A production process of high-potassium base compound fertilizer

Abstract

The application discloses a production process of high-potassium base compound fertilizer, which comprises the following steps: S1, raw material pretreatment: crushing potassium feldspar to 200 meshes, mixing with 5% sulfuric acid at a mass ratio of 1:3, calcining at 120-130 DEG C for 2-3 hours, washing until the pH is 6.5-7.0, and drying to obtain potassium feldspar activated powder; S2, putting potassium citrate solution, calcium citrate solution, potassium feldspar activated powder, trace element organic acid salt solution, urea, modified zeolite and binder into a high-speed mixer in proportion, uniformly stirring, adopting high-tower granulation to obtain base material particles; S3, drying the base material particles, removing the particles with a diameter less than 2.5 mm, spraying a plurality of composite films on the surface of the base material particles to coat, and drying to obtain coated base material particles; and S4, spraying bacillus subtilis agent on the surface of the coated base material particles, and low-temperature drying to obtain the high-potassium base compound fertilizer. The high-potassium base compound fertilizer produced by the application has high nutrient components, long fertilizer efficiency, small environmental pollution, and can improve the soil environment and improve the crop yield.

Description

Technical Field

[0001] This invention relates to the field of organic fertilizer and microbial fertilizer technology, and in particular to a production process for a high-potassium compound fertilizer. Background Technology

[0002] Potassium is one of the essential nutrients in plants, playing a crucial role in photosynthesis, sugar synthesis, and water regulation. Therefore, potassium fertilizer is indispensable for ensuring crop production. It primarily enhances crop disease resistance, drought tolerance, and root growth, thereby increasing crop yield and quality. Thus, the rational application of potassium fertilizer can significantly improve soil fertility and the crop's growing environment.

[0003] However, traditional potash fertilizers (such as potassium chloride and potassium sulfate) have several problems in their application, affecting their sustainability in modern agricultural production. First, the chloride ions in traditional potash fertilizers, especially potassium chloride, can lead to soil salinization and acidification under long-term application, affecting soil structure and potentially causing salt damage to crops. Second, traditional potash fertilizers have a relatively singular fertilizer effect, providing only potassium and lacking other micronutrients required for crop growth, making it difficult to meet the comprehensive nutritional needs of crops. Furthermore, the release rate of traditional potash fertilizers is difficult to control, especially in areas with abundant rainfall, where fertilizer is easily lost, leading to incomplete nutrient absorption and consequently affecting crop growth. In addition, the limited availability of mineral potassium resources and their price fluctuations increase agricultural production costs, placing considerable pressure on farmers.

[0004] Therefore, this application provides a production process for a high-potassium compound fertilizer to solve the problems of traditional potassium fertilizers, such as single nutrient composition, short fertilizer effect, and large environmental pollution, thereby improving soil and increasing crop yield. Summary of the Invention

[0005] The purpose of this invention is to provide a production process for high-potassium compound fertilizer to solve the problems mentioned in the background art, such as the single nutrient composition, short fertilizer effect, and large environmental pollution of traditional potassium fertilizers.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A production process for a high-potassium compound fertilizer includes the following steps: S1. Raw material pretreatment: Potassium feldspar is pulverized to 200 mesh, mixed with 5% sulfuric acid at a mass ratio of 1:3, calcined at 120-130℃ for 2-3 hours, washed with water until the pH is 6.5-7.0, and dried to obtain activated potassium feldspar powder; S2. 15-20 parts by weight of potassium citrate solution, 4-10 parts by weight of calcium citrate solution, 10-16 parts by weight of activated potassium feldspar powder, 6-8 parts by weight of trace element organic acid salt solution, 10-15 parts by weight of urea, 4-6 parts by weight of modified zeolite, and... S3. Add 1-3 parts by weight of binder to a high-speed mixer and stir until uniform. Then, granulate using a high-tower granulation method to obtain base material granules. S4. Dry the base material granules using a fluidized bed dryer to remove fragments with a diameter of less than 2.5 mm. Spray a biodegradable composite film liquid evenly onto the surface of the granules, and then spray a composite film liquid of potassium humate and sodium alginate evenly for secondary coating. Dry in a fluidized bed at 70°C for 30-40 minutes to obtain coated base material granules. S5. Spray 4-6 parts by weight of Bacillus subtilis inoculant onto the surface of the coated base material granules and dry at a low temperature of 40°C to obtain a high-potassium compound fertilizer.

