Nutrient polymerized polyglutamic acid compound fertilizer and preparation method thereof

Abstract

The invention relates to the technical field of fertilizers, in particular to a nutrient polymerized polyglutamic acid compound fertilizer and a preparation method thereof, and the nutrient polymerized polyglutamic acid compound fertilizer comprises the following raw materials in parts by weight: 6-10 parts of gamma-polyglutamic acid, 25-30 parts of filler, 20-25 parts of a nitrogen source, 12-15 parts of a phosphorus source, 10-14 parts of a potassium source, 4-6 parts of a compound additive and 0.1-0.2 part of a fungicide. In the preparation of the granules, the humic acid powder is coated by a first treating agent prepared from the soluble starch, the salicylic acid, the sodium alginate and the like, so that the activity of the humic acid is effectively protected, and meanwhile, the mechanical strength and the slow-release characteristic of the granules are further enhanced by a second treating agent prepared from the components such as the chitosan and the fulvic acid through a chelation cross-linking effect; in addition, chondroitin sulfate, calcium nitrate, ammonium molybdate and molasses in the batch jointly provide medium trace elements and organic carbon sources, and synchronous release and efficient utilization of nutrients after the fertilizer is applied to soil are ensured.

Description

Technical Field

[0001] This invention relates to the field of fertilizer technology, specifically to a nutrient-polymerized polyglutamic acid compound fertilizer and its preparation method. Background Technology

[0002] Polyglutamic acid compound fertilizer is a type of fertilizer that combines γ-polyglutamic acid as the core synergistic component with basic nutrients such as nitrogen, phosphorus, and potassium, as well as specific functional adjuvants. As a high molecular polymer, γ-polyglutamic acid has properties such as water retention, nitrogen fixation, and chelation of heavy metals. In the agricultural field, it can significantly improve the efficiency of crop nutrient absorption as a fertilizer synergist.

[0003] In existing technologies, although polyglutamic acid-containing compound fertilizers improve basic fertilizer efficiency to a certain extent, the various active components contained therein are difficult to coexist stably in the fertilizer system for a long time and exert a synergistic effect, resulting in the fertilizer efficiency failing to reach the expected level. Based on this, the present invention provides a nutrient-polymerized polyglutamic acid compound fertilizer and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a nutrient-polymerized polyglutamic acid compound fertilizer and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a nutrient-polymerized polyglutamic acid compound fertilizer, comprising the following raw materials in parts by weight: 6-10 parts γ-polyglutamic acid, 25-30 parts filler, 20-25 parts nitrogen source, 12-15 parts phosphorus source, 10-14 parts potassium source, 4-6 parts compound additives, and 0.1-0.2 parts microbial agent; The preparation of the composite additive includes the following steps: S1: Granular material preparation, wherein the raw materials for the granular material include humic acid powder, a first treatment agent, a second treatment agent, and a calcium chloride solution; S2: Preparation of compound material, wherein the raw materials of the compound material include chondroitin sulfate, deionized water, calcium nitrate, ammonium molybdate and molasses, and the mass of the compound material is 20-30% of the mass of the granules; S3: Mixing treatment, the granular material and the compound material are mixed at 200-400 rpm for 20-40 min to obtain the composite additive.

[0006] Preferably, the method for preparing the granules is as follows: humic acid powder is sieved through a 100-mesh sieve and spread evenly on a tray. A first treatment agent is sprayed onto the surface of the humic acid powder, and the mixture is left to stand for 2-3 hours to obtain a mixture. The mixture is then transferred to a mixer, which is set to 40-60 rpm and stirred for 30-40 minutes. During the stirring process, a second treatment agent is sprayed into the mixer, followed by the spraying of calcium chloride solution. The stirring process continues for another 20-30 minutes. The resulting product is then placed in an oven and dried at 40-60°C for 4-6 hours to obtain granules.

[0007] Preferably, the mass of the first treatment agent is 10-15% of the mass of the humic acid powder, the mass of the second treatment agent is 20-25% of the mass of the mixture, the mass of the calcium chloride solution is 10-15% of the mass of the mixture, and the mass concentration of the calcium chloride solution is 15-20%.

