Stable fertilizer for nitrogen fixation and emission reduction of rice field and preparation method thereof

Abstract

The invention relates to the field of fertilizers, in particular to a stable fertilizer for nitrogen fixation and emission reduction of a rice field and a preparation method of the stable fertilizer. The fertilizer core comprises the following components: 28-32 parts of ammonium sulfate, 4-6 parts of monoammonium phosphate, 8-12 parts of potassium sulfate, 0.15-0.50 part of a composite nitrification inhibitor, 1-3.5 parts of zinc sulfate monohydrate and 1-2 parts of borax; wherein the composite nitrification inhibitor is obtained by mixing 3, 4-dimethyl-pyrazole phosphate and a phenylboronic acid-phosphoryl compound in a mass ratio of (2-7): 1. The fertilizer product has a scientific and reasonable formula, the long-acting nutrient content and the trace element substance composition are reasonable, the controlled release function is achieved, nutrients needed by rice growth can be met, the fertilizer utilization rate is increased, and the yield and the quality are improved.

Description

Technical Field

[0001] The present invention relates to the field of fertilizers, and particularly to a stable fertilizer for nitrogen fixation and emission reduction in paddy fields and a preparation method thereof. Background Art

[0002] The total CH4 emissions from paddy fields in China are 7.7 Tg / a, accounting for about 30% of the total global paddy field emissions and about 20% of the total greenhouse gas emissions from all agricultural activities in China. The total N2O emissions from farmland in China are about 0.19 - 0.50 Tg / a, accounting for about 19% - 25% of the total greenhouse gas emissions from agricultural sources. And 23% of the cultivated land area in China is planted with rice, accounting for 18.5% of the world's rice planting area. One of the main driving factors for greenhouse gas emissions from paddy fields is fertilizers. Controlled-release nitrogen fertilizers can improve the stomatal tissue and root morphology of rice, enabling well-developed aerenchyma to secrete more O2 to stimulate the oxidation of CH4 and form more methane consumption pathways. At the same time, the long-term nitrogen supply effect of controlled-release nitrogen fertilizers can promote the transfer of carbohydrates from the leaf sheaths and stems of rice to grains, reducing the participation of photosynthetic products in the process of CH4 production, thereby significantly reducing the CH4 emission flux and total amount in paddy field soil. In addition, adding urease inhibitors and nitrification inhibitors to fertilizers can be used to slow down the hydrolysis of urea amide nitrogen to ammonium nitrogen in the soil and inhibit the nitrification process, so as to reduce gaseous losses such as N2O and N2. However, in the production process of fertilizers, some inhibitors (such as N-butyl thiophosphoric triamide) are prone to decomposition and need to add protectants, which makes the production process complex. And the effect of a single nitrification inhibitor will be affected to a certain extent due to different environmental, soil conditions, fertilization methods, planted crops, etc. Summary of the Invention

[0003] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a stable fertilizer for nitrogen fixation and emission reduction in paddy fields and a preparation method thereof.

[0004] The purpose of the present invention is achieved by the following technical solutions:

[0005] In the first aspect, the present invention discloses a stable fertilizer for nitrogen fixation and emission reduction in paddy fields. The stable fertilizer includes a fertilizer core and a slow-release outer layer. The fertilizer core includes the following components: 28 - 32 parts of ammonium sulfate, 4 - 6 parts of monoammonium phosphate, 8 - 12 parts of potassium sulfate, 0.15 - 0.50 parts of a composite nitrification inhibitor, 1 - 3.5 parts of zinc sulfate monohydrate, and 1 - 2 parts of borax.

[0006] Preferably, the mass of the slow-release outer layer accounts for 0.5 - 1.5% of the total mass of the fertilizer, and the thickness of the slow-release outer layer is 50 - 150 μm.

[0007] Preferably, the composite nitrification inhibitor is obtained by mixing 3,4-dimethyl-pyrazole phosphate (DMPP) and phenylboronic acid-phosphorus compound in a mass ratio of 2-7:1.

[0008] Preferably, the preparation method of the phenylboronic acid-phosphorus compound includes:

[0009] S1. Weigh phytic acid and add it to deionized water, stir to dissolve to obtain a phytic acid solution; weigh 3-aminophenylboronic acid and dissolve it in deionized water, stir to dissolve to obtain an aminophenylboronic acid solution;

[0010] S2. Add the aminophenylboronic acid solution to the phytic acid solution, pour it into a reaction kettle, place the reaction kettle under the condition of 85-125 °C for 6-12 h, after the reaction ends, perform drying treatment to obtain the phenylboronic acid-phosphorus compound.