[0008] As a preferred technical solution of the present invention, the method for preparing the potassium citrate solution is as follows: take 10 parts by weight of pure citric acid and 6-9 parts by weight of 2-5M potassium bicarbonate solution, mix them evenly, add 0.4-1.0% of leveling agent TAN (or leveling agent) of the total weight of the solution, and react at 40-80°C for 2-4 hours to obtain potassium citrate solution.

[0009] The method for preparing the calcium citrate solution is as follows: Take 10 parts by weight of pure citric acid and 6-9 parts by weight of 1-2M calcium hydroxide solution, mix them evenly, add 0.4-1.0% of leveling agent TAN (or leveling agent) of the total weight of the solution, and react at 80-110℃ for 4-6 hours to obtain the calcium citrate solution.

[0010] As a preferred technical solution of the present invention, the method for preparing the trace element organic acid salt solution is as follows: weigh 10-15 parts by weight of pure citric acid and dissolve it in 500 ml of deionized water, heat to 50°C and stir until completely dissolved, separately dissolve 4-6 parts by weight of inorganic salt in 400 mL of deionized water, slowly add it dropwise to the citric acid solution and stir, then adjust the pH to 6.0-7.0 with 1M NaOH solution, add deionized water to make up to 1 L to obtain the trace element organic acid salt solution.

[0011] As a preferred embodiment of the present invention, the inorganic salt is composed of ferrous sulfate, zinc sulfate, manganese sulfate, and ammonium molybdate in a mass ratio of 1:1:1:1.

[0012] As a preferred embodiment of the present invention, the stirring time is 20 to 30 minutes.

[0013] As a preferred embodiment of the present invention, the temperature of the high-tower granulation is 120-150°C, and the particle size of the base particles is 2.5-4.5 mm.

[0014] As a preferred embodiment of the present invention, the temperature of the fluidized bed dryer is 60-80°C and the time is 30-40 minutes.

[0015] As a preferred technical solution of the present invention, the preparation method of the biodegradable composite membrane liquid is as follows: dissolve 3g of chitosan in 2% acetic acid solution to prepare a chitosan solution with a concentration of 3%; dissolve 3g of polylactic acid in 35mL of chloroform, add 5 drops of tributyl citrate and stir to dissolve to obtain a polylactic acid solution;

[0016] Chitosan solution was slowly added to polylactic acid solution, and diatomaceous earth of 5% to 8% of the chitosan solution mass was added. After stirring thoroughly for 1 hour, 5% sodium bicarbonate solution was added dropwise to adjust the pH of the system to 5.5, thus obtaining the biodegradable composite membrane solution.

[0017] As a preferred technical solution of the present invention, the preparation method of the potassium humate and sodium alginate composite membrane solution is as follows: 2g of sodium alginate is added to 98mL of deionized water, stirred at 60°C for 2 hours until completely dissolved, then 1mL of glycerol is added and stirred for 30 minutes to obtain a sodium alginate solution; 5g of potassium humate is added to 95mL of deionized water, stirred at room temperature for 1 hour until completely dissolved, and then filtered to remove insoluble matter to obtain a potassium humate solution;

[0018] Potassium humate solution was slowly added to sodium alginate solution and stirred at 60°C for 1 hour to obtain potassium humate and sodium alginate composite membrane solution.

[0019] As a preferred embodiment of the present invention, during the process of slowly adding the chitosan solution to the polylactic acid solution, the mass ratio of the chitosan solution to the polylactic acid solution is 7:3.

[0020] As a preferred embodiment of the present invention, during the process of slowly adding potassium humate solution to sodium alginate solution, the mass ratio of potassium humate solution to sodium alginate solution is 5:2.