[0008] Preferably, the first treatment agent is prepared by the following method: soluble starch is added to deionized water at 50°C and mixed to obtain a base material, which is then set aside. Salicylic acid and anhydrous ethanol are added to the base material and mixed. The resulting product is processed by a spray dryer to obtain a powder material. The powder material is mixed with sodium alginate solution to obtain a slurry. The slurry is dripped into calcium chloride solution through a spray nozzle and filtered to obtain a solid. The solid is drained of water to obtain the first treatment agent.

[0009] Preferably, the mass ratio of soluble starch to deionized water is 1:8-10, the mass of salicylic acid is 2-4% of the mass of the base material, the mass of anhydrous ethanol is 15-25% of the mass of the base material, the mass ratio of powder material to sodium alginate solution is 1:0.4-0.6, the mass concentration of sodium alginate solution is 2-3%, and the mass concentration of calcium chloride solution is 2%.

[0010] Preferably, the second treatment agent is prepared by the following method: chitosan and glacial acetic acid solution are added to a mixer and stirred at 200-300 rpm for 2-3 hours at 35-40°C. Then, fulvic acid powder and deionized water are added, the temperature is raised to 45-50°C, and the mixture is stirred at 300-500 rpm for 40-60 minutes. Sodium hydroxide solution is added to adjust the pH value to 5-5.5 to obtain the second treatment agent. The mass ratio of chitosan to glacial acetic acid solution is 1:6-8, the mass concentration of glacial acetic acid solution is 1-1.5%, the mass of fulvic acid powder is 30-40% of the mass of chitosan, and the mass of deionized water is 2-3 times the mass of fulvic acid powder.

[0011] Preferably, the method for preparing the compound is as follows: chondroitin sulfate is dissolved in deionized water, heated to 45-55°C, and stirred while maintaining a stirring state. Calcium nitrate, ammonium molybdate, and molasses are added sequentially, and the mixture is kept warm and stirred for 40-60 minutes to obtain the compound.

[0012] Preferably, the mass ratio of chondroitin sulfate to deionized water is 1:10-12, the mass of calcium nitrate is 20-30% of the mass of chondroitin sulfate, and the mass ratio of calcium nitrate, ammonium molybdate, and molasses is 1:0.1-0.2:0.4-0.6.

[0013] Preferably, the filler is bentonite, the nitrogen source is prepared by mixing urea and amino acid powder in a mass ratio of 8:2-3, the phosphorus source is prepared by mixing ammonium polyphosphate and potassium dihydrogen phosphate in a mass ratio of 8:4-5, the potassium source is potassium sulfate, and the bacterial agent is prepared by mixing Bacillus spp., Bacillus megaterium, Bacillus subtilis and Bacillus licheniformis in a mass ratio of 1:0.6-0.8:0.4-0.6:0.1-0.2.

[0014] Preferably, a method for preparing a nutrient-polymerized polyglutamic acid compound fertilizer includes the following steps: weighing each raw material as needed and adding it to a mixer, setting the mixer to 60-100 rpm and stirring for 40-60 minutes, then adding water at 40-50% of the mass of the mixture in the mixer, continuing to stir for 40-60 minutes, granulating the resulting product, and then drying it at 50-60°C for 2-4 hours to obtain the nutrient-polymerized polyglutamic acid compound fertilizer.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In the preparation of granules, the first treatment agent, made of soluble starch, salicylic acid, sodium alginate, etc., coats the humic acid powder, effectively protecting the activity of the humic acid. At the same time, the second treatment agent, made of chitosan, fulvic acid, etc., further enhances the mechanical strength and slow-release characteristics of the granules through chelation and cross-linking. In addition, chondroitin sulfate, calcium nitrate, ammonium molybdate, and molasses in the compounding material provide trace elements and organic carbon sources. After the granules and compounding material are mixed, a stable network structure is formed under the mediation of calcium chloride solution, so that the components are evenly dispersed and immobilized, avoiding the failure caused by component migration and reaction during storage, and ensuring the synchronous release and efficient utilization of nutrients after the fertilizer is applied to the soil.