[0011] Preferably, in the phytic acid solution of S1, the mass ratio of phytic acid to deionized water is 0.22:5-15.

[0012] Preferably, in the aminophenylboronic acid solution of S1, the mass ratio of 3-aminophenylboronic acid to deionized water is 0.05:5-15.

[0013] Preferably, in S2, the mass ratio of the aminophenylboronic acid solution to the phytic acid solution is 6-6.5:1.

[0014] Preferably, the preparation method of the slow-release outer layer includes:

[0015] Mix acrylic acid with deionized water, add sodium hydroxide solution to neutralize to pH = 5-6, then add humic acid, carboxymethyl cellulose, sodium dodecyl sulfate, stir and react at 25 °C for 10 hours, then add ammonium persulfate as an initiator and carboxymethyl chitosan as a crosslinking agent, raise the temperature to 60 °C and react for 4 hours, and obtain the coating material after drying and pulverizing.

[0016] Preferably, in the preparation of the slow-release outer layer, the mass ratio of acrylic acid, humic acid, carboxymethyl cellulose, sodium dodecyl sulfate, ammonium persulfate, carboxymethyl chitosan and deionized water is 10-20:3-8:2-5:0.1-0.5:1.0-1.5:0.2-0.8:30-50.

[0017] Preferably, in the preparation of the slow-release outer layer, the glass transition temperature (Tg) of the coating material is 35-45 °C.

[0018] Preferably, the granulation particle size of the fertilizer core is 2-4 mm, and the particle compressive strength ≥ 15 N (compression rate 5 mm / min).

[0019] Second aspect, the present invention provides a method for preparing a stable fertilizer for nitrogen fixation and emission reduction in paddy fields, comprising the following steps:

[0020] (1) Weigh ammonium sulfate, monoammonium phosphate, potassium sulfate, compound nitrification inhibitor, zinc sulfate monohydrate, and borax according to the ratio, and mix and grind them to a particle size ≤ 100 μm to form a uniform powder;

[0021] (2) Add the powder to a disk granulator, granulate at a rotational speed of 20 - 40 rpm, and spray a polyvinyl alcohol solution with a mass fraction of 30 - 40% as a binder to obtain fertilizer cores with a particle size of 2 - 4 mm;

[0022] (3) Spray the slow-release outer layer material onto the surface of the fertilizer cores through a fluidized bed coater, control the coating temperature at 45 - 55 °C, and the wind speed at 1.5 - 2.5 m 3 / h until the slow-release outer layer is completely covered;

[0023] (4) After drying and screening, the finished fertilizer is obtained.

[0024] Preferably, in step (2), the spraying rate of the binder is 5 - 10 mL / min, and the inclination angle of the granulator is 45 - 60°.

[0025] Preferably, the stable fertilizer is suitable for rice planting, the fertilization method is one-time fertilization, the application rate is 50 - 60 kg / mu, and it is applied 3 - 5 days before rice transplanting.

[0026] The beneficial effects of the present invention are as follows:

[0027] (1) Compared with the prior art, the composite design of the fertilizer of the present invention can protect the nitrification inhibitor, avoid the decomposition of the nitrification inhibitor during the preparation of the stable fertilizer, and improve the action efficiency of the nitrification inhibitor. Among them, humic acid is introduced into the coating slow-release outer layer material to adjust the soil pH and enhance the adsorption capacity of the nitrification inhibitor in an acidic environment; in addition, DMPP is compounded with phenylboronic acid-phosphoramide compound to simultaneously inhibit urea hydrolysis and nitrification, reducing ammonia volatilization and nitrate leaching.

[0028] (2) The phenylboronic acid-phosphorus acyl compound prepared by the present invention is obtained through the phosphorylation reaction of phytic acid and 3-aminophenylboronic acid. The obtained product has both the ability to regulate nitrogen transformation of the phosphoramide group and the dynamic responsiveness of the boric acid group. When compounded with DMPP, it can better improve nitrogen fertilizer utilization rate and reduce environmental pollution.

