Fertilizer synergist based on ESBAP system as well as preparation method and application of fertilizer synergist

Abstract

The invention relates to the technical field of fertilizers, in particular to a fertilizer synergist based on an ESBAP system as well as a preparation method and application of the fertilizer synergist. The fertilizer synergist comprises the following components in parts by weight: 20-30 parts of modified polyaspartic acid, 10-20 parts of a nitrification inhibitor, 1-5 parts of a function enhancer and 5-10 parts of filler, the modified polyaspartic acid is obtained by grafting polyaspartic acid to 8-amino octanoic acid. The fertilizer synergist provided by the invention is high in stability and small in acid-base influence, and the utilization rate of the fertilizer can be remarkably increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of fertilizers, and particularly relates to a fertilizer synergist based on the ESBAP system, a preparation method thereof, and an application thereof. Background Art

[0002] In agricultural production, after fertilizers are applied to the soil, they will be lost for various reasons. For example, ammonium nitrogen in nitrogen fertilizers is easily volatilized, and nitrate nitrogen is easily leached by rainwater. According to statistics, without any measure intervention, the utilization rate of nitrogen fertilizers may be only 30%-50%. By using fertilizer synergists, such as nitrification inhibitors can inhibit the conversion of ammonium nitrogen to nitrate nitrogen, and urease inhibitors can slow down the hydrolysis rate of urea, thereby reducing the volatilization and leaching loss of nitrogen, and significantly improving the utilization rate of nitrogen fertilizers. This means that when achieving the same crop yield target, the application amount of fertilizers can be reduced. And fertilizer synergists can make the nutrients in fertilizers slowly release or release at an appropriate time. For example, some coated fertilizer synergists can continuously provide nutrients according to the needs of crop growth within a certain period, avoiding nutrient waste caused by excessive one-time fertilization and possible damage to plants. Such a precise nutrient supply method can, in the long run, reduce the fertilizer purchase cost and labor cost.

[0003] Polyaspartic acid (PASP) can be used as a fertilizer synergist. The polyaspartic acid molecular chain contains a large number of carboxyl groups (-COOH) and amino groups (-NH 2 ), and these functional groups can chelate with a variety of metal ions. For example, for calcium (Ca 2 + ), magnesium (Mg 2+ ), iron (Fe 3+ ), zinc (Zn 2+) Metal ions such as [metal ions] can be combined with polyaspartic acid through coordination bonds to form stable chelates. In fertilizers, it can prevent these metal ions from reacting with other substances to form precipitation reactions, keeping nutrients in a state that can be absorbed and utilized by plants. For example, in phosphate fertilizers, it can chelate iron and aluminum ions in the soil, preventing phosphorus from forming insoluble iron phosphate and aluminum phosphate precipitates with these ions, thereby improving the effectiveness of phosphate fertilizers. In addition, polyaspartic acid can adsorb on the surface of soil particles, playing a role in dispersing soil particles. It makes the aggregation state between soil particles more reasonable, increases the porosity of the soil, and improves the air permeability and water permeability of the soil. A good soil structure is beneficial to the growth of plant roots and the absorption of nutrients. For example, in clayey soils, polyaspartic acid can reduce the adhesiveness of the soil, making the soil loose; in sandy soils, it can increase the aggregation of the soil, preventing the soil from being too loose. However, in a soil environment with a relatively strong acidity, some functions of polyaspartic acid may be inhibited. Because the activity of functional groups such as carboxyl and amino groups in its molecule is affected by the soil pH. For example, in acidic soils, the concentration of hydrogen ions is relatively high, which may compete with polyaspartic acid for the chelation sites of metal ions, thereby reducing its chelation ability for nutrients and affecting the fertilizer efficiency enhancement effect. In addition, the stability and persistence of polyaspartic acid in the soil are restricted by various factors. For example, in the case of strong water erosion or frequent drainage in the soil, polyaspartic acid may be partially washed away, resulting in a decrease in its concentration in the soil and affecting its continuous role in enhancing fertilizer efficiency. In addition, some enzymes or chemical reactions in the soil may also decompose polyaspartic acid, shortening its effective action time in the soil and unable to play a long-term and effective role like some more stable soil conditioners.

