Fertilizer used during cabbage planting and high-yield planting method

Abstract

The invention discloses a fertilizer used during cabbage planting and a high-yield planting method, belongs to the technical field of compound fertilizers, and aims to solve the problems that in the prior art, a fertilizer used during cabbage planting is incomplete in nutrient element proportion and is not suitable for whole-cycle growth of cabbages; the hydrolysis defect exists when polyurethane coating is adopted. The invention provides a fertilizer used during cabbage planting. The fertilizer is formed by in-situ polymerization of a coating solid liquid A and a coating solid liquid B on the surface of a compound fertilizer, the coating solid liquid A is prepared from toluene-2, 4-diisocyanate, a coalescing agent and modified biochar powder; and the coated solid liquid B comprises polyhydric alcohols, degradable monomers and a chain extender. The modified biochar powder is obtained by modifying biochar with a sodium silicate solution, and has the advantages of slow release and heavy metal absorption; the compound fertilizer comprises ammonium bicarbonate, diammonium phosphate, potassium sulfate, polypropylene glycol, calcium silicate slag and rare earth element cerium, is rich in nutrient elements, and has the advantages of high temperature resistance and hydrolysis resistance.

Description

Technical Field

[0001] The invention relates to the technical field of compound fertilizers, and in particular to a fertilizer used in cabbage planting and a high-yield planting method. Background Art

[0002] Cabbage, also known as kale, is rich in protein, fat and other nutrients, and has extremely high edible value. In addition, cabbage is cold-resistant, disease-resistant, adaptable, easy to store and transport, and is very popular among people. For a long time, due to the influence of traditional cultivation models and experience, the amount of fertilizer input for vegetable crops has been large, which not only caused nutrient imbalance, limited yield increase, economic waste and environmental pollution, but also reduced the safety and quality of vegetables. Therefore, it is necessary to achieve precise fertilization of cabbage according to the fertilizer requirement law of cabbage, soil fertilizer supply performance and fertilizer effect, so as to achieve the high-yield, high-quality, high-efficiency and environmentally friendly cultivation goals of vegetable production and promote the sustainable development of the vegetable industry.

[0003] However, direct application of fertilizers during cabbage planting can easily lead to fertilizer nutrient loss due to fertilizer volatilization and rainwater leaching, resulting in resource waste and environmental pollution. Therefore, the development of a series of slow-release fertilizers with water absorption and water retention functions is of great significance to improving water resources and fertilizer utilization. In addition, in order to achieve the purpose of precision fertilization, it is necessary to adjust the fertilizer use structure, optimize the ratio of nitrogen, phosphorus and potassium, promote the coordination of macroelements and trace elements, guide the optimization and upgrading of fertilizer products, and vigorously promote high-efficiency new fertilizers.

[0004] Patent application CN105111402A discloses a method for preparing a vegetable oil-based polyurethane coated fertilizer with improved water-blocking properties. The modified vegetable oil polyol and isocyanate resin liquid are mixed evenly and then coated on the surface of urea particles. The coating liquid is cross-linked and cured to finally form a polyurethane coated urea slow-release fertilizer. However, the film material and core material in the above-mentioned fertilizer have a single nutrient element that can be absorbed by vegetable crops and the content is relatively small, which is not conducive to the full-cycle growth of vegetable crops; in addition, in order to alleviate the disadvantage of easy hydrolysis of the preparation of coated fertilizers, a certain amount of hydrolysis stabilizer is added to the above-mentioned coated fertilizers, but the above-mentioned hydrolysis stabilizer cannot be absorbed by crops. Summary of the invention

[0005] The purpose of the present invention is to provide a fertilizer used in cabbage planting and a high-yield planting method, which is used to solve the technical problems in the prior art that the nutrient elements of film materials and core materials are single, which is not conducive to the full-cycle growth of vegetable crops; the coated fertilizer used is easy to hydrolyze, and the added hydrolysis stabilizer cannot be absorbed by vegetable crops.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A fertilizer used in cabbage planting, characterized in that the fertilizer is obtained by in-situ polymerization of coated solid liquid A and coated solid liquid B on the surface of a composite fertilizer to form a film;

[0008] In terms of weight, the coating solid liquid A includes 40-50 parts of toluene-2,4-diisocyanate, 3-5 parts of a film-forming aid and 1-5 parts of modified biochar powder; the coating solid liquid B includes 30-40 parts of a polyol, 5-10 parts of a degradable monomer and 5-10 parts of a chain extender.