[0021] As a preferred embodiment of the present invention, the sprayed biodegradable composite film liquid accounts for 20% to 25% of the mass of the base material particles, and the sprayed potassium humate and sodium alginate composite film liquid accounts for 15% to 17% of the mass of the base material particles.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This invention involves spraying a multi-layer composite membrane coating solution during the preparation of high-potassium compound fertilizer. First, a biodegradable composite membrane solution is sprayed. By combining the mechanical properties of polylactic acid (PLA) with the bioactivity of chitosan, a novel material with both environmental friendliness and functionality is formed. PLA serves as the matrix material, and its adjustable degradation rate controls the release cycle of active substances within the membrane. Chitosan in the composite membrane solution reduces potassium ion fixation through chelation, ensuring stable release of fertilizer efficacy in soils with pH values ​​of 4–8. This solves the problem of poor adaptability of traditional materials in acidic / alkaline soils. Furthermore, it can induce crops to produce γ-aminobutyric acid (GABA), promoting potassium absorption, enhancing drought resistance, and increasing yield. By adjusting the ratio of PLA to chitosan, the composite membrane can be completely degraded in a short time, avoiding microplastic pollution. The addition of diatomaceous earth reduces the crystalline bond strength, prolonging the anti-caking effect. Potassium humate and sodium alginate are coated twice, which has the dual advantages of slow nutrient release and soil improvement: the former prolongs the fertilizer effect through colloidal adsorption and ion exchange, while the latter achieves pH-responsive controlled release with a porous structure; at the same time, the two work together to regulate soil pH, improve water retention, and enhance crop stress resistance. In addition, their biodegradability avoids microplastic pollution, combining environmental friendliness and agricultural sustainability.

[0024] 2. In the preparation of high-potassium compound fertilizer, modified zeolite is added. Modified zeolite, through its cation exchange capacity (such as the exchange of sodium and calcium ions with potassium ions), fixes potassium ions in the fertilizer within the crystal channels, reducing leaching losses. On the other hand, it can also adsorb heavy metals such as lead and cadmium in the soil through ion exchange, reducing their bioavailability. The porous structure of zeolite forms a "nutrient reservoir," gradually releasing potassium according to the crop's growth needs, achieving a slow-release and controlled-release effect. Furthermore, zeolite itself contains potassium and trace elements such as iron and zinc, which can supplement soil nutrient deficiencies. Zeolite can also regulate the opening and closing of stomata, reduce water evaporation, adsorb soil pathogens, enhance the activity of crop antioxidant enzymes, and mitigate stress damage.

[0025] 3. In the preparation of high-potassium compound fertilizer, this invention involves spraying Bacillus subtilis inoculant. As a dominant microbial group, Bacillus subtilis can rapidly colonize the soil, inhibiting the growth of harmful pathogens (such as Fusarium and Pythium) through competition for nutrients and ecological niches, thereby reducing disease occurrence and lowering the need for chemical pesticides. The organic acids and enzymes secreted by Bacillus subtilis can decompose insoluble phosphorus, potassium, and organic matter in the soil, releasing fixed nutrients and improving fertilizer utilization. The polysaccharides produced by the metabolism of the bacteria can promote the formation of soil aggregates, enhance the soil's water and fertilizer retention capacity, and alleviate soil compaction caused by long-term application of chemical fertilizers. When Bacillus subtilis reproduces in the soil, its metabolic activities can accelerate the decomposition of organic components such as potassium humate in the coated fertilizer, promoting the release of organic nutrients and forming a "slow and fast" supply mode with inorganic nutrients. At the same time, the inoculant forms a biofilm on the coating surface, which can further slow down the water infiltration rate, working synergistically with the coating to prolong the nutrient release time and match the needs of crops throughout their entire growth period. Attached Figure Description

