Water-retaining compound fertilizer, preparation method and application thereof
Patent Information
- Application Number
- CN202611178546.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-05
- Publication Date
- 2026-10-16
AI Technical Summary
因此种植作物时灌溉水下渗速度快，水分利用率低于40%，同时肥料养分流失严重，氮素利用率低
[0048] 1. The compound fertilizer product prepared by this invention combines with the soil to form fixed aggregates, which promotes fertilizer and water retention and is not easily lost with water.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of agricultural production technology, and relates to a water-retaining compound fertilizer, its preparation method, and its application. Background Technology
[0002] Soils in arid regions of Northwest and North my country, as well as along the Yellow River, are characterized by large porosity, rapid water infiltration, and poor water and fertilizer retention capacity. Therefore, irrigation water infiltrates quickly during crop cultivation, resulting in water use efficiency below 40%, and significant nutrient loss, particularly low nitrogen utilization. These problems lead to low crop germination rates and severe nutrient deficiency in the later stages of growth. Existing water-retaining fertilizers are mostly general-purpose materials such as potassium polyacrylate, polyacrylamide, and superabsorbent polymers, which suffer from the following main problems: poor soil affinity, easily washed away by water; lack of environmental responsiveness, unable to adjust release according to temperature changes; low mechanical strength, easily damaged by sand friction; and rapid nutrient release, failing to meet the needs of crops throughout their entire growth cycle.
[0003] Therefore, there is an urgent need for a fertilizer that is suitable for soil characteristics, has temperature response capabilities, and is long-lasting, water-retaining, and slow-release. Summary of the Invention
[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a water-retaining compound fertilizer, its preparation method and application.
[0005] To achieve this objective, the present invention adopts the following technical solution:
[0006] In a first aspect, the present invention provides a water-retaining compound fertilizer, which comprises, from the inside out, a bentonite-diatomite composite, a temperature-sensitive hydrogel, fertilizer nutrients, and a temperature-responsive membrane.
[0007] The raw materials for preparing the temperature-responsive membrane include polyglutamic acid, chitosan, and water.
[0008] This invention aims to address the problems of rapid soil moisture loss, large soil porosity, and low water and fertilizer retention capacity in arid regions such as Northwest and North China, providing a temperature-responsive water-retaining compound fertilizer suitable for arid soils. This fertilizer is prepared and encapsulated through a multi-layered material consisting of a mineral framework, temperature-sensitive hydrogel, nutrient core, and a surface-responsive layer. It can sense temperature changes in highly permeable soil environments, achieving the retention and release of water and nutrients, thus solving the problems of soil water and fertilizer leakage, low fertilizer nutrient utilization, and short-lived fertilizer effects. This invention comprehensively utilizes various materials to form a temperature-responsive water-retaining compound fertilizer suitable for arid soils. After application to the soil, it improves soil aggregate structure, promotes nutrient and water retention, and intelligently senses external temperature, responding to temperature changes to retain and release water. Furthermore, the fertilizer particles are rigidly supported by a mineral framework, flexibly bonded together by temperature-sensitive hydrogel, and densely protected by a surface-responsive layer. The layers are chemically bonded and strengthened, resulting in increased particle strength, strong slow-release of fertilizer nutrients, and long-lasting nutrient release. The fertilizer prepared by this invention has a water absorption rate of 350 g / g in the soil and a water retention time that is 2.3 times longer. It is suitable for crops such as corn, cotton, and potatoes in the arid Northwest region and can significantly reduce irrigation frequency and nutrient loss rate.
[0009] The fertilizer has a water absorption ratio of ≥180 g / g in soil, a solubility of <5% at 5℃, and a solubility of >60% at 35℃. The hybrid microspheres have a particle size of 2.0-4.75 mm and a compressive strength of >40 N / sphere. After applying the fertilizer, the number of irrigations in the soil can be reduced by 2-4 times.
[0010] In some embodiments, the mass ratio of the bentonite-diatomite composite, the thermosensitive hydrogel, the fertilizer nutrients, and the temperature-responsive membrane is (1-2):(1.5-3.5):(50-95):(0.1-0.3).
[0011] The specific point values in (1-2) can all be selected from 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc.; the specific point values in (1.5-3.5) can all be selected from 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, etc.; the specific point values in (50-95) can all be selected from 50, 52, 55, 58, 60, 62, 65, 68, 70, 72, 75, 78, 80, 82, 85, 88, 90, 92, 95, etc.; the specific point values in (0.1-0.3) can all be selected from 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, etc. Other specific point values within the above range can also be selected, which will not be elaborated here.
