Special fertilizer for improving quality of Yunnan black tea and preparation method thereof

Abstract

The invention discloses a special formula fertilizer for improving the quality of Yunnan black tea and a preparation method, and the special formula fertilizer comprises the following raw materials in parts by mass: 9-11 parts of humic acid, 48-50 parts of urea, 8-12 parts of diammonium phosphate, 1.5-2.5 parts of ammonium polyphosphate, 14-16 parts of potassium sulfate, 1.5-2.5 parts of magnesium oxide, 0.8-1.2 parts of nanometer magnesium oxide, 0.2-0.3 part of borax, 0.1-0.2 part of copper sulfate, 0.5-0.6 part of zinc sulfate and 0.02-0.08 part of ammonium molybdate. 5.62 to 16.38 parts of diatomite; the special fertilizer is prepared by adopting a granulating method of a granulator. The special fertilizer is suitable for Yunnan black tea production areas in Yunnan province, and solves the problems of tea quality reduction and the like caused by factors such as no fertilizer application, single fertilizer application type, unreasonable fertilizer ratio, lack of medium trace elements and the like in the areas.

Description

Technical Field

[0001] This invention relates to the field of fertilizer preparation and utilization technology, specifically to a special fertilizer for improving the quality of Yunnan black tea and its preparation method. Background Technology

[0002] Yunnan boasts a rich variety of teas, with Pu'er tea, Dianhong tea, and brick tea being the most famous. Dianhong tea, hailed as a "famous tea among teas," is a type of Gongfu tea made from large-leaf varieties. Its production ranks third among the six major tea categories in Yunnan. Also known as Yunnan black tea or Dianhong, it is mainly produced in Lincang, Fengqing, Menghai, Baoshan, Xishuangbanna, Dehong, and other areas along the Lancang River in Yunnan, including terrace Dianhong tea and Dianhong tea made from century-old ancient trees.

[0003] Abundant rainfall and a warm, humid climate are conducive to the formation of high-quality Yunnan black tea, but they can also lead to soil acidification due to the leaching of cations such as calcium and magnesium. Excessive nitrogen fertilizer application further exacerbates soil acidification and cation leaching in tea gardens. As a perennial leaf-producing plant, tea trees, once planted, selectively absorb large amounts of nutrients from a fixed soil source over a long period, easily leading to nutrient deficiencies and imbalances, especially micronutrients, thus affecting tea yield and quality. Replenishing soil nutrients through fertilization to meet the nutrient needs of normal tea tree growth and development is a crucial way to improve tea yield and quality. Fertilizer contributes 41% to tea yield growth, ranking first among factors. Fertilization is also an important factor in improving tea quality indicators such as amino acids, tea polyphenols, and water-soluble extracts.

[0004] Currently, there are many specialized fertilizers for tea cultivation, but there are no reports on fertilizers specifically designed for Dianhong tea that take into account the variety of Dianhong tea, the nutrient content of the soil in the production area, and the characteristics of Dianhong tea quality formation and nutrient requirements. Summary of the Invention

[0005] Based on the above-mentioned prior art, the present invention provides a special fertilizer for improving the quality of Dianhong tea and its preparation method. The special fertilizer of the present invention is applicable to the Dianhong tea producing area in Yunnan Province and solves the problems of declining tea quality caused by factors such as lack of fertilization, single type of fertilizer, unreasonable fertilizer ratio, and lack of micronutrients in the region.

[0006] The technical solution adopted to achieve the above-mentioned objectives of this invention is as follows:

[0007] A special fertilizer for improving the quality of Dianhong black tea comprises the following raw materials in parts by weight: 9-11 parts humic acid, 48-50 parts urea, 8-12 parts diammonium phosphate, 1.5-2.5 parts ammonium polyphosphate, 14-16 parts potassium sulfate, 1.5-2.5 parts magnesium oxide, 0.8-1.2 parts nano magnesium oxide, 0.2-0.3 parts borax, 0.1-0.2 parts copper sulfate, 0.5-0.6 parts zinc sulfate, 0.02-0.08 parts ammonium molybdate, and 5.62-16.38 parts diatomaceous earth.