[0009] Furthermore, the preparation method of the compound fertilizer comprises the following steps:

[0010] A1, ammonium bicarbonate, diammonium phosphate and potassium sulfate are mixed evenly, then added into a grinder and ground into 200-300 mesh, and then polypropylene alcohol is added and mixed evenly to obtain component A;

[0011] A2. Evenly mix calcium silicate slag and rare earth element lanthanum, add them into a grinder and grind them to 100-200 mesh to obtain component B; evenly mix component A and component B to obtain a compound fertilizer.

[0012] Furthermore, in step A1, the ratio of ammonium bicarbonate, diammonium phosphate, potassium sulfate and polypropylene alcohol is 10-15:5-10:5-10:5-10 in parts by weight; and in step A2, the ratio of calcium silicate slag and rare earth element lanthanum is 3-5:1-3 in parts by weight.

[0013] Furthermore, the modified biochar powder in the coated solid liquid A is prepared by the following steps:

[0014] B1. Pyrolyze rice straw at 400-500°C for 4-6 hours to obtain pyrolyzed straw; then use a standard sieve to sieve the pyrolyzed straw to obtain a 30-60 mesh powder, which is biochar powder; dry the biochar powder at 100-105°C for 24 hours to obtain pretreated biochar;

[0015] B2. Sodium silicate and deionized water are mixed to obtain a sodium silicate aqueous solution; the pretreated biochar is immersed in the sodium silicate aqueous solution, mixed and reacted at 30-40° C. for 30-60 minutes, and then filtered to obtain modified biochar; the modified biochar is ball-milled to 100 mesh to obtain modified biochar powder.

[0016] Furthermore, in step B2, the dosage ratio of sodium silicate to deionized water is 15-20 g:50 mL; the dosage ratio of pretreated biochar to sodium silicate aqueous solution is 10-20 g:50 mL.

[0017] Furthermore, the film-forming aid is obtained by mixing 1-2 parts of paraffin wax and 2-3 parts of rosin; the polyol is one of castor oil, soybean oil polyol or palm oil; the degradable monomer is any one of starch or chitosan; and the chain extender is sorbitol.

[0018] As another aspect of the present invention, a method for preparing a fertilizer used in cabbage planting comprises the following steps:

[0019] S1, toluene-2,4-diisocyanate, film-forming aid and modified biochar powder are mixed evenly to obtain coating solid liquid A; polyol, degradable monomer and chain extender are mixed evenly to obtain coating solid liquid B;

[0020] S2. The compound fertilizer is placed in a coating machine and preheated to 100-110° C.; the coated solid liquid A is preheated to 60-80° C., the coated solid liquid B is preheated to 80-100° C., and then the coated solid liquid A and the coated solid liquid B are sprayed onto the surface of the compound fertilizer in sequence using an atomizing nozzle; the temperature of the coating machine is set to 80-100° C. and maintained for 10-30 minutes to obtain the coated fertilizer; the coated fertilizer is naturally cooled to room temperature to obtain a fertilizer used for cabbage planting.

[0021] A high-yield cabbage planting method, comprising adding fertilizer used in cabbage planting to the soil of an experimental field, and then transplanting cabbage seedlings; wherein the planting density of the cabbage seedlings is 5.5-6.5 plants / m 2 The density of fertilizer used in cabbage planting is 0.1-0.2kg / m 2 .

[0022] The present invention has the following beneficial effects:

[0023] 1. The present invention uses a composite fertilizer as the wall core, and obtains a polyurethane wall material by in-situ polymerization of a coated solid liquid A and a coated solid liquid B. Coated solid liquid A includes a polyisocyanate monomer, a film-forming aid and a modified biochar powder; coated solid liquid B includes a polyol, a reducible monomer and a chain extender; the coated solid liquid A and the coated solid liquid B are sprayed on the surface of the composite fertilizer by atomization to obtain the fertilizer used for cabbage planting of the present invention. Among them, the modified biochar powder is obtained by pyrolysis of rice straw; the biochar produced by pyrolysis of rice straw contains a certain amount of nitrogen, phosphorus, potassium and other nutrients, which has a certain promoting effect on plant growth. Sodium silicate reacts with water to generate organosilanol, which contains a large number of hydroxyl functional groups; the surface of biochar contains functional groups such as hydroxyl, carboxyl, and aldehyde, which can be combined with organosilanol by hydrogen bonds, covalent bonds, etc. to obtain modified biochar powder. The hydroxyl functional groups in the organosilanol can react with toluene-2,4-diisocyanate in the coating solid liquid A, thereby increasing the compactness of the coating solid liquid A and the coating solid liquid B. In addition, sodium silicate itself can alleviate the absorption and accumulation of heavy metals by vegetables such as cabbage; biochar, as a carbon-rich substance, has a large specific surface area and porous structure. As a component of the coating material, it can become an excellent slow-release carrier for compound fertilizers, alleviate the loss of compound fertilizers, and thus improve the utilization rate of fertilizers.