[0029] (3) The compound nitrification inhibitor added in the present invention can reduce NO3 in the soil -- The accumulation of N reduces N2O emissions; the degradation of the slow-release film material can increase the soil pH and reduce the substrate for CH4 formation. At the same time, the fertilizer core consists of (NH4)2SO4 and K2SO4, and sulfate-reducing bacteria in the presence of SO4 2- have an obvious inhibitory effect on methane-producing bacteria, further reducing CH4 emissions.

[0030] (4) The fertilizer product of the present invention has a scientific and reasonable formula, with a reasonable composition of long-acting nutrients and trace element substances, and has a controlled-release function, which can meet the nutrient requirements of rice growth, improve fertilizer utilization rate, and increase yield and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the following drawings.

[0032] Figure 1 It is a comparative curve graph of CH4 emission fluxes after applying the products of Examples 1-5 of the present invention and the control group fertilizer.

[0033] Figure 2 It is a comparative curve graph of N2O emission fluxes after applying the products of Examples 1-5 of the present invention and the control group fertilizer. DETAILED DESCRIPTION OF THE INVENTION

[0034] The technical solutions of the present invention will be described below through specific specific examples. It should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combined steps, or other method steps can be inserted between these clearly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Moreover, unless otherwise stated, the numbers of the method steps are only convenient tools for identifying the method steps, rather than limiting the arrangement order of the method steps or the scope of the present invention that can be implemented. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope that the present invention can be implemented.

[0035] In order to better understand the above technical solutions, the exemplary embodiments of the present invention will be described in more detail below. Although the exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0036] The present invention will be further described below in conjunction with the following embodiments.

[0037] Example 1

[0038] A stable fertilizer for nitrogen fixation and emission reduction in paddy fields:

[0039] The stable fertilizer comprises a fertilizer core and a slow-release outer layer. The fertilizer core comprises the following components: 28 parts of ammonium sulfate, 4 parts of monoammonium phosphate, 8 parts of potassium sulfate, 0.15 part of a compound nitrification inhibitor, 1 part of zinc sulfate monohydrate, and 1 part of borax.

[0040] The compound nitrification inhibitor is obtained by mixing 3,4-dimethyl-pyrazole phosphate (DMPP) and phenylboronic acid-phosphorus compound in a mass ratio of 6.5:1.

[0041] The preparation method of the phenylboronic acid-phosphorus compound comprises:

[0042] S1. Weigh phytic acid and add it to deionized water. The mass ratio of phytic acid to deionized water is 0.22:10. Stir and dissolve to obtain a phytic acid solution. Weigh 3-aminophenylboronic acid and dissolve it in deionized water. The mass ratio of 3-aminophenylboronic acid to deionized water is 0.05:10. Stir and dissolve to obtain an aminophenylboronic acid solution.

[0043] S2. Add the aminophenylboronic acid solution to the phytic acid solution. The mass ratio of the aminophenylboronic acid solution to the phytic acid solution is 6.2:1. Pour it into a reaction kettle, place the reaction kettle under the condition of 105 °C for 8 h. After the reaction is completed, perform a drying treatment to obtain the phenylboronic acid-phosphorus compound.

[0044] The slow-release outer layer is prepared by the following method:

[0045] Mix 10 parts of acrylic acid with 30 parts of deionized water, add 10% sodium hydroxide solution to neutralize to pH 5, then add 3 parts of humic acid, 2 parts of carboxymethyl cellulose, and 0.1 part of sodium dodecyl sulfate. Stir and react at 25 °C for 10 hours. Then add 1 part of ammonium persulfate (added in two portions) as an initiator and 0.2 part of carboxymethyl chitosan as a crosslinking agent. Heat up to 60 °C and react for 4 hours. After drying and pulverizing, a coating material is obtained.

[0046] The preparation method of the above stable fertilizer comprises the following steps:

[0047] (1) Weigh ammonium sulfate, monoammonium phosphate, potassium sulfate, compound nitrification inhibitor, zinc sulfate monohydrate, and borax according to the ratio, mix and grind to a particle size ≤100 μm to form a uniform powder;

[0048] (2) Add the powder to a disk granulator, granulate at a rotation speed of 20 rpm, the inclination angle of the granulator is 45°, and spray a 30% mass fraction of polyvinyl alcohol solution as a binder at a spraying rate of 5 mL / min to obtain a fertilizer core with a particle size of 2 mm;

[0049] (3) Spray the slow-release outer layer material onto the surface of the fertilizer core through a fluidized bed coater, control the coating temperature at 45 °C, and the wind speed at 1.5 m 3 / h until the slow-release outer layer is completely covered;

[0050] (4) After drying, sieve to obtain the finished fertilizer.

