A functional compound fertilizer containing soil conditioner and its preparation method

Abstract

This invention relates to the field of agricultural fertilizer technology, and discloses a functional compound fertilizer containing a soil conditioner and its preparation method. The fertilizer provided by this invention is composed of nitrogen, phosphorus, and potassium sources, a compound soil conditioner, microencapsulated functional microbial agents, chelated trace elements, and a slow-release coating agent. The preparation method includes raw material pretreatment, step-by-step mixing, granulation, and coating processes. The fertilizer provided by this invention addresses the shortcomings of existing banana-specific fertilizers, such as poor synergy between soil conditioning and nutrient distribution, mismatch between fertilizer release and growth cycle, and limited stress resistance. It can precisely improve acidic banana plantation soil, achieve dynamic nutrient release, improve fertilizer utilization, reduce the incidence of banana wilt disease, significantly increase yield and fruit quality, is suitable for various cultivation models, and possesses both practical and environmental value.

Description

Technical Field

[0001] This invention relates to the field of agricultural fertilizer technology, and more specifically, to a functional compound fertilizer containing soil conditioner and its preparation method. Background Technology

[0002] Bananas, as a globally important tropical economic crop, have a long growth cycle and require large amounts of fertilizer. They have a balanced need for macronutrients such as nitrogen, phosphorus, and potassium, as well as micronutrients such as calcium, magnesium, boron, and zinc, and also have high requirements for soil conditions. Currently, various technical solutions have been developed in the field of banana-specific compound fertilizers, but many problems still need to be solved in their practical application, as follows: Soil acidification is a serious problem in major banana-producing areas of my country, such as Guangdong Province, Guangxi Zhuang Autonomous Region, and Hainan Province. The proportion of banana plantations with a pH value below 5.0 has reached 28%. This acidic environment not only reduces the availability of nutrients such as phosphorus and calcium but also easily breeds pathogens such as Fusarium, inducing banana wilt disease. While existing technologies include methods to adjust soil acidity using lime and calcium magnesium phosphate fertilizers, simply applying alkaline conditioners can easily lead to sudden changes in local soil pH, disrupting the balance of the soil microbial community. Furthermore, most conditioners have poor compatibility with fertilizer components, easily causing nutrient fixation or loss. For example, when calcium magnesium phosphate fertilizer is mixed with conventional fertilizers, it is difficult to simultaneously achieve the acidification improvement effect and the synergistic release of nitrogen, phosphorus, and potassium nutrients. The nutrient requirements of bananas differ significantly during the vegetative growth stage, flower bud differentiation stage, and budding and fruiting stage, requiring a dynamic supply model of appropriate nitrogen in the early stage, precise phosphorus in the middle stage, and sufficient potassium in the later stage. Existing banana-specific fertilizers mostly employ single slow-release technology or fixed ratios. For example, some blended fertilizers use calcium magnesium phosphate powder coating to prevent moisture decomposition, but they do not achieve phased release control of nutrients. Although conventional controlled-release fertilizers can extend the release period, it is difficult to dynamically adjust the release rate according to the nutrient requirements of bananas at different growth stages, resulting in a fertilizer utilization rate of only 30%-40%, which not only wastes resources but also exacerbates agricultural non-point source pollution.

[0003] Furthermore, some existing technologies focus solely on nutrient supply while neglecting soil health maintenance; a few fertilizers containing soil conditioners only address acidification, lacking the ability to enhance banana resistance (such as lodging resistance and wilt resistance). For example, the method disclosed in patent application CN106852250A controls banana wilt by improving soil acidity, applying precise fertilization, and intercropping with peanuts, but requires complex cultivation management measures, is cumbersome, and unsuitable for large-scale monoculture banana plantations; while conventional fertilizers containing microbial agents suffer from poor compatibility with chemical fertilizers and low survival rates, making it difficult to function stably in banana growing environments. Soil types vary significantly across banana growing regions in my country (e.g., Hainan red soil, Guangxi red soil), and large-scale cultivation coexists with small-scale, scattered farming, while the adoption rate of new technologies such as integrated water and fertilizer management is gradually increasing. Existing specialized fertilizers are mostly general formulas that have not been optimized for different soil fertility, planting density and irrigation modes. For example, blended fertilizers that are suitable for alkaline soils in the north cannot be adapted to acidic red soils in the south. Traditional granular fertilizers are prone to clogging in drip irrigation systems and cannot meet the needs of integrated water and fertilizer cultivation.

