阅读说明：本技术 一种缓释肥料及其制备方法 (Slow-release fertilizer and preparation method thereof ) 是由 王永红 徐文斌 吴玉龙 张洪江 于 2020-12-31 设计创作，主要内容包括：本发明涉及肥料技术领域,公开了一种缓释肥料,其是以肥料颗粒为肥料芯,以聚乳酸-壳聚糖共聚物为内包覆材料,以聚己内酯-聚氨酯嵌段共聚物为外包覆材料,制备得到的一种缓释肥料。还公开了缓释肥料的制备方法,取肥料颗粒置于包膜机中,加入聚乳酸-壳聚糖共聚物,进行第一次包膜,干燥冷却得到第一包覆物；将第一包覆物投入包膜机中,加入聚己内酯-聚氨酯嵌段共聚物,进行第二次包膜,干燥冷却得到第二包覆物,第二包覆物即为缓释肥料。本申请通过对肥料芯进行双重包覆,内包覆材料成膜性好,因而内包覆材料能够封堵外包覆材料的微孔,减缓缓释速度；内包覆材料逐渐降解的过程中,对外包覆材料的微孔的封堵消失,加快缓释速度。(The invention relates to the technical field of fertilizers and discloses a slow-release fertilizer which is prepared by taking fertilizer particles as a fertilizer core, polylactic acid-chitosan copolymer as an inner coating material and polycaprolactone-polyurethane block copolymer as an outer coating material. Putting fertilizer granules into a coating machine, adding polylactic acid-chitosan copolymer, performing primary coating, drying and cooling to obtain a first coating; and putting the first coating into a coating machine, adding polycaprolactone-polyurethane segmented copolymer, carrying out secondary coating, drying and cooling to obtain a second coating, wherein the second coating is the slow-release fertilizer. According to the fertilizer core, the fertilizer core is doubly coated, and the film forming property of the inner coating material is good, so that the inner coating material can plug micropores of the outer coating material, and the slow release speed is reduced; in the process of gradually degrading the inner coating material, the blockage of micropores of the outer coating material disappears, and the slow release speed is accelerated.)

1. The slow release fertilizer is characterized by being prepared by taking fertilizer granules as a fertilizer core, taking polylactic acid-chitosan copolymer as an inner coating material and taking polycaprolactone-polyurethane segmented copolymer as an outer coating material.

2. The slow release fertilizer according to claim 1, which comprises the following components in parts by weight: 75-90 parts of a fertilizer core, 1-5 parts of an inner coating material and 10-25 parts of an outer coating material.

3. The slow release fertilizer according to claim 1 or 2, wherein the polylactic acid-chitosan copolymer is prepared by the method comprising,

(1) dissolving polylactic acid in an organic solvent to prepare a polylactic acid solution with the mass concentration of 5-18%;

(2) heating and preserving heat at 20-30 ℃, dissolving chitosan in 1% acetic acid solution to obtain chitosan solution with mass concentration of 50-85%, and adding a dispersing agent and an organic solvent for blending treatment to obtain chitosan blending solution;

(3) and (3) blending the polylactic acid solution and the chitosan blending solution, adding a polymerization agent, and reacting at 70-95 ℃ for 3-5 hours to obtain the polylactic acid-chitosan copolymer.

4. The slow release fertilizer according to claim 3, characterized in that the polylactic acid-chitosan copolymer comprises, by weight, 15-30 parts of polylactic acid, 25-65 parts of chitosan, 5-15 parts of a polymerization agent, and 0.1-0.3 part of a dispersing agent.