[0051] Example 2

[0052] A stability fertilizer for nitrogen fixation and emission reduction in paddy fields:

[0053] The stability fertilizer comprises a fertilizer core and a slow-release outer layer. The fertilizer core comprises the following components: 28 parts of ammonium sulfate, 4 parts of monoammonium phosphate, 8 parts of potassium sulfate, 0.35 part of a compound nitrification inhibitor, 1 part of zinc sulfate monohydrate, and 1 part of borax.

[0054] The compound nitrification inhibitor is obtained by mixing 3,4-dimethyl-pyrazole phosphate (DMPP) and phenylboronic acid-phosphorus compound in a mass ratio of 5:1. The preparation of the phenylboronic acid-phosphorus compound is the same as that in Example 1.

[0055] The slow-release outer layer is prepared by the following method:

[0056] Mix 12 parts of acrylic acid with 40 parts of deionized water, add 20% sodium hydroxide solution to neutralize to pH 5.5, then add 5 parts of humic acid, 3 parts of carboxymethyl cellulose, and 0.3 part of sodium dodecyl sulfate, stir and react at 25 °C for 10 hours, then add 1.2 parts of ammonium persulfate (added in two portions) as an initiator and 0.4 part of carboxymethyl chitosan as a crosslinking agent, raise the temperature to 60 °C and react for 4 hours, dry and pulverize to obtain the coating material;

[0057] The preparation method of the above stability fertilizer comprises the following steps:

[0058] (1) Weigh ammonium sulfate, monoammonium phosphate, potassium sulfate, compound nitrification inhibitor, zinc sulfate monohydrate, and borax according to the ratio, mix and grind to a particle size ≤100 μm to form a uniform powder;

[0059] (2) Add the powder to a disk granulator, granulate at a rotation speed of 30 rpm, the inclination angle of the granulator is 55°, spray a 35% polyvinyl alcohol solution as a binder at a spraying rate of 7 mL / min to obtain a fertilizer core with a particle size of 2.5 mm;

[0060] (3) Spray the slow-release outer layer material onto the surface of the fertilizer core through a fluidized bed coater, control the coating temperature at 50 °C, and the wind speed at 1.5 m 3 / h until the slow-release outer layer is completely covered;

[0061] (4) After drying, sieve to obtain the finished fertilizer.

[0062] Example 3

[0063] A stable fertilizer for nitrogen fixation and emission reduction in paddy fields:

[0064] The stable fertilizer comprises a fertilizer core and a slow-release outer layer. The fertilizer core comprises the following components: 28 parts of ammonium sulfate, 4 parts of monoammonium phosphate, 8 parts of potassium sulfate, 0.50 part of a compound nitrification inhibitor, 1 part of zinc sulfate monohydrate, and 1 part of borax;

[0065] The compound nitrification inhibitor is obtained by mixing 3,4-dimethyl-pyrazole phosphate (DMPP) and phenylboronic acid-phosphorus acyl compound in a mass ratio of 4:1. The preparation of the phenylboronic acid-phosphorus acyl compound is the same as that in Example 1.

[0066] The slow-release outer layer is prepared by the following method:

[0067] Mix 15 parts of acrylic acid with 40 parts of deionized water, add 30% sodium hydroxide solution to neutralize to pH 6, then add 6 parts of humic acid, 5 parts of carboxymethyl cellulose, and 0.5 part of sodium dodecyl sulfate, stir and react at 25°C for 10 hours, then add 1.5 parts of ammonium persulfate (added in two portions) as an initiator and 0.6 part of carboxymethyl chitosan as a crosslinking agent, raise the temperature to 60°C and react for 4 hours, dry and pulverize to obtain the coating material;

[0068] The preparation method of the above stable fertilizer comprises the following steps:

[0069] (1) Weigh ammonium sulfate, monoammonium phosphate, potassium sulfate, compound nitrification inhibitor, zinc sulfate monohydrate, and borax according to the ratio, mix and grind to a particle size ≤100 μm to form a uniform powder;

[0070] (2) Add the powder to a disk granulator, granulate at a rotation speed of 40 rpm, the inclination angle of the granulator is 50°, spray a 40% mass fraction polyvinyl alcohol solution as a binder at a spraying rate of 9 mL / min to obtain a fertilizer core with a particle size of 3 mm;

[0071] (3) Spray the slow-release outer layer material onto the surface of the fertilizer core through a fluidized bed coater, control the coating temperature at 50°C, and the wind speed at 2 m 3 / h until the slow-release outer layer is completely covered;

[0072] (4) Screen after drying to obtain the finished fertilizer.