[0004] In summary, developing a functional compound fertilizer that combines precise soil conditioning, dynamic nutrient supply, stress resistance and efficiency enhancement, and is suitable for different banana planting scenarios, has become a key need to solve the current pain points in banana planting and promote the sustainable development of the industry. Summary of the Invention

[0005] In view of this, the present invention proposes a functional compound fertilizer containing soil conditioner and its preparation method, aiming to solve the technical problems of the current banana-specific compound fertilizer, such as poor soil acidification improvement and nutrient synergy, low utilization rate due to nutrient release not matching the banana growth cycle, disconnect between stress resistance and soil improvement functions, and weak adaptability to different soils and cultivation modes.

[0006] On the one hand, the present invention proposes a functional compound fertilizer containing a soil conditioner, which, by weight, includes the following components: 25-35 parts of nitrogen source, 8-15 parts of phosphorus source, 30-40 parts of potassium source, 10-20 parts of compound soil conditioner, 2-5 parts of functional microbial agent, 3-8 parts of chelated trace elements, 2-6 parts of slow-release coating agent, and 1-3 parts of binder. The nitrogen source is a mixture of urea and ammonium humate in a weight ratio of 2:1. The composite soil conditioner is a mixture of modified calcium magnesium phosphate fertilizer, oyster shell powder and humic acid, with a weight ratio of 5:3:2. The modified calcium magnesium phosphate fertilizer is obtained by calcining and pulverizing calcium magnesium phosphate fertilizer, and then loading humic acid synergist onto its surface.

[0007] More preferably, the humic acid synergist has a mass fraction of 5%.

[0008] More preferably, the chelated trace elements consist of EDTA-chelated calcium, EDTA-chelated magnesium, boric acid, and zinc sulfate heptahydrate in a weight ratio of 4:3:2:1.

[0009] More preferably, the phosphorus source is a mixture of monoammonium phosphate and activated phosphate rock powder in a weight ratio of 3:1; the potassium source is a mixture of potassium chloride and potassium silicate in a weight ratio of 4:1.

[0010] More preferably, the functional microbial agent is a complex of Bacillus subtilis, Bacillus amyloliquefaciens and Rhizobium, with a viable count ≥2×10 CFU / g and a weight ratio of 3:2:1.

[0011] More preferably, the functional bacterial agent is microencapsulated, and the encapsulating material is a mixture of sodium alginate and chitosan in a weight ratio of 1:1.

[0012] More preferably, the slow-release coating agent is a compound of nano-sized polyurethane and sulfur in a weight ratio of 3:2; the binder is sodium carboxymethyl cellulose.

[0013] On the other hand, the present invention also proposes a method for preparing the above-mentioned functional compound fertilizer containing soil conditioner, comprising the following steps: S1. Calcium magnesium phosphate fertilizer is calcined and pulverized. After pulverization, 5% by mass of humic acid synergist is loaded on its surface to obtain modified calcium magnesium phosphate fertilizer. The modified calcium magnesium phosphate fertilizer is mixed with oyster shell powder and humic acid and then pulverized to 200-300 mesh to obtain a composite soil conditioner. S2. Functional bacterial agents were encapsulated in sodium alginate-chitosan microcapsules to obtain microencapsulated functional bacterial agents; S3. Weigh out the nitrogen source, phosphorus source and potassium source according to the weight parts, stir them to obtain the first mixture; S4. Add the composite soil conditioner and chelated trace elements to the first mixture and stir to obtain the second mixture; S5. The second mixture is mixed with a binder and granulated. The product obtained from the granulation is sprayed with a slow-release coating agent and microencapsulated functional bacteria agent is added for coating treatment to obtain the functional compound fertilizer containing soil conditioner.

[0014] More preferably, in step S1, the calcination temperature of the calcium magnesium phosphate fertilizer is 500-600℃, and the calcination time is 2-3 hours; the particle size of the calcium magnesium phosphate fertilizer is 200 mesh.