[0008] Furthermore, the particle size of the nano-magnesium oxide is 15-100 nm.

[0009] Furthermore, the ammonium polyphosphate has an average degree of polymerization of 2-3, a polymerization rate of 70-75%, a nitrogen content of 13-14%, a total phosphorus content of 57-59%, and a total nutrient content of ≥71%.

[0010] Furthermore, the humic acid mentioned is mineral-derived humic acid.

[0011] A method for preparing a special fertilizer to improve the quality of Dianhong tea includes the following steps:

[0012] S1. Mix urea, ammonium polyphosphate, diammonium phosphate, magnesium oxide and potassium sulfate and pulverize them to obtain the core material;

[0013] S2. Add the core material to the granulator for granulation to obtain the core.

[0014] S3. While granulating to prepare the core, humic acid, nano magnesium oxide, borax, copper sulfate, zinc sulfate and ammonium molybdate are mixed and pulverized to obtain the coating material.

[0015] S4. After the core granulation is completed, add the coating material into the granulator and continue granulation to obtain granules.

[0016] S5. The granular material is successively dried, sieved, and cooled to obtain the special fertilizer for improving the quality of Dianhong tea. A method for applying this special fertilizer for improving the quality of Dianhong tea includes the following steps:

[0017] The special fertilizer for improving the quality of Dianhong tea as described in claim 1 shall be applied by trenching, with an application rate of 80-100 kg / mu, and shall be applied three times throughout the year. The three applications shall be made in early February, late May and early August, respectively, with the proportions of the three applications being 40%, 30% and 30% of the total annual fertilizer application.

[0018] Furthermore, when the tea tree is a terrace tea tree, a 20-30cm deep strip trench is dug along the edge of the terrace tea tree canopy, and the special fertilizer for improving the quality of Yunnan black tea is applied into the strip trench.

[0019] When the tea tree is an ancient tea tree, dig a 20-30cm deep fox-shaped trench along the edge of the ancient tea tree crown and apply the special fertilizer for improving the quality of Yunnan black tea into the fox-shaped trench.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0021] 1. The special fertilizer of this invention is formulated based on the nutrient content of the soil and trees in the Dianhong tea producing areas, making it suitable for Dianhong tea planting areas in Yunnan where micronutrient deficiency is common. Experiments were conducted in three Dianhong tea producing areas. The results showed that this special fertilizer significantly increases the yield of fresh Dianhong tea leaves, significantly increases the content of free amino acids, tea polyphenols, and caffeine, and decreases the content of water-soluble extracts. It also shows a trend towards increasing soluble sugars and total flavonoids. Simultaneously, this special fertilizer significantly increases the content of nitrogen, phosphorus, zinc, copper, and sulfur in tea leaves, decreases the aluminum content, increases the relative abundance of eutrophic microorganisms (actinomycetes and verrucous microorganisms) in tea garden soil, and decreases the abundance of oligotrophic microorganisms, thereby improving the diversity and composition of the microbial community in tea garden soil and providing a foundation for improving tea yield and quality.

[0022] 2. The addition of nano-magnesium oxide to the special fertilizer of this invention can effectively reduce the amount of magnesium fertilizer required in Yunnan black tea producing areas, improve the bioavailability of magnesium, and reduce soil acidification caused by magnesium ion leaching.

[0023] 3. The addition of ammonium polyphosphate to the special fertilizer of this invention can effectively reduce the fixation of phosphorus by iron and aluminum ions in acidic soil, thereby increasing the availability of phosphorus and reducing the fixation of soil trace elements, thus improving the availability of phosphorus and trace elements in tea gardens. Attached Figure Description

[0024] Figure 1 The membership function values ​​of soil fertility limiting factors affecting the yield and quality of Dianhong tea gardens are shown in the figure.