[0024] 2. The present invention uses compound fertilizer as the wall core, phosphorus, nitrogen and potassium as the macroelements required for plant growth, ammonium bicarbonate as the nitrogen source, diammonium phosphate as the phosphorus source, and potassium sulfate as the potassium source; waste calcium silicate slag is used as silicon fertilizer, and silicon is deposited on the epidermis of cabbage plants to make them silicified, which has the effect of disease resistance and insect resistance. Adding a small amount of rare earth element lanthanum can promote the growth of underdeveloped root systems. Adding highly water-absorbent polymer polypropylene alcohol to the above-mentioned nutrient elements can improve the stable performance of compound fertilizers in high temperature and humid environments, and further improve the utilization efficiency of preparing compound fertilizers. Ammonium bicarbonate, as a nitrogen fertilizer, is volatile at room temperature and pressure and has a strong ammonia odor, and its volatility increases with increasing temperature and humidity. In addition, water can accelerate the deliquescence of ammonium bicarbonate and cause it to agglomerate. The decomposition of ammonium bicarbonate will further cause nitrogen loss, and it is an extremely unstable nitrogen. Potassium sulfate, as a water-soluble potash fertilizer, is prone to deliquescence. By coating the above compound fertilizer, the loss rate of the compound fertilizer can be reduced, thereby improving the absorption efficiency of nutrient elements by vegetable crops such as cabbage. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] This embodiment provides a method for preparing a compound fertilizer used in cabbage planting, comprising the following steps:

[0028] According to weight parts, 10 parts of ammonium bicarbonate, 5 parts of diammonium phosphate and 5 parts of potassium sulfate are mixed evenly, then added to a grinder and ground to 200 mesh, and then 5 parts of polypropylene alcohol are added and mixed evenly to obtain component A; 3 parts of calcium silicate slag and 1 part of rare earth element lanthanum are mixed evenly, then added to a grinder and ground to 100 mesh to obtain component B; the above components A and B are mixed evenly to obtain a composite fertilizer.

[0029] Example 2

[0030] This embodiment provides a method for preparing a compound fertilizer used in cabbage planting, comprising the following steps:

[0031] According to weight parts, 12 parts of ammonium bicarbonate, 8 parts of diammonium phosphate and 6 parts of potassium sulfate are mixed evenly, then added to a grinder and ground to 300 mesh, and then 6 parts of polypropylene alcohol are added and mixed evenly to obtain component A; 4 parts of calcium silicate slag and 2 parts of rare earth element cerium are mixed evenly, then added to a grinder and ground to 100 mesh to obtain component B; the above components A and B are mixed evenly to obtain a composite fertilizer.

[0032] Example 3

[0033] This embodiment provides a method for preparing a compound fertilizer used in cabbage planting, comprising the following steps:

[0034] According to weight parts, 15 parts of ammonium bicarbonate, 10 parts of diammonium phosphate and 10 parts of potassium sulfate are mixed evenly, then added to a grinder and ground to 200 mesh, and then 10 parts of polypropylene alcohol are added and mixed evenly to obtain component A; 5 parts of calcium silicate slag and 3 parts of rare earth elements are mixed evenly, then added to a grinder and ground to 200 mesh to obtain component B; the above components A and B are mixed evenly to obtain a composite fertilizer.

[0035] Example 4

[0036] This embodiment provides a method for preparing a fertilizer used in cabbage planting, comprising the following steps:

[0037] S1. Pyrolyze rice straw at 400°C for 6 hours to obtain pyrolyzed straw; then use a standard sieve to sieve the pyrolyzed straw to obtain a 30-mesh powder, which is biochar powder; then place the biochar powder in an electric heated forced air drying oven at 100°C and dry it for 24 hours to obtain pretreated biochar.