[0004] For example, CN102491829A discloses a nitrogen fertilizer efficiency enhancer composition, which can be in a solid dosage form or a liquid dosage form. It includes 5%-12% of polyaspartic acid, 1%-5% of hydroquinone, and 1%-5% of dicyandiamide. The solid dosage form also includes 1%-20% of a functional auxiliary and a filler, and the liquid dosage form also includes 1%-20% of an emulsifier and water. This application delays the loss of nitrogen fertilizer in the soil through a plant root absorption regulator, a soil urease inhibitor, and a soil nitrification inhibitor, and ensures its rapid absorption by crop roots. However, its stability is poor and it is greatly affected by acidity and alkalinity.

[0005] As disclosed in CN108503469A, an organic chelated selenium fertilizer synergist, its preparation method and application are provided. The weight ratio of polyaspartate, organic chelated zinc and organic chelated selenium is 5-1:5-20:3-14, preferably 8-12:10-15:6-10. This application separates inorganic selenium and organic selenium by using ethanol, ensuring the content of organic selenium in the fertilizer and effectively preventing the problem that inorganic selenium and polyaspartate slowly chelate to form water-insoluble substances at room temperature. However, the stability of polyaspartic acid has not been improved and is easily affected by the soil acid-base stability.

[0006] In view of this, the present invention is specifically proposed. Summary of the Invention

[0007] The object of the present invention is to provide a fertilizer synergist based on the ESBAP system, its preparation method and application. The fertilizer synergist provided by the present invention has strong stability and small influence of acid and alkali, and can significantly improve the utilization rate of fertilizers.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] In the first aspect, the present invention provides a fertilizer synergist based on the ESBAP system, comprising the following components by weight: 20-30 parts of modified polyaspartic acid, 10-20 parts of nitrification inhibitor, 1-5 parts of functional enhancer, and 5-10 parts of filler;

[0010] The modified polyaspartic acid is obtained by grafting 8-aminocaprylic acid onto polyaspartic acid.

[0011] In a preferred embodiment, the preparation method of the modified polyaspartic acid is as follows:

[0012] Mix β-benzyl-L-aspartic acid-N-carboxylic anhydride, dimethylformamide and dichloromethane, then add 8-aminocaprylic acid for a first reaction, extract and dry to obtain a solid phase. After mixing the solid phase with tetrahydrofuran, adjust the pH to 10-12 for a second reaction, extract and purify using a dialysis bag with a molecular weight of 400-1000Da to obtain modified polyaspartic acid.

[0013] In a preferred embodiment, the mass ratio of β-benzyl-L-aspartic acid-N-carboxylic anhydride, dimethylformamide, dichloromethane and 8-aminocaprylic acid is 1:(2-5):(10-30):(0.3-0.6).

[0014] In a preferred embodiment, the conditions of the first reaction are: reacting at 30-50 °C for 48-72 hours under an argon atmosphere.

[0015] In a preferred embodiment, the mass ratio of the solid phase to tetrahydrofuran is 1:(40 - 80).

[0016] In a preferred embodiment, the conditions for the secondary reaction are: reaction temperature 0 - 5°C, reaction time 18 - 36 h.

[0017] The present invention effectively overcomes the disadvantages of poor stability of polyaspartic acid used as a fertilizer synergist and being greatly affected by soil acidity and alkalinity by grafting 8 - aminocaprylic acid onto polyaspartic acid, and further improves the utilization rate of fertilizers.

