Fertilizer for degrading urea residues in soil and improving utilization rate of fertilizer and preparation method

Abstract

The invention relates to the technical field of fertilizers, in particular to a fertilizer for degrading urea residues in soil and improving the utilization rate of the fertilizer and a preparation method, and the fertilizer is prepared by mixing urea, a bioactive enzyme compound, a slow-release carrier, a microbial agent, a microelement chelate and a dispersing aid according to a specific proportion. A biological active enzyme compound is introduced to regulate urea decomposition, a slow-release carrier is combined to delay nutrient release, the synergistic effect of compound microbial flora is achieved, and a microelement chelate and a dispersing aid are added to optimize the performance. The fertilizer can effectively degrade urea residues in soil, reduce nutrient loss, improve the fertilizer utilization rate and improve the soil structure, is suitable for fertilization of field crops, commercial crops and horticultural plants, and has remarkable practical application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural environmental protection and fertilizers, and specifically relates to a fertilizer for degrading urea residues in soil and improving fertilizer utilization rate, and a preparation method thereof. Background Art

[0002] Urea, as an important nitrogen fertilizer, is widely used in agricultural production. However, the problem of its residue in soil has gradually attracted attention. After application, urea is likely to not be fully absorbed by crops due to hydrolysis, volatilization, or leaching, resulting in reduced fertilizer utilization rate and potential environmental impacts. After retrieval, a urea-containing fertilizer and its production method with the publication number CN108463447B were disclosed on June 22, 2021. This patent provides a granular urea-containing fertilizer, and improves the fertilizer performance by adding specific additives (such as a combination of amino-containing polymers or oligomers and functionalized vinyl compounds). However, although this technical solution improves the stability of the fertilizer to a certain extent, it does not specifically solve the problem of degrading urea residues in soil. In addition, the types and ratios of additives in this fertilizer formula are complex, which may lead to cumbersome production processes, and there is a lack of clear verification of the effect of degrading urea residues, and the actual utilization rate of the fertilizer still needs to be further improved.

[0003] The problem of degrading urea residues in soil involves complex biochemical processes, including microbial decomposition, enzymatic reactions, and the influence of environmental factors. Current research mainly focuses on delaying the decomposition rate of urea by improving the fertilizer formula or adding functional additives to reduce losses. However, these methods usually focus on improving the slow-release performance of fertilizers, and pay less attention to the degradation of urea residues. For example, some technologies control nutrient release by introducing polymer coatings or composite materials, but such methods may increase production costs and have limited effects on treating residual urea in soil.

[0004] In practical applications, how to effectively degrade urea residues in soil and improve fertilizer utilization rate remains an urgent technical problem to be solved. Although existing technologies have improved the performance of fertilizers to a certain extent, there are limitations in the degradation of urea residues, especially the exploration in formula design and process optimization is insufficient. Therefore, developing a new type of fertilizer and preparation method that can both degrade urea residues in soil and improve fertilizer utilization rate has important practical significance and application value. Summary of the Invention

[0005] The present invention relates to the technical field of fertilizers, and particularly to a fertilizer for degrading urea residues in soil and improving fertilizer utilization rate, as well as a preparation method thereof. In order to solve the problem of urea residues in soil after being applied as a nitrogen fertilizer in the prior art, which leads to low fertilizer utilization rate and potential environmental impacts, and the prior art fails to specifically solve the technical problem of urea residue degradation, a new type of fertilizer and its preparation method are provided.

[0006] The present invention provides a fertilizer for degrading urea residues in soil and improving fertilizer utilization rate. The fertilizer is prepared by mixing the following components in a specific proportion through a specific process: urea, bioactive enzyme complex, slow-release carrier, microbial inoculant, trace element chelate, and dispersing aid. By weight, the components and their contents in the fertilizer are as follows:

[0007] Urea: 40.0 - 60.0 parts by weight;

[0008] Bioactive enzyme complex: 10.0 - 25.0 parts by weight;

[0009] Slow-release carrier: 15.0 - 30.0 parts by weight;

[0010] Microbial inoculant: 5.0 - 15.0 parts by weight;

[0011] Trace element chelate: 1.0 - 5.0 parts by weight;

[0012] Dispersing aid: 0.5 - 3.0 parts by weight.