5. The slow release fertilizer according to claim 1, wherein the polycaprolactone-polyurethane block copolymer is prepared by a method comprising:

(1) dissolving stannous octoate, polyethylene glycol and epsilon-caprolactone in toluene to form a raw material solution, introducing argon into the raw material solution, sealing, reacting for 24 hours at 150 ℃, cooling, dissolving with chloroform, precipitating with absolute ethyl alcohol, repeating for 2-4 times, and drying to obtain an intermediate;

(2) dehydrating polyether polyol, cooling to 40-50 ℃, adding an intermediate, quickly stirring for 20-35 min, adding diisocyanate, heating to 100 ℃ for reaction, and when the mass fraction of-NCO is 6-8%, carrying out vacuum defoaming and cooling to room temperature to obtain a prepolymer;

(3) and dissolving the prepolymer in a solvent, adding a chain extender, and stirring at room temperature to obtain the polycaprolactone-polyurethane segmented copolymer.

6. The slow release fertilizer according to claim 5, wherein the molar ratio of the raw materials of each component of the polycaprolactone-polyurethane block copolymer is that stannous octoate: polyethylene glycol: epsilon-caprolactone: polyether polyol: the ratio of diisocyanate to the chain extender is 0.1-2: 1-10: 30-99: 70-100: 30-50: 4-12.

7. The slow release fertilizer of claim 5, wherein the chain extender is a glycol comprising at least one of ethylene glycol, propylene glycol, 1, 4-butanediol, diethanolamine, triethanolamine, and methyldiethanolamine.

8. The slow release fertilizer of claim 5, wherein the polyether polyol is a polyether polyol having a functionality of 2 or 3 and a molecular weight of 400-1000.

9. The slow release fertilizer of claim 1, wherein the fertilizer granules comprise any one of a fulvic acid compound fertilizer, an NPK compound fertilizer, urea, monoammonium phosphate, or diammonium phosphate.

10. A method of producing a slow release fertilizer as claimed in any one of claims 1 to 9, comprising the steps of:

putting fertilizer granules into a coating machine, adding polylactic acid-chitosan copolymer, performing primary coating, drying and cooling to obtain a first coating; and putting the first coating into a coating machine, adding polycaprolactone-polyurethane segmented copolymer, carrying out secondary coating, drying and cooling to obtain a second coating, wherein the second coating is the slow-release fertilizer.

Technical Field

The invention relates to the technical field of fertilizers, in particular to a slow-release fertilizer and a preparation method thereof.

Background

The current slow release fertilizers are mainly classified into three types, (1) film-coated type, for example, urea sulfide, resin-coated urea, composite coated urea, ammonium phosphate potassium salt-coated urea, etc.; (2) synthetic sparingly soluble forms such as urea formaldehyde, magnesium ammonium phosphate, and the like; (3) chemical inhibitors such as stabilized fertilizers and the like; (4) matrix composite and cementing controlled release type, such as controlled release fertilizer, humic acid type fertilizer, etc.

In particular, a coated fertilizer is one of the mainstream fertilizer types of the current slow release fertilizer, and is formed by coating a surface of fertilizer particles with a coating. According to the difference of coating materials, the coating type slow release fertilizer can be divided into an organic coating slow release fertilizer and an inorganic coating slow release fertilizer, wherein, the inorganic coating material such as the sulfur-coated urea has the defects of high dissolution and release speed of the fertilizer, high decomposition and loss speed of the fertilizer and undesirable slow release effect because sulfur is easy to break. The organic coating material is not easy to degrade in soil and is easy to remain in agricultural soil to cause soil degradation and serious pollution.

Therefore, research and development of a coated fertilizer with good slow release performance and green degradation is a technical problem which needs to be solved urgently at present.

The patent with publication number CN108610189A discloses an inclusion compound type slow-release urea fertilizer and a preparation method thereof, wherein the slow-release urea fertilizer adopts polycaprolactone as a coating material; the patent with publication number CN104163728B discloses a double-coated long-acting slow-release fertilizer and a preparation method thereof, wherein the long-acting slow-release fertilizer adopts polyurethane as a coating material.

