Tea tree selenium-rich fertilizer and preparation method thereof

Abstract

The invention relates to the technical field of fertilizers for tea gardens, and discloses a selenium-rich fertilizer for tea trees and a preparation method of the selenium-rich fertilizer. 4-8 parts of ammonium nitrate; 2.1 to 3.5 parts of calcium ammonium nitrate; 6-11 parts of ammonium sulfate nitrate; 10 to 14 parts of triple superphosphate; 15-19 parts of powdered rock phosphate; 22-28 parts of plant ash; 8 to 12 parts of sodium selenite; 7 to 9 parts of selenosulfinic acid; 0.4 to 1.3 parts of zinc; 0.73 to 1.12 parts of iron; 0.56 to 0.84 part of manganese; 4-7 parts of lime; 1-3 parts of sulfur; 0.81 to 0.93 part of bentonite; by adding the sodium selenite and the selenosulfinic acid in a set proportion into the raw materials and combining a staged preparation process, efficient and stable selenium fertilizer production can be realized, so that the selenium content in the tea leaves is increased, and the problems that the selenium content in the tea leaves is insufficient due to lack of addition of selenium elements in an existing tea tree fertilizer and the selenium content in the tea leaves is low are finally solved. The requirement of the market on the selenium-rich tea cannot be met.

Description

Technical Field

[0001] The invention relates to the technical field of tea garden fertilizers, in particular to a tea tree selenium-enriched fertilizer and a preparation method thereof. Background Art

[0002] Selenium is a relatively rare trace element and also a multifunctional life nutrient. It has the functions of scavenging free radicals, anti-oxidation (50-100 times that of vitamin E), strongly inhibiting the production of lipid peroxides, enhancing immune function (20-30 times), protecting biological cell membranes, enhancing prostate regulation, preventing blood clots, and removing cholesterol. It has similar effects to insulin and can significantly promote the ability of cells to absorb sugar, promote blood circulation, prevent skin aging, reduce the carcinogenicity of carcinogens, eliminate mutated cancer cells in the body, and prevent the division and growth of cancer cells. In 1973, the World Health Organization (WHO) confirmed that selenium is the first-line trace element of the 14 trace elements necessary for human life. Selenium deficiency will seriously affect human health. Therefore, selenium is known as the "spark of life", "king of anti-cancer", and "guardian of the heart". In the past two decades, scientists around the world have confirmed through experimental research that there are more than 40 human diseases known to be related to selenium deficiency. Including cancer, cardiovascular and cerebrovascular diseases, diabetes, liver disease, thyroid hormone imbalance, etc. Some diseases, especially those that endanger the health of the elderly: cardiovascular and cerebrovascular diseases, senile constipation, senile hypertension, stroke, endocrine metabolic diseases, diabetes, prostatic hyperplasia, brain atrophy, etc. are all related to selenium deficiency. After iodine deficiency has attracted widespread attention and attention, selenium deficiency has become a hot topic in scientific research at home and abroad. Tea has the function of enriching selenium. It absorbs inorganic selenium in the soil and forms organic selenium in the body. Since then, drinking selenium-enriched tea has become one of the important ways for people to supplement selenium, and it is convenient and easy. However, some areas are also accompanied by undesirable minerals such as lead and mercury, which are not suitable for direct human consumption.

[0003] Studies have shown that an appropriate amount of selenium can promote the growth of tea trees and improve the quality of tea leaves. It also has antioxidant and anti-aging effects. However, the existing tea tree fertilizers lack the addition of selenium, resulting in insufficient selenium content in the tea leaves, which cannot meet the market demand for selenium-rich tea.

[0004] In view of the shortcomings of the prior art in solving this problem, the present invention is to overcome this shortcoming. The selenium-rich fertilizer can not only meet the growth requirements of tea trees, but also effectively increase the selenium content in tea leaves, thereby increasing the nutritional value of tea leaves. Summary of the invention

[0005] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a selenium-rich fertilizer for tea trees and a preparation method thereof, which has the advantage of high selenium content and solves the problem that the existing tea tree fertilizer lacks the addition of selenium, resulting in insufficient selenium content in tea leaves and failing to meet the market demand for selenium-rich tea.

