Double control nitrogen release suspension type urea formaldehyde multi-element liquid fertilizer fine preparation process and application method

Abstract

The application belongs to the technical field of slow / controlled release fertilizer, and particularly relates to a preparation process and application method of a double-controlled nitrogen release suspended type urea-formaldehyde multi-nutrient element liquid fertilizer, a certain amount of urea, formaldehyde and water are added; after reaction, urea-formaldehyde particle stabilizer is added and uniformly mixed, and the reaction is continued; a fertilizer system containing at least one nutrient element other than nitrogen and a nutrient synergist are added, and after uniform stirring, a double-controlled nitrogen release suspended type urea-formaldehyde multi-nutrient element liquid fertilizer prepolymer is obtained; the double-controlled nitrogen release suspended type urea-formaldehyde multi-nutrient element liquid fertilizer prepolymer is reacted in a high-speed shearing dispersion equipment to obtain a double-controlled nitrogen release suspended type urea-formaldehyde multi-nutrient element liquid fertilizer. The application significantly improves the fluidity of the liquid fertilizer by controlling the structure of the dispersed particle mainly in the form of urea-formaldehyde in the liquid fertilizer, and the liquid fertilizer does not clog for a long time.

Description

Technical Field

[0001] This invention belongs to the field of slow / controlled release fertilizer technology, specifically relating to a simplified preparation process and application method of a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer. Background Technology

[0002] The low nutrient utilization efficiency of traditional fertilizers leads to resource waste and environmental pollution, thus giving rise to slow / controlled-release fertilizers. Urea-formaldehyde-based slow-release nitrogen fertilizers, with their advantages of good slow-release effect and long-lasting fertilizer effect, have become a popular variety in the slow / controlled-release fertilizer field, and are of great significance in promoting the upgrading of the nitrogen fertilizer industry and alleviating environmental pressure.

[0003] Liquid fertilizers have gained widespread attention due to their advantages such as rapid absorption, flexible formulation, and environmental friendliness, especially with the rapid development of integrated water / fertilizer technology. Urea-formaldehyde liquid fertilizers are mainly divided into two types: clear liquid and suspension. Clear liquid urea-formaldehyde liquid fertilizers have limited nitrogen slow-release effects and poor storage stability; suspension urea-formaldehyde liquid fertilizers, on the other hand, suffer from cumbersome preparation processes and difficulty in controlling product quality.

[0004] Nitrogen, ranking first among the mineral nutrients required by plants, is an essential nutrient for crop growth and has a decisive impact on crop growth and yield. However, traditional nitrogen fertilizers, such as urea, suffer from low nitrogen utilization rates during application due to volatilization, leaching, and nitrification. Currently, the utilization rate in the current season is only 30%-50%, which not only increases production costs but also poses a serious threat to the environment. Therefore, improving nitrogen fertilizer utilization, reducing nitrogen loss, and mitigating the resulting environmental pollution have become key focuses of agricultural research.

[0005] Fertilizer synergists are substances produced through biological, physical, and chemical processes and added to fertilizers to stimulate plant nutrient absorption, increase nutrient availability, or improve nutrient utilization efficiency. They are mainly divided into two categories: biological fertilizer synergists and chemical fertilizer synergists. Chemical fertilizer synergists are further divided into urease inhibitors and nitrification inhibitors. Urease inhibitors inhibit the activity of urease in the soil, slowing down the hydrolysis of urea, thereby reducing ammonia volatilization in the soil and improving nitrogen fertilizer utilization efficiency. Nitrification inhibitors inhibit the nitrification rate of nitrogen in the soil, reducing NO3-. - This reduces nitrogen accumulation, leaching, and N2O emission losses, thereby improving the nitrogen use efficiency of fertilizers. Summary of the Invention

[0006] To address the problems of cumbersome preparation processes, difficulty in controlling product quality, limited nitrogen slow-release effect, and poor storage stability in existing urea-formaldehyde liquid fertilizers, this invention provides a simplified preparation process and application method for a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer.