[0012] In some embodiments, the mass ratio of polyglutamic acid, chitosan and water is (2-8):(1-4):(88-97).
[0013] The specific point values in (2-8) can all be selected from 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, etc. The specific point values in (1-4) can all be selected from 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, etc. The specific point values in (88-97) can all be selected from 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, etc. Other specific point values within the above range can also be selected, which will not be elaborated here.
[0014] In some embodiments, the bentonite-diatomite composite is prepared by a method comprising the following steps: mixing bentonite and diatomite, mixing with a silane coupling agent solution, and granulating to obtain the composite.
[0015] In some embodiments, the mass ratio of the bentonite, diatomaceous earth and silane coupling agent solution is (3-6):(2-4):(0.1-0.6).
[0016] The specific point values in (3-6) can all be selected from 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, etc.; the specific point values in (2-4) can all be selected from 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, etc.; the specific point values in (0.1-0.6) can all be selected from 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, etc. Other specific point values within the above range can also be selected, which will not be elaborated here.
[0017] In some embodiments, the mass percentage of silane coupling agent in the silane coupling agent solution is 1-5%, such as 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. Other specific values within the above range can be selected, and will not be elaborated here.
[0018] In some embodiments, the solvent for the silane coupling agent solution is ethanol.
[0019] In some embodiments, the particle size of the bentonite and diatomite is independently 1-10 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc. Other specific point values within the above range can be selected, and will not be described in detail here.
[0020] In some embodiments, the mixing temperature is 50-90°C and the time is 2-5 hours.
[0021] Temperatures can be selected from 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, etc., and time can be selected from 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, etc. Other specific values within the above range can be selected, which will not be elaborated here.
[0022] In some embodiments, the raw materials for preparing the thermosensitive hydrogel include polymeric N-isopropylacrylamide, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate, and water.
[0023] In some embodiments, the total mass percentage of N-P2O5-K2O in the fertilizer nutrients is 40% or more, such as 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 65%, 70%, etc. Other specific values within the above range can be selected, and will not be elaborated here.
[0024] Fertilizer nutrients include nitrogen, phosphorus, potassium, and micronutrients.
[0025] In some embodiments, the particle size of the bentonite-diatomite composite is 1-3 mm, such as 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, etc. Other specific values within the above range can be selected, and will not be described in detail here.
[0026] In some embodiments, the thickness of the temperature-responsive film is 3-8 μm, such as 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc. Other specific values within the above range can be selected, and will not be described in detail here.
[0027] In some embodiments, the particle size of the water-retaining compound fertilizer is 2-4 mm, such as 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm, 4 mm, etc. Other specific values within the above range can be selected, and will not be elaborated here.
[0028] In some embodiments, the raw materials for preparing the thermosensitive hydrogel include, by mass parts, 1-3 parts of polymeric N-isopropylacrylamide, 1-2 parts of acrylamide, 0.1-0.5 parts of N,N'-methylenebisacrylamide, 0.2-0.5 parts of potassium persulfate, and 1-2 parts of water.
[0029] The mass fractions of polymeric N-isopropylacrylamide can be selected as 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, 3 parts, etc.; the mass fractions of acrylamide can be selected as 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2 parts, etc.; the mass fractions of N,N'-methylenebisacrylamide can be selected as 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, etc.; the mass fractions of potassium persulfate can be selected as 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, etc.; and the mass fractions of water can be selected as 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, etc. Other specific values within the above ranges can be selected, and will not be elaborated here.
[0030] In a second aspect, the present invention provides a method for preparing the water-retaining compound fertilizer according to the first aspect, the method comprising:
[0031] (1) The bentonite-diatomite composite was mixed with the raw materials for the preparation of thermosensitive hydrogel to obtain the first mixture;
[0032] (2) Grind the fertilizer nutrients and mix them with the first mixture in a molten state to obtain the second mixture;
[0033] (3) Spray the mixture of polyglutamic acid, chitosan and water onto the surface of the second mixture to obtain the final product.