In the above-mentioned patent publications, when polycaprolactone is used as a coating material, polycaprolactone is a biodegradable material, and although polycaprolactone has excellent biodegradability, polycaprolactone has a defect of poor strength, and polycaprolactone is damaged during production and transportation, thereby affecting the slow release effect of the fertilizer. When the polyurethane is used as a coating material, the polyurethane is a material with certain degradation performance and has excellent performances such as high elasticity, wear resistance, low temperature resistance, solvent resistance and the like; however, the polyurethane has strong water resistance and slow degradation speed, so that the fertilizer has slow release effect, and if the polyurethane is left in the environment for a long time, the environment is easily polluted.

Therefore, the preparation of qualified slow-release fertilizer is a technical problem which is urgently needed to be solved at present.

Disclosure of Invention

< technical problem >

The slow-release fertilizer is used for overcoming the defects of poor strength, slow degradation speed and poor slow-release effect of the fertilizer in the coating material adopted by the current slow-release fertilizer.

In view of this, a first object of the present invention is to provide a slow release fertilizer, which ensures the degradability of the coating material and can also improve the slow release performance of the fertilizer.

The second purpose of the invention is to provide a preparation method of the slow release fertilizer, which is simple, has no toxic solvent and is suitable for rapid mass production.

< technical means >

The invention provides a slow-release fertilizer, which is prepared by taking fertilizer particles as a fertilizer core, polylactic acid-chitosan copolymer as an inner coating material and polycaprolactone-polyurethane segmented copolymer as an outer coating material.

The technical mechanism adopted by the application is as follows:

(1) the application of polycaprolactone-polyurethane block copolymer is selected for use as an outer coating material, polyurethane is network structure cross-linked polymer, block copolymerization is carried out through caprolactone and polyurethane to form copolymer, the problem that the intensity that adds polycaprolactone alone and arouse is low, easy damaged can be improved on the one hand, on the other hand, add the degradation rate that caprolactone can regulate and control polyurethane, the slow-release speed of avoiding adding polyurethane alone and arousing is too slow, degradation rate is slow, remain in the problem that arouses the pollution in the environment.

(2) The internal coating material adopts polylactic acid-chitosan copolymer, the chitosan has good film forming property, and can well coat the fertilizer, but the chitosan has low film strength and is easy to damage in the process of manufacturing and transportation, so that the film is broken, and nutrients are easy to dissolve out; polylactic acid is degradable high polymer material, and it has better toughness, ductility and film forming ability, and polylactic acid carries out modification to chitosan, can promote the intensity of cladding effect, coating film and reduce cladding material's degradation speed to form the cladding material that has stable slow release effect.

(3) If only polylactic acid-chitosan copolymer is adopted as a coating material, the slow release effect is not ideal, because chitosan has water absorption and is easy to absorb water molecules in the environment to form a hydration layer, so that the degradation of polylactic acid-chitosan is accelerated to a certain extent. Therefore, after the fertilizer is coated by the polylactic acid-chitosan, the caprolactone-polyurethane segmented copolymer is adopted for secondary coating so as to further control the release speed of the fertilizer nutrients.

(4) The fertilizer core is doubly coated by taking fertilizer particles as the fertilizer core, and the inner coating material has good film forming property, so that the inner coating material can plug micropores of the outer coating material and slow down the slow release speed; in the process of gradually degrading the inner coating material, the plugging effect on micropores of the outer coating material disappears, and the nutrient release speed is accelerated. Meanwhile, the chitosan has excellent water retention property and can adsorb water molecules, so that the slow release fertilizer has a certain water retention effect.

Secondly, the invention provides a preparation method of a slow release fertilizer, which comprises the following steps:

putting fertilizer granules into a coating machine, adding polylactic acid-chitosan copolymer, performing primary coating, drying and cooling to obtain a first coating; and (3) putting the first coating into a coating machine, adding polycaprolactone-polyurethane segmented copolymer, coating for the second time, drying and cooling to obtain a second coating, wherein the second coating is the slow release fertilizer.