[0007] This invention is achieved through the following technical solution: a simplified preparation process for a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer, comprising the following steps:

[0008] (1) Add a certain amount of urea, formaldehyde, cellulose and water to reactor A, wherein the molar ratio of urea to formaldehyde is 0.1~1:1, the mass ratio of cellulose to the total mass of urea and formaldehyde is 1~10:1, and the amount of water added is 10~80% of the total mass of urea, formaldehyde and cellulose; react at 50~90℃ for 0.5~3h, dry the obtained reaction product at 80~120℃ to constant weight, and pulverize it to obtain urea-formaldehyde grafted cellulose, which is urea-formaldehyde particle stabilizer;

[0009] (2) Add a certain amount of urea, formaldehyde and water to reactor B, wherein the molar ratio of urea to formaldehyde is 10~20:1 and the amount of water added is 10~50% of the total mass of urea and formaldehyde; after reacting at 30~60℃ for 0.5~3h, add the urea-formaldehyde particle stabilizer obtained in step (1) and mix evenly, and continue to react for 0.5~3h; add a fertilizer system containing at least one nutrient element other than nitrogen and a nutrient enhancer, and stir evenly to obtain a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer prepolymer;

[0010] (3) React the prepolymer of dual-control nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer in a high-speed shear dispersion device for 15-30 min to obtain dual-control nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer.

[0011] As a further improvement to the process technology of the present invention, in steps (1) and (2), the formaldehyde is at least one of formaldehyde aqueous solution, solid paraformaldehyde, and gaseous formaldehyde.

[0012] As a further improvement to the process technology of the present invention, in step (1), the cellulose is selected from at least one of carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and polyanionic cellulose.

[0013] As a further improvement to the process technology of the present invention, in step (2), the amount of urea-formaldehyde particle stabilizer added is 0 to 10% of the total mass of urea and formaldehyde in step (2), and is not 0.

[0014] As a further improvement to the process technology of the present invention, in step (2), the fertilizer system containing at least one nutrient element other than nitrogen is selected from at least one of phosphate fertilizer, potassium fertilizer, medium-element fertilizer and micro-element fertilizer.

[0015] As a further improvement to the process technology of the present invention, the phosphate fertilizer is selected from at least one of hydroxyapatite, ammonium dihydrogen phosphate, superphosphate, potassium tripolyphosphate and potassium dihydrogen phosphate; the potassium salt fertilizer is selected from at least one of potassium sulfate, potassium chloride, potassium nitrate and potassium carbonate.

[0016] As a further improvement to the process technology of the present invention, in step (2), the nutrient enhancer is a chemical nutrient enhancer; the chemical nutrient enhancer is selected from at least one of urease inhibitors and nitrification inhibitors.

[0017] As a further improvement to the process technology of the present invention, in step (2), the ratio of the amount of fertilizer system containing at least one nutrient element other than nitrogen to the mass of urea in step (2) is 0~5:1 and not 0; the amount of nutrient enhancer added is 0~5% of the mass of urea in step (2) and not 0.

[0018] As a further improvement to the process technology of the present invention, in step (3), the high-speed shear dispersion equipment is selected from one of the high-speed dispersion emulsifier, colloid mill and sand mill.

[0019] On the other hand, the present invention provides a method for applying a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer, including foliar spraying, seed soaking, root dipping, injection application, drenching, watering, sprinkler irrigation or drip irrigation; the application rate is 8-15 kg nitrogen / acre.

[0020] The simplified preparation process of the dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer provided by this invention has the following advantages compared with the prior art:

[0021] (1) The suspended urea-formaldehyde liquid fertilizer produced by the process of the present invention significantly improves the fluidity of the liquid fertilizer by controlling the structure of the dispersed particles mainly composed of urea-formaldehyde, and does not clump when stored for a long time. In addition, the liquid fertilizer has excellent dispersibility, can be mixed with irrigation water in any proportion, and the mixed system has good stability, low sedimentation rate when stored for a long time, and will not clog the application system during use.