[0015] More preferably, in step S5, the particle size of the product obtained by the granulation treatment is 2-4 mm; and the temperature during the coating treatment is 30-35℃.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Precise and efficient soil conditioning, achieving synergistic improvement of acidification and activation of nutrients: In the compound soil conditioner, modified calcium magnesium phosphate fertilizer and oyster shell powder work together to slowly release calcium and magnesium ions, avoiding sudden changes in soil pH and maintaining a stable pH of 6.0-6.5, effectively regulating soil acidity; while humic acid not only enhances the compatibility of the conditioner with chemical fertilizers, but also activates fixed phosphorus and potassium in the soil, improves nutrient availability, improves soil aggregate structure, and promotes the balance of microbial communities.

[0017] 2. Dynamic nutrient release matched to the banana growth cycle, significantly improving utilization: Through the optimization of the slow-release coating agent and the microencapsulation of functional microbial agents, the nutrient release is achieved in stages: nitrogen is slowly released during the vegetative growth period to avoid excessive vegetative growth; phosphorus and micronutrients are precisely released during the flower bud differentiation period to promote flower bud differentiation; potassium and silicon are efficiently released during the fruiting period, which greatly improves fertilizer utilization and enhances fruit quality.

[0018] 3. Synergistic effects enhance banana resistance, yield, and quality: In the compound functional microbial agent, Bacillus subtilis and Bacillus amyloliquefaciens inhibit the reproduction of pathogens such as Fusarium, reducing the incidence of banana wilt by more than 35%; Rhizobium synergistically enhances soil nitrogen fixation capacity with humic acid, reducing nitrogen fertilizer application; Potassium silicate and chelated trace elements enhance the resilience of banana plants and improve lodging resistance.

[0019] 4. Wide adaptability and simplified application process: The fertilizer of this invention can adjust the component ratio according to different soil fertility, and is suitable for various banana planting soils such as red soil and red soil; the granular form is suitable for manual fertilization and mechanized fertilization, and the microencapsulated bacterial agent improves the applicability of the fertilizer in the water and fertilizer integration system, which can meet the different needs of large-scale and decentralized planting, and is convenient to apply, reducing labor costs. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a flowchart illustrating a method for preparing a functional compound fertilizer containing a soil conditioner, as provided in an embodiment of the present invention. Detailed Implementation

[0021] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] On the one hand, the present invention proposes a functional compound fertilizer containing a soil conditioner, characterized in that, by weight, it comprises the following components: 25-35 parts nitrogen source, 8-15 parts phosphorus source, 30-40 parts potassium source, 10-20 parts compound soil conditioner, 2-5 parts functional microbial agent, 3-8 parts chelated trace elements, 2-6 parts slow-release coating agent, and 1-3 parts binder; Specifically, the nitrogen source is a mixture of urea and ammonium humate, wherein the weight ratio of urea to ammonium humate is 2:1.

[0023] Understandably, urea, once applied to the soil, is rapidly absorbed by the banana roots, meeting the urgent nitrogen needs of banana seedlings during the vegetative growth stage, from seedling stage to before flower bud differentiation, thus promoting leaf expansion and robust stems. Ammonium humate, on the other hand, provides a continuous supply of nitrogen from flower bud differentiation to fruiting, preventing poor fruit development due to insufficient nitrogen supply later on. A 2:1 ratio of urea and ammonium humate balances nitrogen release, addressing the issues of rapid nitrogen loss and low utilization rate associated with urea alone, while also compensating for the slow effect and insufficient early-stage nitrogen supply of ammonium humate alone, thus meeting the nitrogen needs of bananas throughout their entire growth cycle. When urea is applied alone, nitrogen utilization is typically less than 35%; the humic acid in ammonium humate has strong adsorption and chelation capabilities, combining with the ammonium nitrogen produced by urea decomposition, reducing nitrogen volatilization and leaching losses. With a 2:1 ratio, urea provides readily available nitrogen to quickly meet growth needs, while the humic acid component of ammonium humate plays a role in nitrogen fixation and fertilizer retention, significantly reducing fertilizer usage and agricultural non-point source pollution. The humic acid in ammonium humate, together with the mineral humic acid and modified calcium magnesium phosphate in the compound soil conditioner, forms a synergistic effect. On the one hand, they can jointly promote the formation of soil aggregates and improve the compaction problem of acidic banana plantation soil; on the other hand, they can activate the fixed phosphorus, calcium, magnesium and other nutrients in the soil, improving the overall nutrient availability of the fertilizer.