[0016] 2. In this invention, the polymerization and long-term slow release of nutrients are achieved through the synergistic effect of γ-polyglutamic acid and composite additives. γ-polyglutamic acid, with its strong water retention and anionic properties, can effectively chelate nutrients such as nitrogen, phosphorus, and potassium, reducing their loss. The functional components in the composite additives further combine with the polyglutamic acid molecular chains to form a more elastic nutrient carrier network. This network structure can be gradually degraded in the soil, achieving controlled release of nutrients, significantly extending the fertilizer effect period, and improving fertilizer utilization, thus meeting the nutritional needs of crops throughout their entire growth period.

[0017] 3. In this invention, the microenvironment created by the compound additive provides protection and carbon and nitrogen sources for functional microbial agents such as Bacillus megaterium and Bacillus megaterium, enabling them to maintain high activity in fertilizer granules. After being applied to the soil, the microbial agents rapidly colonize and multiply, working synergistically with polyglutamic acid, humic acid, etc., to activate phosphorus and potassium elements fixed in the soil, produce growth-promoting substances, and inhibit soil-borne pathogens, thereby simultaneously achieving the multiple benefits of efficient nutrient utilization, soil improvement, and enhanced crop resistance. Attached Figure Description

[0018] Figure 1 The present invention provides a flowchart of a nutrient-polymerized polyglutamic acid compound fertilizer and its preparation method. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that the raw materials used in the following embodiments are all commercially available.

[0021] Example 1: A nutrient-polymerized polyglutamic acid compound fertilizer comprises the following raw materials in parts by weight: 6 parts γ-polyglutamic acid, 25 parts filler, 20 parts nitrogen source, 12 parts phosphorus source, 10 parts potassium source, 4 parts compound additive and 0.1 parts microbial agent; The filler material is bentonite, the nitrogen source is prepared by mixing urea and amino acid powder in a mass ratio of 8:2, the phosphorus source is prepared by mixing ammonium polyphosphate and potassium dihydrogen phosphate in a mass ratio of 8:4, the potassium source is potassium sulfate, and the bacterial agent is prepared by mixing Bacillus spp., Bacillus megaterium, Bacillus subtilis and Bacillus licheniformis in a mass ratio of 1:0.6:0.4:0.1.

[0022] The preparation of the composite additive includes the following steps: S1: Granular material preparation, the raw materials for granules include humic acid powder, first treatment agent, second treatment agent and calcium chloride solution; S2: Preparation of the compounding material, the raw materials of which include chondroitin sulfate, deionized water, calcium nitrate, ammonium molybdate and molasses, and the mass of the compounding material is 20% of the mass of the granules; S3: Mixing treatment, the granular material and the compound material are mixed at 200 rpm for 20 min to obtain the composite additive.

[0023] The method for preparing granules is as follows: Humic acid powder is sieved through a 100-mesh sieve and spread evenly on a tray. The first treatment agent is sprayed onto the surface of the humic acid powder, and the mixture is left to stand for 2 hours to obtain a mixture. The mixture is then transferred to a mixer, which is set to 40 rpm and stirred for 30 minutes. During the stirring process, the second treatment agent is sprayed into the mixer, followed by the spraying of calcium chloride solution. The stirring process continues for another 20 minutes. The resulting product is then sent to an oven, which is set to 40°C and dried for 4 hours to obtain granules.

[0024] The first treatment agent has a mass of 10% of the humic acid powder mass, the second treatment agent has a mass of 20% of the mixture mass, the calcium chloride solution has a mass of 10% of the mixture mass, and the calcium chloride solution has a mass concentration of 15%.

[0025] The first treatment agent is prepared by the following method: soluble starch is added to deionized water at 50°C and mixed to obtain a base material, which is then set aside. Salicylic acid and anhydrous ethanol are added to the base material and mixed. The resulting product is processed by a spray dryer to obtain a powder material. The powder material is mixed with sodium alginate solution to obtain a slurry. The slurry is dripped into calcium chloride solution through a spray nozzle and filtered to obtain a solid. The solid is drained of water to obtain the first treatment agent.

[0026] The mass ratio of soluble starch to deionized water is 1:8, the mass of salicylic acid is 2% of the mass of the base material, the mass of anhydrous ethanol is 15% of the mass of the base material, the mass ratio of powder material to sodium alginate solution is 1:0.4, the mass concentration of sodium alginate solution is 2%, and the mass concentration of calcium chloride solution is 2%.