< advantageous effects >

The beneficial effects of the application are as follows:

(1) according to the fertilizer core, the fertilizer core is doubly coated, and the film forming property of the inner coating material is good, so that the inner coating material can plug micropores of the outer coating material, and the slow release speed is reduced; in the process of gradually degrading the inner coating material, the blockage of micropores of the outer coating material disappears, and the nutrient release speed is accelerated.

(2) According to the application, the polycaprolactone-polyurethane segmented copolymer is used as a coating material, so that the degradation speed of the copolymer can be controlled, and the slow release effect of the fertilizer can be ensured while the degradability of the coating material is ensured.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The invention provides a slow-release fertilizer, which is prepared by taking fertilizer particles as a fertilizer core, polylactic acid-chitosan copolymer as an inner coating material and polycaprolactone-polyurethane segmented copolymer as an outer coating material.

The invention comprises the following components in parts by weight: 75-90 parts of a fertilizer core, 1-5 parts of an inner coating material and 10-25 parts of an outer coating material.

In the invention, the fertilizer granules comprise any one of fulvic acid compound fertilizer, NPK compound fertilizer, urea, ammonium dihydrogen phosphate or diammonium hydrogen phosphate.

In the invention, the preparation method of the polylactic acid-chitosan copolymer comprises the following steps:

(1) dissolving polylactic acid in an organic solvent to prepare a polylactic acid solution with the mass concentration of 5-18%;

(2) heating and preserving heat at 20-30 ℃, dissolving chitosan in 1% acetic acid solution to obtain chitosan solution with mass concentration of 50-85%, and adding a dispersing agent and an organic solvent for blending treatment to obtain chitosan blending solution;

(3) and (3) blending the polylactic acid solution and the chitosan blending solution, adding a polymerization agent, and reacting at 70-95 ℃ for 3-5 hours to obtain the polylactic acid-chitosan copolymer.

In the invention, the polylactic acid-chitosan copolymer comprises, by weight, 15-30 parts of polylactic acid, 25-65 parts of chitosan, 5-15 parts of a polymerization agent and 0.1-0.3 part of a dispersing agent.

In the present invention, the dispersant is a diglyceride or a triglyceride.

In the invention, the organic solvent is trichloromethane or EMIMAc.

In the invention, the polymerization agent is polyvinylpyrrolidone.

The preparation method of the polycaprolactone-polyurethane segmented copolymer comprises the following steps:

(1) dissolving stannous octoate, polyethylene glycol and epsilon-caprolactone in toluene to form a raw material solution, introducing argon into the raw material solution, sealing, reacting for 24 hours at 150 ℃, cooling, dissolving with chloroform, precipitating with absolute ethyl alcohol, repeating for 2-4 times, and drying to obtain an intermediate;

(2) dehydrating polyether polyol, cooling to 40-50 ℃, adding an intermediate, quickly stirring for 20-35 min, adding diisocyanate, heating to 100 ℃ for reaction, and when the mass fraction of-NCO is 6-8%, carrying out vacuum defoaming and cooling to room temperature to obtain a prepolymer;

(3) and dissolving the prepolymer in a solvent, adding a chain extender, and stirring at room temperature to obtain the polycaprolactone-polyurethane segmented copolymer.

The PEG has good water solubility and low toxicity, and the hydrophilicity of the polyurethane and the polycaprolactone can be improved by modifying the PEG, so that the slow release effect of the fertilizer is improved, and the fertilizer is slowly released in the fertilizer effect period.

In the invention, the molar ratio of the raw materials of each component of the polycaprolactone-polyurethane segmented copolymer is as follows: polyethylene glycol: epsilon-caprolactone: polyether polyol: the ratio of diisocyanate to the chain extender is 0.1-2: 1-10: 30-99: 70-100: 30-50: 4-12.

In the present invention, the molecular weight of polyethylene glycol is 6000.

