Preparation method and application of slow-release fertilizer with water-retaining and drought-resisting functions

Abstract

The invention relates to a slow-release fertilizer with water-retaining and drought-resisting functions, which comprises the following components in percentage by weight: 0-18% of a water-retaining agent compound, 35-45% of a slow-release carrier and 35-60% of a functional additive. The water-retaining agent compound is prepared by mixing 8 parts of polyacrylamide and 4 parts of weathered coal; the slow-release carrier comprises an inner sulfur coating layer with the thickness of 50 microns and an outer polyurethane resin coating layer with the thickness of 80 microns, and the functional additive is formed by mixing 3 parts of zinc sulfate, 2 parts of a mixed microbial agent, 20 parts of soybean meal, 5 parts of humic acid and 20 parts of light calcium carbonate. The water and fertilizer coupling efficiency is improved, the stress resistance of crops is enhanced, the ecological systematicness of soil is improved, the environmental and economic benefits are improved, and the problems that an existing chemical fertilizer is single in function and limited in soil improvement effect are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical fertilizers, in particular to a preparation method and application of slow-release fertilizer with water-retaining and drought-resistant functions. BACKGROUND

[0002] The so-called "release" refers to the process of converting nutrients from chemical substances into effective forms that can be directly absorbed and utilized by plants; "slow release" refers to the release rate of chemical substance nutrients being much smaller than the release rate of plant available nutrients after the application of instant fertilizer to soil; "controlled release" refers to making the release of nutrients in accordance with the set release mode consistent with the law of nutrient absorption by crops through various control mechanisms. Therefore, organic nitrogen compound fertilizers that can be decomposed under biological or chemical action are usually referred to as slow-release fertilizers, and coating fertilizers that are not sensitive to biological and chemical factors are usually referred to as controlled-release fertilizers.

[0003] The frequent high-temperature drought weather caused by global climate change has caused serious harm to crop production. As an effective drought-resistant means, the soil water-retaining agent has strong water absorption capacity and can absorb hundreds or even thousands of times of its own weight of water at a very fast speed. The water-retaining agent has high water-retaining performance and will not lose water after absorbing enough water due to high temperature and strong drought in the external environment. The water-retaining agent can absorb water when it is wet and release water when it is dry, and the supply and absorption of water can be reversed at any time.

[0004] In arid and semiarid areas, water resources are scarce and the soil water-retaining capacity is poor, which are the main factors restricting agricultural development. Although the traditional fertilizer can provide nutrients, it has the following defects: 1. Insufficient water-retaining performance: the fertilizer particles have poor water absorption, which cannot effectively store soil water, resulting in weak drought resistance of crops; 2. Uncontrolled nutrient release: the rapid release of nutrients is easy to be lost, the utilization rate is low, and the excessive release in the early stage is easy to cause seedling burn; 3. Limited soil improvement capacity: it cannot improve the structure of saline-alkali or sandy soil in a targeted manner, which limits the growth of crops. In the prior art, although progress has been made in water retention, slow release or soil improvement, the function is relatively single, and the improvement effect on the soil is relatively limited, which needs to be improved. Therefore, the present application provides a preparation method and application of slow-release fertilizer with water-retaining and drought-resistant functions to solve the above problems. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a preparation method and application of slow-release fertilizer with water-retaining and drought-resistant functions, which has the advantages of good soil improvement effect, etc., and solves the problem of single function of the existing chemical fertilizer and the limited improvement effect on the soil.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a slow-release fertilizer with water-retaining and drought-resistant functions, which comprises the following components in percentage by weight: 0-18% of a water-retaining agent compound, 35-45% of a slow-release carrier, and 35-60% of a functional additive. The water-retaining agent compound is formed by mixing 8 parts of polyacrylamide with 4 parts of weathered coal; The slow-release carrier comprises an inner sulfur coating layer with a thickness of 50 μm and an outer polyurethane resin coating layer with a thickness of 80 μm; The functional additive is formed by mixing 3 parts of zinc sulfate, 2 parts of mixed bacteria agent, 20 parts of soybean meal powder, 5 parts of humic acid and 20 parts of light calcium carbonate.

[0007] Further, the mixed bacteria agent is a mixture of Bacillus subtilis and Bacillus megaterium, the mass ratio of Bacillus subtilis to Bacillus megaterium is 1:1, and the concentration of the activated mixed bacteria agent is 5×10 9 CFU / mL.

[0008] Further, the slow-release carrier has a dissolution rate of 8% / 24h in distilled water at 25°C, and the mass ratio of the inner sulfur coating layer to the outer polyurethane resin coating layer is 1:1.2.