[0027] The second treatment agent was prepared by the following method: chitosan and glacial acetic acid solution were added to a mixer and stirred at 200 rpm for 2 hours at 35°C. Then, fulvic acid powder and deionized water were added, the temperature was raised to 45°C, and the mixture was stirred at 300 rpm for 40 minutes. Sodium hydroxide solution was added to adjust the pH value to 5 to obtain the second treatment agent. The mass ratio of chitosan to glacial acetic acid solution was 1:6, the mass concentration of glacial acetic acid solution was 1%, the mass of fulvic acid powder was 30% of the mass of chitosan, and the mass of deionized water was twice the mass of fulvic acid powder.

[0028] The method for preparing the compound is as follows: Chondroitin sulfate is dissolved in deionized water, heated to 45°C, and stirred. Calcium nitrate, ammonium molybdate, and molasses are added sequentially, and the mixture is kept warm and stirred for 40 minutes to obtain the compound.

[0029] The mass ratio of chondroitin sulfate to deionized water is 1:10, the mass of calcium nitrate is 20% of the mass of chondroitin sulfate, and the mass ratio of calcium nitrate, ammonium molybdate, and molasses is 1:0.1:0.4.

[0030] A method for preparing a nutrient-polymerized polyglutamic acid compound fertilizer includes the following steps: weighing each raw material as needed and adding it to a mixer, setting the mixer to 60 rpm and stirring for 40 min, then adding water equal to 40% of the mass of the mixture in the mixer, continuing to stir for 40 min, granulating the resulting product, and then drying it at 50°C for 2 h to obtain the nutrient-polymerized polyglutamic acid compound fertilizer.

[0031] Example 2: A nutrient-polymerized polyglutamic acid compound fertilizer comprises the following raw materials in parts by weight: 8 parts γ-polyglutamic acid, 28 parts filler, 23 parts nitrogen source, 13 parts phosphorus source, 12 parts potassium source, 5 parts compound additive and 0.15 parts microbial agent; The filler material is bentonite, the nitrogen source is prepared by mixing urea and amino acid powder in a mass ratio of 8:2.5, the phosphorus source is prepared by mixing ammonium polyphosphate and potassium dihydrogen phosphate in a mass ratio of 8:4.5, the potassium source is potassium sulfate, and the bacterial agent is prepared by mixing Bacillus spp., Bacillus megaterium, Bacillus subtilis and Bacillus licheniformis in a mass ratio of 1:0.7:0.5:0.15.

[0032] The preparation of the composite additive includes the following steps: S1: Granular material preparation, the raw materials for granules include humic acid powder, first treatment agent, second treatment agent and calcium chloride solution; S2: Preparation of the compounding material, the raw materials of which include chondroitin sulfate, deionized water, calcium nitrate, ammonium molybdate and molasses, and the mass of the compounding material is 25% of the mass of the granules; S3: Mixing treatment, the granular material and the compound material are mixed at 300 rpm for 30 min to obtain the composite additive.

[0033] The method for preparing granules is as follows: Humic acid powder is sieved through a 100-mesh sieve and spread evenly in a tray. The first treatment agent is sprayed onto the surface of the humic acid powder, and the mixture is left to stand for 2.5 hours to obtain a mixture. The mixture is then transferred to a mixer, which is set to 50 rpm and stirred for 35 minutes. During the stirring process, the second treatment agent is sprayed into the mixer, followed by the spraying of calcium chloride solution. The stirring process continues for another 25 minutes. The resulting product is then sent to an oven, which is set to 50°C and dried for 5 hours to obtain granules.

[0034] The mass of the first treatment agent is 13% of the mass of the humic acid powder, the mass of the second treatment agent is 22% of the mass of the mixture, the mass of the calcium chloride solution is 13% of the mass of the mixture, and the mass concentration of the calcium chloride solution is 18%.

[0035] The first treatment agent is prepared by the following method: soluble starch is added to deionized water at 50°C and mixed to obtain a base material, which is then set aside. Salicylic acid and anhydrous ethanol are added to the base material and mixed. The resulting product is processed by a spray dryer to obtain a powder material. The powder material is mixed with sodium alginate solution to obtain a slurry. The slurry is dripped into calcium chloride solution through a spray nozzle and filtered to obtain a solid. The solid is drained of water to obtain the first treatment agent.