[0024] Specifically, the composite soil conditioner is a mixture of modified calcium magnesium phosphate fertilizer, oyster shell powder and humic acid, wherein the weight ratio of the modified calcium magnesium phosphate fertilizer, oyster shell powder and humic acid is 5:3:2; the modified calcium magnesium phosphate fertilizer is obtained by calcining and pulverizing calcium magnesium phosphate fertilizer and then loading a humic acid synergist onto its surface, wherein the mass fraction of the humic acid synergist is preferably 5%.

[0025] Understandably, modified calcium magnesium phosphate fertilizer, as the core acid-regulating and nutrient-activating component, undergoes a process where its crystal structure is broken after calcination at 500-600℃, increasing the release efficiency of effective components such as calcium, magnesium, and phosphorus by over 30%. Surface loading with humic acid synergists not only solves the problems of poor compatibility between ordinary calcium magnesium phosphate fertilizer and chemical fertilizers, which can easily lead to nutrient fixation, but also promotes banana root development through phosphorus supply, while calcium and magnesium enhance the cell wall toughness of banana plants, reducing the risk of fruit cracking and lodging. The acid-regulating process of oyster shell powder is gentle, avoiding sudden increases or decreases in soil pH that could disrupt the microbial community. Simultaneously, oyster shell powder continuously replenishes calcium, precisely matching the high calcium requirements of bananas and effectively preventing top rot caused by calcium deficiency in acidic soils. Mineral-derived humic acid can serve as a component of soil conditioners, promoting soil aggregate formation in acidic banana plantations through its colloidal properties, reducing soil bulk density, and enhancing water and fertilizer retention capacity. Furthermore, it can chelate elements such as phosphorus, zinc, and boron fixed in the soil, improving nutrient availability. Simultaneously, humic acid provides a carbon source for functional microbial agents, promoting the reproduction of beneficial microorganisms and enhancing soil disease resistance. However, applying modified calcium magnesium phosphate fertilizer alone results in a long acidification cycle and limited soil structure improvement; applying oyster shell powder alone has insufficient nutrient activation capacity; and applying humic acid alone has a weak alkalinity-regulating effect, making it difficult to quickly raise the pH of acidic soil to a suitable range for banana cultivation. The three components work synergistically: the rapid acid-regulating effect of modified calcium magnesium phosphate fertilizer and the slow-acting acid-stabilizing effect of oyster shell powder can achieve precise control of soil pH; humic acid not only enhances the dispersibility of modified calcium magnesium phosphate fertilizer and oyster shell powder in the soil, but also avoids nutrient fixation when alkaline components come into contact with chemical fertilizers, ultimately achieving a compound effect of rapidly improving acidified soil, maintaining soil health for a long time, and simultaneously supplementing micronutrients.

[0026] Specifically, preferably, the chelated trace elements consist of EDTA-chelated calcium, EDTA-chelated magnesium, boric acid, and zinc sulfate heptahydrate in a weight ratio of 4:3:2:1.