[0006] (II) Technical solution In order to achieve the above-mentioned purpose, the present invention provides the following technical solution: a selenium-rich fertilizer for tea trees, the raw materials of the selenium fertilizer and their weight parts are: 13-17 parts of liquid ammonia; 4-8 parts of ammonium nitrate; 2.1-3.5 parts of calcium ammonium nitrate; 6-11 parts of ammonium sulfate nitrate; 10-14 parts of double superphosphate; 15-19 parts of phosphate rock powder; 22-28 parts of wood ash; 8-12 parts of sodium selenite; 7-9 parts of selenosulfonic acid; 0.4-1.3 parts of zinc; 0.73-1.12 parts of iron; 0.56-0.84 parts of manganese; 4-7 parts of lime; 1-3 parts of sulfur; 0.81-0.93 parts of bentonite; 15-18 parts of starch.

[0007] Preferably, the raw materials of the selenium fertilizer and their weight parts are: 13 parts of liquid ammonia; 8 parts of ammonium nitrate; 2.3 parts of calcium ammonium nitrate; 9 parts of ammonium sulfate nitrate; 11 parts of double superphosphate; 16 parts of phosphate rock; 25 parts of wood ash; 11 parts of sodium selenite; 8 parts of selenosulfinic acid; 0.9 parts of zinc; 0.79 parts of iron; 0.64 parts of manganese; 6 parts of lime; 1.6 parts of sulfur; 0.9 parts of bentonite; and 17 parts of starch.

[0008] Preferably, the raw materials of the selenium fertilizer and their weight parts are: 16 parts of liquid ammonia; 5 parts of ammonium nitrate; 2.2 parts of calcium ammonium nitrate; 6 parts of ammonium sulfate nitrate; 12 parts of double superphosphate; 18 parts of phosphate rock; 25 parts of wood ash; 10 parts of sodium selenite; 8 parts of selenosulfinic acid; 0.7 parts of zinc; 0.96 parts of iron; 0.64 parts of manganese; 6 parts of lime; 2.5 parts of sulfur; 0.88 parts of bentonite; and 16 parts of starch.

[0009] Preferably, the raw materials of the selenium fertilizer and their weight parts are: 15 parts of liquid ammonia; 5 parts of ammonium nitrate; 2.9 parts of calcium ammonium nitrate; 10 parts of ammonium sulfate nitrate; 13 parts of double superphosphate; 17 parts of phosphate rock; 27 parts of wood ash; 11 parts of sodium selenite; 7.5 parts of selenosulfinic acid; 0.88 parts of zinc; 0.91 parts of iron; 0.74 parts of manganese; 6.6 parts of lime; 2.6 parts of sulfur; 0.90 parts of bentonite; and 15.5 parts of starch.

[0010] Preferably, the liquid ammonia, ammonium nitrate, calcium ammonium nitrate and ammonium sulfate nitrate together constitute a nitrogen source, the double superphosphate and phosphate rock powder together constitute a phosphorus source, the wood ash constitutes a potassium source, the sodium selenite and selenosulfinic acid together constitute a selenium source, the zinc, iron and manganese together constitute trace elements, the lime and sulfur together constitute a soil conditioner, and the bentonite and starch are a filler and a binder, respectively.

[0011] Preferably, a method for preparing a tea tree selenium-rich fertilizer is prepared according to the raw materials of the tea tree selenium-rich fertilizer and their weight parts, comprising the following preparation steps: Step 1: Raw material preparation: weigh all raw materials according to the formula weight and set aside; Step 2: Mixing: Mix the above raw materials in different orders under set conditions to form a uniform fertilizer base material; Step 3, granulation: the selenium fertilizer base material is granulated by a rolling granulator to form granular fertilizer; Step 4: Drying: Infrared drying of selenium fertilizer particles; Step 5. Quality monitoring: During the preparation process, the quality and selenium content of raw materials and finished products are tested. The finished product is qualified when the quality test passes and the selenium content reaches 2% to 4%.