[0022] (2) The suspended urea-formaldehyde liquid fertilizer produced by the process of the present invention can flexibly adjust the content of macro-, medium and micronutrient elements according to the soil characteristics of different regions and the nutrient requirements of crops at different growth stages, so as to accurately meet the needs of crops for various nutrients throughout the entire growth cycle in different regions.

[0023] (3) The process of this invention improves the slow-release effect and stability of the liquid fertilizer by optimizing the structure of the urea-formaldehyde-based dispersed particles. In addition, after application, the urea-formaldehyde particles in the liquid fertilizer form a stable network structure in the soil, which can slowly release nutrients, prolong the effective action time of the fertilizer, reduce nutrient loss, and improve fertilizer utilization efficiency.

[0024] (4) Improve nitrogen utilization efficiency by using dual control technology. This invention effectively combines urea-formaldehyde slow-release technology with chemical nutrient inhibition technology. It uses urea-formaldehyde slow-release fertilizer to control the nitrogen release rate, while using urease inhibitors to inhibit the hydrolysis of urea in the soil, or using nitrification inhibitors to inhibit the nitrification of ammonium nitrogen in the soil. This achieves dual control of nitrogen release, thereby significantly improving nitrogen fertilizer utilization efficiency and effectively reducing nitrogen loss and the resulting environmental pollution. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The appearance of the dual-controlled nitrogen-release suspension urea-formaldehyde multi-nutrient liquid fertilizer prepared for Example 2 on day 0 and day 30, as well as the results of the Tyndall effect analysis using a laser pointer.

[0028] Figure 2 The curve showing the change in dispersed phase particle size over time of the dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer prepared in Example 2.

[0029] Figure 3 The static water nitrogen release curve of the dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer prepared in Example 2. Detailed Implementation

[0030] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0032] This invention provides a specific embodiment of a simplified preparation process for a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer, comprising the following steps:

[0033] (1) Add a certain amount of urea, formaldehyde, cellulose and water to reactor A, wherein the molar ratio of urea to formaldehyde is 0.1~1:1, the mass ratio of cellulose to the total mass of urea and formaldehyde is 1~10:1, and the amount of water added is 10~80% of the total mass of urea, formaldehyde and cellulose; react at 50~90℃ for 0.5~3h, dry the obtained reaction product at 80~120℃ to constant weight, and pulverize it to obtain urea-formaldehyde grafted cellulose, which is urea-formaldehyde particle stabilizer;

[0034] (2) Add a certain amount of urea, formaldehyde and water to reactor B, wherein the molar ratio of urea to formaldehyde is 10~20:1 and the amount of water added is 10~50% of the total mass of urea and formaldehyde; after reacting at 30~60℃ for 0.5~3h, add the urea-formaldehyde particle stabilizer obtained in step (1) and mix evenly, and continue to react for 0.5~3h; add a fertilizer system containing at least one nutrient element other than nitrogen and a nutrient enhancer, and stir evenly to obtain a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer prepolymer;

[0035] (3) React the prepolymer of dual-control nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer in a high-speed shear dispersion device for 15-30 min to obtain dual-control nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer.

[0036] Preferably, the ratio of the amount of fertilizer system containing at least one nutrient element other than nitrogen to the mass of urea in step (2) is 0 to 5:1 and not 0; the amount of nutrient enhancer added is 0 to 5% of the mass of urea in step (2) and not 0.

[0037] In one embodiment of the present invention, in steps (1) and (2), the formaldehyde is at least one of formaldehyde aqueous solution, solid paraformaldehyde, and gaseous formaldehyde.

[0038] In another embodiment of the present invention, in step (1), the cellulose is selected from at least one of carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and polyanionic cellulose.

[0039] In one embodiment of the present invention, in step (2), the amount of urea-formaldehyde particle stabilizer added is 0 to 10% of the total mass of urea and formaldehyde in step (2), and is not 0.