[0013] Among them, the bioactive enzyme complex is compounded by urease inhibitor and urease according to a mass ratio of (3 - 8):(1 - 3); the urease inhibitor is selected from one or more of phenylphosphorodiamide (PPD), N-butylthiophosphoric triamide (NBPT); the urease is selected from one or more of urease, protease, lipase.

[0014] Furthermore, the slow-release carrier is a composite of porous inorganic material and polymer. The porous inorganic material is selected from one or more of diatomite, bentonite, zeolite powder; the polymer is selected from one or more of polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate (PHA); the mass ratio of the porous inorganic material to the polymer is (1 - 5):(1 - 3).

[0015] Further, the microbial inoculant includes nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria, and the mass ratio of the nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria is (2 - 5):(1 - 3):(1 - 2); the nitrogen-fixing bacteria are selected from one or more of the genus Rhizobium and the genus Azospirillum; the phosphorus-solubilizing bacteria are selected from one or more of the genus Bacillus and the genus Pseudomonas; the potassium-solubilizing bacteria are selected from one or more of the genus Silicate bacteria.

[0016] Further, the trace element chelate is composed of chelates of iron, zinc, copper, and manganese, and the molar ratio of iron, zinc, copper, and manganese is (1 - 3):(1 - 2):(0.5 - 1):(0.5 - 1); the chelating agent is selected from one or more of ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and citric acid.

[0017] Further, the dispersion aid is a mixture of a surfactant and nano-scale silica, and the mass ratio of the surfactant to nano-scale silica is (1 - 3):(0.5 - 1); the surfactant is selected from one or more of sodium dodecyl sulfate (SDS), polyoxyethylene ether (PEG), and polyacrylamide (PAM).

[0018] The present invention also provides a preparation method of the above fertilizer, including the following steps:

[0019] Step 1: Perform a first drying treatment on urea, control the temperature at 50 - 70 °C, and the time at 3 - 5 h to remove the moisture on the surface of urea particles; perform a second drying treatment on the slow-release carrier, control the temperature at 80 - 100 °C, and the time at 2 - 4 h to remove the internally adsorbed moisture; perform a third low-temperature drying treatment on the microbial inoculant, control the temperature at 30 - 40 °C, and the time at 4 - 6 h to maintain its biological activity;

[0020] Step 2: Grind the urease inhibitor and urea-decomposing enzyme in the bioactive enzyme complex to a particle size less than 100 μm respectively, and then mix them evenly by high-speed stirring at a stirring rate of 300 - 500 rad / min for 5 - 10 min to obtain the bioactive enzyme complex;

[0021] Step 3: Mix the porous inorganic material and the polymer in the slow-release carrier according to a mass ratio of (1 - 5):(1 - 3), and then melt-blend and granulate them through a twin-screw extruder, control the extrusion temperature at 120 - 160 °C, and the screw speed at 100 - 200 r / min to obtain slow-release carrier particles;

[0022] Step 4: Mix the chelates of iron, zinc, copper, and manganese in the trace element chelate according to the molar ratio of (1 - 3):(1 - 2):(0.5 - 1):(0.5 - 1), add an appropriate amount of deionized water to dissolve, and after forming a uniform solution, perform spray drying. Control the spray drying temperature at 100 - 120 °C to obtain trace element chelate particles;

[0023] Step 5: Mix the surfactant in the dispersion aid and nano - silica according to the mass ratio of (1 - 3):(0.5 - 1), and disperse evenly through a high - speed shear emulsifier. Control the shear rate at 1000 - 2000 rpm and the time at 3 - 5 min to obtain the dispersion aid;

[0024] Step 6: Mix the urea in Step 1, the bioactive enzyme complex in Step 2, the slow - release carrier particles in Step 3, the trace element chelate particles in Step 4, the dispersion aid in Step 5, and the microbial inoculant in proportion, and mix evenly through a double - shaft mixer. Control the mixing time at 10 - 15 min and the mixing rate at 50 - 100 rpm to obtain the premix;

[0025] Step 7: Granulate the premix in Step 6 through a granulator. Control the granulation temperature at 40 - 60 °C and the particle diameter at 2 - 5 mm, and then cool to room temperature through a cooling device to obtain the fertilizer.