[0026] Figure 1 This is a production flow diagram of the high-potassium compound fertilizer of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The inner layer is coated with a biodegradable composite membrane solution, using polylactic acid (PLA) as the matrix. Its adjustable degradation rate precisely controls the release cycle of active substances within the membrane. The introduction of chitosan endows the membrane with biological activity; its chelating effect reduces potassium ion fixation in the soil, allowing for stable release of fertilizer effects across a wide pH range of 4–8, overcoming the limitations of traditional materials in adapting to acidic and alkaline environments. Furthermore, chitosan can induce crops to synthesize γ-aminobutyric acid (GABA), promoting potassium absorption and enhancing drought resistance, ultimately leading to increased yield. By optimizing the PLA to chitosan ratio, the composite membrane can completely degrade within six months, avoiding microplastic pollution. The addition of diatomaceous earth further reduces the bonding force of crystallization bonds, significantly extending the anti-caking period. The outer layer uses a secondary coating of potassium humate and sodium alginate. Potassium humate prolongs nutrient release time through colloidal adsorption and ion exchange, while the porous structure of sodium alginate enables pH-responsive controlled release. Together, they regulate soil pH, improve water retention, and enhance crop disease resistance. This hybrid membrane is also biodegradable, and together with the outer layer, it forms an "environmentally friendly, functionally efficient, and sustainable" fertilizer system, providing a green solution for modern agriculture.

[0029] Modified zeolite, with its unique ion exchange and porous structure, achieves the dual functions of efficient nutrient management and soil environment regulation: The cation exchange sites on its crystal surface preferentially adsorb potassium ions from fertilizers, fixing them within microporous channels and effectively reducing potassium leaching loss; simultaneously, it competitively adsorbs heavy metal ions such as lead and cadmium from the soil, reducing their biomigability through complexation and precipitation. The well-developed porous system within the zeolite forms a "nutrient slow-release reservoir," gradually releasing potassium along with the crop root absorption gradient, extending the release period to match the crop's needs throughout its entire growth cycle. Furthermore, it contains potassium and trace elements such as iron and zinc, which can specifically replenish soil nutrient gaps. By regulating stomatal opening and closing, adsorbing pathogens, and enhancing antioxidant enzyme activity, it improves crop stress resistance, ultimately achieving stable and increased yields.

[0030] Bacillus subtilis, as a dominant functional microbial community in soil, possesses multiple ecological regulation and nutrient activation capabilities: it rapidly colonizes to form a biological barrier, competitively inhibiting the nutrition and ecological niches of pathogens such as Fusarium and Pythium, thus reducing the incidence of soil-borne diseases and significantly decreasing reliance on chemical pesticides; its secreted metabolites, such as organic acids, phosphatases, and chitinases, can efficiently decompose insoluble phosphorus, potassium, and organic matter in the soil, converting fixed nutrients into available forms and improving fertilizer utilization; its extracellular polysaccharides can promote the formation of soil aggregates, enhance water and fertilizer retention capacity, and alleviate the compaction problem caused by chemical fertilizer application. Furthermore, its metabolic processes accelerate the decomposition of organic components such as potassium humate in coated fertilizers, forming a "slow-and-fast complementary" supply mode with inorganic nutrients. Simultaneously, the bacterial film and coating synergistically delay water penetration, extending the nutrient release cycle and precisely matching the needs of crops throughout their entire growth cycle.

[0031] like Figure 1As shown, a production process for a high-potassium compound fertilizer includes the following steps: S1. Raw material pretreatment: Potassium feldspar is pulverized to 200 mesh, mixed with 5% sulfuric acid at a mass ratio of 1:3, calcined at 120-130℃ for 2-3 hours, washed with water until the pH is 6.5-7.0, and dried to obtain activated potassium feldspar powder. S2. 15-20 parts by weight of potassium citrate solution, 4-10 parts by weight of calcium citrate solution, 10-16 parts by weight of activated potassium feldspar powder, 6-8 parts by weight of trace element organic acid salt solution, 10-15 parts by weight of urea, 4-6 parts by weight of modified zeolite, and 1-3 parts by weight of binder are added to a high-speed mixer, stirred for 20-30 minutes, and then granulated using a high-tower granulation method to obtain base material granules. S3. Dry the base material granules in a fluidized bed dryer at 60-80℃ for 30-40 minutes to remove fragments smaller than 2.5mm in diameter. Evenly spray the granule surface with a biodegradable composite film solution equal to 20%-25% of the base material granule mass. Then, spray a second coating with a composite film solution of potassium humate and sodium alginate equal to 15%-17% of the base material granule mass. Dry in a fluidized bed at 70℃ for 30-40 minutes to obtain coated base material granules. S4. Spray 4-6 parts by weight of Bacillus subtilis inoculant onto the surface of the coated base material granules and dry at a low temperature of 40℃ to obtain a high-potassium compound fertilizer.