[0012] Preferably, the mixing process in step 2 is: adding liquid ammonia, ammonium nitrate, calcium ammonium nitrate and ammonium sulfate nitrate into a mixer, mixing and stirring for 10 minutes at a temperature of 35-40°C; adding double superphosphate, phosphate rock powder, zinc, iron and manganese, mixing and stirring for 15 minutes at a temperature of 40-50°C; adding wood ash and starch, mixing and stirring for 7 minutes at a temperature of 55-60°C; adding sodium selenite, selenosulfinic acid and bentonite, mixing and stirring for 30 minutes at a temperature of 40-45°C; finally, using lime and sulfur to adjust the acidity and alkalinity of the mixture, and when the pH is between 9-10, the selenium fertilizer base material is prepared.

[0013] Preferably, the particle formation conditions in step three are as follows: the rotation speed of the rolling granulator is set between 50rpm-60rpm, the inclination angle is set between 12 degrees and 14 degrees, the pressure is set between 1.5MPa-2.0MPa, the particle size is set between 1.5mm-2.0mm, and granular selenium fertilizer is made at room temperature and a humidity of 10% to 15%.

[0014] Preferably, the drying conditions in step 4 are: the drying temperature is set to 100-120° C., the drying time is set to 20-25 min, and the moisture content of the selenium fertilizer is detected every 10 min during the drying process until the moisture content reaches between 1% and 2%.

[0015] Preferably, the quality monitoring of step five: the selenium content in the raw materials should reach 0.1% to 0.5% to be qualified, and the finished selenium fertilizer made from the raw materials is subjected to selenium content determination, particle uniformity test, moisture content determination, pH value determination and heavy metal content determination. After the determination is qualified, and the selenium content in the finished selenium fertilizer reaches 2%-4%, it is qualified.

[0016] Compared with the prior art, the present invention provides a tea tree selenium-rich fertilizer and a preparation method thereof, which has the following beneficial effects: 1. The present invention helps to achieve efficient and stable selenium fertilizer production by adding sodium selenite and selenosulfinic acid in a set ratio to the raw materials, combined with a staged preparation process, and mixing different types of raw materials in stages under different temperature conditions. This design avoids reaction conflicts between raw materials and can ensure the stability of each component. The active ingredients in some raw materials are easily degraded or ineffective at high temperatures. By controlling the temperature in stages, these active ingredients can be protected while retaining the effective ingredients in the raw materials. The above measures can stably maintain the selenium content in the selenium fertilizer between 0.2% and 0.4%, which optimizes the release effect of the selenium fertilizer during tea tree planting and optimizes the selenium content in the tea tree. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart was prepared for the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] See also Figure 1 A selenium-rich fertilizer for tea trees. The raw materials of the selenium fertilizer and their weight parts are: 13-17 parts of liquid ammonia; 4-8 parts of ammonium nitrate; 2.1-3.5 parts of calcium ammonium nitrate; 6-11 parts of ammonium sulfate nitrate; 10-14 parts of double superphosphate; 15-19 parts of phosphate rock powder; 22-28 parts of wood ash; 8-12 parts of sodium selenite; 7-9 parts of selenosulfonic acid; 0.4-1.3 parts of zinc; 0.73-1.12 parts of iron; 0.56-0.84 parts of manganese; 4-7 parts of lime; 1-3 parts of sulfur; 0.81-0.93 parts of bentonite; and 15-18 parts of starch.

[0020] Specifically, liquid ammonia, ammonium nitrate, calcium ammonium nitrate and ammonium sulfate nitrate together constitute a nitrogen source, the heavy superphosphate and phosphate rock powder together constitute a phosphorus source, the wood ash constitutes a potassium source, the sodium selenite and selenosulfinic acid together constitute a selenium source, the zinc, iron and manganese together constitute trace elements, the lime and sulfur together constitute a soil conditioner, and the bentonite and starch are a filler and a binder, respectively.