[0036] The mass ratio of soluble starch to deionized water is 1:9, the mass of salicylic acid is 3% of the mass of the base material, the mass of anhydrous ethanol is 20% of the mass of the base material, the mass ratio of powder material to sodium alginate solution is 1:0.5, the mass concentration of sodium alginate solution is 2.5%, and the mass concentration of calcium chloride solution is 2%.

[0037] The second treatment agent was prepared by the following method: chitosan and glacial acetic acid solution were added to a mixer and stirred at 250 rpm for 2.5 h at 38 °C. Then, fulvic acid powder and deionized water were added, the temperature was raised to 48 °C, and the mixture was stirred at 400 rpm for 50 min. Sodium hydroxide solution was added to adjust the pH value to 5.3 to obtain the second treatment agent. The mass ratio of chitosan to glacial acetic acid solution was 1:7, the mass concentration of glacial acetic acid solution was 1.2%, the mass of fulvic acid powder was 35% of the mass of chitosan, and the mass of deionized water was 2.5 times the mass of fulvic acid powder.

[0038] The method for preparing the compound is as follows: Chondroitin sulfate is dissolved in deionized water, heated to 50°C, and stirred. Calcium nitrate, ammonium molybdate, and molasses are added sequentially, and the mixture is kept warm and stirred for 50 minutes to obtain the compound.

[0039] The mass ratio of chondroitin sulfate to deionized water is 1:11, the mass of calcium nitrate is 25% of the mass of chondroitin sulfate, and the mass ratio of calcium nitrate, ammonium molybdate, and molasses is 1:0.15:0.5.

[0040] A method for preparing a nutrient-polymerized polyglutamic acid compound fertilizer includes the following steps: weighing each raw material as needed and adding it to a mixer, setting the mixer to 80 rpm and stirring for 50 min, then adding water equal to 45% of the mass of the mixture in the mixer, continuing to stir for 50 min, granulating the resulting product, and then drying it at 55°C for 3 h to obtain the nutrient-polymerized polyglutamic acid compound fertilizer.

[0041] Example 3: A nutrient-polymerized polyglutamic acid compound fertilizer comprises the following raw materials in parts by weight: 10 parts γ-polyglutamic acid, 30 parts filler, 25 parts nitrogen source, 15 parts phosphorus source, 14 parts potassium source, 6 parts compound additive and 0.2 parts microbial agent; The filler material is bentonite, the nitrogen source is prepared by mixing urea and amino acid powder in a mass ratio of 8:3, the phosphorus source is prepared by mixing ammonium polyphosphate and potassium dihydrogen phosphate in a mass ratio of 8:5, the potassium source is potassium sulfate, and the bacterial agent is prepared by mixing Bacillus spp., Bacillus megaterium, Bacillus subtilis and Bacillus licheniformis in a mass ratio of 1:0.8:0.6:0.2.

[0042] The preparation of the composite additive includes the following steps: S1: Granular material preparation, the raw materials for granules include humic acid powder, first treatment agent, second treatment agent and calcium chloride solution; S2: Preparation of the compounding material, the raw materials of which include chondroitin sulfate, deionized water, calcium nitrate, ammonium molybdate and molasses, and the mass of the compounding material is 30% of the mass of the granules; S3: Mixing treatment, the granular material and the compound material are mixed at 400 rpm for 40 min to obtain the composite additive.

[0043] The method for preparing granules is as follows: Humic acid powder is sieved through a 100-mesh sieve and spread evenly on a tray. A first treatment agent is sprayed onto the surface of the humic acid powder, and the mixture is left to stand for 3 hours to obtain a mixture. The mixture is then transferred to a mixer, which is set to 60 rpm and stirred for 40 minutes. During the stirring process, a second treatment agent is sprayed into the mixer, followed by the spraying of calcium chloride solution. The mixture is then stirred for another 30 minutes. The resulting product is then placed in an oven and dried at 60°C for 6 hours to obtain granules.

