Lignosulfonate-containing carbon-based fertilizer and preparation method thereof

Abstract

The invention belongs to the technical field of soil fertility improvement, and particularly relates to a lignosulfonate-containing carbon-based fertilizer and a preparation method thereof. The lignosulfonate-containing carbon-based fertilizer is prepared from the following raw materials: 12% of biomass charcoal, 5% of lignosulfonate, 20% of bentonite, 20-25% of urea, 12-30% of diammonium hydrogen phosphate and 14-26% of potassium sulfate. The preparation method comprises the following steps: uniformly mixing biomass charcoal, urea, diammonium hydrogen phosphate, potassium sulfate and lignosulfonate with 3 / 4 amount of bentonite, granulating, adding the residual bentonite in batches when particles are preliminarily formed, continuously granulating, forming complete particles, and drying to obtain the lignosulfonate-containing carbon-based fertilizer. The product provided by the invention has the effects of improving soil nutrient status, improving fertilizer utilization efficiency, slowly controlling the fertilizer and the like, can solve the problems of unbalanced nutrients in soil, improving the nutrient utilization efficiency and the like, and realizes the effect of improving the fertility of the soil.

Description

Technical Field

[0001] The invention belongs to the technical field of soil fertilization, and more specifically relates to a carbon-based fertilizer containing lignin sulfonate and a preparation method thereof. Background Art

[0002] Traditional chemical fertilizers, such as nitrogen fertilizers, can lead to soil acidification if used in large quantities. The phosphorus element in phosphate fertilizers can easily lead to eutrophication of water bodies when entering water bodies with water. Long-term use of organic fertilizers can cause soil compaction, reduce soil porosity, and affect soil aeration and water permeability. There are environmental risks in the production and use of organic fertilizers. For example, untreated farmyard manure may carry harmful organisms such as pathogens and insect eggs. If it is not properly handled during the composting process, it will also produce odor and greenhouse gas emissions. Its long-term use will have a negative impact on soil quality. The existing fertilizer nutrient supply is unbalanced and cannot simultaneously meet the needs of crops for multiple nutrients at different growth stages. Some fertilizers have a short effective period and require frequent fertilization, which increases agricultural production costs. At the same time, improper application will also affect crop growth. How to solve the problem of improving soil fertility, promoting healthy crop growth, and ensuring sustainable agricultural development while making full use of fertilizers has become an important direction of current research and development.

[0003] Existing soil fertilization technologies mainly include: application of organic fertilizers, such as farmyard manure, green manure, compost, etc.; chemical improvement technology, such as application of lime and gypsum as soil conditioners; reasonable crop rotation; returning straw to the field, etc. However, the above schemes currently have problems such as soil nutrient imbalance and low fertilizer utilization rate, and do not fundamentally solve the soil fertilization problem. How to provide a fertilizer with slow-release fertilizer to improve fertilizer utilization efficiency and thus improve soil nutrient conditions has become a problem that technicians in this field urgently need to overcome. Summary of the invention

[0004] The purpose of the present invention is to provide a carbon-based fertilizer containing lignin sulfonate and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art, thereby improving the soil nutrient status and increasing the fertilizer utilization efficiency.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is to provide a carbon-based fertilizer containing lignin sulfonate, wherein the raw materials include, by mass percentage, 12% biochar, 5% lignin sulfonate, 20% bentonite, 20-25% urea, 12-30% diammonium hydrogen phosphate and 14-26% potassium sulfate.

[0007] Optionally, the carbon-based fertilizer containing lignin sulfonate comprises, by mass percentage, the following raw materials: 12% biochar, 5% lignin sulfonate, 20% bentonite, 24.1% urea, 13% diammonium hydrogen phosphate and 25.9% potassium sulfate.

[0008] Optionally, the carbon-based fertilizer containing lignin sulfonate comprises, by mass percentage, the following raw materials: 12% biochar, 5% lignin sulfonate, 20% bentonite, 20% urea, 28.7% diammonium hydrogen phosphate and 14.3% potassium sulfate.

[0009] Optionally, the lignin xanthate is specifically a by-product produced during the sulfite pulping process in the papermaking industry.