[0073] Example 4

[0074] A stable fertilizer for nitrogen fixation and emission reduction in paddy fields:

[0075] The stable fertilizer includes a fertilizer core and a slow-release outer layer. The fertilizer core includes the following components: 30 parts of ammonium sulfate, 5 parts of monoammonium phosphate, 10 parts of potassium sulfate, 0.35 part of compound nitrification inhibitor, 2 parts of zinc sulfate monohydrate, and 1.5 parts of borax.

[0076] The compound nitrification inhibitor is obtained by mixing 3,4-dimethyl-pyrazole phosphate (DMPP) and phenylboronic acid-phosphoryl compound in a mass ratio of 5.5:1. The preparation of the phenylboronic acid-phosphoryl compound is the same as that in Example 1.

[0077] The slow-release outer layer is prepared by the following method:

[0078] Mix 20 parts of acrylic acid with 50 parts of deionized water, add 25% sodium hydroxide solution to neutralize to pH 5.5, then add 5 parts of humic acid, 2 parts of carboxymethyl cellulose, and 0.3 part of sodium dodecyl sulfate, stir and react at 25°C for 10 hours, then add 1.5 parts of ammonium persulfate (added in two portions) as an initiator and 0.8 part of carboxymethyl chitosan as a crosslinking agent, raise the temperature to 60°C and react for 4 hours, and obtain the coating material after drying and pulverizing.

[0079] The preparation method of the above stable fertilizer includes the following steps:

[0080] (1) Weigh ammonium sulfate, monoammonium phosphate, potassium sulfate, compound nitrification inhibitor, zinc sulfate monohydrate, and borax according to the ratio, mix and grind them to a particle size of ≤100 μm to form a uniform powder.

[0081] (2) Add the powder to a disk granulator, granulate at a rotation speed of 40 rpm, with the inclination angle of the granulator being 60°, and spray a 40% by mass polyvinyl alcohol solution as a binder at a spraying rate of 10 mL / min to obtain a fertilizer core with a particle size of 2 mm.

[0082] (3) Spray the slow-release outer layer material onto the surface of the fertilizer core through a fluidized bed coater, control the coating temperature at 55°C, and the wind speed at 1.5 m 3 / h until the slow-release outer layer completely covers.

[0083] (4) Screen after drying to obtain the finished fertilizer.

[0084] Example 5

[0085] A stable fertilizer for nitrogen fixation and emission reduction in paddy fields:

[0086] The stable fertilizer includes a fertilizer core and a slow-release outer layer. The fertilizer core includes the following components: 32 parts of ammonium sulfate, 6 parts of monoammonium phosphate, 12 parts of potassium sulfate, 0.50 part of compound nitrification inhibitor, 3 parts of zinc sulfate monohydrate, and 2 parts of borax.

[0087] The composite nitrification inhibitor is obtained by mixing 3,4-dimethyl-pyrazole phosphate (DMPP) and phenylboronic acid-phosphorus compound in a mass ratio of 4:1. The preparation of the phenylboronic acid-phosphorus compound is the same as that in Example 1.

[0088] The slow-release outer layer is prepared by the following method:

[0089] Mix 20 parts of acrylic acid with 50 parts of deionized water, add 25% sodium hydroxide solution to neutralize to pH 5, then add 6 parts of humic acid, 3 parts of carboxymethyl cellulose, and 0.5 part of sodium dodecyl sulfate, stir and react at 25 °C for 10 hours, and then add 1 part of ammonium persulfate (added in two portions) as an initiator and 0.8 part of carboxymethyl chitosan as a cross-linking agent, raise the temperature to 60 °C and react for 4 hours, and obtain the coating material after drying and pulverizing;

[0090] The preparation method of the above-mentioned stable fertilizer includes the following steps:

[0091] (1) Weigh ammonium sulfate, monoammonium phosphate, potassium sulfate, composite nitrification inhibitor, zinc sulfate monohydrate, and borax according to the ratio, mix and grind to a particle size of ≤100 μm to form a uniform powder;

[0092] (2) Add the powder to a disk granulator, granulate at a rotation speed of 30 rpm, the inclination angle of the granulator is 50°, and spray a 30% by mass polyvinyl alcohol solution as a binder at a spraying rate of 6 mL / min to obtain a fertilizer core with a particle size of 4 mm;

[0093] (3) Spray the slow-release outer layer material onto the surface of the fertilizer core through a fluidized bed coater, control the coating temperature at 45 °C, and the wind speed at 2.5 m 3 / h until the slow-release outer layer is completely covered;

[0094] (4) After drying and screening, the finished fertilizer is obtained.