[0021] Specifically, a method for preparing a tea tree selenium-rich fertilizer is prepared according to the raw materials of the tea tree selenium-rich fertilizer and their weight parts, and comprises the following preparation steps: Step 1: Raw material preparation: weigh all raw materials according to the formula weight and set aside; Step 2: Mixing: Mix the above raw materials in different orders under set conditions to form a uniform fertilizer base material; Step 3, granulation: the selenium fertilizer base material is granulated by a rolling granulator to form granular fertilizer; Step 4: Drying: Infrared drying of selenium fertilizer particles; Step 5. Quality monitoring: During the preparation process, the quality and selenium content of raw materials and finished products are tested. The finished product is qualified when the quality test passes and the selenium content reaches 2% to 4%.

[0022] Specifically, the mixing process in step 2 is as follows: liquid ammonia, ammonium nitrate, calcium ammonium nitrate and ammonium sulfate nitrate are added into a mixer, and mixed and stirred for 10 minutes at a temperature of 35-40°C; heavy superphosphate, phosphate rock powder, zinc, iron and manganese are added, and mixed and stirred for 15 minutes at a temperature of 40-50°C; wood ash and starch are added, and mixed and stirred for 7 minutes at a temperature of 55-60°C; sodium selenite, selenosulfinic acid and bentonite are added, and mixed and stirred for 30 minutes at a temperature of 40-45°C; finally, the acidity and alkalinity of the mixture are adjusted with lime and sulfur, and when the pH is between 9 and 10, the selenium fertilizer base material is prepared.

[0023] The advantages are: by mixing different types of raw materials under different temperature conditions, the staged mixing can avoid reaction conflicts between the raw materials, thereby ensuring the stability of each component, and some components in some raw materials are prone to degradation or failure at high temperatures. By controlling the temperature in stages, the active ingredients in the raw materials can be protected while retaining the effective ingredients in the raw materials.

[0024] Specifically, the particle formation conditions in step three are as follows: the rotation speed of the rolling granulator is set between 50rpm-60rpm, the inclination angle is set between 12 degrees and 14 degrees, the pressure is set between 1.5MPa-2.0MPa, and the particle size is set between 1.5mm-2.0mm. Granular selenium fertilizer is made at room temperature and humidity of 10% to 15%.

[0025] Specifically, the drying conditions in step 4 are: the drying temperature is set to 100-120°C, the drying time is set to 20-25min, and the moisture content of the selenium fertilizer is tested every 10min during the drying process until the moisture content reaches between 1% and 2%.

[0026] Specifically, the quality monitoring of step five: the selenium content in the raw materials should reach 0.1% to 0.5% to be qualified, and the finished selenium fertilizer made from the raw materials is subjected to selenium content determination, particle uniformity test, moisture content determination, pH value determination and heavy metal content determination. After the determination is qualified, and the selenium content in the finished selenium fertilizer reaches 2%-4%, it is qualified. Example 1

[0027] The raw materials of selenium fertilizer and their weight parts are: 13 parts of liquid ammonia; 8 parts of ammonium nitrate; 2.3 parts of calcium ammonium nitrate; 9 parts of ammonium sulfate nitrate; 11 parts of double superphosphate; 16 parts of phosphate rock; 25 parts of wood ash; 11 parts of sodium selenite; 8 parts of selenosulfinic acid; 0.9 parts of zinc; 0.79 parts of iron; 0.64 parts of manganese; 6 parts of lime; 1.6 parts of sulfur; 0.9 parts of bentonite; and 17 parts of starch. Example 2

[0028] The raw materials of selenium fertilizer and their weight parts are: 16 parts of liquid ammonia; 5 parts of ammonium nitrate; 2.2 parts of calcium ammonium nitrate; 6 parts of ammonium sulfate nitrate; 12 parts of double superphosphate; 18 parts of phosphate rock; 25 parts of wood ash; 10 parts of sodium selenite; 8 parts of selenosulfinic acid; 0.7 parts of zinc; 0.96 parts of iron; 0.64 parts of manganese; 6 parts of lime; 2.5 parts of sulfur; 0.88 parts of bentonite; and 16 parts of starch. Example 3

[0029] The raw materials of selenium fertilizer and their weight parts are: 15 parts of liquid ammonia; 5 parts of ammonium nitrate; 2.9 parts of calcium ammonium nitrate; 10 parts of ammonium sulfate nitrate; 13 parts of double superphosphate; 17 parts of phosphate rock; 27 parts of wood ash; 11 parts of sodium selenite; 7.5 parts of selenosulfinic acid; 0.88 parts of zinc; 0.91 parts of iron; 0.74 parts of manganese; 6.6 parts of lime; 2.6 parts of sulfur; 0.90 parts of bentonite; and 15.5 parts of starch.

