactic acid solution; the mass fraction of the polylactic acid aqueous solution is 10%.

[0078] Weigh 1 kg of perilla meal and soak it in 20 kg of glucono-delta-lactone solution (2% by mass). Disperse the mixture at 1000 r / min for 10 min, then add 0.035 kg of Bacillus licheniformis powder (with an effective viable count ≥ 20 billion / g) and continue dispersing for 20 min. Filter out the perilla meal, evenly spray 0.003 kg of Bacillus licheniformis powder onto the surface, and then evenly spray 2 kg of polylactic acid solution. After drying and dispersing, the finished coated perilla meal is obtained.

[0079] Example 1: A method for soil remediation using biochar in crop rotation:

[0080] S1. Weigh the cultivated soil and the composite filler at a mass ratio of 8:1 and mix them evenly to obtain the initial mixture; the composite filler is composed of the loaded biochar particles prepared in Preparation Example 1, the loaded cottonseed hulls prepared in Preparation Example 4, and the coated perilla meal prepared in Preparation Example 7, with a mass ratio of 1:0.7:0.3.

[0081] S2. Add the initial mixture to the soil of the cultivated land. The amount of composite filler is 280 kg per acre of cultivated land. It can be prepared by plowing and watering.

[0082] Example 2: The difference between this example and Example 1 is that:

[0083] S1. Weigh the cultivated soil and the composite filler at a mass ratio of 6:1 and mix them evenly to obtain the initial mixture. The composite filler consists of the loaded biochar particles prepared in Preparation Example 2, the loaded cottonseed hulls prepared in Preparation Example 5, and the coated perilla meal prepared in Preparation Example 8, with a mass ratio of 1:0.5:0.5.

[0084] S2. Add the initial mixture to the soil of the cultivated land. The amount of composite filler is 250 kg per acre of cultivated land. It can be prepared by plowing and watering.

[0085] Example 3: The difference between this example and Example 1 is that:

[0086] S1. Weigh the cultivated soil and the composite filler at a mass ratio of 10:1 and mix them evenly to obtain the initial mixture; the composite filler is composed of the loaded biochar particles prepared in Preparation Example 3, the loaded cottonseed hulls prepared in Preparation Example 6, and the coated perilla meal prepared in Preparation Example 9, with a mass ratio of 1:0.8:0.2.

[0087] S2. Add the initial mixture to the soil of the cultivated land. The amount of composite filler is 300 kg per acre of cultivated land. It can be prepared by plowing and watering.

[0088] Example 4: The difference between this example and Example 1 is that:

[0089] No Bacillus subtilis powder was added during the preparation of the biochar pellets; no lactic acid bacteria powder was added during the preparation of the cottonseed hulls; and no Bacillus licheniformis powder was added during the preparation of the coated perilla meal.

[0090] Example 5: The difference between this example and Example 1 is that:

[0091] No binder or fiber was added during the preparation of the biochar particles.

[0092] Example 6: The difference between this example and Example 1 is that:

[0093] In the preparation of biochar particles, bamboo fiber and cotton fiber are replaced with chopped glass fiber of equal mass, with the length of the chopped glass fiber being 3 mm.

[0094] Example 7: The difference between this example and Example 1 is that:

[0095] No starch solution or casein was added to the fiber filaments during the preparation of the biochar particles.

[0096] Example 8: The difference between this example and Example 1 is that:

[0097] During the preparation of the biochar particles, no fucoidan solution was added to the binder.

[0098] Example 9: The difference between this example and Example 1 is that:

[0099] In the preparation of cottonseed hulls, an equal mass of epoxy resin solution replaced the ethyl cellulose ethanol solution; the epoxy resin solution consisted of epoxy resin E51 and curing agent T31 in a mass ratio of 100:40.

[0100] Example 10: The difference between this example and Example 1 is that:

[0101] No shell powder or lauric acid was added to the ethyl cellulose solution during the preparation of the cottonseed hulls.

[0102] Example 11: The difference between this example and Example 1 is that:

[0103] In the preparation of coated perilla meal, the glucono-delta-lactone solution was replaced with an equal mass of water.

[0104] Example 12: The difference between this example and Example 1 is that:

[0105] During the preparation of coated perilla meal, no polycaprolactone or fructose was added to the polylactic acid solution.

[0106] Comparative Example 1: The difference between this comparative example and Example 1 is that:

[0107] The composite filler consists of 1 kg of biochar granules, 0.7 kg of cottonseed hulls, and 0.3 kg of perilla meal.

[0108] Comparative Example 2: This comparative example differs from Example 1 in that:

[0109] The composite filler is biochar particles.

[0110] The soil used in the following performance testing experiments were all from trial fields in Changchun City, Jilin Province.