[0018] Specifically, 8 - aminocaprylic acid - modified polyaspartic acid introduces a part of 8 - aminocaprylic acid into its molecular structure through chemical modification. This structural change enhances the stability of the polymer. The long - chain structure and special functional groups of 8 - aminocaprylic acid can enhance the adsorption of the modified polyaspartic acid to soil particles, making it adhere more firmly to the soil and reducing the possibility of being washed away by water. At the same time, the new molecular structure may enhance its tolerance to enzymes in the soil and reduce the decomposition rate, thereby prolonging its effective action time in the soil and more stably exerting the function of the fertilizer synergist. In addition, 8 - aminocaprylic acid - modified polyaspartic acid has better adaptability in soils with different pH values. The addition of 8 - aminocaprylic acid adds new chemical active sites to the molecular structure, and these sites can still maintain a certain chelating ability and soil improvement effect in acidic or alkaline soil environments. For example, in acidic soils, functional groups such as the amino group of 8 - aminocaprylic acid can form stable coordination structures with metal ions, supplementing the chelating function of polyaspartic acid inhibited by the acidic environment, thereby effectively chelating nutrients in a wider range of soil pH values, improving the utilization rate of fertilizers, and improving the soil structure. And 8 - aminocaprylic acid - modified polyaspartic acid can better exert a synergistic effect. Its modified molecular structure can combine more effectively with various fertilizer components. For example, it can tightly chelate fertilizers containing trace elements such as zinc and iron, preventing the fixation of trace elements by the soil and improving their effectiveness. At the same time, 8 - aminocaprylic acid - modified polyaspartic acid can also interact with beneficial microorganisms in the soil. It can provide a more suitable living environment for microorganisms, promote the growth and reproduction of microorganisms, and the microorganisms can further decompose organic substances, releasing more nutrients and jointly improving the synergistic effect of fertilizers with the modified polyaspartic acid.

[0019] In terms of improving fertilizer utilization efficiency, the molecular structure of 8 - aminocaprylic acid - modified polyaspartic acid endows it with excellent nutrient chelating ability. On the one hand, functional groups such as carboxyl and amino groups in polyaspartic acid itself can chelate with metal ions; on the other hand, the introduction of 8 - aminocaprylic acid increases new active sites. Their combined action can tightly bind various nutrient ions in fertilizers, such as ammonium nitrogen, potassium ions, calcium ions, and trace elements (such as zinc ions, iron ions), etc. These chelated nutrients are not easily fixed by the soil or leached away. At the same time, this chelation structure enables slow release of nutrients. As the plant roots absorb and with the changes in soil environmental conditions (such as pH, microbial activities, etc.), the chelated nutrients are gradually released, providing a continuous and stable nutrient supply for plants. In terms of soil improvement, the modified polyaspartic acid can improve the aggregate structure of the soil. It adsorbs on the surface of soil particles and makes the soil particles aggregate together through intermolecular interactions, increasing soil porosity. The presence of 8 - aminocaprylic acid can further regulate the living environment of soil microorganisms and promote the growth of beneficial microorganisms. These beneficial microorganisms release more nutrients that can be absorbed by plants during the process of decomposing organic matter, and at the same time, they can also produce some substances that promote plant growth, such as plant hormones. Plant roots grow more vigorously in this loose and fertile soil environment. The growth of plant roots, in turn, secretes some organic substances, further improving the soil structure and forming a virtuous cycle. At the same time, 8 - aminocaprylic acid - modified polyaspartic acid can enhance the stress resistance of plants. It can regulate the osmotic pressure inside plant cells, enabling plants to maintain normal physiological functions of cells under adverse conditions such as drought or salinization. At the same time, the optimized effect of this modified polyaspartic acid on nutrient absorption also plays a role. It ensures that plants can effectively absorb nutrients in adverse environments by increasing root vitality and regulating the permeability of cell membranes. For example, in a drought environment, plant roots can better absorb the chelated water and nutrients in the soil, thus maintaining their own growth and metabolism.

[0020] In a preferred embodiment, the nitrification inhibitor is thiourea.

