Water-retaining and antibacterial composite fertilizer and preparation method thereof

Abstract

The application discloses a kind of water-retaining antibacterial compound fertilizer and preparation method thereof, comprising, nitrogen fertilizer, phosphate fertilizer, potassium fertilizer, water-retaining antibacterial microsphere and white clay;Wherein, with the mass fraction of each raw material, the nitrogen fertilizer is 15-25 parts, the phosphate fertilizer is 28-35 parts, the potassium fertilizer is 25-35 parts, the water-retaining antibacterial microsphere is 13-18 parts, and the white clay is 10-15 parts;Water-retaining antibacterial microsphere is made by high water-retaining carboxymethyl chitosan and acid modified centipede extract mixture.This application water-retaining antibacterial compound fertilizer uses water-retaining antibacterial microsphere, which is made by adding acid modified centipede extract to high water-retaining carboxymethyl chitosan, which can effectively improve the antioxidant activity and water-retaining antibacterial capacity of high water-retaining carboxymethyl chitosan;After water-retaining antibacterial microsphere is applied to soil, it absorbs water and expands, which can change the soil from compact to loose, increase the pore, thereby improve the soil permeability, increase the soil water content and soil porosity, reduce the soil bulk density, play the role of antibiosis, and promote crop growth.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fertilizer water-retention and antibacterial, and particularly relates to a water-retention and antibacterial compound fertilizer and a preparation method thereof. BACKGROUND

[0002] The compound fertilizer refers to a fertilizer containing two or more than two of nitrogen, phosphorus and potassium elements, and has high total nutrient content, more types of nutrient elements, compact structure, uniform nutrient release and stable fertilizer effect. The chemical fertilizer plays an important role in agricultural fertilization, and can provide a good nutrient environment for plants. The compound fertilizer is generally in the form of granules, has small hygroscopicity, is not easy to be caked, and is convenient for storage and application, especially for mechanized fertilization. Since the compound fertilizer has less auxiliary components, the packaging, storage and transportation costs can be saved, and the fertilizer utilization rate can be improved.

[0003] In the growth process of crops, in order to achieve the effect of soil water-retention and antibacterial, a substance with water-retention and antibacterial properties can be combined with the fertilizer through a process. The water-retention fertilizer was first developed in the United States. After the development of urea-formaldehyde fertilizer in the United States, the research on water-retention fertilizer started, and the yield of crops was continuously increased. The water-retention fertilizer can fully play the synergistic effect of fertilizer and water, promote the growth and development of plants and the accumulation of organic matter, increase the yield and quality of crops, and improve the fertilizer utilization rate, and has a great application prospect in agriculture.

[0004] However, there is no report on adding antibacterial substances to the water-retention fertilizer to further improve the soil environment. SUMMARY

[0005] This section aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0006] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0007] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art, and to provide a water-retention and antibacterial compound fertilizer.

[0008] To solve the above technical problems, the present application provides the following technical scheme: a water-retention and antibacterial compound fertilizer, comprising, nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, water-retention and antibacterial microspheres and white clay;

[0009] wherein, in terms of mass fraction of each raw material, the nitrogen fertilizer is 15-25 parts, the phosphorus fertilizer is 28-35 parts, the potassium fertilizer is 25-35 parts, the water-retention and antibacterial microspheres are 13-18 parts, and the white clay is 10-15 parts.

[0010] The water-retaining antibacterial microspheres are made of high water-retaining carboxymethyl chitosan and acid-modified centipede extract.

[0011] As a preferred scheme of the water-retaining antibacterial compound fertilizer, the preparation method of the water-retaining antibacterial microspheres comprises the following steps:

[0012] The carboxymethyl chitosan is dried and frozen to obtain frozen carboxymethyl chitosan.

[0013] The frozen carboxymethyl chitosan is stirred and dissolved in a sucrose solution, and high water-retaining carboxymethyl chitosan is obtained by removing water through distillation.

[0014] The dried centipede is ground to obtain centipede powder.

[0015] The centipede powder is extracted in ethanol to obtain an extract.

[0016] NaH2PO4 solution is added to the extract to obtain acid-modified centipede extract.