[0026] Further, in Step 1, the first drying treatment of the urea uses a hot - air circulation drying device, and the hot - air flow rate is controlled at 1 - 3 m / s; the second drying treatment of the slow - release carrier uses a vacuum drying device, and the vacuum degree is controlled at 0.05 - 0.1 MPa; the third low - temperature drying treatment of the microbial inoculant uses a freeze - drying device, and the freezing temperature is controlled at - 20 °C to - 40 °C.

[0027] Further, during the high - speed stirring in Step 2, the humidity of the mixing system is adjusted by adding a small amount of deionized water, and the humidity is controlled at 5 - 10% to promote the uniform distribution of the urease inhibitor and the urea - decomposing enzyme.

[0028] Further, the twin - screw extruder in Step 3 includes six temperature zones, and the temperatures of each zone are set as follows: Zone 1: 120 - 140 °C, Zone 2: 130 - 150 °C, Zone 3: 140 - 160 °C, Zone 4: 130 - 150 °C, Zone 5: 120 - 140 °C, Zone 6: 110 - 130 °C; the length - diameter ratio of the screw is 30:1, and the feeding speed is 20 - 40 Hz.

[0029] Further, for the spray drying equipment in Step 4, the inlet air temperature is 150 - 180 °C, the outlet air temperature is 80 - 100 °C, and the nozzle pressure is 0.2 - 0.4 MPa.

[0030] Further, the diameter of the shearing head of the high-speed shearing emulsifier described in step 5 is 5 - 10 cm, and the shearing gap is 0.5 - 1 mm.

[0031] Further, the granulator described in step 7 is a rotary granulator, and the rotation rate is controlled at 30 - 50 rpm, and the aperture of the granulation screen is 2 - 5 mm.

[0032] The present invention also provides an application of the above fertilizer, and the fertilizer is suitable for fertilizing field crops, cash crops and horticultural plants, and can effectively degrade urea residues in the soil and improve fertilizer utilization rate.

[0033] The technical effects of the present invention are as follows:

[0034] 1. The fertilizer provided by the present invention combines the functions of urease inhibitor and urea-decomposing enzyme by introducing a bioactive enzyme complex, can regulate the decomposition process of urea in the soil, reduce the loss caused by hydrolysis or volatilization of urea, and at the same time promote the degradation of urea residues, and significantly improve the fertilizer utilization rate.

[0035] 2. The slow-release carrier selected by the present invention is composed of a porous inorganic material and a polymer composite, has good adsorption and slow-release properties, can delay the release rate of urea, avoid the rapid loss of nutrients, and at the same time provide a suitable growth environment for the microbial inoculant and promote the exertion of its activity.

[0036] 3. The present invention constructs an efficient microbial flora by compounding nitrogen-fixing bacteria, phosphorus-solubilizing bacteria and potassium-solubilizing bacteria, can act synergistically on nitrogen, phosphorus and potassium elements in the soil, further improve the utilization efficiency of fertilizers, and at the same time improve the soil structure and enhance soil fertility.

[0037] 4. The trace element chelates added by the present invention ensure the balanced supply of trace elements such as iron, zinc, copper and manganese through reasonable proportion design, meet the growth requirements of crops, and at the same time avoid the antagonistic effect caused by excessive single element.

[0038] 5. The present invention uses a dispersion aid to optimize the dispersibility and uniformity of fertilizer particles, can be quickly dispersed and fully contact with the soil during the fertilization process, and improves the actual use effect of the fertilizer.

[0039] In summary, through specific formula design and process optimization, the present invention provides a new fertilizer that can both degrade urea residues in the soil and improve fertilizer utilization rate, solves the deficiencies in the prior art, and has important practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is the change of soil urea residue amount of the present invention.

[0041] The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, but do not constitute a limitation to the present invention. Detailed implementation manners

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0044] Embodiment 1

[0045] A fertilizer for degrading urea residues in soil and improving fertilizer utilization rate

[0046] The fertilizer is prepared from the following components according to the weight ratio:

[0047] Urea: 40.0 parts by weight;

[0048] Bioactive enzyme complex: 10.0 parts by weight;

[0049] Slow-release carrier: 15.0 parts by weight;

[0050] Microbial inoculum: 5.0 parts by weight;

[0051] Trace element chelate: 1.0 part by weight;

[0052] Dispersing aid: 0.5 part by weight.