[0111] Microbiological testing was conducted using the methods of Examples 1-12 and Comparative Examples 1-2 for soil remediation. Soil remediation was carried out after the autumn harvest, and the content of Bacillus subtilis, lactic acid bacteria, and Bacillus licheniformis in the remediated soil was tested again on May 20 of the following year, and the data were recorded.

[0112] Heavy metal detection was performed on soil remediation using the methods of Examples 1-12 and Comparative Examples 1-2, respectively.

[0113] The test soil was artificially contaminated with 10.5% heavy metal Cd. The test soil was then remediated, and the decrease in the amount of exchangeable heavy metal Cd in the soil before and after 6 months was calculated.

[0114] Crop production testing was conducted using the methods of Examples 1-12 and Comparative Examples 1-2 for soil remediation. The height of the corn stalk and the length of the longest corn root were measured. For each set of examples and comparative examples, 1 square meter of cultivated land was used to record the average height and length. " / " indicates that the corresponding example or comparative example did not test this item.

[0115] Table 1 Performance Test Table

[0116]

[0117] As can be seen from Examples 1-3 and Table 1, the method of this application can quickly and efficiently repair soil, promote crop growth, reduce heavy metal content, and increase the content of beneficial bacteria.

[0118] Combining Examples 1 and 4-12 with Table 1, it can be seen that no bacterial powder was added in Example 4. Compared with Example 1, the content of each bacterial species in Example 4 was lower than the corresponding data in Example 1, the reduction in heavy metals was lower than in Example 1, and the crop height was lower than in Example 1. This indicates that the addition of bacterial powder can increase the content of beneficial bacteria in the soil, reduce the content of heavy metals, and promote crop growth.

[0119] In Example 5, no binder or fiber was added during the preparation of the biochar particles. Compared with Example 1, the content of each microorganism in Example 5 was lower than the corresponding data in Example 1, the reduction in heavy metals was lower than in Example 1, and the crop height was lower than in Example 1. This indicates that the addition of binder and fiber not only binds heavy metals but also provides nutrients for the growth and reproduction of microorganisms and increases the organic matter content in the soil, thereby promoting crop growth and achieving the effect of rapid soil remediation.

[0120] In Example 6, during the preparation of biochar particles, bamboo fiber and cotton fiber were replaced with the same mass of chopped glass fiber. Compared with Example 1, the content of each bacterial species in Example 6 was lower than the corresponding data in Example 1, the reduction in heavy metals was lower than in Example 1, and the crop height was lower than in Example 1. This indicates that chopped glass fiber cannot promote the growth of bacteria and crops, nor can it bind heavy metal substances, thus easily affecting the soil remediation effect.

[0121] In Example 7, no starch solution or casein was added to the fiber filaments during the preparation of biochar particles. Compared with Example 1, the content of each strain in Example 7 was lower than the corresponding data in Example 1, the reduction in heavy metals was lower than in Example 1, and the crop height was lower than in Example 1. This indicates that the combination of starch solution and casein facilitates the formation of a cross-linked network, which on the one hand blocks the influence of winter ice crystals on the microorganisms, and on the other hand provides the nutrients required for microbial growth, thus promoting crop growth.

[0122] In Example 8, during the preparation of biochar particles, no fucoidan solution was added to the binder. Compared to Example 1, the content of each bacterial species in Example 8 was lower than the corresponding data in Example 1, the reduction in heavy metals was lower than in Example 1, and the crop height was lower than in Example 1. This indicates that fucoidan can promote bacterial growth and achieve the effect of rapid soil remediation.

[0123] In Example 9, during the preparation of cottonseed hulls, an equal mass of epoxy resin solution was used to replace the ethyl cellulose ethanol solution. Compared to Example 1, the content of each bacterial species in Example 9 was lower than the corresponding data in Example 1, the decrease in heavy metals was lower than in Example 1, and the crop height was lower than in Example 1. This indicates that ethyl cellulose can be biodegraded and provide nutrients for organisms.

[0124] In Example 10, during the preparation of cottonseed hulls, no shell powder and lauric acid were added to the ethyl cellulose solution. Compared to Example 1, the content of each microorganism in Example 10 was lower than the corresponding data in Example 1, the reduction in heavy metals was lower than in Example 1, and the crop height was lower than in Example 1. This indicates that the addition of shell powder and lauric acid can regulate heavy metals in the soil, and shell powder can loosen the soil and increase the organic matter content in the soil, thereby promoting crop growth.

[0125] In Example 11, during the preparation of coated perilla meal, the glucono-delta-lactone solution was replaced with the same mass of water. Compared to Example 1, the content of each bacterial strain in Example 11 was lower than the corresponding data in Example 1, the reduction in heavy metals was lower than in Example 1, and the crop height was lower than in Example 1. This indicates that the lipophilic perilla meal is convenient for adsorbing the lipophilic groups of glucono-delta-lactone, while the hydrophilic groups face outwards, which facilitates coating and protects the bacteria from being affected by ice crystals in winter. Furthermore, glucono-delta-lactone contains sugar, which can also promote the growth and reproduction of bacteria, achieving the effect of rapid soil repair after spring.