[0044] The mass of the first treatment agent is 15% of the mass of the humic acid powder, the mass of the second treatment agent is 25% of the mass of the mixture, the mass of the calcium chloride solution is 15% of the mass of the mixture, and the mass concentration of the calcium chloride solution is 20%.

[0045] The first treatment agent is prepared by the following method: soluble starch is added to deionized water at 50°C and mixed to obtain a base material, which is then set aside. Salicylic acid and anhydrous ethanol are added to the base material and mixed. The resulting product is processed by a spray dryer to obtain a powder material. The powder material is mixed with sodium alginate solution to obtain a slurry. The slurry is dripped into calcium chloride solution through a spray nozzle and filtered to obtain a solid. The solid is drained of water to obtain the first treatment agent.

[0046] The mass ratio of soluble starch to deionized water is 1:10, the mass of salicylic acid is 4% of the mass of the base material, the mass of anhydrous ethanol is 25% of the mass of the base material, the mass ratio of powder material to sodium alginate solution is 1:0.6, the mass concentration of sodium alginate solution is 3%, and the mass concentration of calcium chloride solution is 2%.

[0047] The second treatment agent was prepared by the following method: chitosan and glacial acetic acid solution were added to a mixer and stirred at 300 rpm for 3 hours at 40°C. Then, fulvic acid powder and deionized water were added, the temperature was raised to 50°C, and the mixture was stirred at 500 rpm for 60 minutes. Sodium hydroxide solution was added to adjust the pH value to 5.5 to obtain the second treatment agent. The mass ratio of chitosan to glacial acetic acid solution was 1:8, the mass concentration of glacial acetic acid solution was 1.5%, the mass of fulvic acid powder was 40% of the mass of chitosan, and the mass of deionized water was 3 times the mass of fulvic acid powder.

[0048] The method for preparing the compound is as follows: Chondroitin sulfate is dissolved in deionized water, heated to 55°C, and stirred. Calcium nitrate, ammonium molybdate, and molasses are added sequentially, and the mixture is kept warm and stirred for 60 minutes to obtain the compound.

[0049] The mass ratio of chondroitin sulfate to deionized water is 1:12, the mass of calcium nitrate is 30% of the mass of chondroitin sulfate, and the mass ratio of calcium nitrate, ammonium molybdate, and molasses is 1:0.2:0.6.

[0050] A method for preparing a nutrient-polymerized polyglutamic acid compound fertilizer includes the following steps: weighing each raw material as needed and adding it to a mixer, setting the mixer to 100 rpm and stirring for 60 min, then adding water equal to 50% of the mass of the mixture in the mixer, continuing to stir for 60 min, granulating the resulting product, and then drying it at 60°C for 4 h to obtain the nutrient-polymerized polyglutamic acid compound fertilizer.

[0051] Comparative Example 1: The difference between this comparative example and Example 1 is that no first treatment agent or second treatment agent is sprayed during the preparation of the granules in this comparative example.

[0052] Comparative Example 2 differs from Example 1 in that no compounding materials are added during the preparation of the composite additive in this comparative example.

[0053] Comparative Example 3 differs from Example 1 in that it does not contain a bacterial agent.

[0054] Performance testing: The compound fertilizers prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing; Compressive strength: The compressive strength (N) was tested according to GB / T 10516-2012 standard and recorded in Table 1; Initial nutrient dissolution rate and cumulative release rate: The initial dissolution rate (%) at 24 h and the cumulative release rate (%) at 28 d were tested according to HG / T 4215-2011 standard and recorded in Table 1; Survival rate of microbial agents during storage: In accordance with the NY / T 798-2015 standard, the survival rate (%) of microbial agents during 90 days of storage was tested and recorded in Table 1; Pot experiment: Following the industry's general pot experiment method, the potted plant was Chinese cabbage. The culture medium was prepared by mixing the compound fertilizer and loam prepared in Examples 1-3 and Comparative Examples 1-3 at a ratio of 1:100. The culture period was 30 days. The plant dry weight growth rate (%) was measured and recorded in Table 1.