[0034] Compound fertilizer nutrients are ground into ultrafine dry powder and evenly sprinkled into a fluidized "hot" particle group at 55℃. Simultaneously, a very small amount of plasticizer is sprayed to instantly "melt" and adhere the powder. After 10 minutes, a 0.15 mm nutrient coating forms on the core surface, requiring no drying. Thermosensitive hydrogel, formed by copolymerizing N-isopropylacrylamide and acrylamide, has a critical sensing temperature of 32-35℃ and combines with a mineral framework to form hybrid microspheres.
[0035] After spraying a polyglutamic acid and chitosan composite solution, the mixture is air-dried to form a biodegradable responsive film with a thickness of about 3 μm, resulting in the final product with a particle size of 2-4 mm and a moisture content of <5%.
[0036] In some embodiments, the mixing of the bentonite-diatomite composite with the raw materials for the preparation of the thermosensitive hydrogel specifically includes: mixing the bentonite-diatomite composite with polymerized N-isopropylacrylamide, acrylamide, and N,N'-methylenebisacrylamide, adding potassium persulfate aqueous solution dropwise, and reacting.
[0037] Using a mineral sphere core as a solid-phase substrate, water-soluble thermosensitive monomers N-isopropylacrylamide, comonomer acrylamide, and crosslinking agent N,N′-methylenebisacrylamide are dispersed in an aqueous system. By heating, the initiator potassium persulfate decomposes to generate free radicals, causing the monomers to undergo addition polymerization on the surface of the mineral sphere core. At the same time, the crosslinking agent N,N′-methylenebisacrylamide connects the linear polymer chains into a three-dimensional network gel structure. Finally, the gel layer tightly coats the surface of the sphere core, forming hybrid microspheres. The thermosensitive critical temperature is controlled to 32-35℃.
[0038] In some embodiments, the fertilizer nutrients are further mixed with a plasticizer when mixed with the molten first mixture.
[0039] In some embodiments, the reaction is carried out at a temperature of 50-70°C for a time of 2-5 hours.
[0040] Temperatures can be selected from 50℃, 52℃, 55℃, 58℃, 60℃, 62℃, 65℃, 68℃, 70℃, etc., and time can be selected from 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h, 4.2 h, 4.5 h, 4.8 h, 5 h, etc. Other specific point values within the above range can be selected, which will not be elaborated here.
[0041] In some embodiments, the amount of plasticizer added is 0.1-0.3%, such as 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, etc. Other specific values within the above range can be selected, and will not be described in detail here.
[0042] In some embodiments, the plasticizer includes one or more of dibutyl phthalate (DBP), dimethyl phthalate (DMP), and diethyl phthalate (DEP).
[0043] In some embodiments, the mixing temperature is 50-80°C and the time is 1-10 minutes.
[0044] Temperatures can be selected from 50℃, 52℃, 55℃, 58℃, 60℃, 62℃, 65℃, 68℃, 70℃, 72℃, 75℃, 78℃, 80℃, etc., and time can be selected from 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, etc. Other specific values within the above range can be selected, which will not be elaborated here.
[0045] Thirdly, the present invention provides an application of the water-retaining compound fertilizer according to the first aspect in agricultural production in arid regions.
[0046] The water-retaining compound fertilizer described in this invention is suitable for corn, cotton, and potato crops.
[0047] Compared with the prior art, the present invention has the following beneficial effects:
[0048] 1. The compound fertilizer product prepared by this invention combines with the soil to form fixed aggregates, which promotes fertilizer and water retention and is not easily lost with water.
[0049] 2. The compound fertilizer product prepared by this invention, after being applied to the soil, is responsive to the environment and can adjust its water absorption and release according to the ambient temperature. It releases water when the temperature is above 35℃ and absorbs water when the temperature is below 32℃, thus adjusting the water release process according to the environment to meet the growth needs of crops under different temperature conditions.
[0050] 3. The compound fertilizer prepared by this invention has high mechanical strength, compressive strength of more than 40N, and slow release of nutrients to meet the long-term needs of soil crops throughout their entire growth period. Detailed Implementation
[0051] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0052] The sources of the active ingredients in the products involved in the following examples and comparative examples are as follows (only the active ingredients are shown; other necessary excipients contained in commercially available raw materials are not described):
[0053] The bentonite was purchased from Zhejiang Fenghong New Material Co., Ltd., and its trade name is nano-grade sodium-based bentonite.
[0054] The diatomite was purchased from Jilin Changbaishan Diatomite Co., Ltd., and its product was marketed as nano-grade diatomite.