[0021] The particularly preferred thiourea of the present invention can overcome the disadvantages of polyaspartic acid in fertilizer synergists and further improve fertilizer utilization efficiency in terms of enhancing the stability of polyaspartic acid, improving nutrient conversion, and enhancing stress resistance.

[0022] Specifically, thiourea can improve the stability of polyaspartic acid by regulating the chemical environment of the soil. Thiourea has a certain inhibitory effect on the activities of soil microorganisms, especially those that may decompose polyaspartic acid. When thiourea is present, it can reduce the decomposition of polyaspartic acid by microorganisms and extend the effective action time of polyaspartic acid in the soil. At the same time, thiourea can buffer the change of soil pH to a certain extent, providing a relatively stable chemical environment for polyaspartic acid, so that it can better maintain its own structure and function in acidic or alkaline soils. In addition, thiourea is a nitrification inhibitor, which can effectively inhibit the conversion of ammonium nitrogen to nitrate nitrogen. When used in combination with polyaspartic acid, thiourea can make up for the deficiency of polyaspartic acid in the control of nitrogen transformation. It ensures that there is enough ammonium nitrogen in the soil for plants to absorb and utilize, while reducing the loss of nitrogen caused by leaching. This synergistic effect enables the nitrogen in the fertilizer to be utilized more effectively by plants, improving the utilization rate of the fertilizer. And thiourea can regulate the chemical properties of the soil to a certain extent, reducing the impact of soil salinization on plants. When used together with polyaspartic acid, thiourea can provide a more suitable growth environment for plants by controlling the nitrogen form and nutrient availability in the soil. At the same time, the two can better regulate the physiological processes in plant cells and enhance the resistance of plants to adverse conditions such as salinity. When growing crops in saline-alkali soil, the fertilizer synergist containing thiourea and polyaspartic acid can significantly improve the survival rate and growth status of plants.

[0023] In a preferred embodiment, the function enhancer is seaweed polysaccharide.

[0024] In a preferred embodiment, the molecular weight of the seaweed polysaccharide is 1000 - 2000 kDa.

[0025] The present invention further adds seaweed polysaccharide, overcomes the disadvantages of polyaspartic acid and thiourea when used as fertilizer synergists, and further synergistically improves the fertilizer utilization rate.

[0026] Specifically, as a nitrification inhibitor, thiourea may have a certain non-selective inhibition on soil microorganisms during the process of inhibiting soil nitrification. Polyaspartic acid may lose its effective function relatively quickly under the action of microbial decomposition. When the two are used together, it may cause the imbalance of the soil microbial community structure and affect the normal function of the soil ecosystem. While seaweed polysaccharide can provide rich carbon sources for soil microorganisms. It contains various sugar components and can promote the growth and reproduction of beneficial microorganisms (such as nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, etc.). The activities of these beneficial microorganisms can, to a certain extent, reduce the non-selective inhibitory effect of thiourea on microorganisms. At the same time, there may be a competitive relationship between the microorganisms that decompose seaweed polysaccharide and those that decompose polyaspartic acid, slowing down the decomposition rate of polyaspartic acid.

[0027] In addition, although polyaspartic acid has a certain ability to retain fertilizers, in some arid areas or areas with severe soil erosion, its water retention ability may be limited. Thiourea mainly focuses on the control of nitrogen transformation and makes less direct contribution to soil water and fertilizer retention. Seaweed polysaccharide has excellent water absorption and water retention properties. It can absorb and retain a large amount of water, forming a structure similar to a "miniature reservoir". In the soil, the stored water can provide a continuous water source for plant growth and also help with the dissolution and diffusion of fertilizer nutrients.

[0028] Furthermore, when thiourea and polyaspartic acid are used together, the improvement of plant stress resistance mainly focuses on nutrient supply and partial improvement of the soil environment, and the enhancement effect on plant stress resistance in some extreme environments (such as high temperature, low temperature, high salt, etc.) may not be ideal. Seaweed polysaccharide contains plant hormone analogs, such as active ingredients like auxin and cytokinin. These ingredients can regulate the physiological processes of plants. In high-temperature or low-temperature environments, seaweed polysaccharide can regulate the osmotic pressure inside plant cells, stabilize the cell membrane structure, and enhance plant stress resistance. In a high-salt environment, it can help plants reduce salt absorption and alleviate salt damage.