[0009] Another technical problem solved by the present application is to provide a preparation method of slow-release fertilizer with water-retaining and drought-resistant functions, comprising the following specific steps: S1: 8 parts of polyacrylamide and 4 parts of weathered coal are added into a reaction kettle, stirred at a temperature of 60°C and a rotation speed of 150 rpm for 30 min to form a water-retaining agent compound; S2: an inner sulfur coating layer with a thickness of 50 μm is prepared by fluidized bed coating process using 15 parts of urea-formaldehyde and 8 parts of sulfur-coated urea as base materials, and then 10 parts of polyurethane resin is sprayed to form an outer polyurethane resin coating layer with a thickness of 80 μm, and the total coating thickness is 130 μm; S3: the water-retaining agent compound, the slow-release carrier, 3 parts of zinc sulfate, 2 parts of mixed bacteria agent, 20 parts of soybean meal powder, 5 parts of humic acid and 20 parts of light calcium carbonate are mixed and stirred at a temperature of 25°C for 60 min; S4: slow-release fertilizer particles are prepared by a disc granulator, dried by hot air to a water content of 4%, and then sieved to obtain slow-release fertilizer finished products.

[0010] Further, the polyacrylamide in step S1 has a molecular weight of 12 million, the weathered coal has an airflow mesh number of 80-120 mesh, and the organic matter content of the weathered coal is ≥55%.

[0011] Further, the urea-formaldehyde in step S2 has a condensation degree of 35%, the coated urea has a coating thickness of 50 μm, the polyurethane resin has a solid content of 40%, the inlet air temperature of the fluidized bed coating process is 70°C, the spraying pressure is 0.3 MPa, and the rotation speed of the atomizing disc is 120 rpm.

[0012] Further, the zinc sulfate in step S3 has a purity of ≥98%, and the concentration of the bacteria solution is 5×109 CFU / mL, the carbon-nitrogen ratio of soybean meal powder is 25:1, and the organic matter content of humic acid is 60%.

[0013] Further, the particle size of the slow-release fertilizer particles in step S4 is 2-4 mm, and the temperature of the hot air is 50-60℃.

[0014] Another technical problem solved by the present application is to provide an application of slow-release fertilizer with water retention and drought resistance function. The slow-release fertilizer is used as base fertilizer in an area with annual rainfall of ≤300 mm, and the application amount is 400 kg / hm².

[0015] Compared with the prior art, the technical scheme of the present application has the following beneficial effects: 1. The preparation method and application of the slow-release fertilizer with water retention and drought resistance function, by adopting a double-layer coating structure, the nitrogen utilization rate reaches 45%, the phosphorus utilization rate is increased to 38%, the water available to crops under drought conditions is increased by more than 3 times by cooperating with the water retention agent compound, the irrigation frequency is reduced by 40%, and the water and fertilizer coupling efficiency is improved; 2. The preparation method and application of the slow-release fertilizer with water retention and drought resistance function, by the synergistic effect of zinc sulfate and microbial inoculant, the content of permeation regulating substances in corn leaves is increased by 65%, the photosynthetic rate maintenance rate under drought stress reaches 78%, the root activity of poplar is increased by 2.3 times, and the survival rate is increased by 42%, thereby enhancing the stress resistance of crops; 3. The preparation method and application of the slow-release fertilizer with water retention and drought resistance function, by organic matter and humic acid, the bulk density of sand ginger black soil is reduced by 0.25 g / cm³, the porosity is increased by 18%, the pH value of saline-alkali soil is decreased by 0.8 units per year, the microbial activity promotes the formation of soil aggregates, and the carbon pool management index is increased by 40%, thereby realizing the benign cycle of "water retention-soil improvement-rooting", and improving the soil ecosystem; 4. The preparation method and application of the slow-release fertilizer with water retention and drought resistance function, by controlling the nitrogen loss rate at 8% / 24h, which is reduced by 60% compared with the technology of patent 1, the risk of non-point source pollution is greatly reduced, the crop yield is increased by 15%-22%, and the ecological and economic values are combined, thereby improving the environmental and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The flowchart of the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0018] A slow-release fertilizer with water-retention and drought-resistance functions, which comprises, by weight percentage: 0-18% of a water-retention agent compound (the water-retention agent compound is formed by mixing 8 parts of polyacrylamide with 4 parts of weathered coal), 35-45% of a slow-release carrier (the slow-release carrier comprises an inner layer of sulfur-coated film with a thickness of 50 μm and an outer layer of polyurethane resin-coated film with a thickness of 80 μm), and 35-60% of functional additives (the functional additives are formed by mixing 3 parts of zinc sulfate, 2 parts of a mixed bacterial agent, 20 parts of soybean meal powder, 5 parts of humic acid, and 20 parts of light calcium carbonate).