[0038] S2, 15g of sodium silicate and 50mL of deionized water were mixed and added to a 150mL beaker, mixed at room temperature for 30min to obtain a sodium silicate aqueous solution; then 10g of pretreated biochar was soaked in 50mL of sodium silicate aqueous solution, and then the beaker was transferred to a water bath, heated to 30°C, mixed and stirred at 100r / min for 30min, and then filtered to obtain modified biochar. The modified biochar was added to a ball mill for ball milling to obtain a modified biochar powder with a particle size of 100 mesh.

[0039] S3. According to weight parts, 40 parts of toluene-2,4-diisocyanate, 1 part of paraffin, 2 parts of rosin and 1 part of modified biochar powder are mixed, and the mixture is stirred at 100 r / min for 20 minutes to obtain coated solid liquid A.

[0040] S4. According to parts by weight, 30 parts of polyol, 5 parts of degradable monomer and 5 parts of chain extender sorbitol are mixed evenly to obtain coating solid liquid B.

[0041] S5. Preheat the composite fertilizer in a coating machine to 100° C.; preheat the coated solid liquid A to 60° C., preheat the coated solid liquid B to 80° C., and then spray the coated solid liquid A and the coated solid liquid B onto the surface of the composite fertilizer prepared in Example 1 in sequence using an atomizing nozzle; maintain the temperature of the coating machine at 80° C. for 30 min to obtain a coated fertilizer; and naturally cool the coated fertilizer to room temperature to obtain a fertilizer for cabbage planting.

[0042] Example 5

[0043] This embodiment provides a method for preparing a fertilizer used in cabbage planting, comprising the following steps:

[0044] S1. Pyrolyze rice straw at 500°C for 4 hours to obtain pyrolyzed straw; then use a standard sieve to sieve the pyrolyzed straw to obtain a 50-mesh powder, which is biochar powder; then place the biochar powder in an electric heated forced air drying oven at 102°C and dry it for 24 hours to obtain pretreated biochar.

[0045] S2, 18g of sodium silicate and 50mL of deionized water were mixed and added to a 150mL beaker, mixed at room temperature for 50min to obtain a sodium silicate aqueous solution; then 15g of pretreated biochar was soaked in 50mL of sodium silicate aqueous solution, and then the beaker was transferred to a water bath, heated to 35°C, mixed and stirred at 150r / min for 50min, and then filtered to obtain modified biochar. The modified biochar was added to a ball mill for ball milling to obtain a modified biochar powder with a particle size of 100 mesh.

[0046] S3. According to weight parts, 45 parts of toluene-2,4-diisocyanate, 2 parts of paraffin, 3 parts of rosin and 2 parts of modified biochar powder are mixed, and the mixture is stirred at 120 r / min for 25 minutes to obtain coated solid liquid A.

[0047] S4. According to parts by weight, 36 parts of polyol, 6 parts of degradable monomer and 6 parts of chain extender sorbitol are mixed evenly to obtain coating solid liquid B.

[0048] S5. Preheat the composite fertilizer in a coating machine to 105° C.; preheat the coated solid liquid A to 70° C., preheat the coated solid liquid B to 90° C., and then spray the coated solid liquid A and the coated solid liquid B onto the surface of the composite fertilizer prepared in Example 2 using an atomizing nozzle; maintain the temperature of the coating machine at 90° C. for 20 min to obtain a coated fertilizer; and naturally cool the coated fertilizer to room temperature to obtain a fertilizer for cabbage planting.

[0049] Example 6

[0050] This embodiment provides a method for preparing a fertilizer used in cabbage planting, comprising the following steps:

[0051] S1. Pyrolyze rice straw at 450°C for 5 hours to obtain pyrolyzed straw; then use a standard sieve to sieve the pyrolyzed straw to obtain a 60-mesh powder, which is biochar powder; then place the biochar powder in an electric heated forced air drying oven at 105°C and dry it for 24 hours to obtain pretreated biochar.

[0052] S2, 20g of sodium silicate and 50mL of deionized water were mixed and added to a 150mL beaker, mixed at room temperature for 60min to obtain a sodium silicate aqueous solution; then 20g of pretreated biochar was soaked in 50mL of sodium silicate aqueous solution, and then the beaker was transferred to a water bath, heated to 40°C, mixed and stirred at 200r / min for 60min, and then filtered to obtain modified biochar. The modified biochar was added to a ball mill for ball milling to obtain a modified biochar powder with a particle size of 100 mesh.