[0025] Figure 2 Figure showing the results of influencing the α-diversity of soil microorganisms in Dianhong tea gardens.

[0026] Figure 3 The results of the interaction between bacteria and eukaryotic LEfSe in the trenches of Dianhong tea gardens are shown in the figure. Detailed Implementation

[0027] The present invention will now be described in detail with reference to specific embodiments, but these embodiments are not to be construed as limiting the scope of protection of the present invention in any sense.

[0028] Unless otherwise specified, the "%" mentioned in this invention refers to a percentage by mass.

[0029] Unless otherwise specified, the term "parts" in this invention refers to parts by mass.

[0030] Example 1

[0031] 1. During the spring tea harvesting season in April 2023, soil and leaf samples were collected from 81 tea gardens in seven counties and one district of Lincang, namely Linxiang District, Fengqing County, Yun County, Cangyuan County, Gengma County, Shuangjiang County, Yongde County, and Zhenkang County. The samples were collected from ancient tea trees and terrace tea gardens (ancient tea trees aged between 100 and 500 years and terrace tea gardens aged between 10 and 30 years). The soil and leaf samples were collected from the tea gardens to conduct on-site investigation and sampling analysis of the soil and tree nutrient status. Combined with the tea quality and the soil fertility index, the main nutrient barrier factors affecting the yield and quality of tea gardens were identified.

[0032] The results of the survey sampling analysis are as follows:

[0033] The nutrient content of soils for different tea quality groups is shown in Table 1 below:

[0034] Table 1. Nutrient content of soils for different tea quality groups

[0035]

[0036] The nutrient content of leaves of different tea qualities is shown in Table 2 below:

[0037] Table 2 Nutrient content of leaves of different tea qualities

[0038]

[0039] The influence of soil fertility limiting factors affecting tea garden yield and quality, such as Figure 1 As shown;

[0040] Table 1-2 and Figure 1 The results indicate that deficiencies in available phosphorus, exchangeable magnesium, exchangeable calcium, available sulfur, copper, zinc, boron, and molybdenum in the soil of tea gardens in the main production areas of Dianhong black tea are important limiting factors for soil fertility, and these deficiencies are more severe in terrace tea gardens. Higher nitrogen, phosphorus, sulfur, and zinc content in tea leaves, along with lower aluminum content, are nutrient conditions for the formation of high-quality Dianhong black tea, and are also one of the reasons for the quality differences between ancient tree tea and terrace tea.

[0041] 3. Based on the analysis results in step 2, a special fertilizer for improving the quality of Dianhong tea was developed. The raw materials of this special fertilizer are as follows (by weight): 10 parts humic acid, 49 parts urea, 10 parts diammonium phosphate, 2 parts ammonium polyphosphate, 15 parts potassium sulfate, 2 parts magnesium oxide, 1 part nano-magnesium oxide, 0.25 parts borax, 0.15 parts copper sulfate, 0.55 parts zinc sulfate, 0.05 parts ammonium molybdate, and 10 parts diatomaceous earth. Its N:P₂O₅:K₂O ratio is 24-26:5-6:8-9, and it contains 1.8 parts MgO, 0.9 parts nano-magnesium oxide, 0.25 parts borax, 0.15 parts copper sulfate, 0.55 parts zinc sulfate, and 0.05 parts ammonium molybdate.

[0042] 4. The preparation method of the above-mentioned special fertilizer for improving the quality of Dianhong tea is as follows:

[0043] A. Mix urea, ammonium polyphosphate, diammonium phosphate, and potassium sulfate evenly and pulverize to a certain fineness (60 mesh) to obtain the core material;

[0044] B. Add the core material to a rotary drum granulator (or disc granulator), where it is humidified and heated in the rolling bed to agglomerate and granulate, thus obtaining the core material;

[0045] C. While granulating to prepare the core, humic acid, magnesium oxide, nano magnesium oxide, borax, copper sulfate, zinc sulfate ammonium molybdate and diatomaceous earth are mixed evenly and pulverized to a certain fineness (60 mesh) to obtain the coating material.