[0040] In another embodiment of the present invention, in step (2), the fertilizer system containing at least one nutrient element other than nitrogen is selected from at least one of phosphate fertilizer, potassium fertilizer, medium-element fertilizer and micro-element fertilizer.

[0041] In one embodiment of the present invention, the phosphate fertilizer is selected from at least one of hydroxyapatite, ammonium dihydrogen phosphate, superphosphate, potassium tripolyphosphate, and potassium dihydrogen phosphate; the potassium salt fertilizer is selected from at least one of potassium sulfate, potassium chloride, potassium nitrate, and potassium carbonate.

[0042] In another embodiment of the present invention, in step (2), the nutrient enhancer is a chemical nutrient enhancer; the chemical nutrient enhancer is selected from at least one of urease inhibitors and nitrification inhibitors. The urease inhibitor may be any one of organic urease inhibitors, inorganic urease inhibitors, natural product urease inhibitors, and artificially synthesized compound urease inhibitors; the nitrification inhibitor may be any one of heterocyclic compound nitrification inhibitors, thiourea compound nitrification inhibitors, and biologically derived nitrification inhibitors.

[0043] In one embodiment of the present invention, in step (3), the high-speed shear dispersion equipment is selected from one of a high-speed dispersion emulsifier, a colloid mill, and a sand mill.

[0044] On the other hand, the present invention provides a method for applying a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer, including foliar spraying, seed soaking, root dipping, injection application, drenching, watering, sprinkler irrigation or drip irrigation; the application rate is 8-15 kg nitrogen / acre.

[0045] The performance testing of this invention adopts the following standards:

[0046] 1) Laser pointer Tyndall effect test: Take an appropriate amount of liquid fertilizer and dilute it according to the mass ratio of liquid fertilizer to deionized water of 1:10. Place the diluted and uniform liquid fertilizer at room temperature and let it stand for 30 minutes. Then, irradiate it with a laser pointer in a dark room and observe whether a clear light path appears. Record whether the Tyndall effect occurs.

[0047] 2) Dispersed phase particle size test in suspension liquid fertilizer: A scraper fineness gauge with a range of 0-50μm is used for testing. 2-3 drops of sample are dropped into the depth of the groove of the scraper fineness gauge, and scraped uniformly from top to bottom within 3 seconds. Within 5 seconds, the viewing angle is made at an angle of 15-30° with the groove plane. The distribution of particles in the scraping mark is quickly observed against the light, and the particle size value is read according to the scale line.

[0048] 3) Test for water-insoluble matter in suspended liquid fertilizer: Weigh 1g of liquid fertilizer (accurate to 0.001g) at room temperature (25±5)℃, place it in a beaker, add 250mL of water, stir thoroughly for 3min, let stand for (15±3)min, and then filter it using a glass crucible filter that has been dried to constant weight in a drying oven at (110±2)℃. Place the filtered filter in a drying oven and dry it at (110±2)℃ for 1h. After removing it and cooling it to room temperature, weigh it. The blank test is exactly the same except that no sample is added.

[0049] 4) Liquid Fertilizer Slow-Release Performance Test: The nitrogen nutrient release performance and initial release rate were characterized by a static water release test. 5 mL of liquid fertilizer was directly added to a bottle containing 100 mL of deionized water and incubated in a 25°C constant temperature water bath. Samples were taken on days 1, 3, 5, 7, 10, 14, and 28. The solution was digested using the sulfuric acid-hydrogen peroxide method, and the nitrogen content was determined using the Kjeldahl method. The cumulative nutrient release rate was calculated, and the result on the first day was the initial release rate.