[0032] All raw materials used in this invention are commercially available.

[0033] Example 1:

[0034] A production process for a high-potassium compound fertilizer includes the following steps:

[0035] S1. Raw material pretreatment: Potassium feldspar is crushed to 200 mesh, mixed with 5% sulfuric acid at a mass ratio of 1:3, calcined at 130℃ for 3 hours, washed with water until pH is 7.0, and dried to obtain activated potassium feldspar powder.

[0036] S2. 20 parts by weight of potassium citrate solution, 10 parts by weight of calcium citrate solution, 16 parts by weight of potassium feldspar activated powder, 8 parts by weight of trace element organic acid salt solution, 15 parts by weight of urea, 6 parts by weight of modified zeolite and 3 parts by weight of binder are put into a high-speed mixer and stirred for 30 minutes. Then, the mixture is granulated in a high tower to obtain the base material particles at a temperature of 150℃ and a particle size of 4.5mm.

[0037] S3. The base material particles are dried in a fluidized bed dryer at 80°C for 40 minutes to remove fragments with a diameter of less than 2.5 mm. 25% of the base material particle mass of biodegradable composite film liquid is evenly sprayed onto the particle surface. Then, a second coating is applied by spraying a 17% potassium humate and sodium alginate composite film liquid. The particles are then dried in a fluidized bed at 70°C for 40 minutes to obtain coated base material particles.

[0038] S4. Spray 6 parts by weight of Bacillus subtilis inoculant onto the surface of the coated substrate particles and dry at a low temperature of 40℃ to obtain a high-potassium compound fertilizer.

[0039] Example 2:

[0040] A production process for a high-potassium compound fertilizer includes the following steps:

[0041] S1. Raw material pretreatment: Potassium feldspar is crushed to 200 mesh, mixed with 5% sulfuric acid at a mass ratio of 1:3, calcined at 120℃ for 2 hours, washed with water until pH is 6.5, and dried to obtain activated potassium feldspar powder.

[0042] S2. Add 15 parts by weight of potassium citrate solution, 4 parts by weight of calcium citrate solution, 10 parts by weight of potassium feldspar activated powder, 6 parts by weight of trace element organic acid salt solution, 10 parts by weight of urea, 4 parts by weight of modified zeolite and 1 part by weight of binder into a high-speed mixer, stir for 20 minutes, and then granulate in a high tower to obtain base material particles at a temperature of 120℃ and a particle size of 2.5mm.

[0043] S3. Dry the base material particles in a fluidized bed dryer at 60°C for 30 minutes to remove particles smaller than 2.5 mm in diameter. Spray a 20% biodegradable composite film liquid (based on the mass of the base material particles) evenly onto the particle surface. Then, spray a 15% potassium humate and sodium alginate composite film liquid (based on the mass of the base material particles) for secondary coating. Dry in a fluidized bed at 70°C for 30 minutes to obtain coated base material particles.

[0044] S4. Spray 4 parts by weight of Bacillus subtilis inoculant onto the surface of the coated granules and dry at a low temperature of 40℃ to obtain a high-potassium compound fertilizer.

[0045] Example 3:

[0046] A production process for a high-potassium compound fertilizer includes the following steps:

[0047] S1. Raw material pretreatment: Potassium feldspar is crushed to 200 mesh, mixed with 5% sulfuric acid at a mass ratio of 1:3, calcined at 125℃ for 2.5 hours, washed with water until pH is 6.7, and dried to obtain activated potassium feldspar powder.