[0053] In this embodiment, the bioactive enzyme complex is compounded by urease inhibitor and urease according to a mass ratio of 3:1; the urease inhibitor is selected from phenylphosphorodiamide; the urease is selected from urease.

[0054] In this embodiment, the slow-release carrier is compounded by porous inorganic material and polymer according to a mass ratio of 1:1; the porous inorganic material is selected from diatomite; the polymer is selected from polylactic acid.

[0055] In this embodiment, the microbial inoculum includes nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria. The mass ratio of the nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria is 2:1:1. The nitrogen-fixing bacteria are selected from the genus Rhizobium. The phosphorus-solubilizing bacteria are selected from the genus Bacillus. The potassium-solubilizing bacteria are selected from the genus Silicate bacteria.

[0056] In this embodiment, the trace element chelate is composed of chelates of iron, zinc, copper, and manganese. The molar ratio of iron, zinc, copper, and manganese is 1:1:0.5:0.5. The chelating agent is selected from ethylenediaminetetraacetic acid.

[0057] In this embodiment, the dispersion aid is prepared by compounding a surfactant and nanoscale silica in a mass ratio of 1:0.5. The surfactant is selected from sodium dodecyl sulfate.

[0058] The preparation method of the fertilizer is characterized by comprising the following steps:

[0059] Step 1: Perform a first drying treatment on urea, controlling the temperature at 50 to 70 °C and the time at 3 to 5 hours; perform a second drying treatment on the slow-release carrier, controlling the temperature at 80 to 100 °C and the time at 2 to 4 hours; perform a third low-temperature drying treatment on the microbial inoculum, controlling the temperature at 30 to 40 °C and the time at 4 to 6 hours.

[0060] Step 2: Grind the urease inhibitor and urea-decomposing enzyme in the bioactive enzyme complex to a particle size less than 100 microns respectively and then mix them evenly. The stirring rate is 300 to 500 revolutions per minute, and the stirring time is 5 to 10 minutes.

[0061] Step 3: Mix the porous inorganic material and the polymer in the slow-release carrier and then melt-blend and granulate them through a twin-screw extruder. Control the extrusion temperature at 120 to 160 °C and the screw speed at 100 to 200 revolutions per minute.

[0062] Step 4: Mix the chelates of iron, zinc, copper, and manganese in the trace element chelate and then add deionized water to dissolve them. After forming a solution, perform spray drying, controlling the spray drying temperature at 100 to 120 °C.

[0063] Step 5: Mix the surfactant and nanoscale silica in the dispersion aid and then disperse them evenly through a high-speed shear emulsifier. Control the shear rate at 1000 to 2000 revolutions per minute and the time at 3 to 5 minutes.

[0064] Step 6: Mix the urea in Step 1, the bioactive enzyme complex in Step 2, the slow-release carrier particles in Step 3, the trace element chelate particles in Step 4, the dispersion aid in Step 5, and the microbial inoculum in proportion. Control the mixing time at 10 to 15 minutes and the mixing rate at 50 to 100 revolutions per minute.

[0065] Step 7: Granulate the premix in Step 6 using a granulator, control the granulation temperature to be 40 to 60 °C, the particle diameter to be 2 to 5 mm, and then cool it to room temperature.

[0066] Among them, for the first drying treatment of the urea in Step 1, a hot air circulation drying device is used, and the hot air flow rate is controlled to be 1 to 3 m / s; for the second drying treatment of the slow-release carrier, a vacuum drying device is used, and the vacuum degree is controlled to be 0.05 to 0.1 MPa; for the third low-temperature drying treatment of the microbial inoculant, a freeze-drying device is used, and the freezing temperature is controlled to be -20 °C to -40 °C.

[0067] Among them, the twin-screw extruder in Step 3 includes six temperature zones, and the temperatures of each zone are set as follows: Zone 1 is 120 to 140 °C, Zone 2 is 130 to 150 °C, Zone 3 is 140 to 160 °C, Zone 4 is 130 to 150 °C, Zone 5 is 120 to 140 °C, and Zone 6 is 110 to 130 °C; the screw length-diameter ratio is 30:1, and the feeding speed is 20 to 40 Hz.

[0068] Among them, the granulator in Step 7 is a rotary granulator, the rotation rate is controlled to be 30 to 50 revolutions per minute, and the aperture of the granulation screen is 2 to 5 mm.