In the invention, the chain extender is dihydric alcohol, and the dihydric alcohol comprises at least one of ethylene glycol, propylene glycol, 1, 4-butanediol, diethanolamine, triethanolamine or methyldiethanolamine.

In the present invention, the solvent is ethanol.

In the present invention, the diisocyanate includes at least one of naphthalene diisocyanate, toluene diisocyanate dimer, hexamethylene diisocyanate, p-xylylene diisocyanate, hexamethylene diisocyanate biuret, dimethylbiphenyl diisocyanate, and triphenylmethane triisocyanate.

In the present invention, the polyether polyol is a polyether polyol having a functionality of 2 or 3 and a molecular weight of 400-1000.

Secondly, the invention provides a preparation method of a slow release fertilizer, which comprises the following steps:

putting fertilizer granules into a coating machine, adding polylactic acid-chitosan copolymer, performing primary coating, drying and cooling to obtain a first coating; and putting the first coating into a coating machine, adding polycaprolactone-polyurethane segmented copolymer, coating for the second time, drying and cooling to obtain a second coating, wherein the second coating is the slow-release fertilizer.

< example >

Example 1

The slow release fertilizer comprises a fertilizer core, an inner coating material and an outer coating material, and is specifically prepared by taking urea as the fertilizer core, polylactic acid-chitosan copolymer as the inner coating material and polycaprolactone-polyurethane segmented copolymer as the outer coating material.

The preparation method comprises the following steps of,

(1) preparing an inner coating material:

dissolving polylactic acid in chloroform to prepare a polylactic acid solution with the mass concentration of 12%; heating and preserving heat at 20-30 ℃, dissolving chitosan in 1% acetic acid solution to obtain chitosan solution with the mass concentration of 70%, and simultaneously adding diglyceride and trichloromethane for blending treatment to obtain chitosan blending solution; and (3) blending the polylactic acid solution and the chitosan blend, adding polyvinylpyrrolidone, and reacting for 4 hours at the temperature of 70-95 ℃ to obtain the polylactic acid-chitosan copolymer.

Wherein, the weight portions of polylactic acid 25, chitosan 50, polyvinylpyrrolidone 12 and diglyceride 0.2.

(2) Preparing an outer coating material:

dissolving stannous octoate, polyethylene glycol and epsilon-caprolactone in toluene to form a raw material solution, introducing argon into the raw material solution, sealing, reacting for 24 hours at 150 ℃, cooling, dissolving with chloroform, precipitating with absolute ethyl alcohol, repeating for 2-4 times, and drying to obtain an intermediate; dehydrating polyether polyol, cooling to 40-50 ℃, adding an intermediate, quickly stirring for 20-35 min, adding toluene diisocyanate, heating to 100 ℃ for reaction, and when the mass fraction of-NCO is 6-8%, carrying out vacuum defoaming and cooling to room temperature to obtain a prepolymer; and dissolving the prepolymer in ethanol, adding propylene glycol, and stirring at room temperature to obtain the polycaprolactone-polyurethane segmented copolymer.

Wherein the molar ratio of the raw materials of each component of the polycaprolactone-polyurethane segmented copolymer is as follows: polyethylene glycol: epsilon-caprolactone: polyether polyol: toluene diisocyanate and propylene glycol were 0.5:6:75:85:40: 7. The molecular weight of polyethylene glycol is 6000.

(3) Preparing a slow-release fertilizer:

putting urea particles into a coating machine, adding polylactic acid-chitosan copolymer, carrying out primary coating, drying and cooling to obtain a first coating; and putting the first coating into a coating machine, adding polycaprolactone-polyurethane segmented copolymer, carrying out secondary coating, drying and cooling to obtain a second coating, wherein the second coating is the slow-release fertilizer. The mass ratio of the urea to the dry base of the polylactic acid-chitosan copolymer to the dry base of the polycaprolactone-polyurethane block copolymer is 85:5: 20.