[0050] The specific embodiments of the present invention will be described in detail below. Example 1

[0051] A simplified preparation process for a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer includes the following steps:

[0052] (S1) Add a certain amount of urea, a 37wt% formaldehyde aqueous solution, carboxymethyl cellulose and water to reactor A. The molar ratio of formaldehyde in the urea to the formaldehyde aqueous solution is 0.8:1, and the mass ratio of carboxymethyl cellulose to the total mass of formaldehyde in the urea and formaldehyde aqueous solutions is 10:1. The amount of water added is 40% of the total mass of formaldehyde and carboxymethyl cellulose in the urea, formaldehyde aqueous solution and the formaldehyde aqueous solution. After reacting at 50°C for 3 hours, the reaction product is dried at 120°C to constant weight and pulverized to obtain urea-formaldehyde grafted carboxymethyl cellulose, which is a urea-formaldehyde particle stabilizer.

[0053] (S2) Add a certain amount of urea, a 37wt% formaldehyde aqueous solution, and water to reactor B. The molar ratio of urea to formaldehyde in the formaldehyde aqueous solution is 10:1. The amount of water added is 50% of the total mass of formaldehyde in the urea and formaldehyde aqueous solution. After reacting at 50°C for 2 hours, add the urea-formaldehyde particle stabilizer obtained in step (S1) and mix evenly. The amount of urea-formaldehyde particle stabilizer added is 1% of the total mass of formaldehyde in the urea and formaldehyde aqueous solution in step (S2). Continue the reaction for 2 hours. Add ammonium dihydrogen phosphate and the urease inhibitor N-butylthiophosphoric triamine and mix evenly. The mass ratio of ammonium dihydrogen phosphate to urea in step (S2) is 1:2, and the mass ratio of N-butylthiophosphoric triamine to urea in step (S2) is 0.01:1. Obtain the dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer prepolymer.

[0054] (S3) The prepolymer of dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer was reacted in a high-speed dispersion emulsifier for 15 min to obtain dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer.

[0055] The prepared dual-controlled nitrogen-release suspension urea-formaldehyde multi-nutrient liquid fertilizer contains 157 g / L of nitrogen, 126 g / L of P2O5, and 9.2 g / L of water-insoluble matter, with an initial nitrogen release rate of 24.4%. When planting corn, the liquid fertilizer is applied at a rate of 80 L / mu using a sprayer. Example 2

[0056] A simplified preparation process for a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer includes the following steps:

[0057] (S1) Add a certain amount of urea, solid paraformaldehyde, methylcellulose and water to reactor A, wherein the molar ratio of formaldehyde structural units contained in urea to paraformaldehyde is 0.5:1, the mass ratio of methylcellulose to the total mass of urea and paraformaldehyde is 10:1, and the amount of water added is 20% of the total mass of urea, paraformaldehyde and methylcellulose; react at 80°C for 2 hours, dry the reaction product at 100°C to constant weight, and pulverize it to obtain urea-formaldehyde grafted methylcellulose, which is a urea-formaldehyde particle stabilizer.

[0058] (S2) Add a certain amount of urea, solid paraformaldehyde and water to reactor B, wherein the molar ratio of formaldehyde structural units contained in urea to paraformaldehyde is 15:1, and the amount of water added is 50% of the total mass of urea and paraformaldehyde. After reacting at 40°C for 3 hours, add the urea-formaldehyde particle stabilizer obtained in step (S1) and mix evenly, wherein the amount of urea-formaldehyde particle stabilizer added is 0.5% of the total mass of urea and paraformaldehyde in step (S2), and continue to react for 3 hours; add ammonium dihydrogen phosphate, potassium sulfate and nitration inhibitor dicyandiamide and mix evenly, wherein the mass ratio of ammonium dihydrogen phosphate to urea in step (S2) is 1:5, the mass ratio of potassium sulfate to ammonium dihydrogen phosphate is 1:3, and the mass ratio of dicyandiamide to urea in step (S2) is 0.005:1; and obtain a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer prepolymer.

[0059] (S3) Add the prepolymer of dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer to a colloid mill and react for 10 min to obtain dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer.

[0060] The prepared dual-controlled nitrogen-release suspension urea-formaldehyde multi-nutrient liquid fertilizer contains 185 g / L of nitrogen, 109 g / L of P2O5, 79 g / L of K2O, and 8.0 g / L of water-insoluble matter, with an initial nitrogen release rate of 27.5%. When planting corn, the liquid fertilizer is applied at a rate of 60 L / mu using a sprayer.