[0069] Example 2

[0070] A fertilizer for degrading urea residues in soil and improving fertilizer utilization rate

[0071] The fertilizer is prepared from the following components according to the weight ratio:

[0072] Urea: 60.0 parts by weight;

[0073] Bioactive enzyme complex: 25.0 parts by weight;

[0074] Slow-release carrier: 30.0 parts by weight;

[0075] Microbial inoculant: 15.0 parts by weight;

[0076] Trace element chelate: 5.0 parts by weight;

[0077] Dispersing aid: 3.0 parts by weight.

[0078] In this example, the bioactive enzyme complex is compounded from a urease inhibitor and a urease according to a mass ratio of 8:3; the urease inhibitor is selected from N-butyl thiophosphoryl triamide; the urease is selected from protease.

[0079] In this example, the slow-release carrier is compounded from a porous inorganic material and a polymer according to a mass ratio of 5:3; the porous inorganic material is selected from bentonite; the polymer is selected from polycaprolactone.

[0080] In this embodiment, the microbial inoculum includes nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria. The mass ratio of the nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria is 5:3:2. The nitrogen-fixing bacteria are selected from the genus Azospirillum. The phosphorus-solubilizing bacteria are selected from the genus Pseudomonas. The potassium-solubilizing bacteria are selected from the genus Silicate bacteria.

[0081] In this embodiment, the trace element chelate is composed of chelates of iron, zinc, copper, and manganese. The molar ratio of iron, zinc, copper, and manganese is 3:2:1:1. The chelating agent is selected from diethylenetriaminepentaacetic acid.

[0082] In this embodiment, the dispersion aid is prepared by compounding a surfactant and nanoscale silica in a mass ratio of 3:1. The surfactant is selected from polyoxyethylene ethers.

[0083] The preparation method of the fertilizer refers to Example 1.

[0084] Example 3

[0085] A fertilizer for degrading urea residues in soil and improving fertilizer utilization rate

[0086] The fertilizer is prepared from the following components according to the weight ratio:

[0087] Urea: 50 parts by weight;

[0088] Bioactive enzyme complex: 15 parts by weight;

[0089] Sustained-release carrier: 20 parts by weight;

[0090] Microbial inoculum: 8 parts by weight;

[0091] Trace element chelate: 3 parts by weight;

[0092] Dispersion aid: 2 parts by weight.

[0093] In this embodiment, the bioactive enzyme complex is prepared by compounding a urease inhibitor and a urea-decomposing enzyme in a mass ratio of 5:2. The urease inhibitor is selected from phenylphosphorodiamidate. The urea-decomposing enzyme is selected from lipase.

[0094] In this embodiment, the sustained-release carrier is prepared by compounding a porous inorganic material and a polymer in a mass ratio of 4:2. The porous inorganic material is selected from zeolite powder. The polymer is selected from polyhydroxyalkanoates.

[0095] In this embodiment, the microbial inoculum includes nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria. The mass ratio of the nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria is 3:2:2. The nitrogen-fixing bacteria are selected from the genus Azospirillum. The phosphorus-solubilizing bacteria are selected from the genus Pseudomonas. The potassium-solubilizing bacteria are selected from the genus Silicate bacteria.

[0096] In this embodiment, the trace element chelate is composed of chelates of iron, zinc, copper, and manganese, and the molar ratio of iron, zinc, copper, and manganese is 2:2:1:1; the chelating agent is selected from citric acid.

[0097] In this embodiment, the dispersion aid is prepared by compounding a surfactant and nano-scale silica in a mass ratio of 2:1; the surfactant is selected from polyacrylamide.

[0098] The preparation method of the fertilizer refers to Example 1.

[0099] Experimental verification:

[0100] I. Experimental purpose

[0101] Verify the actual effect of the new fertilizer on degrading urea residues in soil and improving fertilizer utilization rate, and provide a scientific basis for its popularization and application.

[0102] II. Experimental materials and methods

[0103] (I) Experimental materials

[0104] Test soil: Select farmland soil containing a certain amount of urea residue. After testing, the initial soil urea residue is 35 - 50 mg / kg.

[0105] Test crop: Select wheat, the local main cultivated crop, with the variety of Jimai 22.