[0030] Comparative Example 1 The raw materials of the selenium fertilizer and their weight parts are: 13 parts of liquid ammonia; 8 parts of ammonium nitrate; 2.3 parts of calcium ammonium nitrate; 9 parts of ammonium sulfate nitrate; 11 parts of double superphosphate; 16 parts of phosphate rock; 25 parts of wood ash; 8 parts of selenosulfinic acid; 0.9 parts of zinc; 0.79 parts of iron; 0.64 parts of manganese; 6 parts of lime; 1.6 parts of sulfur; 0.9 parts of bentonite; 17 parts of starch (based on Example 1, 11 parts of sodium selenite are removed).

[0031] Comparative Example 2 The raw materials of selenium fertilizer and their weight parts are: 16 parts of liquid ammonia; 5 parts of ammonium nitrate; 2.2 parts of calcium ammonium nitrate; 6 parts of ammonium sulfate nitrate; 12 parts of double superphosphate; 18 parts of phosphate rock; 25 parts of plant ash; 10 parts of sodium selenite; 0.7 parts of zinc; 0.96 parts of iron; 0.64 parts of manganese; 6 parts of lime; 2.5 parts of sulfur; 0.88 parts of bentonite; 16 parts of starch (8 parts of selenosulfinic acid are removed on the basis of Example 2).

[0032] Comparative Example 3 The raw materials of the selenium fertilizer and their weight parts are: 20 parts of liquid ammonia; 1 part of ammonium nitrate; 9 parts of calcium ammonium nitrate; 2 parts of ammonium sulfate nitrate; 14 parts of double superphosphate; 17 parts of phosphate rock; 27 parts of wood ash; 20 parts of sodium selenite; 26 parts of selenosulfinic acid; 0.88 parts of zinc; 0.91 parts of iron; 0.74 parts of manganese; 6.6 parts of lime; 2.6 parts of sulfur; 0.90 parts of bentonite; 15.5 parts of starch (the weight parts of the formula are adjusted based on Example 3).

[0033] The raw materials of the above Examples 1-3 and Comparative Examples 1-3 were subjected to selenium content determination, and the raw materials were made into finished selenium fertilizers. The selenium content of the finished products was determined again, and particle uniformity test, moisture content determination, pH value determination and heavy metal content determination were added. The content determination data and quality inspection data of the above two stages are listed in the following Table 1: Table 1 ; ; Note: Determination method: Atomic absorption spectrometry is used to determine selenium content; sieving method is used to evaluate particle uniformity; drying method is used to determine moisture content; pH meter is used to measure pH value; ICP-MS is used to detect heavy metal content.

[0034] Qualification standards: Set the qualified range of various indicators. The selenium content should be between 2% and 4%, the particle uniformity should reach more than 95%, the moisture content should be controlled between 1% and 2%, the pH value should be between 7.0 and 7.5, and the heavy metal content should be lower than the national food safety standard limit.

[0035] Beneficial effects of the embodiments of the present invention: Selenium content control: measured by atomic absorption spectrometry, the selenium content of the raw materials and finished products in all embodiments was between 2% and 4%, which met the qualified standards, indicating that the present invention has stability in controlling the selenium content.

[0036] Particle uniformity: The screening method was used for evaluation. The uniformity of the raw materials and finished products in all embodiments reached more than 95%, meeting the qualification standard, indicating that the present invention performs best in controlling particle uniformity and helps to improve product quality and use effect.