[0061] Figure 1 In Example 2 of this invention, the dual-controlled nitrogen release suspension-type urea-formaldehyde multi-nutrient liquid fertilizer exhibited excellent stability within 30 days of storage, showing no stratification or sedimentation at the bottom, indicating that the preparation method of this invention can ensure the uniform dispersion of the liquid fertilizer over a long period. Furthermore, a significant Tyndall effect was observed during the test, not only visually demonstrating the presence of particles in the liquid fertilizer but also reflecting its good dispersibility and stability. Because the urea-formaldehyde-based dispersed particles in the liquid fertilizer are tightly coated by the urea-formaldehyde particle stabilizer and form a stable suspension system, particle aggregation and sedimentation are effectively avoided. This stable dispersed particle structure maintains uniformity during long-term storage and use, ensuring the storage stability and ease of use of the liquid fertilizer product.

[0062] Figure 2 In the study, the size of the urea-formaldehyde multinutrient liquid fertilizer, primarily composed of urea-formaldehyde particles, remained consistently between 2.5 and 2.6 μm within 30 days, demonstrating excellent stability. This stability primarily stems from the urea-formaldehyde particle stabilizer forming a protective film by tightly coating the urea-formaldehyde-based dispersed particles, effectively preventing direct contact between particles and aggregation caused by van der Waals forces or electrostatic interactions. This dual mechanism ensures that the dispersed particles in the liquid fertilizer maintain a uniform dispersion state over a long period, significantly improving the stability and dispersibility of the liquid fertilizer.

[0063] Figure 3 In the study, the cumulative nitrogen release rate of the dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer gradually increased from 27.5% on day 1 to 43.7% on day 28. This result indicates that the liquid fertilizer has good slow-release performance and can continuously release nitrogen over a long period of time, meeting the continuous nitrogen demand of crops during growth, and is suitable for use in cash crops or field crops. Example 3

[0064] A simplified preparation process for a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer includes the following steps:

[0065] (S1) Add a certain amount of urea, solid paraformaldehyde, polyanionic cellulose and water to reactor A. The molar ratio of formaldehyde structural units contained in urea to paraformaldehyde is 1:1, the mass ratio of polyanionic cellulose to the total mass of urea and paraformaldehyde is 5:1, and the amount of water added is 40% of the total mass of urea, paraformaldehyde and polyanionic cellulose. React at 90°C for 1 hour, dry the reaction product at 80°C to constant weight, and pulverize it to obtain urea-formaldehyde grafted polyanionic cellulose, which is a urea-formaldehyde particle stabilizer.

[0066] (S2) Add a certain amount of urea, solid paraformaldehyde and water to reactor B, wherein the molar ratio of formaldehyde structural units contained in urea to paraformaldehyde is 20:1, and the amount of water added is 40% of the total mass of urea and paraformaldehyde. After reacting at 60°C for 1 hour, add the urea-formaldehyde particle stabilizer obtained in step (S1) and mix evenly, wherein the amount of urea-formaldehyde particle stabilizer added is 2% of the total mass of urea and paraformaldehyde in step (S2), and continue to react for 1 hour; add ammonium dihydrogen phosphate, potassium chloride and nitration inhibitor 3,4-dimethylpyrazole phosphate and mix evenly, wherein the mass ratio of ammonium dihydrogen phosphate to urea in step (S2) is 1:4, the mass ratio of potassium chloride to ammonium dihydrogen phosphate is 1:2, and the mass ratio of 3,4-dimethylpyrazole phosphate to urea in step (S2) is 0.01:1; to obtain a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer prepolymer.

[0067] (S3) Add the prepolymer of dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer to a colloid mill and react for 10 min to obtain dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer.