[0017] The high water-retaining carboxymethyl chitosan and the acid-modified centipede extract are mixed and spray dried to obtain the water-retaining antibacterial microspheres.

[0018] As a preferred scheme of the water-retaining antibacterial compound fertilizer, the freezing temperature is-20℃, and the freezing treatment time is 150 min.

[0019] As a preferred scheme of the water-retaining antibacterial compound fertilizer, the sucrose solution has a mass concentration of 20%, and the mass ratio of the frozen carboxymethyl chitosan to the sucrose solution is 1:10.

[0020] As a preferred scheme of the water-retaining antibacterial compound fertilizer, the distillation treatment temperature is 100℃, and the treatment time is 180 min.

[0021] As a preferred scheme of the water-retaining antibacterial compound fertilizer, the mass-volume ratio of the centipede powder to ethanol is 1:5, and the mass concentration of the ethanol is 80%.

[0022] As a preferred scheme of the water-retaining antibacterial compound fertilizer, the ratio of the extract to the NaH2PO4 solution is 1:20.

[0023] As a preferred scheme of the water-retaining and antibacterial compound fertilizer, the high water-retaining carboxymethyl chitosan is mixed with the acid-modified centipede extract, wherein the ratio of the high water-retaining carboxymethyl chitosan to the acid-modified centipede extract is 1:8, and the spray drying is performed with the parameters of an air inlet flow of 25 m 3 / h, an inlet temperature of 160 DEG C, and a feeding flow of 4.0 mL / min.

[0024] Another object of the present application is to provide a preparation method of a water-retaining and antibacterial compound fertilizer, which overcomes the defects in the prior art and comprises the following steps,

[0025] The urea, diammonium phosphate, potassium sulfate, water-retaining and antibacterial microspheres and white clay are weighed, and the components are fed into a granulating pulverizer, the raw materials are sufficiently pulverized by a grinding roller, and the ground particles are screened by a vibrating wheel in cooperation with a vibrating bar;

[0026] The materials are uniformly mixed by a double-shaft mixing device without damaging the physical properties of the materials, and the solid raw materials are reacted and bonded to form particles in the granulator by rotation of a drum granulator;

[0027] The compound fertilizer produced by the drum granulator is dried and screened to obtain the water-retaining and antibacterial compound fertilizer.

[0028] As a preferred scheme of the preparation method of the water-retaining and antibacterial compound fertilizer, the nitrogen fertilizer is 15-25 parts, the phosphorus fertilizer is 28-35 parts, the potassium fertilizer is 25-35 parts, the water-retaining and antibacterial microspheres are 13-18 parts, and the white clay is 10-15 parts.

[0029] The present application has the following advantages:

[0030] (1) The water-retaining agent used in the water-retaining and antibacterial compound fertilizer is high water-retaining carboxymethyl chitosan, the water-retaining performance of which is greatly improved by modification, and the carboxymethyl chitosan has good moisture absorption and retention, antibacterial property and biodegradability, can effectively inhibit soil water evaporation, increase soil moisture content and promote plant absorption of nutrient elements.

[0031] (2) The antibacterial agent used in the water-retaining and antibacterial compound fertilizer is acid-modified centipede extract, and the centipede has the functions of anticoagulation, antibiosis, moisture retention and water retention, etc., and after acid modification and extraction, the centipede extract can effectively inhibit pathogenic fungi, has the characteristics of improving soil microbial environment and reducing plant diseases and insect pests.

[0032] (3) The water-retaining and antibacterial microspheres used in the water-retaining and antibacterial compound fertilizer are prepared by adding acid-modified centipede extract to high water-retaining carboxymethyl chitosan, which can effectively improve the antioxidant activity and water-retaining and antibacterial capacity of the high water-retaining carboxymethyl chitosan; after the water-retaining and antibacterial microspheres are applied to the soil, water absorption and expansion can make the soil change from compact to loose, and the pore increases, thereby improving the soil permeability, increasing the soil water content and soil porosity, and reducing the soil bulk density, playing an antibacterial role and promoting the growth of crops. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned objectives, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the embodiments of the present application.