[0037] Moisture content control: measured by the drying method, the moisture content of the raw materials and finished products in all embodiments was controlled between 1% and 2%, which met the qualified standards, indicating that the present invention has stability in controlling the moisture content, which is beneficial to prolonging the shelf life of the product.

[0038] pH value control: measured using a pH meter, the pH values ​​of the raw materials and finished products in all embodiments were between 7.0 and 7.5, meeting the qualification standards, indicating that the present invention has consistency in pH value control, which helps to maintain the acid-base balance of the product.

[0039] Control of heavy metal content: Through ICP-MS detection, the heavy metal content of raw materials and finished products in all embodiments was lower than the national food safety standard limit, and no heavy metal pollution was detected, indicating that the present invention has high safety in controlling heavy metal content, which is beneficial to protecting the health of consumers.

[0040] In summary, the embodiments of the present invention have reached qualified standards in terms of selenium content, particle uniformity, moisture content, pH value and heavy metal content, indicating that the formula of the present invention has high stability and consistency. Example 4

[0041] The selenium fertilizer product prepared by the present invention was applied to tea garden A (with the same soil type and climatic conditions).

[0042] Comparative Example 4 The conventional tea fertilizer without selenium was applied to tea garden B (same soil type and climatic conditions).

[0043] Under the same irrigation, fertilization and pruning conditions, one quarter later, the tea leaves of Example 4 and Comparative Example 4 after fertilization were picked, and the selenium content of the finished tea leaves was measured. The measured data are shown in Table 2: Table 2 ; According to the industry standard "NY / T 600-2002 Selenium-enriched Tea", the selenium content of selenium-enriched tea ranges from 0.25 to 4.0 mg / kg, and the selenium content of tea leaves from Tea Garden A fully meets this standard and even reaches a relatively high level, while the selenium content of tea leaves from Tea Garden B is far below this standard, indicating that the selenium fertilizer product prepared by the present invention is effective in increasing the selenium content of tea leaves.

[0044] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A selenium-rich fertilizer for tea trees, characterized in that: The raw materials of the selenium fertilizer and their weight parts are: 13-17 parts of liquid ammonia; 4-8 parts of ammonium nitrate; 2.1-3.5 parts of calcium ammonium nitrate; 6-11 parts of ammonium sulfate nitrate; 10-14 parts of double superphosphate; 15-19 parts of phosphate rock powder; 22-28 parts of wood ash; 8-12 parts of sodium selenite; 7-9 parts of selenosulfinic acid; 0.4-1.3 parts of zinc; 0.73-1.12 parts of iron; 0.56-0.84 parts of manganese; 4-7 parts of lime; 1-3 parts of sulfur; 0.81-0.93 parts of bentonite; and 15-18 parts of starch.

2. A tea tree selenium-rich fertilizer according to claim 1, characterized in that: The raw materials of the selenium fertilizer and their weight parts are: 13 parts of liquid ammonia; 8 parts of ammonium nitrate; 2.3 parts of calcium ammonium nitrate; 9 parts of ammonium sulfate nitrate; 11 parts of double superphosphate; 16 parts of phosphate rock; 25 parts of wood ash; 11 parts of sodium selenite; 8 parts of selenosulfinic acid; 0.9 parts of zinc; 0.79 parts of iron; 0.64 parts of manganese; 6 parts of lime; 1.6 parts of sulfur; 0.9 parts of bentonite; and 17 parts of starch.

3. A tea tree selenium-rich fertilizer according to claim 1, characterized in that: The raw materials of the selenium fertilizer and their weight parts are: 16 parts of liquid ammonia; 5 parts of ammonium nitrate; 2.2 parts of calcium ammonium nitrate; 6 parts of ammonium sulfate nitrate; 12 parts of double superphosphate; 18 parts of phosphate rock; 25 parts of wood ash; 10 parts of sodium selenite; 8 parts of selenosulfinic acid; 0.7 parts of zinc; 0.96 parts of iron; 0.64 parts of manganese; 6 parts of lime; 2.5 parts of sulfur; 0.88 parts of bentonite; and 16 parts of starch.