[0055] Table 1:

[0056] Analysis and comparison of the data in the table above show that the test data of Examples 1-3 are significantly better and more stable than those of Comparative Examples 1-3. Among them, the compressive strength is higher and the surface fertilizer is not easily pulverized during storage. This is due to the coating of the first treatment agent and the cross-linking effect of the second treatment agent, which together construct a solid granular skeleton and slow down the rapid invasion of water and the dissolution rate of nutrients. This keeps the initial nutrient dissolution rate at a low level in the first 24 hours and ensures that the nutrients can be continuously and stably released within 28 days, with a good slow-release effect. In addition, the compound additive creates a protected microenvironment for the microbial agent and provides carbon and nitrogen sources, so that it can still maintain high activity after 90 days of storage. After the fertilizer is applied to the soil, these highly active functional strains can work synergistically with γ-polyglutamic acid, humic acid, etc., to significantly promote the absorption and transformation of nutrients by Chinese cabbage, thereby achieving the highest plant dry weight growth rate. Further analysis revealed a sharp decrease in compressive strength in Comparative Example 1, indicating that the first and second treatment agents are crucial for constructing a stable granular structure. Their absence resulted in loose and brittle particles, leading not only to deterioration of physical properties but also a surge in the initial 24-hour dissolution rate. This is because the broken particles provide a rapid release channel for water and nutrients, completely eliminating the slow-release function. Simultaneously, the fragile particles cannot effectively protect the microbial agent, significantly reducing its survival rate and ultimate growth-promoting effect. This data clearly demonstrates that surface modification treatment is fundamental to achieving fertilizer slow release and microbial agent protection. Comparative Example 2 exhibited compressive strength and microbial agent survival rate similar to the examples, but its 28-day cumulative release rate and... The low plant dry weight growth rate indicates the absence of micronutrients such as calcium and molybdenum, as well as organic carbon sources, provided by the compound feed. Even if macronutrients such as nitrogen, phosphorus, and potassium are released, the crop cannot obtain comprehensive and balanced nutrition. In particular, specific nutrient deficiencies are prone to occur in the middle and late stages of growth, limiting the full realization of its growth potential. This also verifies the irreplaceable role of compound feed in achieving "synergistic effect". Among them, the survival rate of the microbial agent during the storage period of Comparative Example 3 was 0, which directly led to its lowest plant dry weight growth rate among all fertilization treatments. This data proves that the growth-promoting effect depends on the biological activity function of the microbial agent. Without the microbial agent, the fertilizer can only provide chemical nutrients and loses the core advantage of biological synergistic effect.

[0057] By comparing and analyzing the relevant data in the table, it can be seen that the nutrient-polymerized polyglutamic acid compound fertilizer prepared by this invention has good performance and excellent storage stability. This indicates that the nutrient-polymerized polyglutamic acid compound fertilizer provided by this invention has a broader market prospect and is more suitable for promotion.

[0058] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A nutrient-polymerized polyglutamic acid compound fertilizer, characterized in that: It includes the following raw materials in parts by weight: 6-10 parts γ-polyglutamic acid, 25-30 parts filler, 20-25 parts nitrogen source, 12-15 parts phosphorus source, 10-14 parts potassium source, 4-6 parts compound additives and 0.1-0.2 parts microbial agent; The preparation of the composite additive includes the following steps: S1: Granular material preparation, wherein the raw materials for the granular material include humic acid powder, a first treatment agent, a second treatment agent and calcium chloride solution; S2: Preparation of the compounding material, wherein the raw materials of the compounding material include chondroitin sulfate, deionized water, calcium nitrate, ammonium molybdate and molasses, and the mass of the compounding material is 20-30% of the mass of the granules; S3: Mixing treatment, the granular material and the compound material are mixed at 200-400 rpm for 20-40 min to obtain the composite additive.

2. The polyglutamic acid compound fertilizer with nutrient polymerization according to claim 1, characterized in that, The method for preparing the granules is as follows: humic acid powder is sieved through a 100-mesh sieve and spread evenly on a tray. A first treatment agent is sprayed onto the surface of the humic acid powder, and the mixture is left to stand for 2-3 hours to obtain a mixture. The mixture is then transferred to a mixer, which is set to 40-60 rpm and stirred for 30-40 minutes. During the stirring process, a second treatment agent is sprayed into the mixer, followed by the spraying of calcium chloride solution. The stirring process continues for another 20-30 minutes. The resulting product is then placed in an oven and dried at 40-60°C for 4-6 hours to obtain the granules.