[0106] Fertilizers: The fertilizer of Example 1, ordinary urea, and conventional compound fertilizer.

[0107] (II) Experimental design

[0108] Adopt a randomized block design, set 4 treatment groups, with 3 replicates for each treatment group, and the plot area is 20 square meters. The specific treatments are as follows:

[0109] Treatment A: Apply the fertilizer of Example 1 and evenly spread it at a rate of 30 kg per mu.

[0110] Treatment B: Apply ordinary urea and evenly spread it at a rate of 30 kg per mu. This is the control for traditional fertilizers.

[0111] Treatment C: Apply conventional compound fertilizer and evenly spread it at a rate of 30 kg per mu as the control for compound fertilizers.

[0112] Treatment D: Do not apply fertilizer as the blank control.

[0113] (III) Experimental steps

[0114] Land preparation: Deep plow and harrow the experimental field to make the soil loose and uniform.

[0115] Fertilization: According to the fertilization plan designed in the experiment, the fertilizer was evenly spread on the soil surface before sowing, and then plowed to fully mix the fertilizer with the soil.

[0116] Sowing: According to the local wheat planting habit, drill seeding was carried out. The sowing depth was 3 - 5 cm, and the seeding rate was 15 kg per mu.

[0117] Field management: During the experiment, the field management measures for each treatment group were kept consistent, including irrigation, weeding, pest and disease control, etc.

[0118] (IV) Sample collection and analysis

[0119] Soil sample collection: Soil samples from the 0 - 20 cm soil layer of each plot were collected on the 15th day, 30th day, 45th day, and 60th day after sowing. Five sampling points were randomly selected from each plot, and the collected soil samples were mixed evenly. After removing impurities, they were taken back to the laboratory for analysis. The indophenol blue colorimetric method was used to determine the soil urea residue.

[0120] Crop sample collection: At the wheat harvest stage, 10 wheat plants were randomly selected from each plot and divided into above - ground parts (stems, leaves, ears) and underground parts (roots). They were respectively blanched, dried, weighed, and then ground. The Kjeldahl method was used to determine the plant nitrogen content. At the same time, the actual wheat yield of each plot was recorded.

[0121] III. Experimental results and analysis

[0122] (I) Changes in soil urea residue

[0123] As Figure 1 shown, the soil urea residue of treatment A (Example 1) was always lower than that of treatment B (ordinary urea) and treatment C (conventional compound fertilizer) throughout the growth period. On the 60th day after sowing, the soil urea residue of treatment A decreased by 57.1% compared with treatment B and by 50% compared with treatment C, indicating that the new fertilizer can effectively degrade the urea residue in the soil.

[0124] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "including", "comprising" or any other variant thereof is intended to cover non - exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0125] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention. The scope of the invention is defined by the appended claims and their equivalents.

[0126] The above description of the present invention and its embodiments is not restrictive. What is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. In general, if those of ordinary skill in the art are inspired by it and, without departing from the purpose of the present invention, design similar structural modes and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A fertilizer for degrading urea residues in soil to improve fertilizer utilization rate, characterized in that, The fertilizer is prepared from the following components according to the weight ratio: Urea: 40.0 to 60.0 parts by weight; Bioactive enzyme complex: 10.0 to 25.0 parts by weight; Sustained-release carrier: 15.0 to 30.0 parts by weight; Microbial inoculant: 5.0 to 15.0 parts by weight; Trace element chelate: 1.0 to 5.0 parts by weight; Dispersing aid: 0.5 to 3.0 parts by weight.

2. The fertilizer according to claim 1, characterized in that, The bioactive enzyme complex is compounded from a urease inhibitor and a urea-decomposing enzyme according to a mass ratio of 3 to 8 and 1 to 3; the urease inhibitor is selected from one or more of phenylphosphorodiamide and N-butylthiophosphoryl triamide; the urea-decomposing enzyme is selected from one or more of urease, protease, and lipase.

3. The fertilizer according to claim 1, characterized in that, The sustained-release carrier is compounded from a porous inorganic material and a polymer according to a mass ratio of 1 to 5 and 1 to 3; the porous inorganic material is selected from one or more of diatomite, bentonite, and zeolite powder; the polymer is selected from one or more of polylactic acid, polycaprolactone, and polyhydroxyalkanoate.