[0010] The second technical solution of the present invention is to provide a method for preparing the above-mentioned carbon-based fertilizer containing lignin sulfonate, the steps comprising:

[0011] The biomass charcoal, urea, diammonium hydrogen phosphate, potassium sulfate and lignin sulfonate are uniformly mixed with 3 / 4 amount of bentonite and then granulated. When the granules are initially formed, the remaining bentonite is added in batches and granulation is continued. After the complete granules are formed, the charcoal-based fertilizer containing lignin sulfonate is obtained by drying.

[0012] Optionally, water spraying is used to assist granulation during the preparation process.

[0013] Optionally, the drying temperature is 60° C. and the drying time is 3 to 5 hours.

[0014] The third technical solution of the present invention is to provide an application of the above-mentioned carbon-based fertilizer containing lignin sulfonate in the field of soil fertilization technology.

[0015] The present invention discloses the following technical effects:

[0016] In the present invention, lignin sulfonate cooperates with biochar, urea, diammonium hydrogen phosphate, and potassium sulfate, that is, the surface of the biochar-based fertilizer has a dense covering layer, and contains mineral crystals inside. This structure makes nitrogen, phosphorus, and potassium nutrients evenly distributed on the surface and internal structure of the fertilizer, which is conducive to the uniform release of nutrients and the absorption of plants; lignin sulfonate can form a stable covalent bond with nitrogen (such as nitrogen in urea), and this chemical bond is conducive to the slow release of nitrogen, reducing the volatilization and loss of nitrogen, thereby improving the utilization efficiency of nitrogen fertilizer. This makes it have the effects of improving soil nutrient conditions, improving fertilizer utilization efficiency, slow-release fertilizer, etc., can solve the problems of nutrient imbalance in the soil and improving nutrient utilization efficiency, and achieve soil fertilization effect. At the same time, the use of bentonite can improve the physical properties of fertilizer particles and enhance fertilizer stability; the use of lignin sulfonate can strengthen the surface functional groups of fertilizers related to nitrogen fixation, thereby improving the effectiveness of nitrogen in carbon-based fertilizers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0018] Figure 1 The physicochemical properties of the soil after rice harvest in Examples 1 to 2 and Comparative Examples 1 to 4 are shown in Table 1, wherein a is the soil organic carbon content, b is the soil total nitrogen content, c is the soil ammonium nitrogen content, d is the soil nitrate nitrogen content, e is the soil available phosphorus content, and f is the soil available potassium content.

[0019] Figure 2 Schematic diagram of the soil column test device.

[0020] Figure 3 is the single leaching rate of nitrogen from fertilizers with different formulas.

[0021] Figure 4 is the cumulative nitrogen leaching rate of fertilizers with different formulas. DETAILED DESCRIPTION

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0024] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0025] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0026] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0027] The raw materials used in the present invention are all commercially available products, and the purchase channels do not affect the realization of the technical effects.

[0028] The lignin sulfonate used in the specific embodiment of the present invention is specifically a by-product produced during the sulfite pulping process in the papermaking industry.

[0029] During the pulping process, lignin reacts with sulfurous acid and its salts (such as sodium sulfite, magnesium sulfite) to form lignin sulfonic acid, which then combines with cations in the solution to form lignin sulfonates (such as sodium lignin sulfonate, magnesium lignin sulfonate).

[0030] Example 1

[0031] The preparation steps of the carbon-based fertilizer containing lignin sulfonate are:

[0032] S1. Raw material preparation: biochar 12.0%, lignin sulfonate 5.0%, bentonite 20.0%, urea 24.1%, diammonium hydrogen phosphate 13.0%, potassium sulfate 25.9%;

[0033] S2. The biochar, urea, diammonium phosphate, potassium sulfate, lignin sulfonate and 75% bentonite are mixed evenly and granulated. Deionized water is sprayed during the granulation process to assist the granulation. When the granules are initially formed, the remaining bentonite is added in three times and the granulation is continued. After the complete granules are formed, they are placed in an oven and dried at 60°C for 3 to 5 hours to obtain lignin sulfonate charcoal-based fertilizer, which is recorded as lowP:K-LBCF.