4. A tea tree selenium-rich fertilizer according to claim 1, characterized in that: The raw materials of the selenium fertilizer and their weight parts are: 15 parts of liquid ammonia; 5 parts of ammonium nitrate; 2.9 parts of calcium ammonium nitrate; 10 parts of ammonium sulfate nitrate; 13 parts of double superphosphate; 17 parts of phosphate rock powder; 27 parts of wood ash; 11 parts of sodium selenite; 7.5 parts of selenosulfinic acid; 0.88 parts of zinc; 0.91 parts of iron; 0.74 parts of manganese; 6.6 parts of lime; 2.6 parts of sulfur; 0.90 parts of bentonite; and 15.5 parts of starch.

5. A tea tree selenium-rich fertilizer according to claim 1, characterized in that: The liquid ammonia, ammonium nitrate, calcium ammonium nitrate and ammonium sulfate nitrate together constitute a nitrogen source, the heavy superphosphate and phosphate rock powder together constitute a phosphorus source, the wood ash constitutes a potassium source, the sodium selenite and selenosulfinic acid together constitute a selenium source, the zinc, iron and manganese together constitute trace elements, the lime and sulfur together constitute a soil conditioner, and the bentonite and starch are respectively a filler and a binder.

6. A method for preparing selenium-rich fertilizer for tea trees, characterized in that: The raw materials and weight portions of the tea tree selenium-enriched fertilizer according to claim 1 are prepared, comprising the following preparation steps: Step 1: Raw material preparation: weigh all raw materials according to the formula weight and set aside; Step 2: Mixing: Mix the above raw materials in different orders under set conditions to form a uniform fertilizer base material; Step 3, granulation: the selenium fertilizer base material is granulated by a rolling granulator to form granular fertilizer; Step 4: Drying: Infrared drying of selenium fertilizer particles; Step 5. Quality monitoring: During the preparation process, the quality and selenium content of raw materials and finished products are tested. The finished product is qualified when the quality test passes and the selenium content reaches 2%-4%.

7. The method for preparing a selenium-rich fertilizer for tea trees according to claim 6, characterized in that: The mixing process in step 2 includes: adding liquid ammonia, ammonium nitrate, calcium ammonium nitrate and ammonium sulfate nitrate into a mixer, mixing and stirring for 10 minutes at a temperature of 35-40°C; adding superphosphate, phosphate rock powder, zinc, iron and manganese, mixing and stirring for 15 minutes at a temperature of 40-50°C; adding plant ash and starch, mixing and stirring for 7 minutes at a temperature of 55-60°C; adding sodium selenite, selenosulfinic acid and bentonite, mixing and stirring for 30 minutes at a temperature of 40-45°C; and finally adjusting the acidity and alkalinity of the mixture with lime and sulfur. When the pH value is between 9 and 10, the selenium fertilizer base material is prepared.

8. The method for preparing a selenium-rich fertilizer for tea trees according to claim 6, characterized in that: The particle formation conditions in step three are as follows: the rotation speed of the rolling granulator is set between 50rpm-60rpm, the inclination angle is set between 12 degrees and 14 degrees, the pressure is set between 1.5MPa-2.0MPa, the particle size is set between 1.5mm-2.0mm, and granular selenium fertilizer is made at room temperature and humidity of 10% to 15%.

9. The method for preparing a selenium-rich fertilizer for tea trees according to claim 6, characterized in that: The drying conditions in step 4 are: the drying temperature is set at 100-120° C., the drying time is set at 20-25 min, and the moisture content of the selenium fertilizer is detected every 10 min during the drying process until the moisture content reaches between 1% and 2%.

10. The method for preparing a selenium-rich fertilizer for tea trees according to claim 6, characterized in that: Quality monitoring in step five: the selenium content in the raw materials should be tested to be 0.1% to 0.5% to be qualified, and the finished selenium fertilizer made from the raw materials is subjected to selenium content determination, particle uniformity test, moisture content determination, pH value determination and heavy metal content determination. After the determination is qualified, and the selenium content in the finished selenium fertilizer reaches 2%-4%, it is qualified.

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