Example 2

The difference between the present example and example 1 is that the molar ratio of the raw materials of each component of the polycaprolactone-polyurethane block copolymer is different, and the ratio of stannous octoate: polyethylene glycol: epsilon-caprolactone: polyether polyol: toluene diisocyanate: the propylene glycol was 1:7.2:90:85:40: 7.

Example 3

The difference between the present example and example 1 is that the molar ratio of the raw materials of each component of the polycaprolactone-polyurethane block copolymer is different, and the ratio of stannous octoate: polyethylene glycol: epsilon-caprolactone: polyether polyol: toluene diisocyanate: propylene glycol was 0.5:6:75:100:50: 10.

Example 4

The difference between the present example and example 1 is that the mass ratio of the dry basis of urea, polylactic acid-chitosan copolymer and the dry basis of polycaprolactone-polyurethane block copolymer is 85:3: 20.

Example 5

The difference between the embodiment and the embodiment 1 is that the dry basis mass ratio of the urea, the polylactic acid-chitosan copolymer and the polycaprolactone-polyurethane block copolymer is 85:5: 15.

Example 6

This example differs from example 1 in that urea is replaced by a fulvic acid compound fertilizer. The fulvic acid compound fertilizer comprises 274 parts of potassium sulfate, 181 parts of monoammonium phosphate, 400 parts of urea, 85 parts of ammonium sulfate, 2.5 parts of anhydrous zinc sulfate, 5.9 parts of boric acid, 20 parts of fulvic acid and 30 parts of granulating agent.

< comparative example >

Comparative example 1

The comparative example differs from example 1 in that urea is used as the fertilizer granule and polylactic acid-chitosan copolymer is used as the coating material. The mass ratio of the urea to the polylactic acid-chitosan copolymer on a dry basis is 85: 25.

Comparative example 2

The comparative example differs from example 1 in that urea is used as the fertilizer granule and polycaprolactone-polyurethane block copolymer is used as the coating material. The mass ratio of the urea to the dry basis of the polycaprolactone-polyurethane block copolymer was 85: 25.

Comparative example 3

The comparative example differs from example 1 in that urea is used as fertilizer granules, polylactic acid-chitosan copolymer is used as an inner coating material, and polyurethane is used as an outer coating material. The mass ratio of the urea to the dry base of the polylactic acid-chitosan copolymer to the dry base of the polyurethane is 85:5: 20.

Comparative examples 4 to 6

Comparative examples 4 to 6 differ from comparative examples 1 to 3 in that urea was replaced with a fulvic acid compound fertilizer. The fulvic acid compound fertilizer comprises 274 parts of potassium sulfate, 181 parts of monoammonium phosphate, 400 parts of urea, 85 parts of ammonium sulfate, 2.5 parts of anhydrous zinc sulfate, 5.9 parts of boric acid, 20 parts of fulvic acid and 30 parts of granulating agent.

Comparative example 7

Fulvic acid compound fertilizer: 274 parts of potassium sulfate, 181 parts of monoammonium phosphate, 400 parts of urea, 85 parts of ammonium sulfate, 2.5 parts of anhydrous zinc sulfate, 5.9 parts of boric acid, 20 parts of fulvic acid and 30 parts of granulating agent.

< test example >

Test example 1-measurement of Slow Release Effect of Slow Release Fertilizer

The release rates of 24h, 7d, 28d, 56d and 90d were determined by using examples 1-5 as test groups 1-5 and comparative examples 1-3 as control groups 1-3, and the determination method was as shown in GB/T23348-2009, and the test results are shown in Table 1. The measurement temperature was 25 ℃.