[0068] The prepared dual-controlled nitrogen-release suspension urea-formaldehyde multi-nutrient liquid fertilizer contains 180 g / L of nitrogen, 127 g / L of P2O5, 90 g / L of K2O, and 7.8 g / L of water-insoluble matter, with an initial nitrogen release rate of 30.1%. When planting corn, the liquid fertilizer is applied at a rate of 65 L / mu using a sprayer.

[0069] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A simplified preparation process for a dual-controlled nitrogen release suspension-type urea-formaldehyde multi-nutrient liquid fertilizer, characterized in that, Includes the following steps: (1) Add a certain amount of urea, formaldehyde, cellulose and water to reactor A, wherein the molar ratio of urea to formaldehyde is 0.1~1:1, the mass ratio of cellulose to the total mass of urea and formaldehyde is 1~10:1, and the amount of water added is 10~80% of the total mass of urea, formaldehyde and cellulose; react at 50~90℃ for 0.5~3h, dry the obtained reaction product at 80~120℃ to constant weight, and pulverize it to obtain urea-formaldehyde grafted cellulose, which is urea-formaldehyde particle stabilizer; (2) Add a certain amount of urea, formaldehyde and water to reactor B, wherein the molar ratio of urea to formaldehyde is 10~20:1, and the amount of water added is 10~50% of the total mass of urea and formaldehyde; after reacting at 30~60℃ for 0.5~3h, add the urea-formaldehyde particle stabilizer obtained in step (1) and mix evenly, and continue to react for 0.5~3h; add a fertilizer system containing at least one nutrient element other than nitrogen and a nutrient enhancer, and stir evenly to obtain a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer prepolymer; in step (2), the amount of urea-formaldehyde particle stabilizer added is 0~10% of the total mass of urea and formaldehyde in step (2) and is not 0; (3) React the prepolymer of dual-control nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer in a high-speed shear dispersion device for 15-30 min to obtain dual-control nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer.

2. The simplified preparation process of a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer according to claim 1, characterized in that, In steps (1) and (2), the formaldehyde is at least one of formaldehyde aqueous solution, solid paraformaldehyde, and gaseous formaldehyde.

3. The simplified preparation process of the dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer according to claim 1, characterized in that, In step (1), the cellulose is selected from at least one of carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and polyanionic cellulose.

4. The simplified preparation process of a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer according to claim 1, characterized in that, In step (2), the fertilizer system containing at least one nutrient element other than nitrogen is selected from at least one of phosphate fertilizer, potash fertilizer, medium-element fertilizer and micro-element fertilizer.

5. The simplified preparation process of a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer according to claim 4, characterized in that, The phosphate fertilizer is selected from at least one of hydroxyapatite, ammonium dihydrogen phosphate, superphosphate, potassium tripolyphosphate, and potassium dihydrogen phosphate; the potassium salt fertilizer is selected from at least one of potassium sulfate, potassium chloride, potassium nitrate, and potassium carbonate.

6. The simplified preparation process of a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer according to claim 1, characterized in that, In step (2), the nutrient enhancer is a chemical nutrient enhancer; the chemical nutrient enhancer is selected from at least one of urease inhibitors and nitrification inhibitors.

7. The simplified preparation process of a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer according to claim 1, characterized in that, In step (2), the ratio of the amount of fertilizer system containing at least one nutrient element other than nitrogen to the mass of urea in step (2) is 0 to 5:1 and not 0; the amount of nutrient enhancer added is 0 to 5% of the mass of urea in step (2) and not 0.

8. The simplified preparation process of a dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer according to claim 1, characterized in that, In step (3), the high-speed shear dispersion equipment is selected from one of the following: high-speed dispersion emulsifier, colloid mill and sand mill.

9. The application method of the dual-controlled nitrogen release suspension urea-formaldehyde multi-nutrient liquid fertilizer prepared according to claims 1-8 includes foliar spraying, seed soaking, root dipping, injection application, drenching application, watering application, sprinkler irrigation application or drip irrigation application; the application rate is 8-15 kg nitrogen / mu.

Images