[0029] In a preferred embodiment, the filler is one or more of nitrogen-containing fertilizers, phosphorus-containing fertilizers, and potassium-containing fertilizers.

[0030] In a preferred embodiment, the nitrogen-containing fertilizer is one or more of urea, ammonium chloride, ammonium sulfate, and ammonium bicarbonate.

[0031] In a preferred embodiment, the phosphorus-containing fertilizer is one or more of superphosphate, calcium magnesium phosphate, triple superphosphate, monoammonium phosphate, and diammonium phosphate.

[0032] In a preferred embodiment, the potassium-containing fertilizer is one or more of potassium sulfate, potassium chloride, potassium nitrate, and potassium dihydrogen phosphate.

[0033] In a second aspect, an embodiment of the present invention provides a preparation method of a fertilizer synergist based on the ESBAP system as described above, including the following steps:

[0034] Mix modified polyaspartic acid, nitrification inhibitor, function enhancer, and filler, and grind and sieve to obtain the fertilizer synergist.

[0035] In a preferred embodiment, the sieve mesh used for sieving is 200 - 300 meshes.

[0036] In a third aspect, an embodiment of the present invention provides an application of a fertilizer synergist based on the ESBAP system as described above in fertilizers.

[0037] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0038] 1. The present invention effectively overcomes the disadvantages of poor stability of polyaspartic acid used as a fertilizer synergist and being greatly affected by soil acidity and alkalinity through grafting polyaspartic acid with 8 - aminocaprylic acid, and further improves the utilization rate of fertilizers.

[0039] 2. The particularly preferred thiourea of the present invention can overcome the disadvantages of polyaspartic acid in the fertilizer synergist, and further improve the utilization rate of fertilizers in terms of enhancing the stability of polyaspartic acid, improving nutrient conversion, and enhancing stress resistance.

[0040] 3. The present invention further adds seaweed polysaccharide, which overcomes the disadvantages of polyaspartic acid and thiourea when used as fertilizer synergists, and further synergistically improves the utilization rate of fertilizers. Specific Embodiments

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] Unless otherwise specified, the raw materials and reagents used in the present invention are all obtained commercially.

[0043] Seaweed polysaccharide with a molecular weight of 1200 kDa was purchased from Qingdao Poly Ocean Algae Industry Group Co., Ltd.

[0044] β - benzyl - L - aspartic acid - N - carboxylic anhydride was purchased from Shanghai Liko Pharmaceutical Chemistry Co., Ltd.

[0045] Polyaspartic acid with a molecular weight of 500 Da, Hebei Xietong Chemical Co., Ltd.

[0046] Example 1

[0047] This example provides a preparation method of a fertilizer synergist based on the ESBAP system, including the following steps:

[0048] By mass, 22 parts of modified polyaspartic acid, 13 parts of thiourea, 3 parts of seaweed polysaccharide with a molecular weight of 1200 kDa, and 6 parts of diammonium phosphate are mixed, ground through a 200 - mesh sieve to obtain the fertilizer synergist.

[0049] The preparation method of the modified polyaspartic acid is as follows:

[0050] Mix 1 part of β-benzyl-L-aspartic acid-N-carboxylic anhydride, 3 parts of dimethylformamide and 18 parts of dichloromethane by mass. Then add 0.5 part of 8-aminooctanoic acid and react at 35 °C for 58 hours under an argon atmosphere. Extract and dry to obtain a solid phase. Mix 1 part of the solid phase with 50 parts of tetrahydrofuran, adjust the pH to 11, react at 0 °C for 22 h, extract and purify using a dialysis bag with a molecular weight cut-off of 500 Da to obtain modified polyaspartic acid.