TABLE 1 Release Rate results for different slow release fertilizers

As can be seen from the experimental results in table 1, compared with the control group 1, the control group 1 uses polylactic acid-chitosan as the slow release layer, so that the slow release rate of the prepared fertilizer granules is faster, and urea is rapidly lost. The release rate of the experimental group is lower than that of the control group 1, which shows that the release rate of the urea can be reduced by coating the urea in a mode of the inner organic modified polysaccharide film layer and the outer copolymerization block film layer, so that the slow release purpose is achieved. Compared with the control group 2, the release rate of the experimental group is higher than that of the control group 2, the control group 2 adopts polycaprolactone-polyurethane block copolymer as a slow release layer, the polycaprolactone-polyurethane block copolymer is used for coating the fertilizer core, and the slow release layer has a certain thickness, so that the urea release rate of the prepared fertilizer particles is low, and the slow release effect of the urea is poor. The cumulative urea release of the control group 3 was lower in the experimental group than in the control group 3 because the network structure of the polyurethane was dense and its ability to prevent urea release was strong.

Test example 2 Potato field test

(ii) test sample

A potato fertilizer efficiency verification field test was performed with example 6 as test group 6 and comparative examples 4 to 7 as control groups 4 to 7. Three replicates were set up for each sample set.

Experimental community

Area of test cell: 33.6m²；

Cell width: setting 4.8 m;

cell aspect ratio: the setting was 1.46: 1.

③ field operation

The planting variety is the tuber.

The seeding density is 100 cm of row spacing, 24 cm of plant spacing and 2780 plants/mu.

The selection of the test site is: chong state track town in Ming dynasty is selected as a test area. The area selection needs to have the following conditions: land preparation, protection row setting and test land division; the single irrigation and single row of the community avoid the serial irrigation and the serial row; the soil nutrient conditions of the test site are analyzed, wherein the soil nutrient conditions comprise organic matters, total nitrogen, available phosphorus, available potassium, a pH value and the like, and the soil analysis result comprises that the organic matters are 2.55 percent, the pH value is 6.11, the alkaline hydrolysis nitrogen is 204.03mg/kg, the available phosphorus is 3.72ppm, the available potassium is 66.86mg/kg, the exchangeable calcium is 19.93cmol/L, the exchangeable magnesium is 4.37cmol/L, the available sulfur is 14.81ppm, the available copper is 1.40mg/kg, the available manganese is 9.00mg/kg, the available sulfur is 14.81mg/kg, the available zinc is 1.71mg/kg, and the available boron is 14.56 mg/kg.

Sowing time: year 2020, 1 month and 13 days

Fertilizing measures are as follows: fertilizing with the seeds in the sowing period. The fertilizing amount is 100 kg/mu. The actual fertilization varieties and the fertilization amount of each cell are shown in a table 2.

TABLE 2 actual fertilizer variety and fertilizer application amount in each district

Processing number	Plot area (mu)	Kind of fertilizer	Amount of fertilizer applied (kg/cell)
				1	0.05	Not applying fertilizer	0
2	0.05	Compound fertilizer 1 (control group 4)	4.1
				3	0.05	Compound fertilizer 2 (control group 5)	4.1
4	0.05	Compound fertilizer 3 (control group 6)	4.1
				5	0.05	Compound fertilizer 4 (control group 7)	4.1
5	0.05	Compound fertilizer 5 (test group 6)	4.1

Field management: except for fertilization, other field management measures are consistent, and the field management is consistent with local habit management.

Potato yields are shown in table 3.

TABLE 3 Potato yields for different Compound Fertilizer treatments

Sample (I)	Not applying fertilizer	Compound fertilizer 1	Compound fertilizer 2	Compound fertilizer 3	Compound fertilizer 4	Compound fertilizer 5
							Yield (kg/mu)	1500	1974	2120	2050	1721	2210

The experimental results in table 3 show that the potato yield of the compound fertilizer 5 is the highest, 2210 kg/mu; the yield of the unfertilized potatoes is the lowest, and is 1500 kg/mu; the potato yields of the compound fertilizers 1-4 are all lower than the potato yield of the compound fertilizer 5.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.