[0019] A preparation method of a slow-release fertilizer with water-retention and drought-resistance functions, comprising the following specific steps: S1: preparing a water-retention agent compound: 8 parts of polyacrylamide (chemical formula , molecular weight 1200 million, CAS number 9003-05-8) and 4 parts of weathered coal (airflow sieve mesh number of weathered coal 80-120 mesh, organic matter content of weathered coal ≥55%) are added into a reaction kettle, stirred at 150 rpm at 60°C for 30 min to form a uniform compound, and the reaction equation is: ; S2: preparing a slow-release carrier: 15 parts of urea-formaldehyde (chemical formula , molecular weight 120.11, condensation degree 35%, CAS number 68131-72-8) and 8 parts of sulfur-coated urea (SCU, coating thickness 50 μm) are used as base materials to prepare an inner layer of sulfur-coated film by fluidized bed coating process, the inlet air temperature is 70°C, the spraying pressure is 0.3 MPa, the atomizing disc rotation speed is 120 rpm, and an inner layer of sulfur-coated film with a thickness of 50 μm is formed, and then 10 parts of polyurethane resin (chemical formula , solid content 40%, CAS number 9011-05-6) is sprayed to form an outer layer of polyurethane resin-coated film, and the total coating thickness after curing is 130 μm; S3: mixing functional additives: The water-retention agent compound, the slow-release carrier, 3 parts of zinc sulfate (chemical formula , purity 99%, CAS number 7733-02-0), 2 parts of a mixed bacterial agent (mass ratio of Bacillus subtilis to Bacillus megaterium 1:1, concentration of the activated mixed bacterial agent 5×10 9 CFU / mL), 20 parts of soybean meal powder (carbon-nitrogen ratio 25:1), 5 parts of humic acid (organic matter content 60%), and 20 parts of light calcium carbonate (CAS number 471-34-1) are mixed and stirred at 25°C for 60 min; S4: granulation: The slow-release fertilizer granules (with a particle size of 2-4 mm) were made by a disc granulator (with an inclination angle of 45° and a rotation speed of 30 rpm), dried by hot air at 50°C to a moisture content of 4%, and sieved to obtain the finished slow-release fertilizer product.

[0020] Example 1 The composition is calculated by weight percentage: Water-retaining agent complex 12% (mass ratio of polyacrylamide and weathered coal is 8:4); 38% sustained-release carrier (50 μm thick inner sulfur coating layer and 80 μm thick outer polyurethane resin coating layer); Functional additives 50% (zinc sulfate, mixed bacterial agent (Bacillus subtilis and Bacillus megaterium in a mass ratio of 1:1), soybean meal powder, humic acid and light calcium carbonate in a mass ratio of 3:2:20:5:20); Performance: Water retention rate is 68%, nitrogen release cycle is 90 days, and corn yield is increased by 18%.

[0021] Example 2 The composition is calculated by weight percentage: Water-retaining agent complex 15% (mass ratio of polyacrylamide and weathered coal is 10:5); 35% sustained-release carrier (50 μm thick inner sulfur coating layer and 80 μm thick outer polyurethane resin coating layer); Functional additives 50% (zinc sulfate, mixed bacterial agent (Bacillus subtilis and Bacillus megaterium in a mass ratio of 1:1), soybean meal powder, humic acid and light calcium carbonate in a mass ratio of 3:2:20:5:20); Performance: Water retention rate is 75%, nitrogen release cycle is 90 days, and wheat yield is increased by 22%.

[0022] Example 3 The composition is calculated by weight percentage: Water-retaining agent complex 12% (mass ratio of polyacrylamide and weathered coal is 8:4); 40% sustained-release carrier (60 μm thick inner sulfur coating layer and 100 μm thick outer polyurethane resin coating layer); Functional additives 48% (zinc sulfate, mixed bacterial agent (Bacillus subtilis and Bacillus megaterium in a mass ratio of 1:1), soybean meal powder, humic acid and light calcium carbonate in a mass ratio of 3:2:20:5:18); Performance: The nitrogen release cycle is 105 days, and the poplar survival rate is increased by 40%.