[0034] After testing, the effective nutrient content of the fertilizer prepared in this embodiment is 35%, NP 2 O 5 -K 2 O=14.0-7.0-14.0.

[0035] Example 2

[0036] The preparation steps of the carbon-based fertilizer containing lignin sulfonate are:

[0037] S1. Raw material preparation: biochar 12.0%, lignin sulfonate 5.0%, bentonite 20.0%, urea 20.0%, diammonium hydrogen phosphate 28.7%, potassium sulfate 14.3%;

[0038] S2. The biochar, urea, diammonium hydrogen phosphate, potassium sulfate, lignin sulfonate and 75% bentonite are mixed evenly and granulated. Deionized water is sprayed during the granulation process to assist the granulation. When the granules are initially formed, the remaining bentonite is added in three times and the granulation is continued. After the complete granules are formed, they are placed in an oven and dried at 60°C for 3 to 5 hours to obtain lignin sulfonate charcoal-based fertilizer, which is recorded as highP:K-LBCF.

[0039] After testing, the effective nutrient content of the fertilizer prepared in this embodiment is 38.5%, NP 2 O 5 -K 2 O=15.4-15.4-7.7.

[0040] Comparative Example 1

[0041] The steps for preparing fertilizer are:

[0042] S1. Raw material preparation: bentonite 20.0%, urea 30.6%, diammonium hydrogen phosphate 16.5%, potassium sulfate 32.9%;

[0043] S2. Urea, diammonium hydrogen phosphate, potassium sulfate and 75% bentonite are mixed evenly and granulated. Deionized water is sprayed during the granulation process to assist granulation. When the granules are initially formed, the remaining bentonite is added in three times and granulation is continued. After the complete granules are formed, they are placed in an oven and dried at 60°C for 3 to 5 hours to obtain fertilizer granules, which are recorded as lowP:K-CF.

[0044] After testing, the effective nutrient content of the fertilizer prepared in this comparative ratio is 44.5%, NP 2 O 5 -K 2 O=17.8-8.9-17.8.

[0045] Comparative Example 2

[0046] The steps for preparing fertilizer are:

[0047] S1. Raw material preparation: biochar 12.0%, bentonite 20.0%, urea 26.0%, diammonium hydrogen phosphate 14.0%, potassium sulfate 28.0%;

[0048] S2. The biochar, urea, diammonium hydrogen phosphate, potassium sulfate and 75% bentonite are mixed evenly and granulated. Deionized water is sprayed during the granulation process to assist granulation. When the granules are initially formed, the remaining bentonite is added in three times and granulation is continued. After the complete granules are formed, they are placed in an oven and dried at 60°C for 3 to 5 hours to obtain fertilizer granules, which are recorded as lowP:K-BCF.

[0049] After testing, the effective nutrient content of the fertilizer prepared in this comparative ratio is 38.0%, NP 2 O 5 -K 2 O=15.2-7.6-15.2.

[0050] Comparative Example 3

[0051] The steps for preparing fertilizer are:

[0052] S1. Raw material preparation: bentonite 20.0%, urea 25.5%, diammonium hydrogen phosphate 36.4%, potassium sulfate 18.1%;

[0053] S2. Urea, diammonium hydrogen phosphate, potassium sulfate and 75% bentonite are mixed evenly and granulated. Deionized water is sprayed during the granulation process to assist granulation. When the granules are initially formed, the remaining bentonite is added in three times and granulation is continued. After the complete granules are formed, they are placed in an oven and dried at 60°C for 3 to 5 hours to obtain fertilizer granules, which are recorded as highP:K-CF.

[0054] After testing, the effective nutrient content of the fertilizer prepared in this comparative ratio is 49.0%, NP 2 O 5 -K 2 O=19.6-19.6-9.8.

[0055] Comparative Example 4

[0056] The steps for preparing fertilizer are:

[0057] S1. Raw material preparation: biochar 12.0%, bentonite 20.0%, urea 21.6%, diammonium hydrogen phosphate 31.0%, potassium sulfate 15.4%;

[0058] S2. The biochar, urea, diammonium hydrogen phosphate, potassium sulfate, lignin sulfonate and 75% bentonite are mixed evenly and granulated. Deionized water is sprayed during the granulation process to assist granulation. When the granules are initially formed, the remaining bentonite is added in three times and granulation is continued. After the complete granules are formed, they are placed in an oven and dried at 60°C for 3 to 5 hours to obtain fertilizer granules, which are recorded as highP:K-BCF.