[0055] The polymeric N-isopropylacrylamide was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. under the trade name polyN-isopropylacrylamide.
[0056] The 18-12-18 compound fertilizer was purchased from Xinyangfeng Agricultural Technology Co., Ltd., and its product is called Zinc Phosphorus Beauty 18-12-18 Compound Fertilizer.
[0057] The polyglutamic acid was purchased from Nanjing Xuankai Biotechnology Co., Ltd. under the trade name γ-polyglutamic acid.
[0058] Chitosan was purchased from Shaanxi Runfeng Biotechnology Co., Ltd. and its trade name is chitosan oligosaccharide.
[0059] The silane coupling agent KH-550 was purchased from Henan Jijia Chemical Products Co., Ltd., and its trade name is silane coupling agent KH550.
[0060] Example 1
[0061] This embodiment provides a water-retaining compound fertilizer, which comprises, by weight, 1.5 parts bentonite-diatomite composite, 2.5 parts thermosensitive hydrogel, 60 parts fertilizer nutrients, and 0.2 parts temperature-responsive membrane. The bentonite-diatomite composite is prepared by mixing bentonite, diatomite, and 5% silane coupling agent KH-550 ethanol solution in a weight ratio of 4:3:0.5. The thermosensitive hydrogel is prepared by mixing polymeric N-isopropylacrylamide, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate, and water in a weight ratio of 2:1.5:0.3:0.3:1.5. The fertilizer nutrients are 18-12-18 compound fertilizer. The temperature-responsive membrane is composed of polyglutamic acid, chitosan, and water in a weight ratio of 4:1:95.
[0062] Its preparation method is as follows:
[0063] (1) Mineral skeleton granulation: Bentonite and diatomite are mixed at 60℃ for 4 h, and 5% ethanol solution of silane coupling agent KH-550 is sprayed in. The mixture is then granulated into 1 mm spheres by a small rotary drum granulator and dried in an oven at 105℃ for 2 h to obtain spheres.
[0064] (2) In-situ polymerization of thermosensitive gel: The core of the ball was put into a 500 mL three-necked flask, and N-isopropylacrylamide, acrylamide, and N,N'-methylenebisacrylamide were added. A potassium persulfate solution with a concentration of 0.015 g / mL was added dropwise at 65 °C and reacted for 4 h to obtain “mineral-gel” hybrid microspheres.
[0065] (3) Hot powder instant melting process to encapsulate nutrients: Grind 18-12-18 compound fertilizer into ultra-fine dry powder, evenly sprinkle it into a fluidized "hot" particle group at 55℃, and add 0.2% dibutyl phthalate spray to make the powder "melt" and stick firmly. After 10 minutes, a 2 mm nutrient coating is formed on the core surface.
[0066] (4) Coating of the responsive membrane: Using a small fluidized bed with an inlet air temperature of 30 °C, the γ-PGA composite responsive membrane solution was sprayed onto the surface of the microspheres at a rate of 2 mL / min. The particle size was 2.5 mm and the critical induction temperature was 33 °C.
[0067] Example 2
[0068] This embodiment provides a water-retaining compound fertilizer, which comprises, by weight, 1 part bentonite-diatomite composite, 3.5 parts thermosensitive hydrogel, 50 parts fertilizer nutrients, and 0.3 parts temperature-responsive membrane. The raw materials for preparing the bentonite-diatomite composite include bentonite, diatomite, and 5% silane coupling agent KH-550 ethanol solution in a weight ratio of 3:4:0.1. The raw materials for preparing the thermosensitive hydrogel include polymeric N-isopropylacrylamide, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate, and water in a weight ratio of 1:2:0.1:0.5:2. The fertilizer nutrients are 18-12-18 compound fertilizer. The temperature-responsive membrane is polyglutamic acid, chitosan, and water in a weight ratio of 2:4:94.
[0069] Its preparation method is as follows:
[0070] (1) Mineral skeleton granulation: Bentonite and diatomite are mixed at 50℃ for 5 h, and 5% ethanol solution of silane coupling agent KH-550 is sprayed in. The mixture is then granulated into 1 mm spheres by a small rotary drum granulator and dried in an oven at 105℃ for 2 h to obtain spheres.