[0126] In Example 12, during the preparation of coated perilla meal, no polycaprolactone or fructose was added to the polylactic acid solution. Compared to Example 1, the content of each microbial strain in Example 12 was lower than the corresponding data in Example 1, the reduction in heavy metals was lower than in Example 1, and the crop height was lower than in Example 1. This indicates that polycaprolactone and fructose are easily adsorbed on the surface of perilla meal to form a film layer, while fructose can ensure the growth and reproduction of microorganisms. At the same time, perilla meal has good air permeability, thereby achieving rapid soil remediation.

[0127] Based on Example 1 and Comparative Examples 1-2, and in conjunction with Table 1, it can be seen that the composite filler in Comparative Example 1 consisted of 1 kg of biochar particles, 0.7 kg of cottonseed hulls, and 0.3 kg of perilla meal. Compared to Example 1, the content of each microbial species in Comparative Example 1 was lower than the corresponding data in Example 1, the reduction in heavy metals was lower than in Example 1, and the crop height was lower than in Example 1. This indicates that the soil remediation effect of unmodified biochar particles, cottonseed hulls, and perilla meal was poor.

[0128] Comparative Example 2 uses biochar granules as the composite filler. Compared to Example 1, the content of each microbial species in Comparative Example 2 is lower than the corresponding data in Example 1, the reduction in heavy metals is lower than in Example 1, and the crop height is lower than in Example 1. This indicates that the addition of cottonseed hulls and perilla meal can further loosen the soil, improve soil permeability, improve soil remediation efficiency, and promote crop growth.

[0129] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for remediating crop rotation soil using biochar, characterized in that, Includes the following steps: S1. Weigh the cultivated soil and mix it evenly with the composite filler at a mass ratio of 6-10:1 to obtain the initial mixture; the composite filler is composed of biochar particles, cottonseed hulls and coated perilla meal with a mass ratio of 1:0.5-0.8:0.2-0.

5. S2. Add the initial mixture to the soil of the cultivated land. The amount of composite filler in 1 acre of cultivated land is 250-300 kg. It can be done by plowing and watering. The loaded biochar particles were prepared using the following method: Weigh out biochar granules and disperse them in water. Then add Bacillus subtilis powder at a mass ratio of 1:0.01-0.

03. Continue dispersing and then filter out the biochar granules to obtain a semi-finished product. Spray the surface of the semi-finished product with a binder and fiber filaments in sequence at a mass ratio of 1:0.2-0.4:0.1-0.

3. After drying and dispersion, obtain the finished loaded biochar granules. The cottonseed hulls used as the loading material are prepared by the following method: Cottonseed hulls were weighed and dispersed in water, then lactic acid bacteria powder was added and dispersed again. The mass ratio of cottonseed hulls to lactic acid bacteria powder was 1:0.005-0.

015. The cottonseed hulls were then filtered out, and a coating solution was evenly sprayed onto the surface. The mass ratio of cottonseed hulls to coating solution was 1:0.2-0.

5. After drying and dispersion, the finished cottonseed hulls were obtained. The coating solution was an ethyl cellulose solution. The ethyl cellulose solution consisted of an ethyl cellulose ethanol solution (mass ratio 10:0.5-1:1-2), shell powder, and lauric acid. Coated perilla meal is prepared using the following method: Weigh out perilla meal and soak and disperse it in glucono-delta-lactone solution. Then add Bacillus licheniformis powder. The mass ratio of perilla meal to Bacillus licheniformis is 1:0.01-0.

035. After dispersion treatment, filter out perilla meal to obtain loaded perilla meal. Bacillus licheniformis powder was evenly sprayed onto the surface of the perilla meal at a mass ratio of 1:0.001-0.003, followed by an evenly sprayed polylactic acid solution. The mass ratio of the perilla meal to the polylactic acid solution was 1:1-2. After drying, the finished coated perilla meal was obtained.

2. The method for remediating crop rotation soil using biochar according to claim 1, characterized in that, The adhesive solution is composed of sodium alginate solution and fucoidan solution in a mass ratio of 1:1-2.

3. A method for remediating crop rotation soil using biochar according to claim 1, characterized in that, The fiber filament is composed of bamboo fiber, cotton fiber, starch solution and casein in a mass ratio of 1:1-2:0.2-0.5:0.1-0.

3.

4. A method for remediating crop rotation soil using biochar according to claim 1, characterized in that, The polylactic acid solution is made from a polylactic acid aqueous solution, polycaprolactone, and fructose in a mass ratio of 10:0.1-0.4:0.1-0.

2.

5. A method for remediating crop rotation soil using biochar according to claim 4, characterized in that, The gluconolactone solution has a mass fraction of 0.5-2%.

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