[0034] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0035] Secondly, the "one embodiment" or "embodiment" referred to herein means that a specific feature, structure or property can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is separate or alternative to other embodiments.

[0036] Raw material sources in the embodiments of the present application:

[0037] Centipedes were collected in Dagang Street, Tianjin Binhai New Area; carboxymethyl chitosan was purchased from Shaanxi Chenming Biological Technology Co., Ltd.; sucrose was purchased from Langfang Pengcai Fine Chemical Co., Ltd.; ethanol was purchased from Shandong Jibei New Material Co., Ltd.; NaH2PO4 was purchased from Shandong Lujian Chemical Co., Ltd.; urea was purchased from Hebei Guanghui Industry Co., Ltd.; diammonium phosphate was purchased from Jinan Antong New Material Co., Ltd.; potassium sulfate was purchased from Jinan Haiyouxing Chemical Co., Ltd.; white clay was purchased from Lingshou County Chaohui Mineral Product Processing Factory.

[0038] Embodiment 1

[0039] The present embodiment provides a preparation method of a water-retaining and antibacterial compound fertilizer, and the main steps are as follows:

[0040] (1) Preparation of water-retaining and antibacterial microspheres

[0041] The carboxymethyl chitosan is dried in a 60℃ electric heating air drying oven, and then frozen in a-20℃ refrigerator, wherein the freezing treatment time is 150min;

[0042] The carboxymethyl chitosan after freezing treatment is dissolved in 20% sucrose solution by stirring, wherein the mass ratio of the carboxymethyl chitosan after freezing treatment to the sucrose solution is 1:10;

[0043] The high water-retention carboxymethyl chitosan is prepared by removing water through distillation, wherein the distillation treatment temperature is 100°C and the treatment time is 180 min.

[0044] The dried centipedes are put into a 60°C electric heating air drying oven for drying, and after drying, are put into a pulverizer for pulverization to 80 mesh.

[0045] The centipede powder is extracted in 80% ethanol, and NaH2PO4 solution is added to the extracted solution to obtain acid-modified centipede extract, wherein the mass-volume ratio of the centipede powder to the ethanol is 1:5, and the ratio (V:V) of the extract to the NaH2PO4 solution is 1:20.

[0046] The prepared high water-retention carboxymethyl chitosan is mixed with the acid-modified centipede extract, and the mixed solution is dried by a spray dryer to obtain water-retention and antibacterial microspheres, wherein the ratio of the high water-retention carboxymethyl chitosan to the acid-modified centipede extract is 1:8 (g:ml), and the parameters of the spray drying are as follows: air inlet flow rate 25 m 3 / h, inlet temperature 160°C, and feeding flow rate 4.0 mL / min.

[0047] (2) Raw material pulverization

[0048] The raw materials are weighed by weight parts: urea 19 parts, diammonium phosphate 31 parts, potassium sulfate 27 parts, water-retention and antibacterial microspheres 15 parts, and white clay 13 parts. The components are fed into a granular pulverizer, the raw materials are sufficiently pulverized by grinding rollers, and the ground particles are screened by a combination of a vibration wheel and a vibration strip, wherein the particle size of the fertilizer is between 4 and 18 mesh.

[0049] (3) Granulation

[0050] The materials are uniformly mixed by a double-shaft mixing device without damaging the physical properties of the materials, and the solid raw materials are reacted and bonded to form particles in the granulator by rotating the drum granulator, wherein the parameters of the rotating drum granulator are 12 r / min.

[0051] (4) Drying

[0052] The compound fertilizer produced by the drum granulator is dried (at a temperature of 60°C), screened, and packaged to obtain a water-retention and antibacterial compound fertilizer.

[0053] Example 2

[0054] (1) Raw material pulverization

[0055] The components are weighed by parts by weight: urea 23 parts, diammonium phosphate 28 parts, potassium sulfate 25 parts, water-retaining and antibacterial microspheres (same as Example 1) 18 parts, white clay 15 parts. The components are fed into a granule pulverizer, the raw materials are sufficiently pulverized by a grinding roller, and the ground particles are screened by a combination of a vibration wheel and a vibration bar, wherein the particle size of the fertilizer is between 4-18 meshes.