4. The fertilizer according to claim 1, characterized in that, The microbial inoculant includes nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria, and the mass ratio of the nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, and potassium-solubilizing bacteria is 2 to 5, 1 to 3, and 1 to 2; the nitrogen-fixing bacteria are selected from one or more of the genus Rhizobium and the genus Azospirillum; the phosphorus-solubilizing bacteria are selected from one or more of the genus Bacillus and the genus Pseudomonas; the potassium-solubilizing bacteria are selected from one or more of the genus Silicate bacteria.

5. The fertilizer according to claim 1, characterized in that, The trace element chelate is composed of chelates of iron, zinc, copper, and manganese, and the molar ratio of iron, zinc, copper, and manganese is 1 to 3, 1 to 2, 0.5 to 1, and 0.5 to 1; the chelating agent is selected from one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and citric acid.

6. The fertilizer according to claim 1, characterized in that, The dispersing aid is compounded from a surfactant and nanoscale silica according to a mass ratio of 1 to 3 and 0.5 to 1; the surfactant is selected from one or more of sodium dodecyl sulfate, polyoxyethylene ether, and polyacrylamide.

7. A method for preparing the fertilizer according to any one of claims 1 to 6, characterized in that, It includes the following steps: Step 1: Perform the first drying treatment on urea, control the temperature at 50 to 70 °C, and the time at 3 to 5 hours; perform the second drying treatment on the sustained-release carrier, control the temperature at 80 to 100 °C, and the time at 2 to 4 hours; perform the third low-temperature drying treatment on the microbial inoculant, control the temperature at 30 to 40 °C, and the time at 4 to 6 hours; Step 2: Grind the urease inhibitor and the urea-decomposing enzyme in the bioactive enzyme complex to a particle size of less than 100 microns respectively, then mix them evenly, and the stirring rate is 300 to 500 revolutions per minute, and the stirring time is 5 to 10 minutes; Step 3: Mix the porous inorganic material and the polymer in the sustained-release carrier, and then melt-blend and granulate them through a twin-screw extruder, control the extrusion temperature at 120 to 160 °C, and the screw speed at 100 to 200 revolutions per minute; Step 4: Mix the chelates of iron, zinc, copper, and manganese in the trace element chelate, then add deionized water to dissolve them, and spray-dry the formed solution, control the spray-drying temperature at 100 to 120 °C; Step 5: Mix the surfactant in the dispersant aid with nanoscale silica and disperse evenly through a high-speed shear emulsifier, controlling the shear rate at 1,000 to 2,000 revolutions per minute for 3 to 5 minutes; Step 6: Mix the urea in Step 1, the bioactive enzyme complex in Step 2, the slow-release carrier particles in Step 3, the trace element chelate particles in Step 4, the dispersant aid in Step 5, and the microbial inoculant in proportion, controlling the mixing time at 10 to 15 minutes and the mixing rate at 50 to 100 revolutions per minute; Step 7: Granulate the premix in Step 6 through a granulator, controlling the granulation temperature at 40 to 60 °C and the particle diameter at 2 to 5 mm, and then cool to room temperature.

8. The preparation method according to claim 7, characterized in that, For the first drying treatment of the urea in Step 1, a hot air circulation drying device is used, controlling the hot air flow rate at 1 to 3 m / s; for the second drying treatment of the slow-release carrier, a vacuum drying device is used, controlling the vacuum degree at 0.05 to 0.1 MPa; for the third low-temperature drying treatment of the microbial inoculant, a freeze-drying device is used, controlling the freezing temperature at -20 °C to -40 °C.

9. The preparation method according to claim 7, characterized in that, The twin-screw extruder in Step 3 includes six temperature zones, and the temperatures of each zone are set as follows: Zone 1: 120 to 140 °C, Zone 2: 130 to 150 °C, Zone 3: 140 to 160 °C, Zone 4: 130 to 150 °C, Zone 5: 120 to 140 °C, Zone 6: 110 to 130 °C; the screw length-diameter ratio is 30:1, and the feeding speed is 20 to 40 Hz.

10. The preparation method according to claim 7, characterized in that, The granulator in Step 7 is a rotary granulator, controlling the rotation rate at 30 to 50 revolutions per minute and the granulation screen aperture at 2 to 5 mm.

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