[0051] Example 2

[0052] This example provides a preparation method of a fertilizer synergist based on the ESBAP system, including the following steps:

[0053] Mix 28 parts of modified polyaspartic acid, 17 parts of thiourea, 5 parts of seaweed polysaccharide with a molecular weight of 1200 kDa and 8 parts of diammonium phosphate by mass, grind and pass through a 200-mesh sieve to obtain the fertilizer synergist.

[0054] The preparation method of the modified polyaspartic acid is as follows:

[0055] Mix 1 part of β-benzyl-L-aspartic acid-N-carboxylic anhydride, 4 parts of dimethylformamide and 28 parts of dichloromethane by mass. Then add 0.6 part of 8-aminooctanoic acid and react at 35 °C for 72 hours under an argon atmosphere. Extract and dry to obtain a solid phase. Mix 1 part of the solid phase with 60 parts of tetrahydrofuran, adjust the pH to 11, react at 0 °C for 24 h, extract and purify using a dialysis bag with a molecular weight cut-off of 500 Da to obtain modified polyaspartic acid.

[0056] Comparative Example 1

[0057] The difference between this comparative example and Example 1 is that the modified polyaspartic acid is changed to polyaspartic acid with a molecular weight of 500 Da.

[0058] Comparative Example 2

[0059] The difference between this comparative example and Example 1 is that the modified polyaspartic acid is changed to a mixture of 8-aminooctanoic acid and polyaspartic acid with a mass ratio of 1:1.

[0060] Comparative Example 3

[0061] The difference between this comparative example and Example 1 is that the thiourea is changed to dicyandiamide.

[0062] Comparative Example 4

[0063] The difference between this comparative example and Example 1 is that no thiourea is added, and the modified polyaspartic acid is changed to 35 parts.

[0064] Comparative Example 5

[0065] The difference between this comparative example and Example 1 is that no seaweed polysaccharide is added, and the modified polyaspartic acid is changed to 25 parts.

[0066] Performance Test

[0067] The fertilizer synergist obtained in the examples and comparative examples was mixed with urea at 7 wt% to prepare a fertilizer, which was used for crop yield increase.

[0068] Test Example 1, the test crop is corn; the planting density is 4000 plants / mu; a total of four treatments are set up, with 4 replicates, and the area of each plot is 30m 2 , arranged in a randomized block design. The fertilizers obtained from the examples and comparative examples were respectively applied at 50 kg / mu. Fertilization was carried out once at the time of planting, and again at the seedling raising stage and jointing stage. When irrigating, the soil was washed by the water flow to test the agronomic traits and yield of corn, and the average value was taken. The results are shown in Table 1.

[0069] Table 1 Effects of the fertilizers of the examples and comparative examples on the agronomic traits and yield of corn

[0070] Plant height / cm 100-seed weight / g Yield / kg / mu Example 1 242.1 36.8 646.8 Example 2 253.4 38.9 676.2 Comparative Example 1 212.3 30.2 587.5 Comparative Example 2 224.5 32.4 602.1 Comparative Example 3 234.6 34.3 621.2 Comparative Example 4 236.9 35.3 630.6 Comparative Example 5 238.7 35.7 635.1

[0071] Test Example 2, the test crop is lettuce; the planting density is 3000 plants / mu; a total of four treatments are set up, with 4 replicates, and the area of each plot is 30m 2 , arranged in a randomized block design. The fertilizers obtained from the examples and comparative examples were respectively applied at 40 kg / mu. Fertilization was carried out once at the time of planting, and again 40 days later. When irrigating, the soil was washed by the water flow to test the agronomic traits and yield of lettuce, and the average value was taken. The results are shown in Table 2.