[0056] (2) Granulation

[0057] The materials are uniformly mixed by a double-shaft mixing device without damaging the physical properties of the materials, and the solid raw materials are reacted and bonded to form particles in the granulator by the rotation of the drum granulator, wherein the rotation parameter of the drum granulator is 12 r / min.

[0058] (3) Drying

[0059] The compound fertilizer produced by the drum granulator is dried (temperature 60°C), screened, and packaged to obtain the water-retaining and antibacterial compound fertilizer.

[0060] Example 3

[0061] (1) Raw material pulverization

[0062] The components are weighed by parts by weight: urea 23 parts, diammonium phosphate 28 parts, potassium sulfate 25 parts, water-retaining and antibacterial microspheres (same as Example 1) 18 parts, white clay 15 parts. The components are fed into a granule pulverizer, the raw materials are sufficiently pulverized by a grinding roller, and the ground particles are screened by a combination of a vibration wheel and a vibration bar, wherein the particle size of the fertilizer is between 4-18 meshes.

[0063] (2) Granulation

[0064] The materials are uniformly mixed by a double-shaft mixing device without damaging the physical properties of the materials, and the solid raw materials are reacted and bonded to form particles in the granulator by the rotation of the drum granulator, wherein the rotation parameter of the drum granulator is 12 r / min.

[0065] (3) Drying

[0066] The compound fertilizer produced by the drum granulator is dried (temperature 60°C), screened, and packaged to obtain the water-retaining and antibacterial compound fertilizer.

[0067] Comparative Example 1

[0068] (1) Preparation of high water-retention carboxymethyl chitosan

[0069] The carboxymethyl chitosan is dried in a 60°C electric heating air drying oven and then frozen in a -20°C refrigerator, wherein the freezing treatment time is 150 min.

[0070] The carboxymethyl chitosan after the freezing treatment is dissolved in a 20% sucrose solution by stirring, wherein the mass ratio of the carboxymethyl chitosan after the freezing treatment to the sucrose solution is 1:10;

[0071] The high water-retention carboxymethyl chitosan is prepared by removing water through distillation, wherein the distillation treatment temperature is 100°C and the treatment time is 180 min;

[0072] (2) Raw material crushing

[0073] The following components are weighed by weight parts: urea 19 parts, diammonium phosphate 31 parts, potassium sulfate 27 parts, high water-retention carboxymethyl chitosan 15 parts, and white clay 13 parts. The components are fed into a granular crusher, the raw materials are fully crushed by grinding rollers, and the ground particles are screened by a combination of a vibration wheel and a vibration strip, wherein the fertilizer particle size is between 4-18 meshes.

[0074] (3) Granulation

[0075] The materials are uniformly mixed by a double-shaft mixing device without damaging the physical properties of the materials, and the solid raw materials are reacted and bonded into granules in the granulator by rotating the drum granulator, wherein the rotating parameters of the drum granulator are 12 r / min.

[0076] (4) Drying

[0077] The compound fertilizer produced by the drum granulator is dried (at a temperature of 60°C), screened, and packaged to obtain the water-retention and antibacterial compound fertilizer.

[0078] Comparative Example 2

[0079] (1) Preparation of acid-modified centipede extract

[0080] The dried centipedes are placed in a 60°C electric heating air drying oven for drying, and after drying, they are crushed to 80 meshes in a crusher;

[0081] The centipede powder is extracted in 80% ethanol, and NaH2PO4 solution is added to the extracted solution to obtain the acid-modified centipede extract, wherein the mass-volume ratio of the centipede powder to ethanol is 1:5, and the ratio of the extract to the NaH2PO4 solution is 1:20;

[0082] (2) Raw material crushing

[0083] The following components are weighed by weight parts: urea 23 parts, diammonium phosphate 28 parts, potassium sulfate 25 parts, acid-modified centipede extract 18 parts, and white clay 15 parts. The components are fed into a granular crusher, the raw materials are fully crushed by grinding rollers, and the ground particles are screened by a combination of a vibration wheel and a vibration strip, wherein the fertilizer particle size is between 4-18 meshes.