[0048] S2. 17 parts by weight of potassium citrate solution, 7 parts by weight of calcium citrate solution, 13 parts by weight of potassium feldspar activated powder, 7 parts by weight of trace element organic acid salt solution, 12 parts by weight of urea, 5 parts by weight of modified zeolite and 2 parts by weight of binder are put into a high-speed mixer and stirred for 25 minutes. Then, the mixture is granulated in a high tower to obtain the base material particles at a temperature of 135℃ and a particle size of 3.5mm.

[0049] S3. The base material particles are dried in a fluidized bed dryer at 70°C for 35 minutes to remove fragments with a diameter of less than 2.5 mm. 22% of the base material particle mass of biodegradable composite film liquid is evenly sprayed onto the particle surface. Then, 16% of the base material particle mass of potassium humate and sodium alginate composite film liquid is sprayed for secondary coating. The particles are then dried in a fluidized bed at 70°C for 35 minutes to obtain coated base material particles.

[0050] S4. Spray 5 parts by weight of Bacillus subtilis inoculant onto the surface of the coated granules and dry at a low temperature of 40℃ to obtain a high-potassium compound fertilizer.

[0051] Comparative Example 1:

[0052] The difference from Example 1 is that the modified zeolite is removed.

[0053] Comparative Example 2:

[0054] The difference from Example 1 is that no biodegradable composite membrane liquid is sprayed.

[0055] Comparative Example 3:

[0056] The difference from Example 1 is that the potassium humate and sodium alginate composite film solution is not sprayed.

[0057] Comparative Example 4:

[0058] The difference from Example 1 is that the Bacillus subtilis agent sprayed on the surface of the coated particles is removed.

[0059] Comparative Example 5:

[0060] The difference from Example 1 is that the potassium feldspar activating powder is removed.

[0061] The organic fertilizers produced in Examples 1, 2, and 3 and Comparative Examples 1, 2, 3, 4, and 5 were subjected to performance tests.

[0062] Referring to the standard GB / T23348-2009 Slow-Release Fertilizers, 5.0g of the high-potassium compound fertilizers prepared in Examples 1, 2, and 3, and Comparative Examples 1, 2, 3, 4, and 5 were weighed and placed into nylon mesh bags. These bags were then placed in beakers containing 1000mL of deionized water and allowed to stand. The beakers were sealed and placed in an electrically heated constant-temperature incubator at 25±0.5℃. Before each sampling, the nylon bags were removed, and the mixture was stirred thoroughly. After sampling, the mixture was poured out. Excess solution was removed and replaced with 1000 mL of fresh deionized water. The samples were stored in 10 mL centrifuge tubes. The potassium-based compound fertilizers prepared in Examples 1, 2, and 3 and Comparative Examples 1, 2, 3, 4, and 5 were measured at 1 day, 10 days, 20 days, 40 days, and 60 days. The calculation formula was: v = Wn / W, where Wn is the mass fraction of potassium released on day n, and W is the mass fraction of total potassium. The results are shown in Table 1.

[0063] Table 1: Potassium Accumulation and Nutrient Release Rate

[0064] 1d(％) 20d(％) 40d(％) 60dd (%) Example 1 5.7 37.2 69.1 86.4 Example 2 6.2 37.5 70.8 87.5 Example 3 6.0 37.3 69.8 88.2 Comparative Example 1 8.9 49.2 80.5 88.6 Comparative Example 2 9.6 56.3 89.3 95.3 Comparative Example 3 9.3 52.2 87.5 90.1 Comparative Example 4 7.9 47.9 77.4 89.7 Comparative Example 5 7.1 43.5 75.3 87.4