[0053] S3. According to weight parts, 50 parts of toluene-2,4-diisocyanate, 2 parts of paraffin, 3 parts of rosin and 5 parts of modified biochar powder are mixed, and the mixture is stirred at 200 r / min for 30 minutes to obtain coated solid liquid A.

[0054] S4. According to parts by weight, 40 parts of polyol, 10 parts of degradable monomer and 10 parts of chain extender sorbitol are mixed evenly to obtain coating solid liquid B.

[0055] S5. Preheat the composite fertilizer in a coating machine to 110° C.; preheat the coated solid liquid A to 80° C., preheat the coated solid liquid B to 100° C., and then spray the coated solid liquid A and the coated solid liquid B onto the surface of the composite fertilizer prepared in Example 3 using an atomizing nozzle; maintain the temperature of the coating machine at 100° C. for 30 min to obtain a coated fertilizer; and naturally cool the coated fertilizer to room temperature to obtain a fertilizer for cabbage planting.

[0056] Example 7

[0057] This embodiment provides a method for high-yield planting of cabbage, comprising the following steps:

[0058] The fertilizer used for cabbage planting prepared in Example 6 was added to the soil of the test field, and then the cabbage seedlings were transplanted; wherein the planting density of the cabbage seedlings was 5.5 plants / m 2 The density of fertilizer used in cabbage planting is 0.2kg / m 2 .

[0059] Example 8

[0060] This embodiment provides a method for high-yield planting of cabbage, comprising the following steps:

[0061] The fertilizer used for cabbage planting prepared in Example 6 was added to the soil of the test field, and then the cabbage seedlings were transplanted; wherein the planting density of the cabbage seedlings was 6 plants / m 2 The density of fertilizer used in cabbage planting is 0.15kg / m 2 .

[0062] Example 9

[0063] This embodiment provides a method for high-yield planting of cabbage, comprising the following steps:

[0064] The fertilizer used for cabbage planting prepared in Example 6 was added to the soil of the experimental field, and then the cabbage seedlings were transplanted; wherein the planting density of the cabbage seedlings was 6.5 plants / m 2 The density of fertilizer used in cabbage planting is 0.2kg / m 2 .

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 7 is that when the fertilizer prepared in Example 6 for cabbage planting is used, the modified biocarbon powder is not added when preparing the coated solid liquid A.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 7 is that when the fertilizer prepared in Example 6 for cabbage planting is used, no polypropylene alcohol is added when preparing the compound fertilizer.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 7 is that when the fertilizer prepared in Example 6 for cabbage planting is used, the chain extender sorbitol is not added when preparing the coating solid liquid B.

[0071] Performance Test:

[0072] The utilization rates of phosphorus, nitrogen and potassium elements were tested after three months of planting cabbage in Examples 7-9 and Comparative Examples 1-3. The total nitrogen content of cabbage plants was determined by concentrated sulfuric acid-hydrogen peroxide digestion / Kjeldahl nitrogen determination method; the total phosphorus and total potassium contents of cabbage plants were determined by HNO3-H2O2 combined digestion and ICP-AES inductively coupled atomic emission spectrometry.

[0073] Utilization rate of (nitrogen, phosphorus, potassium) elements = [(nitrogen, phosphorus, potassium) element content in cabbage / (nitrogen, phosphorus, potassium) element content in fertilizer] × 100%. See Table 1 for specific test results.

[0074] Table 1. Performance test data of samples

[0075]

[0076] Data Analysis:

[0077] Analyzing the data in Table 1, the cabbage cultivated with the fertilizer prepared in Examples 4-6 in Examples 7-9 of the present invention has a high utilization rate of nitrogen, phosphorus and potassium. However, in Comparative Example 1, when preparing the coated solid-liquid A, the modified biochar powder was not added. As a component of the coating material, biochar can effectively slow-release the compound fertilizer, thereby interfering with the improvement of the utilization rate of the fertilizer. Therefore, the cabbage planted by the high-yield cabbage planting method provided in Comparative Example 1 has a reduced utilization rate of nitrogen, phosphorus and potassium. In Comparative Example 2, when preparing the coating material, polypropylene alcohol was not added, which is not conducive to improving the stability of the compound fertilizer in a high temperature and humid environment; in Comparative Example 3, when preparing the coated solid-liquid B, the chain extender sorbitol was not added, which is not conducive to improving the compatibility and stability of the components of the film layer, and both will reduce the slow-release rate and utilization rate of the prepared fertilizer, which is manifested as a reduced utilization efficiency of nitrogen, phosphorus and potassium nutrients.