[0084] (3) Granulation

[0085] The material is uniformly mixed by a double-shaft mixing device without destroying the physical properties of the material, and the solid raw material is reacted and bonded to form particles in the granulator by rotating the drum granulator, wherein the rotating parameters of the drum granulator are 12 r / min.

[0086] (4) Drying

[0087] The compound fertilizer produced by the drum granulator is dried (temperature is 60℃), screened, and packaged to obtain the water-retaining and antibacterial compound fertilizer.

[0088] Comparative Example 3

[0089] (1) The raw materials are weighed according to the weight parts: urea 16 parts, diammonium phosphate 38 parts, potassium sulfate 38 parts, and white clay 10 parts. The components are fed into a granular pulverizer, the raw materials are fully pulverized by grinding rollers, and the ground particles are screened by a combination of a vibrating wheel and a vibrating bar, wherein the particle size of the fertilizer is between 4-18 meshes.

[0090] (2) Granulation

[0091] The material is uniformly mixed by a double-shaft mixing device without destroying the physical properties of the material, and the solid raw material is reacted and bonded to form particles in the granulator by rotating the drum granulator, wherein the rotating parameters of the drum granulator are 12 r / min.

[0092] (3) Drying

[0093] The compound fertilizer produced by the drum granulator is dried (temperature is 60℃), screened, and packaged to obtain the water-retaining and antibacterial compound fertilizer.

[0094] Application Experiment:

[0095] The experimental site is a potato seed breeding and multiplication base in Kangbao County. The soil pH of the test site is 6.20, the available nitrogen content is 42.81 mg / kg, the available phosphorus content is 28.62 mg / kg, and the available potassium content is 139.02 mg / kg. The test potato variety is V7.

[0096] The water-retaining antibacterial compound fertilizer is used in potato growth and development test, respectively. The test is divided into 7 groups, which are test group 1 (example 1), test group 2 (example 2), test group 3 (example 3), control group 1 (comparative example 1), control group 2 (comparative example 2), control group 3 (comparative example 3) and no fertilizer as a blank control group; the fertilizer amount of test group and control group is 200 kg per mu during the whole process of potato planting, and the test group and the control group are completely the same except that the used fertilizer is different. The blank control group is completely the same as other groups except that no fertilizer is used. Fertilization is carried out at the same time of potato planting, and after 130 days, the soil moisture content, soil bulk density, soil porosity, potato yield, withering death number and pest number are measured.

[0097] Soil moisture content detection: the soil moisture content is detected according to the method in appendix A of NY / T 1121.3-2006.

[0098] Soil bulk density detection: the soil bulk density is detected according to NY / T 1121.4-2006.

[0099] Soil porosity detection: the soil is collected according to NY / T 1121.4-2006, the collected soil sample is dried at 105℃, the soil particle density is detected according to NY / T 1121.23-2010, and the soil porosity is calculated according to the soil bulk density and the soil particle density combined with the definition of soil porosity.

[0100] Potato yield detection:

[0101] (1) Sampling method: the experimental land is equally divided into 3 plots, and 3 theoretical yield measurement sample points are randomly taken in each plot, totally 9 sample points. Each sample point is 10 continuous plants.

[0102] (2) Yield component measurement: the average yield per mu is calculated according to the yield component factor plant number per mu, average single plant weight. 11 rows are measured in the sample point to determine the average row distance, and 11 plants are measured to determine the average plant distance. Plant number per mu = 666.7 ÷ average row distance ÷ average plant distance.

[0103] (3) Calculation formula: sample point theoretical yield per mu (kg) = sample point average theoretical yield per mu × (1-impurity rate) = (sample point potato yield ÷ sample point plant number 10 × plant number per mu) × (1-impurity rate)

[0104] The impurity rate is generally 1.5%.

[0105] Average theoretical yield per mu (kg) (arithmetic mean) = ∑each sample point theoretical yield per mu ÷ sample point number

[0106] Dying number detection: using visual inspection method, randomly sampling 5 points, 100 plants per point, observing and counting the number of dying potato plants.