[0027] Understandably, the addition of chelated micronutrients in specific proportions addresses micronutrient deficiencies in bananas, while simultaneously improving the availability of micronutrients in acidic soils. Furthermore, this component works synergistically with compound soil conditioners, nitrogen, phosphorus, and potassium sources, and functional microbial agents in fertilizers, ensuring a balanced nutrient supply throughout the banana's entire growth cycle. Bananas are a crop with high micronutrient requirements; deficiencies in calcium, magnesium, boron, and zinc directly lead to reduced yields and lower quality. The EDTA-chelated calcium, EDTA-chelated magnesium, boric acid, and zinc sulfate heptahydrate selected in this invention are all essential micronutrients for banana growth. The 4:3:2:1 ratio is optimized based on the different growth stages of bananas and precisely meets their needs. The soils in major banana-producing areas are mostly acidic red soil / latysodium soil. Ordinary inorganic micronutrients (such as calcium sulfate and magnesium sulfate) are easily adsorbed and fixed by iron and aluminum ions in the soil under acidic conditions, resulting in a utilization rate typically less than 20%. EDTA-chelated calcium and magnesium possess stable chelate ring structures, preventing reactions with soil ions and maintaining high activity even in acidic soils with a pH of 4.5-6.5, increasing utilization to over 60%. Boric acid and zinc sulfate heptahydrate complement the chelated components; boron exists in molecular form and is not easily fixed, while zinc, protected by the chelation system, continuously supplies nutrients to the banana roots. Furthermore, the chemical properties of chelated micronutrients are stable, compatible with slow-release coating agents and modified calcium-magnesium-phosphate fertilizers, and will not be degraded by high temperatures or acidic / alkaline environments during fertilizer granulation and coating. Simultaneously, the release rate of chelated elements is synchronized with the slow-release rhythm of nitrogen, phosphorus, and potassium, ensuring continuous supply throughout the banana's vegetative growth, flower bud differentiation, and fruiting stages, avoiding the problem of excessive amounts in the early stages and insufficient amounts in the later stages associated with ordinary micronutrients.

[0028] Specifically, the phosphorus source is preferably a mixture of monoammonium phosphate and activated phosphate rock powder, with a weight ratio of 3:1; the potassium source is preferably a mixture of potassium chloride and potassium silicate, with a weight ratio of 4:1.

[0029] Understandably, monoammonium phosphate (MAP) can be rapidly absorbed by banana roots, meeting the urgent phosphorus needs of bananas during their vegetative growth and flower bud differentiation stages, thus promoting root development and flower bud differentiation. Activated phosphate rock powder, as a slow-release phosphorus source, has a gradual and sustained phosphorus release rate, providing continuous phosphorus supply during the banana fruiting period and preventing poor fruit development due to insufficient phosphorus in the later stages. The combination of these two sources solves the problem of excessive phosphorus supply in the early stages and insufficient phosphorus supply in the later stages that occurs when using a single phosphorus source. After activation treatment, the phosphorus activation degree of activated phosphate rock powder is increased, and its synergistic effect with compound soil conditioners can reduce phosphorus fixation by the soil. At the same time, the acidic properties of MAP can moderately regulate the soil microenvironment, further enhancing phosphorus availability.

[0030] Understandably, potassium chloride can quickly replenish potassium, promoting fruit enlargement and sugar accumulation; potassium silicate not only provides potassium but also replenishes silicon. Silicon can be deposited in the cell walls of banana plants, enhancing stem toughness and leaf hardness, improving the plant's resistance to lodging and pests, and reducing the incidence of wilt disease. When combined with potassium chloride, it can neutralize some of the acidity in acidic soils, forming a synergistic acid-regulating effect with compound soil conditioners, helping to maintain the soil pH within the suitable range of 6.0-6.5; at the same time, it avoids the problem of exacerbating soil acidification that may occur when potassium chloride is applied alone. Potassium silicate releases potassium at a slower rate than potassium chloride. When the two are combined, the potassium release rhythm matches the controlled-release effect of the slow-release coating agent, achieving a continuous supply of potassium and improving the overall utilization rate of potassium fertilizer.

[0031] Specifically, the functional microbial agent is a complex of Bacillus subtilis, Bacillus amyloliquefaciens, and Rhizobium, with a viable count ≥2×10 CFU / g and a weight ratio of 3:2:1.

[0032] Understandably, this invention uses a 3:2:1 mixture of Bacillus subtilis, Bacillus amyloliquefaciens, and Rhizobium as a functional microbial agent. The combination of Bacillus subtilis and Bacillus amyloliquefaciens can target and inhibit the reproduction and infection of Fusarium wilt pathogens in bananas, broadening the antibacterial spectrum and improving the control efficacy. Compared with single strains, the combined use can avoid the development of drug resistance in pathogens. At the same time, the organic acids produced by the metabolism of the three strains can activate phosphorus, potassium, and trace elements fixed in the soil, complementing the nutrients in fertilizers and further improving fertilizer utilization. After colonization, the compound microbial community can optimize the soil microbial community structure, inhibit the growth of harmful bacteria, and promote the formation of soil aggregates. At the same time, it secretes substances such as auxins to stimulate banana root growth, enhance the root system's ability to absorb water and nutrients, and improve the plant's resistance to lodging and stress. After being encapsulated in sodium alginate-chitosan microcapsules, it can withstand the mild high temperature during fertilizer granulation and coating processes, and is compatible with components such as chemical fertilizers and soil conditioners. It is protected from being killed by acidic or alkaline environments, and has a survival rate of ≥90% in the soil, ensuring long-term effectiveness.