[0065] As shown in Table 1, the high-potassium compound fertilizer produced by this invention exhibits better slow-release performance. This is likely due to the excellent adsorption capacity of modified zeolite, which can adsorb nutrients in potassium fertilizer and release them slowly, reducing nutrient loss and ensuring the long-lasting effect of potassium fertilizer in the soil. Furthermore, the porous structure of zeolite improves soil permeability and water retention, promoting healthy root growth. The combination of polylactic acid and chitosan forms a biodegradable composite membrane that can gradually degrade and release nutrients, ensuring slow fertilizer release without environmental pollution. It also enhances the fertilizer's stability and resistance to external environmental influences, effectively extending its service life. Potassium humate helps improve soil structure, increases soil organic matter content, and enhances the soil's potassium adsorption capacity. It also promotes potassium absorption by plants, improves crop resistance, and slows down potassium fertilizer release. Sodium alginate has good biocompatibility, further slowing down the dissolution rate of potassium fertilizer, controlling fertilizer release, and preventing excessively rapid fertilizer effects. This combination of multiple coatings and modified materials greatly improves the slow-release performance of potassium fertilizer, reduces fertilizer waste, and enhances soil fertilizer utilization efficiency.

[0066] At the rice experimental base, eight treatment groups were set up for fertilizing rice, namely Examples 1, 2, and 3 and Comparative Examples 1, 2, 3, 4, and 5. The amount of fertilizer applied was 50-60 kg per mu of rice. The control group received an equal amount of traditional fertilizer. Three parallel experiments were selected for each example and comparative example, and the parallel groups were randomly arranged. One mu of land was selected for each parallel experiment. After the rice matured, its yield, plant height, panicle length, and grain blast incidence rate were measured. The results are shown in Table 2.

[0067] Table 2: Rice Yield and Related Indicators

[0068]

[0069] As shown in Table 2, the high-potassium compound fertilizers produced in Examples 1, 2, and 3, when applied to rice, resulted in higher yields per acre, significantly increased plant height and panicle length, and a certain preventive effect against grain blast. The organic fertilizers produced in Comparative Examples 1, 2, 3, 4, and 5, and the organic fertilizer from the control group, when applied to wheat, resulted in lower wheat yields, lower rice plant height and panicle length, and a weaker preventive effect against grain blast compared to the Example groups.

[0070] Modified zeolite slowly releases potassium fertilizer, ensuring a continuous potassium supply for rice at all growth stages, promoting healthy root development, enhancing plant resistance, and thus increasing rice yield, plant height, and panicle length. A biodegradable composite membrane coating controls the fertilizer release rate, preventing excessive potassium release and improving rice's potassium absorption efficiency. A stable potassium supply helps improve plant height and panicle length, and promotes good tillering and grain weight, thereby increasing yield. A secondary coating of potassium humate and sodium alginate complex improves soil structure, enhances soil water and fertilizer retention capacity, slows fertilizer release, provides a continuous nutrient supply, enhances rice resistance, reduces adverse environmental impacts during growth, and helps increase rice height and panicle length. Bacillus subtilis has biocontrol properties, inhibiting pathogen growth, especially preventing grain blast. By enhancing plant immunity and reducing disease occurrence, it helps stabilize rice growth and increase yield.

[0071] In summary, the high-potassium compound fertilizer produced by this invention has high nutrient content, long-lasting fertilizer effect, no pollution, and can improve the soil environment and increase crop yield.