[0107] Disease and pest number detection: using visual inspection method, randomly sampling 5 points, 100 plants per point, observing and counting the number of potato plants suffering from diseases and pests.

[0108] Table 1 comparison of physical indexes of different treatment groups

[0109]

[0110] From Table 1, it can be seen that after adding the water-retaining and antibacterial compound fertilizer to the soil (test group 1), the soil moisture content and soil porosity are higher than those of the control group 1 and the blank control group, the soil bulk density is lower than that of the control group 1 and the blank control group, the potato yield is higher than that of the control group 1 and the blank control group, and the dying number and pest plant number are lower than those of the control group 1 and the blank control group. This shows that adding acid modified centipede extract to the water-retaining and antibacterial compound fertilizer can better loosen the soil, maintain the water content in the soil, promote the growth of potatoes, and play the role of antibiosis and inhibition of diseases and pests.

[0111] The experimental results of test group 2 are consistent with those of test group 1. This shows that adding high water-retaining carboxymethyl chitosan to the water-retaining and antibacterial compound fertilizer can better loosen the soil, maintain the water content in the soil, promote the growth of potatoes, and play the role of antibiosis and inhibition of diseases and pests.

[0112] The experimental results of test group 3 are also consistent with those of test group 1. This shows that adding water-retaining and antibacterial microspheres to the compound fertilizer can better loosen the soil, maintain the water content in the soil, promote the growth of potatoes, and play the role of antibiosis and inhibition of diseases and pests.

[0113] As can be seen from the above examples, the combination of compound fertilizer and water-retaining and antibacterial microspheres in the present application can effectively improve the soil moisture content and soil porosity, improve the soil structure, reduce the soil bulk density, make the fertilizer play a good role, inhibit diseases and pests, and promote the growth of crops.

[0114] The application discloses a kind of water-retaining antibacterial compound fertilizer and preparation method thereof, including, nitrogen fertilizer, phosphate fertilizer, potassium fertilizer, water-retaining antibacterial microsphere and white clay;Wherein, with the mass fraction of each raw material, the nitrogen fertilizer is 15-25 parts, the phosphate fertilizer is 28-35 parts, the potassium fertilizer is 25-35 parts, the water-retaining antibacterial microsphere is 13-18 parts, and the white clay is 10-15 parts;Water-retaining antibacterial microsphere is made by high water-retaining carboxymethyl chitosan and acid modified centipede extract mixture.This application water-retaining antibacterial compound fertilizer uses water-retaining antibacterial microsphere, which is made by adding acid modified centipede extract into high water-retaining carboxymethyl chitosan, which can effectively improve the antioxidant activity and water-retaining antibacterial capacity of high water-retaining carboxymethyl chitosan;After water-retaining antibacterial microsphere is applied to soil, it absorbs water and expands, which can change the soil from compact to loose, increase pore, thereby improve soil permeability, increase soil moisture content and soil porosity, reduce soil bulk density, play the role of antibiosis, and promote crop growth.

[0115] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and they should be covered in the scope of the present application.

Claims

1. A water-retaining antibacterial compound fertilizer, characterized by: The application relates to a water-retaining and antibacterial compound fertilizer, which comprises the following components in parts by mass: 15-25 parts of nitrogen fertilizer, 28-35 parts of phosphorus fertilizer, 25-35 parts of potassium fertilizer, 13-18 parts of water-retaining and antibacterial microspheres and 10-15 parts of white clay. The preparation method of the water-retaining and antibacterial microspheres comprises the following steps: drying and freezing treatment of carboxymethyl chitosan to obtain the carboxymethyl chitosan after freezing treatment; The carboxymethyl chitosan after freezing treatment is stirred and dissolved in a sucrose solution, and high water-retaining carboxymethyl chitosan is prepared by removing water through a distillation method. The dried centipede is crushed to obtain centipede powder. The centipede powder is extracted in ethanol to obtain an extraction liquid. NaH2PO4 solution is added into the extraction liquid to obtain acid-modified centipede extraction liquid. The high water-retaining carboxymethyl chitosan and the acid-modified centipede extraction liquid are mixed and spray dried to obtain the water-retaining and antibacterial microspheres. The freezing temperature is-20 DEG C, and the freezing treatment time is 150 min. The carboxymethyl chitosan after freezing treatment is stirred and dissolved in a sucrose solution with a mass concentration of 20%, and the mass ratio of the carboxymethyl chitosan after freezing treatment to the sucrose solution is 1:

10.