[0033] Specifically, preferably, the functional bacterial agent is microencapsulated, and the encapsulation material is preferably a mixture of sodium alginate and chitosan, with a weight ratio preferably of 1:1.

[0034] Understandably, the good compatibility of sodium alginate and chitosan mixture allows them to form a dense and porous microcapsule structure. This structure can withstand the mild high-temperature and acid-base environments of fertilizer granulation and coating, protecting the activity of functional microbial agents. It also enables the slow release of the bacterial strains into the soil, extending the duration of effectiveness. Furthermore, the material is biodegradable, environmentally friendly, and compatible with other fertilizer components, ensuring a high survival rate of the microbial agents in the field.

[0035] Specifically, the slow-release coating agent is preferably a compound of nano-sized polyurethane and sulfur, with a weight ratio preferably of 3:2; the binder is preferably sodium carboxymethyl cellulose.

[0036] Understandably, nano-sized polyurethane has excellent film-forming properties, which can form a dense and breathable coating layer and precisely control the nutrient release rate; sulfur has both slow-release and antibacterial effects, which can delay the degradation of the coating and inhibit the reproduction of harmful bacteria in the soil. The combination of the two can achieve dynamic matching between nutrient release and banana growth cycle, and avoid nutrient loss.

[0037] On the other hand, the present invention also proposes a method for preparing the above-mentioned functional compound fertilizer containing soil conditioner, see reference. Figure 1 This includes the following steps: S1. Calcium magnesium phosphate fertilizer is calcined and pulverized. After pulverization, 5% by mass of humic acid synergist is loaded on its surface to obtain modified calcium magnesium phosphate fertilizer. The modified calcium magnesium phosphate fertilizer is mixed with oyster shell powder and humic acid and then pulverized to 200-300 mesh to obtain a composite soil conditioner. Specifically, the preferred calcination temperature for the calcium magnesium phosphate fertilizer is 500-600℃, and the preferred calcination time is 2-3 hours; the preferred particle size of the calcium magnesium phosphate fertilizer is 200 mesh.

[0038] S2. Functional bacterial agents were encapsulated in sodium alginate-chitosan microcapsules to obtain microencapsulated functional bacterial agents; S3. Weigh out the nitrogen source, phosphorus source and potassium source according to the weight parts, stir them to obtain the first mixture; S4. Add the composite soil conditioner and chelated trace elements to the first mixture and stir to obtain the second mixture; S5. The second mixture is mixed with a binder and granulated. The product obtained from the granulation is sprayed with a slow-release coating agent and microencapsulated functional bacteria agent is added for coating treatment to obtain the functional compound fertilizer containing soil conditioner.

[0039] Specifically, the particle size of the product obtained by the granulation process is preferably 2-4 mm; the temperature during the coating process is preferably 30-35℃.

[0040] It is understood that the preparation method provided by this invention enhances nutrient activity through calcination modification of calcium magnesium phosphate fertilizer, and microencapsulation of microbial agents ensures survival rate, laying the foundation for fertilizer function. The stepwise mixing process avoids antagonistic reactions between functional components, ensuring uniform mixing of nutrients, conditioners, and microbial agents, and improving the overall synergistic effect of the fertilizer. The parameters of coating and granulation are controllable, the particle size is adapted to various fertilization modes, and the slow-release coating enables dynamic nutrient release, matching the banana growth cycle. The process is mild and low-consumption, requires no special equipment, is suitable for large-scale production, and the raw materials are readily available and the cost is controllable. The finished product has strong stability and can effectively improve soil, enhance fertilizer efficiency, and strengthen the stress resistance of bananas after application.