[0059] After testing, the effective nutrient content of the fertilizer prepared in this comparative ratio is 42.0%, NP 2 O 5 -K 2 O=16.8-16.8-8.4.

[0060] Comparative Example 5

[0061] The steps for preparing fertilizer are:

[0062] Compared with Example 1, the only difference is that no bentonite component is added.

[0063] Without the addition of bentonite, it is difficult to granulate and the final product is a powdery fertilizer.

[0064] Comparative Example 6

[0065] The steps for preparing fertilizer are:

[0066] S1. Raw material preparation: biochar 12.0%, lignin sulfonate 5.0%, bentonite 20.0%, urea 24.1%, diammonium hydrogen phosphate 13.0%, potassium sulfate 25.9%;

[0067] S2. The biochar, urea, diammonium phosphate, potassium sulfate, lignin sulfonate and bentonite are uniformly mixed and granulated. Deionized water is sprayed during the granulation process to assist the granulation. After the complete particles are formed, they are placed in an oven and dried at 60° C. for 3 to 5 hours to obtain lignin sulfonate carbon-based fertilizer.

[0068] After testing, the effective nutrient content of the fertilizer prepared in this embodiment is 35%, NP 2 O 5 -K 2 O=14.0-7.0-14.0.

[0069] Test example

[0070] Pot experiment:

[0071] Test soil: taken from the rice-wheat rotation soil system, soil clay content 30.2%, silt content 33.6%, sand content 36.2%, soil texture is loamy clay, the basic physical and chemical properties of the surface soil are: bulk density 1.38g / cm 3 , pH 6.79 (1:2.5), organic carbon 14.13 g / kg, total nitrogen 0.97 g / kg, available phosphorus 7.87 mg / kg, and available potassium 69.17 mg / kg.

[0072] The test crop was rice (variety C Liangyou Huazhan), and the test was conducted in the greenhouse of Baima Base of Nanjing Agricultural University. 3.0 kg of test soil was placed in pots with a diameter of 20 cm and a height of 18 cm. The seeds were sown on July 5 and transplanted on July 22. There were 3 holes in each pot and 1 plant in each hole. The total effective nutrient amount applied to each treatment control was 337.5 kg / hm 2 .

[0073] The experiment set up 7 treatments, each with 5 replicates, including NoF treatment group (no fertilizer), lowP:K-LBCF treatment group (Example 1), highP:K-LBCF treatment group (Example 2), lowP:K-CF treatment group (Comparative Example 1), lowP:K-BCF treatment group (Comparative Example 2), highP:K-CF treatment group (Comparative Example 3) and highP:K-BCF treatment group (Comparative Example 4). Fertilizer was applied as basal fertilizer 3 days before rice transplanting. All potted plants were designed with complete blocks. The physical and chemical properties of rice after harvest were as follows Figure 1 As shown, a is the soil organic carbon content, b is the soil total nitrogen content, c is the soil ammonium nitrogen content, d is the soil nitrate nitrogen content, e is the soil available phosphorus content, and f is the soil available potassium content.

[0074] The nitrogen accumulation and nitrogen utilization rate of rice stems, leaves, roots, grains and plants treated with different fertilizers are shown in Table 1.

[0075] Table 1

[0076]

[0077]

[0078] It can be seen from the data in Table 1 that in the lowP:K group, the addition of lignin sulfonate to the carbon-based fertilizer increased the nitrogen accumulation of rice stems and leaves, total nitrogen accumulation, and nitrogen utilization efficiency by 14.5%, 1.4%, and 5.4%, respectively; while in the highP:K group, the addition of lignin sulfonate to the carbon-based fertilizer increased the nitrogen accumulation of rice stems and leaves, nitrogen accumulation in the roots, total nitrogen accumulation, and nitrogen utilization efficiency by 8.5%, 44.8%, 1.9%, and 5.4%, respectively. In the lowP:K group, the addition of biochar and lignin sulfonate to fertilizer increased the stem and leaf nitrogen accumulation, total nitrogen accumulation, and nitrogen use efficiency by 13.7%, 3.2%, and 12.4%, respectively; while in the highP:K group, the addition of biochar and lignin sulfonate to fertilizer increased the rice stem and leaf nitrogen accumulation, root nitrogen accumulation, total nitrogen accumulation, and nitrogen use efficiency by 23.4%, 44.8%, 1.9%, and 7.2%, respectively.