[0072] Table 2 Effects of the fertilizers of the examples and comparative examples on the agronomic traits and yield of lettuce

[0073] Stem diameter / cm Yield / kg / mu Example 1 3.88 3347 Example 2 4.12 3552 Comparative Example 1 2.54 3125 Comparative Example 2 2.86 3198 Comparative Example 3 3.49 3259 Comparative Example 4 3.62 3295 Comparative Example 5 3.68 3305

[0074] From the above performance test results, it can be seen that the fertilizers doped with the fertilizer synergist prepared in the present invention in Examples 1-2 have the best effects, especially the comprehensive performance of Example 2 is the most prominent. This is mainly because the polyaspartic acid in the present invention is modified and compounded with a variety of additives to synergistically improve the fertilizer utilization rate.

[0075] In the comparative example, because the necessary technical solutions are not adopted, its performance in the corresponding performance tests is significantly worse than that of the examples, which better proves the irreplaceability of the specific technical solutions of this application for achieving the technical effects and solving the technical problems.

[0076] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A fertilizer synergist based on the ESBAP system, characterized in that: The composition comprises the following components by weight: 20-30 parts of modified polyaspartic acid, 10-20 parts of nitrification inhibitor, 1-5 parts of functional enhancer, and 5-10 parts of filler; The modified polyaspartic acid is obtained by grafting 8-aminocaprylic acid onto polyaspartic acid.

2. The fertilizer synergist based on the ESBAP system according to claim 1, characterized in that: The preparation method of the modified polyaspartic acid is as follows: β-Benzyl-L-aspartic acid-N-carboxylic acid anhydride, dimethylformamide and dichloromethane are mixed, and then 8-aminooctanoic acid is added for a primary reaction, and a solid phase is obtained by extraction and drying. The solid phase is mixed with tetrahydrofuran and the pH is adjusted to 10-12, and a secondary reaction is carried out. The modified polyaspartic acid is obtained by extraction and purification using a dialysis bag with a molecular weight of 400-1000Da.

3. The fertilizer synergist based on the ESBAP system according to claim 2, characterized in that: The mass ratio of the β-benzyl-L-aspartic acid-N-carboxylic anhydride, dimethylformamide, dichloromethane and 8-aminooctanoic acid is 1:(2-5):(10-30):(0.3-0.6).

4. The fertilizer synergist based on the ESBAP system according to claim 2, characterized in that: The conditions of the primary reaction are: reacting at 30-50° C. for 48-72 hours under an argon atmosphere; And / or, the mass ratio of the solid phase to tetrahydrofuran is 1:(40-80); And / or, the conditions of the secondary reaction are: reaction temperature 0-5°C, reaction time 18-36h.

5. The fertilizer synergist based on the ESBAP system according to claim 1, characterized in that: The nitrification inhibitor is thiourea.

6. The fertilizer synergist based on the ESBAP system according to claim 1, characterized in that: The functional enhancer is seaweed polysaccharide; The molecular weight of the seaweed polysaccharide is 1000-2000 kDa.

7. The fertilizer synergist based on the ESBAP system according to claim 1, characterized in that: The filler is one or more of nitrogen-containing fertilizers, phosphorus-containing fertilizers, and potassium-containing fertilizers.

8. The fertilizer synergist based on the ESBAP system according to claim 7, characterized in that: The nitrogen-containing fertilizer is one or more of urea, ammonium chloride, ammonium sulfate, and ammonium bicarbonate; And / or, the phosphorus-containing fertilizer is one or more of superphosphate, calcium magnesium phosphate, double superphosphate, monoammonium phosphate, and diammonium phosphate; And / or, the potassium-containing fertilizer is one or more of potassium sulfate, potassium chloride, potassium nitrate, and potassium dihydrogen phosphate.

9. A method for preparing a fertilizer synergist based on the ESBAP system according to any one of claims 1 to 8, characterized in that: The following steps are involved: Mixing modified polyaspartic acid, nitrification inhibitor, functional enhancer and filler, grinding and sieving to obtain fertilizer synergist; The sieve used for the sieving is 200-300 meshes.

10. Use of the fertilizer synergist based on the ESBAP system according to any one of claims 1 to 8 in fertilizers.