[0041] Example 1 A functional compound fertilizer containing soil conditioner comprises the following components by weight: 20 parts urea, 10 parts ammonium humate, 9 parts monoammonium phosphate, 3 parts activated phosphate rock powder, 32 parts potassium chloride, 8 parts potassium silicate, 5 parts modified calcium magnesium phosphate fertilizer, 3 parts oyster shell powder, 2 parts humic acid, 1.2 parts Bacillus subtilis, 0.8 parts Bacillus amyloliquefaciens, 1 part rhizobium, 1.6 parts EDTA chelated calcium, 1.2 parts EDTA chelated magnesium, 0.8 parts boric acid, 0.4 parts zinc sulfate heptahydrate, 1.8 parts nano-grade polyurethane, 1.2 parts sulfur, and 2 parts sodium carboxymethyl cellulose.

[0042] Preparation method: S1. Raw material pretreatment: Calcium magnesium phosphate fertilizer is calcined at 550℃ for 2.5h and pulverized to 200 mesh. Humic acid synergist at a mass fraction of 5% of the refined calcium magnesium phosphate fertilizer powder is added and stirred at 30-35℃ at 150-200 r / min for 20min to obtain modified calcium magnesium phosphate fertilizer. The modified calcium magnesium phosphate fertilizer is mixed with oyster shell powder and humic acid, and ball-milled to 250 mesh to obtain a composite soil conditioner. Bacillus subtilis, Bacillus amyloliquefaciens, and rhizobia are mixed and encapsulated in sodium alginate-chitosan microcapsules (sodium alginate to chitosan weight ratio 1:1).

[0043] S2. Basic nutrient mixing: Weigh out urea, ammonium humate, monoammonium phosphate, activated phosphate rock powder, potassium chloride, and potassium silicate, and put them into a double helix mixer. Stir at room temperature for 18 minutes at a speed of 180 r / min. S3. Functional component compounding: Add compound soil conditioner, EDTA chelated calcium, EDTA chelated magnesium, boric acid, and zinc sulfate heptahydrate to the mixer, heat to 45℃, and stir for 28 minutes. S4. Granulation and coating: Add sodium carboxymethyl cellulose and mix evenly. Granulate the mixture using a disc granulator to control the particle size to 2-4 mm. Feed the granulated product into a coating roller and spray in a mixture of nano-sized polyurethane and sulfur as a slow-release coating agent. At the same time, add microencapsulated functional bacteria agent and coat the product at a constant temperature of 32°C for 12 min. S5. Finished product testing and packaging: After cooling to room temperature, the product is screened and tested to confirm that the total nitrogen, phosphorus and potassium content is ≥45%, the bacterial agent survival rate is ≥90%, and the nitrogen slow-release period is ≥120 days. The finished product is then measured and packaged.

[0044] Example 2 A functional compound fertilizer containing soil conditioner comprises the following components by weight: 18 parts urea, 9 parts ammonium humate, 7.5 parts monoammonium phosphate, 2.5 parts activated phosphate rock powder, 28 parts potassium chloride, 7 parts potassium silicate, 4 parts modified calcium magnesium phosphate fertilizer, 2.4 parts oyster shell powder, 1.6 parts humic acid, 0.9 parts Bacillus subtilis, 0.6 parts Bacillus amyloliquefaciens, 0.5 parts rhizobium, 1.2 parts EDTA chelated calcium, 0.9 parts EDTA chelated magnesium, 0.6 parts boric acid, 0.3 parts zinc sulfate heptahydrate, 1.5 parts nano-grade polyurethane, 1 part sulfur, and 1.5 parts sodium carboxymethyl cellulose.

[0045] The preparation method is the same as in Example 1, except that the calcination temperature is adjusted to 500℃, the stirring time to 15 min, and the coating temperature to 30℃. Product testing confirmed that the total nitrogen, phosphorus, and potassium content was ≥42%, the bacterial agent survival rate was ≥90%, and the nitrogen slow-release period was ≥100 days.

[0046] A field trial was conducted in an acidic banana plantation in Hainan (soil pH=4.8) to set up Example 1 of the present invention. The control group and the conventional banana-specific fertilizer group (NPK ratio 15:7:24) were divided into three plots, each with an area of ​​30㎡ and a planting density of 166 plants / acre. All other cultivation conditions were the same.