[0079] Determination method of slow-release fertilizer: soil column leaching test is adopted. In soil column leaching test, fertilizer and soil are mixed and filled into soil column under indoor conditions. Then, it is periodically eluted with water, the filtrate is collected and the nutrient content in the filtrate is determined. This method simulates the physical, chemical and biological environment of fertilizer in soil under natural conditions, thereby reflecting the release characteristics of nutrients in soil.

[0080] The test soil was taken from the surface soil (0-20cm) of a rice-wheat rotation farmland. Basic soil properties: bulk density 1.38g / cm 3 , pH 6.79 (1:2.5), organic carbon 14.13g / kg, total nitrogen 0.97g / kg, available phosphorus 7.87mg / kg, available potassium 69.17mg / kg, remove plant roots and other impurities in the soil, dry naturally, grind and pass through a 2mm sieve, mix evenly, and store for later use.

[0081] Soil column test equipment Figure 2 As shown. The diameter of the PVC column is 5cm and the height is 25cm. A 5.5×5.5cm square PVC board is fixed at the bottom of the soil column, and 3 evenly distributed small holes are punched in the center of each board as leaching outlets. About 2cm of acid-washed quartz sand is laid at the bottom of the soil column, and a layer of 100-mesh nylon mesh is attached. Set the soil column to a height of 15cm, compact it, and evenly cover it with 3g of finished fertilizer granules, then cover it with a 3cm thick soil layer and a 100-mesh nylon mesh.

[0082] Seven treatments were set up, with no fertilizer added (CK) as the blank control, and the other six treatments were added with prepared lowP:K-CF, lowP:K-BCF, lowP:K-LBCF, highP:K-CF, highP:K-BCF, and highP:K-LBCF fertilizers, respectively. Each treatment was set up with 3 replicates. The ambient temperature was controlled at 25±2℃. Water was added to each soil column for the first time until the soil moisture content reached about 70% of the field water holding capacity. The leaching test began after 3 days of equilibrium. Each time, 100ml of deionized water was used for leaching at a flow rate of 2ml / min on the 1st, 3rd, 5th, 10th, and 15th days, and the leaching law of nutrient elements of carbon-based fertilizers was determined by collecting soil leaching solutions. The collected leachate was measured and the volume was recorded, then bottled and stored through a 0.45μm filter membrane, and frozen in a dark refrigerator at -20℃ before being analyzed on the machine.

[0083] Nutrient single leaching mass (m t ) is the product of the nutrient concentration in the soil column leachate of each fertilizer treatment minus the nutrient concentration in the blank control treatment and the volume of the single leaching leachate, as shown in the formula:

[0084] m t =ω·V·n·10 -3

[0085] In the formula, m t is the single leaching mass of nutrients, mg; n is the dilution multiple of the leaching solution; ω is the corresponding nutrient measurement concentration, mg / L; V is the volume of soil column leachate, mL.

[0086] Nutrient single leaching rate (C t) is the percentage of leached nutrient mass to nutrient mass in biomass charcoal-based fertilizer, as shown in the formula:

[0087]

[0088] In the formula, m z It is the total nutrient content in 3g of fertilizer with corresponding ratio, mg; m t is the single leaching mass of nutrients, mg.

[0089] The cumulative nutrient leaching rate is the cumulative sum of each leaching rate.

[0090] Table 2 Analysis results of nitrogen leaching rate of phosphorus / potassium ratio, biochar and lignin sulfonate

[0091]

[0092] Note: c(N)n: single nitrogen leaching rate of leaching on the nth day; c(N)total: cumulative nitrogen leaching rate.