[0078] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0079] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0080] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A fertilizer for cabbage planting, characterized in that: The fertilizer is obtained by in-situ polymerization of coated solid-liquid A and coated solid-liquid B on the surface of the composite fertilizer to form a film; In terms of weight, the coating solid liquid A includes 40-50 parts of toluene-2,4-diisocyanate, 3-5 parts of a film-forming aid and 1-5 parts of modified biochar powder; the coating solid liquid B includes 30-40 parts of a polyol, 5-10 parts of a degradable monomer and 5-10 parts of a chain extender.

2. The fertilizer used for cabbage planting according to claim 1, characterized in that: The preparation method of the compound fertilizer comprises the following steps: A1, ammonium bicarbonate, diammonium phosphate and potassium sulfate are mixed evenly, then added into a grinder and ground into 200-300 mesh, and then polypropylene alcohol is added and mixed evenly to obtain component A; A2. Evenly mix calcium silicate slag and rare earth element lanthanum, add them into a grinder and grind them to 100-200 mesh to obtain component B; evenly mix component A and component B to obtain a compound fertilizer.

3. The fertilizer used for cabbage planting according to claim 2, characterized in that: In step A1, the ratio of ammonium bicarbonate, diammonium phosphate, potassium sulfate and polypropylene alcohol is 10-15:5-10:5-10:5-10 in parts by weight; in step A2, the ratio of calcium silicate slag and rare earth element lanthanum is 3-5:1-3 in parts by weight.

4. The fertilizer used for cabbage planting according to claim 1, characterized in that: The modified biochar powder in the coating solid liquid A is prepared by the following steps: B1. Pyrolyze rice straw at 400-500°C for 4-6 hours to obtain pyrolyzed straw; then use a standard sieve to sieve the pyrolyzed straw to obtain a 30-60 mesh powder, which is biochar powder; dry the biochar powder at 100-105°C for 24 hours to obtain pretreated biochar; B2, sodium silicate and deionized water are mixed to obtain a sodium silicate aqueous solution; the pretreated biochar is immersed in the sodium silicate aqueous solution, mixed and reacted at 30-40° C. for 30-60 minutes, and then filtered to obtain modified biochar; The modified biochar is ball-milled to 100 meshes to obtain modified biochar powder.

5. The fertilizer used for cabbage planting according to claim 4, characterized in that: In step B2, the dosage ratio of sodium silicate to deionized water is 15-20 g:50 mL; the dosage ratio of pretreated biochar to sodium silicate aqueous solution is 10-20 g:50 mL.

6. The fertilizer used for cabbage planting according to claim 1, characterized in that: The film-forming aid is obtained by mixing 1-2 parts of paraffin wax and 2-3 parts of rosin; the polyol is one of castor oil, soybean oil polyol or palm oil; the degradable monomer is any one of starch or chitosan; and the chain extender is sorbitol.

7. The fertilizer used for cabbage planting according to claim 1, characterized in that: The method for preparing the fertilizer used in cabbage planting comprises the following steps: S1, toluene-2,4-diisocyanate, film-forming aid and modified biochar powder are mixed evenly to obtain coating solid liquid A; polyol, degradable monomer and chain extender are mixed evenly to obtain coating solid liquid B; S2. The compound fertilizer is placed in a coating machine and preheated to 100-110° C.; the coated solid liquid A is preheated to 60-80° C., the coated solid liquid B is preheated to 80-100° C., and then the coated solid liquid A and the coated solid liquid B are sprayed onto the surface of the compound fertilizer in sequence using an atomizing nozzle; the temperature of the coating machine is set to 80-100° C. and maintained for 10-30 minutes to obtain the coated fertilizer; the coated fertilizer is naturally cooled to room temperature to obtain a fertilizer used for cabbage planting.

8. A high-yield cabbage planting method, characterized in that: The fertilizer used for planting cabbage according to any one of claims 1 to 6 is added to the soil of the test field, and then cabbage seedlings are transplanted; wherein the planting density of the cabbage seedlings is 5.5-6.5 plants / m 2 The density of fertilizer used in cabbage planting is 0.1-0.2kg / m 2 .

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