[0071] (2) In-situ polymerization of thermosensitive gel: The core of the ball was put into a 500 mL three-necked flask, and N-isopropylacrylamide, acrylamide, and N,N'-methylenebisacrylamide were added. A potassium persulfate solution with a concentration of 0.015 g / mL was added dropwise at 50 °C and reacted for 5 h to obtain “mineral-gel” hybrid microspheres.
[0072] (3) Hot powder instant melting process to encapsulate nutrients: Grind 18-12-18 compound fertilizer into ultra-fine dry powder, evenly sprinkle it into fluidized "hot" particle group at 80℃, and add 0.2% dibutyl phthalate spray to make the powder "melt" and stick firmly. After 10 minutes, a 2 mm nutrient coating is formed on the core surface.
[0073] (4) Coating of the responsive membrane: Using a small fluidized bed with an inlet air temperature of 30 °C, the γ-PGA composite responsive membrane solution was sprayed onto the surface of the microspheres at a rate of 2 mL / min. The particle size was 2.5 mm and the critical induction temperature was 33 °C.
[0074] Example 3
[0075] This embodiment provides a water-retaining compound fertilizer, which comprises, by weight, 2 parts bentonite-diatomite composite, 1.5 parts thermosensitive hydrogel, 95 parts fertilizer nutrients, and 0.1 parts temperature-responsive membrane. The bentonite-diatomite composite is prepared by mixing bentonite, diatomite, and 5% silane coupling agent KH-550 ethanol solution in a weight ratio of 6:2:0.6. The thermosensitive hydrogel is prepared by mixing polymeric N-isopropylacrylamide, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate, and water in a weight ratio of 3:1:0.5:0.2:1. The fertilizer nutrients are 18-12-18 compound fertilizer. The temperature-responsive membrane is composed of polyglutamic acid, chitosan, and water in a weight ratio of 8:4:88.
[0076] Its preparation method is as follows:
[0077] (1) Mineral skeleton granulation: Bentonite and diatomite are mixed at 90℃ for 2 h, and 5% ethanol solution of silane coupling agent KH-550 is sprayed in. The mixture is then granulated into 1 mm spheres by a small rotary drum granulator and dried in an oven at 105℃ for 2 h to obtain the spheres.
[0078] (2) In-situ polymerization of thermosensitive gel: The core of the ball was put into a 500 mL three-necked flask, and N-isopropylacrylamide, acrylamide, and N,N'-methylenebisacrylamide were added. A potassium persulfate solution with a concentration of 0.015 g / mL was added dropwise at 70 °C and reacted for 2 h to obtain “mineral-gel” hybrid microspheres.
[0079] (3) Hot powder instant melting process to encapsulate nutrients: Grind 18-12-18 compound fertilizer into ultra-fine dry powder, evenly sprinkle it into a fluidized "hot" particle group at 50℃, and add 0.2% dibutyl phthalate spray to make the powder "melt" and stick firmly. After 10 minutes, a 2 mm nutrient coating is formed on the core surface.
[0080] (4) Coating of the responsive membrane: Using a small fluidized bed with an inlet air temperature of 30 °C, the γ-PGA composite responsive membrane solution was sprayed onto the surface of the microspheres at a rate of 2 mL / min. The particle size was 2.5 mm and the critical induction temperature was 33 °C.
[0081] Example 4
[0082] This embodiment provides a water-retaining compound fertilizer, which differs from Embodiment 1 only in that the raw materials for preparing the temperature-sensitive hydrogel, which are polymeric N-isopropylacrylamide, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate and water in a mass ratio of 2:1.5:0.3:0.3:1.5, are adjusted to "the raw materials for preparing the temperature-sensitive hydrogel include polymeric N-isopropylacrylamide, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate and water in a mass ratio of 0.5:3:0.3:0.3:1.5". All other components and contents remain unchanged.
[0083] The preparation method is the same as in Example 1.
[0084] Example 5
[0085] This embodiment provides a water-retaining compound fertilizer, which differs from Embodiment 1 only in that the raw materials for preparing the temperature-sensitive hydrogel, which are polymeric N-isopropylacrylamide, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate and water in a mass ratio of 2:1.5:0.3:0.3:1.5, are adjusted to "the raw materials for preparing the temperature-sensitive hydrogel include polymeric N-isopropylacrylamide, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate and water in a mass ratio of 3.2:0.3:0.3:0.3:1.5", remain unchanged in all other components and contents.