[0072] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A process for the production of high potassium-based compound fertilizers, characterized in that, Includes the following steps: S1. Raw material pretreatment: Potassium feldspar is crushed to 200 mesh, mixed with 5% sulfuric acid at a mass ratio of 1:3, calcined at 120~130℃ for 2~3 hours, washed with water until pH is 6.5~7.0, and dried to obtain activated potassium feldspar powder; S2. Add 15-20 parts by weight of potassium citrate solution, 4-10 parts by weight of calcium citrate solution, 10-16 parts by weight of potassium feldspar activated powder, 6-8 parts by weight of trace element organic acid salt solution, 10-15 parts by weight of urea, 4-6 parts by weight of modified zeolite, and 1-3 parts by weight of binder into a high-speed mixer, stir for 20-30 minutes, and then granulate using a high tower to obtain base material particles; S3. Dry the base material particles in a fluidized bed dryer at 60~80℃ for 30~40 minutes to remove fragments with a diameter of less than 2.5mm. Spray a biodegradable composite film liquid evenly onto the surface of the particles, and then spray a composite film liquid of potassium humate and sodium alginate evenly for secondary coating. Dry in a fluidized bed at 70℃ for 30~40 minutes to obtain coated base material particles. S4. Spray 4-6 parts by weight of Bacillus subtilis inoculant onto the surface of the coating base material granules, and dry at a low temperature of 40℃ to obtain a high potassium-based compound fertilizer; The method for preparing the potassium citrate solution is as follows: Take 10 parts by weight of pure citric acid and 6-9 parts by weight of 2-5M potassium bicarbonate solution, mix them evenly, add 0.4-1.0% of leveling agent TAN (or leveling agent) of the total weight of the solution, and react at 40-80℃ for 2-4 hours to obtain potassium citrate solution. The method for preparing the calcium citrate solution is as follows: Take 10 parts by weight of pure citric acid and 6-9 parts by weight of 1-2M calcium hydroxide solution, mix them evenly, add 0.4-1.0% of leveling agent TAN (or leveling agent) of the total weight of the solution, and react at 80-110℃ for 4-6 hours to obtain the calcium citrate solution. The method for preparing the trace element organic acid salt solution is as follows: Weigh 10-15 parts by weight of pure citric acid and dissolve it in 500 ml of deionized water, heat to 50°C and stir until completely dissolved. Separately, dissolve 4-6 parts by weight of inorganic salt in 400 mL of deionized water, slowly add it dropwise to the citric acid solution and stir, then adjust the pH to 6.0-7.0 with 1 M NaOH solution, add deionized water to make up to 1 L to obtain the trace element organic acid salt solution. The temperature of the high-tower granulation is 120~150℃, and the particle size of the base particles is 2.5~4.5mm; The preparation method of the biodegradable composite membrane liquid is as follows: dissolve 3g of chitosan in 2% acetic acid solution to prepare a chitosan solution with a concentration of 3%; dissolve 3g of polylactic acid in 35mL of chloroform, add 5 drops of tributyl citrate and stir to dissolve to obtain a polylactic acid solution. Chitosan solution was slowly added to polylactic acid solution, and diatomaceous earth (5%–8% by weight of chitosan solution) was added. After stirring thoroughly for 1 hour, 5% sodium bicarbonate solution was added dropwise to adjust the pH of the system to 5.5, thus obtaining the biodegradable composite membrane solution. The preparation method of the potassium humate and sodium alginate composite membrane solution is as follows: 2g of sodium alginate is added to 98mL of deionized water and stirred at 60℃ for 2 hours until completely dissolved. Then, 1mL of glycerol is added and stirred for 30 minutes to obtain a sodium alginate solution. 5g of potassium humate is added to 95mL of deionized water and stirred at room temperature for 1 hour until completely dissolved. The insoluble matter is then removed by filtration to obtain a potassium humate solution. The potassium humate solution is slowly added to the sodium alginate solution and stirred at 60℃ for 1 hour to obtain the potassium humate and sodium alginate composite membrane solution. The sprayed biodegradable composite film liquid accounts for 20% to 25% of the mass of the base material particles, and the sprayed potassium humate and sodium alginate composite film liquid accounts for 15% to 17% of the mass of the base material particles.

2. The process for producing a high potassium-based compound fertilizer according to claim 1, characterized in that, The inorganic salt is composed of ferrous sulfate, zinc sulfate, manganese sulfate, and ammonium molybdate in a mass ratio of 1:1:1:

1.

3. The process for producing a high potassium-based compound fertilizer according to claim 1, characterized in that, During the slow addition of the chitosan solution to the polylactic acid solution, the mass ratio of the chitosan solution to the polylactic acid solution is 7:

3.

4. The process for producing a high potassium-based compound fertilizer according to claim 1, characterized in that, During the slow addition of potassium humate solution to sodium alginate solution, the mass ratio of potassium humate solution to sodium alginate solution is 5:2.

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