[0093] Figure 3 is the nitrogen single leaching rate of different formula fertilizers. Figure 3 It can be seen that the single nitrogen leaching rate of different formula fertilizers reached the maximum on the 5th day and then gradually decreased.

[0094] Figure 4 is the cumulative nitrogen leaching rate of fertilizers with different formulas. Figure 4 It can be seen that the cumulative nitrogen leaching rate is lowP:K-CF>highP:K-CF>lowP:K-BCF>lowP:K-LBCF>highP:K-BCF>highP:K-LBCF. The addition of biochar significantly reduced the 1st day, 10th day and cumulative nitrogen leaching rate (Table 2). In the lowP:K group, it was reduced by 19.4%, 22.8%, and 10.8%, respectively. In the highP:K group, it was reduced by 20.7%, 22.1%, and 15.7%, respectively, compared with the treatment without biochar addition. Different phosphorus / potassium ratios had a significant effect on the third-day and cumulative nitrogen leaching rates. The nitrogen leaching rate of the highP:K group was lower than that of the lowP:K group. Compared with lowP:K-BCF, the third-day and cumulative nitrogen leaching rates of highP:K-BCF were reduced by 14.0% and 10.3%, respectively. Compared with lowP:K-LBCF, the nitrogen leaching rates of highP:K-LBCF were reduced by 14.0% and 8.0%, respectively.

[0095] The results of the soil column leaching test in the present invention show that the biochar in the fertilizer prepared by mixed granulation can significantly reduce the cumulative leaching rate of nitrogen from the fertilizer during the entire leaching cycle. Biochar has a significant fixation effect on nitrogen and can significantly reduce the cumulative leaching amount of nitrogen. There is also a significant interaction between biochar and the phosphorus / potassium ratio. For nitrogen leaching, the nitrogen leaching rate of highP:K-LBCF is the lowest, and the nitrogen leaching rate of the highP:K group is lower than that of the lowP:K group, indicating that under the condition of high phosphorus input, the biochar and lignin sulfonate in the fertilizer have a good fixation effect on nitrogen, that is, lignin sulfonate cooperates with biochar, urea, diammonium phosphate, and potassium sulfate to facilitate the slow release of nitrogen, thereby achieving the effect of slow-release fertilizer.

[0096] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0097] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A carbon-based fertilizer containing lignin sulfonate, characterized in that: Calculated by mass percentage, the raw materials include: 12% biochar, 5% lignin sulfonate, 20% bentonite, 20-25% urea, 12-30% diammonium hydrogen phosphate and 14-26% potassium sulfate.

2. The carbon-based fertilizer containing lignin sulfonate according to claim 1, characterized in that: Calculated by mass percentage, the raw materials include: 12% biochar, 5% lignin sulfonate, 20% bentonite, 24.1% urea, 13% diammonium hydrogen phosphate and 25.9% potassium sulfate.

3. The carbon-based fertilizer containing lignin sulfonate according to claim 1, characterized in that: Calculated by mass percentage, the raw materials include: 12% biochar, 5% lignin sulfonate, 20% bentonite, 20% urea, 28.7% diammonium hydrogen phosphate and 14.3% potassium sulfate.

4. The carbon-based fertilizer containing lignin sulfonate according to any one of claims 1 to 3, characterized in that The lignin xanthate is a by-product produced during the sulfite pulping process in the papermaking industry.

5. A method for preparing a carbon-based fertilizer containing lignin sulfonate according to any one of claims 1 to 4, characterized in that the steps include: The biomass charcoal, urea, diammonium hydrogen phosphate, potassium sulfate and lignin sulfonate are uniformly mixed with 3 / 4 amount of bentonite and then granulated. When the granules are initially formed, the remaining bentonite is added in batches and granulation is continued. After the complete granules are formed, the charcoal-based fertilizer containing lignin sulfonate is obtained by drying.

6. The preparation method according to claim 5, characterized in that: The drying temperature is 60° C. and the drying time is 3 to 5 hours.

7. Use of the carbon-based fertilizer containing lignin sulfonate as claimed in any one of claims 1 to 4 in the field of soil fertilization technology.

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