[0086] The preparation method is the same as in Example 1.
[0087] Example 6
[0088] This embodiment provides a water-retaining compound fertilizer, which differs from Embodiment 1 only in that "the temperature-responsive membrane is composed of polyglutamic acid, chitosan and water in a mass ratio of 4:1:95" is changed to "the temperature-responsive membrane is composed of polyglutamic acid, chitosan and water in a mass ratio of 9:1:90", while other components and contents remain unchanged.
[0089] The preparation method is the same as in Example 1.
[0090] Comparative Example 1
[0091] This comparative example provides a water-retaining compound fertilizer, which differs from Example 1 only in that it does not contain bentonite, and the reduced mass of bentonite is allocated to the mass of diatomaceous earth, while other components and contents remain unchanged.
[0092] The preparation method is the same as in Example 1.
[0093] Comparative Example 2
[0094] This comparative example provides a water-retaining compound fertilizer, which differs from Example 1 only in that it does not contain diatomaceous earth, and the reduced mass of diatomaceous earth is allocated to the mass of bentonite, while other components and contents remain unchanged.
[0095] The preparation method is the same as in Example 1.
[0096] Comparative Example 3
[0097] This comparative example provides a water-retaining compound fertilizer, which differs from Example 1 only in that "bentonite, diatomaceous earth and 5% silane coupling agent KH-550 ethanol solution in a mass ratio of 4:3:0.5" is replaced with "calcium powder and 5% silane coupling agent KH-550 ethanol solution in a mass ratio of 7:0.5", while other components and contents remain unchanged.
[0098] The preparation method is the same as in Example 1.
[0099] Comparative Example 4
[0100] This comparative example provides a water-retaining compound fertilizer, which differs from Example 1 only in that it does not contain a polyglutamic acid-chitosan composite film-forming agent, while other components and contents remain unchanged.
[0101] The preparation method is the same as in Example 1.
[0102] Comparative Example 5
[0103] This comparative example provides a water-retaining compound fertilizer, which differs from Example 1 only in that it does not contain bentonite-diatomite compound, while other components and contents remain unchanged.
[0104] The preparation method is the same as in Example 1.
[0105] Comparative Example 6
[0106] This comparative example provides a water-retaining compound fertilizer, which differs from Example 1 only in that it does not contain temperature-sensitive hydrogel, while other components and contents remain unchanged.
[0107] The preparation method is the same as in Example 1.
[0108] Comparative Example 7
[0109] This comparative example provides a water-retaining compound fertilizer, which differs from Example 1 only in that "the temperature-responsive membrane is composed of polyglutamic acid, chitosan and water in a mass ratio of 4:1:95" is replaced with "the temperature-responsive membrane is composed of polyglutamic acid and water in a mass ratio of 5:95", while other components and contents remain unchanged.
[0110] The preparation method is the same as in Example 1.
[0111] Comparative Example 8
[0112] This comparative example provides a water-retaining compound fertilizer, which differs from Example 1 only in that "the temperature-responsive membrane is composed of polyglutamic acid, chitosan and water in a mass ratio of 4:1:95" is replaced with "the temperature-responsive membrane is composed of chitosan and water in a mass ratio of 5:95", while other components and contents remain unchanged.
[0113] The preparation method is the same as in Example 1.
[0114] Test Example 1
[0115] Basic performance testing
[0116] The water absorption rate and salt water (0.9% NaCl) absorption rate of compound fertilizer products were tested according to the NY / T 886-2022 method.
[0117] Particle strength was tested using a particle strength meter.
[0118] The nutrient content of compound fertilizers is tested according to GB8572-8574.
[0119] Table 1
[0120]
[0121] Test Example 2
[0122] Soil-based corn pot experiment
[0123] 1. Experimental Design:
[0124] The tested soil was aeolian sandy soil from Dalad Banner, Inner Mongolia, with a sand content of 82% and a field water holding capacity of 8.1%.
[0125] Materials and reagents: Container: PVC pipe (φ15 cm × 40 cm), with a permeable mesh at the bottom.
[0126] Experimental treatment:
[0127] CK: No water-retaining agent is applied. Apply 18-12-18 ordinary compound fertilizer at a rate of 3 g / kg dry soil (approximately 0.9 g / pot).
[0128] Experimental group: 3 g / kg dry soil (approximately 0.9 g / pot), 5 pots per treatment, arranged completely randomly.