2. The water-retaining antibacterial compound fertilizer according to claim 1, characterized by: The high water-retaining carboxymethyl chitosan is prepared by removing water through a distillation method at a distillation treatment temperature of 100 DEG C for 180 min.

3. The water-retaining antibacterial compound fertilizer according to claim 2, characterized by: The centipede powder is extracted in ethanol with a mass-volume ratio of 1:5 and a mass concentration of 80% of the ethanol.

4. The water-retaining antibacterial compound fertilizer according to claim 1, characterized by: NaH2PO4 solution is added into the extraction liquid with a volume ratio of 1:

20.

5. The water-retaining and antibacterial compound fertilizer according to claim 1, characterized by: The application relates to a water-retaining and antibacterial compound fertilizer, which comprises the following components in parts by mass: 15-25 parts of nitrogen fertilizer, 28-35 parts of phosphorus fertilizer, 25-35 parts of potassium fertilizer, 13-18 parts of water-retaining and antibacterial microspheres and 10-15 parts of white clay.

6. The water-retaining and antibacterial compound fertilizer according to claim 1, characterized by: The preparation method of the water-retaining and antibacterial microspheres comprises the following steps: drying and freezing treatment of carboxymethyl chitosan to obtain the carboxymethyl chitosan after freezing treatment; 7. The water-retaining and antibacterial compound fertilizer according to claim 1, characterized by: The high water-retention carboxymethyl chitosan is mixed with the acid-modified centipede extract, wherein the ratio of the high water-retention carboxymethyl chitosan to the acid-modified centipede extract is 1:8 in g:ml, and the spray drying is performed with the parameters of inlet air flow rate 25 m 3 / h, inlet temperature 160℃, and feed flow rate 4.0 mL / min.

8. The method of producing the water-retaining antibacterial compound fertilizer according to any one of claims 1 to 7, characterized by: The carboxymethyl chitosan after freezing treatment is stirred and dissolved in a sucrose solution, and high water-retaining carboxymethyl chitosan is prepared by removing water through a distillation method. The dried centipede is crushed to obtain centipede powder. The centipede powder is extracted in ethanol to obtain an extraction liquid. NaH2PO4 solution is added into the extraction liquid to obtain acid-modified centipede extraction liquid.

9. The production method according to claim 8, characterized by: The high water-retaining carboxymethyl chitosan and the acid-modified centipede extraction liquid are mixed and spray dried to obtain the water-retaining and antibacterial microspheres. The freezing temperature is-20 DEG C, and the freezing treatment time is 150 min. The carboxymethyl chitosan after freezing treatment is stirred and dissolved in a sucrose solution with a mass concentration of 20%, and the mass ratio of the carboxymethyl chitosan after freezing treatment to the sucrose solution is 1:

10. The high water-retaining carboxymethyl chitosan is prepared by removing water through a distillation method at a distillation treatment temperature of 100 DEG C for 180 min. The centipede powder is extracted in ethanol with a mass-volume ratio of 1:5 and a mass concentration of 80% of the ethanol. NaH2PO4 solution is added into the extraction liquid with a volume ratio of 1:

20. The application relates to a water-retaining and antibacterial compound fertilizer, which comprises the following components in parts by mass: 15-25 parts of nitrogen fertilizer, 28-35 parts of phosphorus fertilizer, 25-35 parts of potassium fertilizer, 13-18 parts of water-retaining and antibacterial microspheres and 10-15 parts of white clay. The preparation method of the water-retaining and antibacterial microspheres comprises the following steps: drying and freezing treatment of carboxymethyl chitosan to obtain the carboxymethyl chitosan after freezing treatment;

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