3. The polyglutamic acid compound fertilizer with nutrient polymerization according to claim 2, characterized in that, The mass of the first treatment agent is 10-15% of the mass of the humic acid powder, the mass of the second treatment agent is 20-25% of the mass of the mixture, the mass of the calcium chloride solution is 10-15% of the mass of the mixture, and the mass concentration of the calcium chloride solution is 15-20%.

4. The polyglutamic acid compound fertilizer with nutrient polymerization according to claim 2, characterized in that, The first treatment agent is prepared by the following method: soluble starch is added to deionized water at 50°C and mixed to obtain a base material, which is then set aside. Salicylic acid and anhydrous ethanol are added to the base material and mixed. The resulting product is processed by a spray dryer to obtain a powder material. The powder material is mixed with sodium alginate solution to obtain a slurry. The slurry is dripped into calcium chloride solution through a spray nozzle and filtered to obtain a solid. The solid is drained of water to obtain the first treatment agent.

5. The polyglutamic acid compound fertilizer with nutrient polymerization according to claim 4, characterized in that, The mass ratio of soluble starch to deionized water is 1:8-10, the mass of salicylic acid is 2-4% of the mass of the base material, the mass of anhydrous ethanol is 15-25% of the mass of the base material, the mass ratio of powder material to sodium alginate solution is 1:0.4-0.6, the mass concentration of sodium alginate solution is 2-3%, and the mass concentration of calcium chloride solution is 2%.

6. The polyglutamic acid compound fertilizer with nutrient polymerization according to claim 2, characterized in that, The second treatment agent is prepared by the following method: chitosan and glacial acetic acid solution are added to a mixer and stirred at 200-300 rpm for 2-3 hours at 35-40°C. Then, fulvic acid powder and deionized water are added, the temperature is raised to 45-50°C, and the mixture is stirred at 300-500 rpm for 40-60 minutes. Sodium hydroxide solution is added to adjust the pH value to 5-5.5 to obtain the second treatment agent. The mass ratio of chitosan to glacial acetic acid solution is 1:6-8, the mass concentration of glacial acetic acid solution is 1-1.5%, the mass of fulvic acid powder is 30-40% of the mass of chitosan, and the mass of deionized water is 2-3 times the mass of fulvic acid powder.

7. The polyglutamic acid compound fertilizer with nutrient polymerization according to claim 1, characterized in that, The method for preparing the compound is as follows: Chondroitin sulfate is dissolved in deionized water, heated to 45-55°C, and stirred. Calcium nitrate, ammonium molybdate, and molasses are added sequentially, and the mixture is kept warm and stirred for 40-60 minutes to obtain the compound.

8. The polyglutamic acid compound fertilizer with nutrient polymerization according to claim 7, characterized in that, The mass ratio of chondroitin sulfate to deionized water is 1:10-12, the mass of calcium nitrate is 20-30% of the mass of chondroitin sulfate, and the mass ratio of calcium nitrate, ammonium molybdate, and molasses is 1:0.1-0.2:0.4-0.

6.

9. The polyglutamic acid compound fertilizer with nutrient polymerization according to claim 1, characterized in that, The filler is bentonite, the nitrogen source is prepared by mixing urea and amino acid powder in a mass ratio of 8:2-3, the phosphorus source is prepared by mixing ammonium polyphosphate and potassium dihydrogen phosphate in a mass ratio of 8:4-5, the potassium source is potassium sulfate, and the bacterial agent is prepared by mixing Bacillus spp., Bacillus megaterium, Bacillus subtilis and Bacillus licheniformis in a mass ratio of 1:0.6-0.8:0.4-0.6:0.1-0.

2.

10. The method for preparing the nutrient-polymerized polyglutamic acid compound fertilizer according to any one of claims 1 to 9, characterized in that, The process includes the following steps: Weigh each raw material as needed and add it to a mixer. Set the mixer to 60-100 rpm and stir for 40-60 minutes. Then add water equal to 40-50% of the mass of the mixture in the mixer and continue stirring for another 40-60 minutes. Granulate the resulting product and then dry it at 50-60°C for 2-4 hours to obtain a nutrient-polymerized polyglutamic acid compound fertilizer.

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