[0095] Control group

[0096] A stable fertilizer for nitrogen fixation and emission reduction in paddy fields:

[0097] The stable fertilizer includes a fertilizer core and a slow-release outer layer. The slow-release outer layer is the same as that in Example 3. The fertilizer core includes the following components: 28 parts of ammonium sulfate, 4 parts of monoammonium phosphate, 8 parts of potassium sulfate, 0.40 part of DMPP, 0.10 part of aminophenylboronic acid, 1 part of zinc sulfate monohydrate, and 1 part of borax.

[0098] The application effect of the present invention is described below in combination with specific tests:

[0099] The experiment was conducted in the experimental field of Ziling Research Base of New Yangfeng Agricultural Technology Co., Ltd. The soil had a pH value of 7.32, an organic matter content of 3.67%, an available nitrogen content of 128.9 mg / kg, an available phosphorus content of 81.5 mg / kg, and an available potassium content of 470.9 mg / kg. The soil type was yellow brown soil, which was suitable for rice cultivation.

[0100] The stable fertilizers prepared in Examples 1 - 5 of the present invention were applied as base fertilizers throughout the plough layer. Additionally, a control group CK was set up, and the fertilization rate for both was 55 kg / mu. Each treatment had 3 replicates, and the field management measures were carried out according to conventional methods. The static chamber - gas chromatography method was used to measure the CH4 and NO2 emission fluxes. During the rice growth period, samples were routinely collected once a week: before and after adding water, and once every 1 - 3 days. The sampling time was from 8:00 - 11:00 in the morning. When sampling, the bottom of the PVC static chamber was placed on a base previously fixed in the soil, and the airtightness of the chamber was ensured by sealing through the flooded layer of the paddy field. Before sampling, the power supply of the micro direct - current fan fixed on the top of the chamber was turned on for 30 s to fully mix the gas inside the chamber. After the chamber was sealed, 50 ml of gas inside the chamber was extracted with a syringe equipped with a three - way valve at 0, 15, and 30 min respectively, and the temperature inside the sampling chamber was recorded simultaneously. The collected gas samples were used to measure the CH4 and N2O concentrations in the gas samples by a gas chromatograph (Agilent GC7890B).

[0101] The test results are shown in the attached drawings of the specification.

[0102] In Figure 1 , the abscissa is the sampling time, and the ordinate is the CH4 emission flux, and its measurement unit is mg / m 2 / h. It can be seen that compared with the control group CK, the fertilizer Examples 1 - 5 of the present invention can significantly reduce the CH4 emission flux in the paddy field during the rice growth process.

[0103] In Figure 2 , the abscissa is the sampling time, and the ordinate is the N2O emission flux, and its measurement unit is mg / m 2 / h. It can be seen that compared with the control group CK, the fertilizer Examples 1 - 5 of the present invention can reduce the N2O emission during the growth stage when the N2O emission flux of rice is the largest.

[0104] In summary, the fertilizer of the present invention can reduce the CH4 and N2O emission fluxes in the paddy field.

[0105] After the rice matured, it was harvested by actual measurement. After manual threshing with a small thresher and drying in the sun, the yield was obtained. The test results are shown in the following table.

[0106]

[0107] It can be seen from the above table that the yield of rice treated with the control group fertilizer is lower than that of the tested rice treated with the fertilizers of Examples 1-5 of the present invention. Therefore, the fertilizer of the present invention has a good effect of increasing the yield of rice.

[0108] In the description of the present specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In the present specification, the schematic representations of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present specification.