[0023] Example 4 The composition is calculated by weight percentage: Water-retaining agent complex 12% (mass ratio of polyacrylamide to weathered coal is 8:4); Slow-release carrier 38% (inner layer of sulfur coating layer with thickness of 50 μm and outer layer of polyurethane resin coating layer with thickness of 80 μm); Functional additive 50% (mass ratio of zinc sulfate, mixed bacterial agent (mass ratio of Bacillus subtilis to Bacillus megaterium is 2:1), soybean meal powder, humic acid and light calcium carbonate is 3:2:20:5:18); Performance: soil phosphorus release efficiency is improved by 30%, and corn yield is improved by 20%.

[0024] Comparative Example 1 Composition is 50% by weight: Water-retaining agent complex 12% (mass ratio of polyacrylamide to weathered coal is 8:4); Slow-release carrier 38%: sulfur coating layer with thickness of 100 μm; Functional additive 50% (mass ratio of zinc sulfate, mixed bacterial agent (mass ratio of Bacillus subtilis to Bacillus megaterium is 1:1), soybean meal powder, humic acid and light calcium carbonate is 3:2:20:5:20); Performance: nitrogen release period is 50 days, and corn yield is only improved by 8%.

[0025] Comparative Example 2 Composition is 50% by weight: Water-retaining agent complex 12% (mass ratio of polyacrylamide to weathered coal is 8:4); Slow-release carrier 38% (inner layer of sulfur coating layer with thickness of 50 μm and outer layer of polyurethane resin coating layer with thickness of 80 μm); Functional additive 50% (mass ratio of zinc sulfate, soybean meal powder, humic acid and light calcium carbonate is 3:20:5:22); Performance: soil organic matter content has no significant change, and wheat yield is improved by 10%.

[0026] Comparative Example 3 Composition is 50% by weight: Slow-release carrier 44% (inner layer of sulfur coating layer with thickness of 50 μm and outer layer of polyurethane resin coating layer with thickness of 80 μm); Functional additive 56% (mass ratio of zinc sulfate, mixed bacterial agent (mass ratio of Bacillus subtilis to Bacillus megaterium is 1:1), soybean meal powder, humic acid and light calcium carbonate is 3:2:22:5:24); Performance: soil organic matter content has no significant change, and wheat yield is improved by 10%.

[0027] Application Example 1 Category: Gansu corn; Site: An'ding district of Dingxi city (annual rainfall 300mm); Method: 400kg / hm² of base fertilizer is applied, combined with drip irrigation; Effect: The yield of corn is 6.2t / hm², which is increased by 29% compared with conventional fertilization (4.8t / hm²).

[0028] Application Example 2 Type: Saline-alkali land poplar in Shandong province; Site: Hekou district of Dongying city (pH value 8.8); Method: 80kg / hm² is applied, combined with straw returning; Effect: The diameter of 3-year-old poplar is increased by 2.1cm, and the survival rate is 95%.

[0029] Application Example 3 Type: Wheat in sand ginger black soil in Henan province; Site: Zhengyang county of Zhumadian city; Method: It is applied by mixing with geopolymer particles (7:1). Effect: The yield of wheat is 7.5t / hm², which is increased by 25% compared with single application of chemical fertilizer (6.0t / hm²).

[0030] The beneficial effects of the application are as follows: 1. The preparation method and application of the slow-release fertilizer with water-retaining and drought-resistant functions, by adopting the double-layer coating structure, the nitrogen utilization rate reaches 45%, the phosphorus utilization rate is increased to 38%, the water-retaining agent compound is combined, the water available to crops under drought conditions is increased by more than 3 times, the irrigation frequency is reduced by 40%, and the water and fertilizer coupling efficiency is improved; 2. The preparation method and application of the slow-release fertilizer with water-retaining and drought-resistant functions, by the synergistic effect of zinc sulfate and microbial agent, the content of permeation regulating substances in corn leaves is increased by 65%, the photosynthetic rate maintenance rate under drought stress reaches 78%, the root activity of poplar is increased by 2.3 times, and the survival rate is increased by 42%, and the stress resistance of crops is enhanced; 3. The preparation method and application of the slow-release fertilizer with water-retaining and drought-resistant functions, by organic matter and humic acid, the bulk density of sand ginger black soil is reduced by 0.25g / cm³, the porosity is increased by 18%, the pH value of saline-alkali soil is decreased by 0.8 units per year, the microbial activity promotes the formation of soil aggregates, and the carbon pool management index is increased by 40%, realizing the benign cycle of "water-retaining-soil-nourishing-rooting", and improving the soil ecosystem; 4. The preparation method and application of the slow-release fertilizer with water-retaining and drought-resistant functions, by controlling the nitrogen loss rate at 8% / 24h, which is reduced by 60% compared with the technology of patent 1, the risk of non-point source pollution is greatly reduced, the yield of crops is increased by 15%-22%, and the ecological and economic values are combined, and the environmental and economic benefits are improved.