[0047] The experimental results were compiled into a table, as shown in Table 1.

[0048]

[0049] Table 1 Comparison of Field Trial Results According to Table 1, the incidence of banana wilt in Example 1 group was 8.3%, while that in the control group was 26.7%; the yield in Example 1 group was 42.5 tons / hectare, while that in the control group was 34.2 tons / hectare; the soil pH in Example 1 group increased to 5.9, while that in the control group decreased to 4.7; and the fertilizer utilization rate in Example 1 group was 68%, while that in the control group was 38%. It can be seen that the fertilizer of this invention is significantly superior to existing technologies in terms of soil improvement, stress resistance enhancement, and yield increase.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A functional compound fertilizer containing a soil conditioner, characterized in that, By weight, it includes the following components: 25-35 parts nitrogen source, 8-15 parts phosphorus source, 30-40 parts potassium source, 10-20 parts compound soil conditioner, 2-5 parts functional microbial agent, 3-8 parts chelated trace elements, 2-6 parts slow-release coating agent, and 1-3 parts binder. The nitrogen source is a mixture of urea and ammonium humate in a weight ratio of 2:

1. The composite soil conditioner is a mixture of modified calcium magnesium phosphate fertilizer, oyster shell powder and humic acid, with a weight ratio of 5:3:

2. The modified calcium magnesium phosphate fertilizer is obtained by calcining and pulverizing calcium magnesium phosphate fertilizer, and then loading humic acid synergist onto its surface.

2. The compound fertilizer according to claim 1, characterized in that, The mass fraction of the humic acid synergist is 5%.

3. The compound fertilizer according to claim 1, characterized in that, The chelated trace elements consist of EDTA-chelated calcium, EDTA-chelated magnesium, boric acid, and zinc sulfate heptahydrate in a weight ratio of 4:3:2:

1.

4. The compound fertilizer according to claim 1, characterized in that, The phosphorus source is a mixture of monoammonium phosphate and activated phosphate rock powder in a weight ratio of 3:1; the potassium source is a mixture of potassium chloride and potassium silicate in a weight ratio of 4:

1.

5. The compound fertilizer according to claim 1, characterized in that, The functional microbial agent is a complex of Bacillus subtilis, Bacillus amyloliquefaciens and Rhizobium, with a viable count ≥2×10 CFU / g and a weight ratio of 3:2:

1.

6. The compound fertilizer according to claim 6, characterized in that, The functional microbial agent is encapsulated in microcapsules. The encapsulation material is a mixture of sodium alginate and chitosan in a weight ratio of 1:

1.

7. The compound fertilizer according to claim 1, characterized in that, The slow-release coating agent is a compound of nano-sized polyurethane and sulfur in a weight ratio of 3:2; the binder is sodium carboxymethyl cellulose.

8. A method for preparing a compound fertilizer as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Calcium magnesium phosphate fertilizer is calcined and pulverized. After pulverization, 5% by mass of humic acid synergist is loaded on its surface to obtain modified calcium magnesium phosphate fertilizer. The modified calcium magnesium phosphate fertilizer is mixed with oyster shell powder and humic acid and then pulverized to 200-300 mesh to obtain a composite soil conditioner. S2. Functional bacterial agents were encapsulated in sodium alginate-chitosan microcapsules to obtain microencapsulated functional bacterial agents; S3. Weigh out the nitrogen source, phosphorus source and potassium source according to the weight parts, stir them to obtain the first mixture; S4. Add the composite soil conditioner and chelated trace elements to the first mixture and stir to obtain the second mixture; S5. The second mixture is mixed with a binder and granulated. The product obtained from the granulation is sprayed with a slow-release coating agent and microencapsulated functional bacteria agent is added for coating treatment to obtain the functional compound fertilizer containing soil conditioner.

9. The preparation method according to claim 8, characterized in that, In step S1, the calcination temperature of the calcium magnesium phosphate fertilizer is 500-600℃, and the calcination time is 2-3 hours; the powder size of the calcium magnesium phosphate fertilizer is 200 mesh.

10. The preparation method according to claim 9, characterized in that, In step S5, the particle size of the product obtained by granulation is 2-4 mm; the temperature during the coating process is 30-35℃.

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