[0109] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A stable fertilizer for nitrogen fixation and emission reduction in rice fields, characterized in that: The stable fertilizer comprises a fertilizer core and a slow-release outer layer, wherein the fertilizer core comprises the following components: 28-32 parts of ammonium sulfate, 4-6 parts of monoammonium phosphate, 8-12 parts of potassium sulfate, 0.15-0.50 parts of a composite nitrification inhibitor, 1-3.5 parts of zinc sulfate monohydrate, and 1-2 parts of borax; The composite nitrification inhibitor is obtained by mixing 3,4-dimethyl-pyrazole phosphate and phenylboronic acid-phosphoryl compound in a mass ratio of 2-7:

1.

2. The stable fertilizer for nitrogen fixation and emission reduction in paddy fields according to claim 1, characterized in that: The mass of the slow-release outer layer accounts for 0.5-1.5% of the total mass of the fertilizer, and the thickness of the slow-release outer layer is 50-150 μm.

3. The stable fertilizer for nitrogen fixation and emission reduction in paddy fields according to claim 1, characterized in that: The preparation method of the phenylboronic acid-phosphoryl compound comprises: S1, weighing phytic acid, adding it to deionized water, stirring and dissolving it to obtain a phytic acid solution; weighing 3-aminophenylboric acid, dissolving it in deionized water, stirring and dissolving it to obtain an aminophenylboric acid solution; S2. Add the aminophenylboric acid solution to the phytic acid solution, pour into a reactor, place the reactor at 85-125° C. for 6-12 hours, and after the reaction is completed, dry to obtain a phenylboric acid-phosphoryl compound.

4. The stable fertilizer for nitrogen fixation and emission reduction in paddy fields according to claim 3, characterized in that: In the phytic acid solution of S1, the mass ratio of phytic acid to deionized water is 0.22:5-15; in the aminophenylboric acid solution of S1, the mass ratio of 3-aminophenylboric acid to deionized water is 0.05:5-15.

5. The stable fertilizer for nitrogen fixation and emission reduction in paddy fields according to claim 3, characterized in that: In S2, the mass ratio of the aminophenylboric acid solution to the phytic acid solution is 6-6.5:

1.

6. The stable fertilizer for nitrogen fixation and emission reduction in paddy fields according to claim 1, characterized in that: The preparation method of the sustained-release outer layer comprises: Acrylic acid is mixed with deionized water, and sodium hydroxide solution is added to neutralize to pH=5-6. Humic acid, carboxymethyl cellulose and sodium dodecyl sulfate are then added. The mixture is stirred and reacted at 25°C for 10 hours. Ammonium persulfate is then added as an initiator and carboxymethyl chitosan is added as a cross-linking agent. The mixture is heated to 60°C and reacted for 4 hours. The coating material is obtained after drying and crushing.

7. The stable fertilizer for nitrogen fixation and emission reduction in paddy fields according to claim 6, characterized in that: In the preparation of the sustained-release outer layer, the mass ratio of acrylic acid, humic acid, carboxymethyl cellulose, sodium lauryl sulfate, ammonium persulfate, carboxymethyl chitosan and deionized water is 10-20:3-8:2-5:0.1-0.5:1.0-1.5:0.2-0.8:30-50.

8. A method for preparing a stable fertilizer for nitrogen fixation and emission reduction in paddy fields according to claim 1, characterized in that: The following steps are involved: (1) Weighing ammonium sulfate, monoammonium phosphate, potassium sulfate, composite nitrification inhibitor, zinc sulfate monohydrate, and borax according to the proportion, mixing and grinding until the particle size is ≤100 μm to form a uniform powder; (2) adding the powder into a disc granulator, granulating at a speed of 20-40 rpm, spraying a polyvinyl alcohol solution having a mass fraction of 30%-40% as a binder, and obtaining a fertilizer kernel with a particle size of 2-4 mm; (3) Spray the slow-release outer layer material onto the surface of the fertilizer core through a fluidized bed coating machine, control the coating temperature to 45-55°C, and the wind speed to 1.5-2.5m 3 / h, until the sustained-release outer layer is completely covered; (4) After drying, the mixture is sieved to obtain finished fertilizer.

9. The stable fertilizer for nitrogen fixation and emission reduction in paddy fields according to claim 8, characterized in that: In the step (2), the binder spraying rate is 5-10 mL / min, and the granulator is tilted at an angle of 45-60 degrees.

10. The stable fertilizer for nitrogen fixation and emission reduction in paddy fields according to claim 8, characterized in that: The stable fertilizer is suitable for rice planting, and the fertilization method is one-time fertilization, the application amount is 50-60kg / mu, and it is applied 3-5 days before rice transplanting.

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