[0031] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the same general inventive concepts embodied by the described embodiments. That is, although the present application is described in terms of particular embodiments and implementations, it is to be understood that the terminology used is for the purpose of descriptive clarity and that it should be taken in a descriptive sense and not a limiting sense.

[0032] While the embodiments of the application have been shown and described herein, it is to be understood that the application is not limited to these embodiments. Rather, many modifications, changes, substitutions, and alterations can be made to the embodiments of the application without departing from the spirit and scope of the application as defined by the appended claims and their equivalents.

Claims

1. A slow-release fertilizer with water-retaining and drought-resistant functions, characterized in that: Its composition by weight percentage is: Water-retaining agent complex 0-18%, slow-release carrier 35-45%, functional additive 35-60%; The water-retaining agent compound is formed by mixing 8 parts of polyacrylamide with 4 parts of weathered coal; The sustained-release carrier comprises an inner sulfur coating layer with a thickness of 50 μm and an outer polyurethane resin coating layer with a thickness of 80 μm; The functional additive is prepared by mixing 3 parts of zinc sulfate, 2 parts of mixed bacterial agent, 20 parts of soybean meal powder, 5 parts of humic acid and 20 parts of light calcium carbonate.

2. The slow-release fertilizer with water-retaining and drought-resistant functions according to claim 1, characterized in that: The mixed bacterial agent is a mixture of Bacillus subtilis and Bacillus megaterium, the mass ratio of Bacillus subtilis to Bacillus megaterium is 1:1, and the concentration of the mixed bacterial agent after activation is 5×10 9 CFU / mL.

3. The slow-release fertilizer with water-retaining and drought-resistant functions according to claim 1, characterized in that: The solubility of the sustained-release carrier in distilled water at 25° C. is 8% / 24h, and the mass ratio of the inner sulfur coating layer to the outer polyurethane resin coating layer is 1:1.

2.

4. A method for preparing a slow-release fertilizer with water-retaining and drought-resistant functions as claimed in claims 1 to 3, characterized in that: The specific steps include: S1: 8 parts of polyacrylamide and 4 parts of weathered coal were added to a reactor and stirred at 150 rpm for 30 min at 60°C to form a water-retaining agent complex; S2: Using 15 parts of urea formaldehyde and 8 parts of sulfur-coated urea as the base material, a 50 μm thick inner sulfur coating layer was prepared by fluidized bed coating process, and then 10 parts of polyurethane resin was sprayed to form an 80 μm thick outer polyurethane resin coating layer, with a total coating thickness of 130 μm; S3: Mix the water-retaining agent complex, slow-release carrier, 3 parts of zinc sulfate, 2 parts of mixed bacterial agent, 20 parts of soybean meal powder, 5 parts of humic acid and 20 parts of light calcium carbonate, and stir at 25°C for 60 minutes; S4: The slow-release fertilizer granules are made by a disc granulator, dried by hot air to a moisture content of 4%, and sieved to obtain the finished slow-release fertilizer.

5. The method for preparing a slow-release fertilizer with water-retaining and drought-resistant functions according to claim 4, characterized in that: The molecular weight of the polyacrylamide in step S1 is 12 million, the air flow sieve mesh number of the weathered coal is 80-120 mesh, and the organic matter content of the weathered coal is ≥55%.

6. The method for preparing a slow-release fertilizer with water-retaining and drought-resistant functions according to claim 4, characterized in that: The condensation degree of urea formaldehyde in step S2 is 35%, the coating thickness of the coated urea is 50 μm, the solid content of the polyurethane resin is 40%, the inlet air temperature of the fluidized bed coating process is 70° C., the spraying pressure is 0.3 MPa, and the atomizing disk speed is 120 rpm.

7. The method for preparing a slow-release fertilizer with water-retaining and drought-resistant functions according to claim 4, characterized in that: The purity of zinc sulfate in step S3 is ≥98%, and the concentration of bacterial solution is 5×10 9 CFU / mL, the carbon-nitrogen ratio of soybean meal is 25:1, and the organic matter content of humic acid is 60%.

8. The method for preparing a slow-release fertilizer with water-retaining and drought-resistant functions according to claim 4, characterized in that: The particle size of the slow-release fertilizer particles in step S4 is 2-4 mm, and the temperature of the hot air is 50-60°C.

9. Use of the slow-release fertilizer with water-retaining and drought-resistant functions as claimed in claims 1 to 3, characterized in that: The slow-release fertilizer is used as base fertilizer in areas with annual rainfall ≤300mm, and the application rate is 400kg / hm².

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