[0129] 2. Routine management and fertilization measures
[0130] (1) Sowing: The corn variety “Xianyu 335”, 6 seeds per pot, and 1 seedling at the three-leaf stage.
[0131] (2) Irrigation: Controlled by weighing method. When the relative soil moisture content drops to 45% FC, supplement irrigation is carried out to 75% FC. The number of irrigations and the amount of water are recorded.
[0132] Table 2
[0133]
[0134] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.
Claims
1. A water-retaining compound fertilizer, characterized in that, The water-retaining compound fertilizer comprises, from the inside out, a bentonite-diatomite composite, a thermosensitive hydrogel, fertilizer nutrients, and a temperature-responsive membrane. The raw materials for preparing the temperature-responsive membrane include polyglutamic acid, chitosan, and water.
2. The water-retaining compound fertilizer according to claim 1, characterized in that, The mass ratio of the bentonite-diatomite composite, thermosensitive hydrogel, fertilizer nutrients, and temperature-responsive membrane is (1-2):(1.5-3.5):(50-95):(0.1-0.3). And / or, the mass ratio of the polyglutamic acid, chitosan and water is (2-8):(1-4):(88-97).
3. The water-retaining compound fertilizer according to claim 1 or 2, characterized in that, The bentonite-diatomite composite is prepared by a method comprising the following steps: mixing bentonite and diatomite, then mixing with a silane coupling agent solution, and granulating to obtain the composite.
4. The water-retaining compound fertilizer according to claim 3, characterized in that, The mass ratio of the bentonite, diatomaceous earth and silane coupling agent solution is (3-6):(2-4):(0.1-0.6); And / or, the silane coupling agent solution contains 1-5% by mass of silane coupling agent; And / or, the solvent of the silane coupling agent solution is ethanol; And / or, the particle size of the bentonite and diatomite is independently 1-10 μm; And / or, the mixing temperature is 50-90℃ and the time is 2-5h.
5. The water-retaining compound fertilizer according to any one of claims 1-4, characterized in that, The raw materials for preparing the thermosensitive hydrogel include polymeric N-isopropylacrylamide, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate, and water. And / or, the total mass percentage of N-P2O5-K2O in the fertilizer nutrients is 40% or more; And / or, the particle size of the bentonite-diatomite composite is 1-3 mm; And / or, the thickness of the temperature-responsive film is 3-8 μm; And / or, the particle size of the water-retaining compound fertilizer is 2-4 mm.
6. The water-retaining compound fertilizer according to any one of claims 1-5, characterized in that, The raw materials for preparing the thermosensitive hydrogel include, by mass parts, 1-3 parts of polymeric N-isopropylacrylamide, 1-2 parts of acrylamide, 0.1-0.5 parts of N,N'-methylenebisacrylamide, 0.2-0.5 parts of potassium persulfate, and 1-2 parts of water.
7. The method for preparing the water-retaining compound fertilizer according to any one of claims 1-6, characterized in that, The preparation method includes: (1) The bentonite-diatomite composite was mixed with the raw materials for the preparation of thermosensitive hydrogel to obtain the first mixture; (2) Grind the fertilizer nutrients and mix them with the first mixture in a molten state to obtain the second mixture; (3) Spray the mixture of polyglutamic acid, chitosan and water onto the surface of the second mixture to obtain the final product.
8. The preparation method according to claim 7, characterized in that, The specific steps of mixing the bentonite-diatomite composite with the raw materials for preparing the thermosensitive hydrogel include: mixing the bentonite-diatomite composite with polymerized N-isopropylacrylamide, acrylamide, and N,N'-methylenebisacrylamide, adding potassium persulfate aqueous solution dropwise, and reacting. And / or, when the fertilizer nutrients are mixed with the first mixture in the molten state, they also include mixing with a plasticizer.
9. The preparation method according to claim 8, characterized in that, The reaction is carried out at a temperature of 50-70℃ for 2-5 hours. And / or, the amount of plasticizer added is 0.1-0.3%; And / or, the plasticizer includes one of di-n-butyl phthalate, dimethyl phthalate, and diethyl phthalate; And / or, the temperature for mixing with the plasticizer is 50-80°C, and the time is 1-10 min.
10. The application of the water-retaining compound fertilizer according to any one of claims 1-6 in agricultural production in arid regions.