[0046] D. After the core granulation is completed, the coating material is added to the granulator and granulation continues to obtain granules;

[0047] E. The granular material is dried, sieved, and cooled (to room temperature) in sequence to obtain the special fertilizer for improving the quality of Dianhong tea.

[0048] Experiment 1: Effect of nano-magnesium oxide on the special fertilizer for improving the quality of Dianhong tea of ​​this invention

[0049] Experimental location: A tea garden in Lincang City, Yunnan Province. The soil is red soil, and its physicochemical properties are as follows: pH 4.62, organic matter 52.61 g / kg, available nitrogen 117.9 mg / kg, available phosphorus 20.12 mg / kg, available potassium 360.99 mg / kg, and exchangeable magnesium 78.32 mg / kg.

[0050] The experimental crops were 8-year-old large-leaf terrace tea.

[0051] Test method:

[0052] 1. A randomized block design was adopted, with a total of 4 fertilization treatments: 3 different magnesium fertilizer forms (magnesium oxide MgO, nano-magnesium oxide MgO NPs, and magnesium sulfate MgSO4) and no magnesium fertilizer (CK). Each treatment was replicated 4 times. The middle 40 meters of the same terrace was divided into 4 segments, each with 4 treatments. The 4 treatments were randomly alternated between upper and lower terraces. The application rates of magnesium oxide and magnesium sulfate were 5 kg / mu, and the application rate of nano-magnesium oxide was 2.5 kg / mu. All 4 fertilization treatments were treated with 100 kg / mu of compound fertilizer with an N:P2O5:K2O ratio of 17:17:17. Urea was also applied at 40 kg / mu in late May and early August.

[0053] 2. At the end of March 2024, approximately 100g of fresh leaves, the third-to-last intact leaf from the new shoots of the year, were collected, dried, and sampled. Magnesium was determined by microwave digestion-inductively coupled plasma-emission spectroscopy (ICP-OES). In October 2024, soil samples from the tea garden were collected, air-dried, and soil pH was determined by water extraction potentiometry (soil-water ratio 1:2.5). Exchangeable magnesium was determined by ammonium acetate extraction-atomic absorption spectrophotometry.

[0054] Experimental results:

[0055] The effects of different magnesium fertilizer treatments on the magnesium content of soil and spring tea leaves in Dianhong tea gardens are shown in Table 3 below:

[0056] Table 3. Effects of different magnesium fertilizer treatments on magnesium content in the soil and spring tea leaves of Dianhong tea gardens.

[0057]

[0058] As shown in Table 3, nano-magnesium oxide can significantly increase the exchangeable magnesium in the 0-20cm soil layer, reduce the migration of magnesium to the 20-40cm layer, slow down soil acidification, and increase the magnesium content in leaves.

[0059] Experiment 2: Effect of ammonium polyphosphate on the special fertilizer for improving the quality of Dianhong tea of ​​this invention

[0060] Experimental location: Indoor cultivation experiment. The soil used was collected from a tea garden in Lincang City, Yunnan Province. The soil was red soil, and its physicochemical properties were as follows: pH 4.62, organic matter 52.61 g / kg, available nitrogen 117.9 mg / kg, available phosphorus 20.12 mg / kg, available potassium 360.99 mg / kg, and exchangeable magnesium 78.32 mg / kg.

[0061] Test method:

[0062] 1. An indoor soil culture method was adopted, and six fertilization treatments were set up according to the type of phosphate fertilizer: no fertilizer (CK), superphosphate (SSP), monoammonium phosphate (MAP), diammonium phosphate (DAP), calcium magnesium phosphate (CMP), and polyphosphate (APP). The culture containers were 500 mL polypropylene plastic cups (9 cm (inner diameter) × 10 cm (height), each containing 150 g of soil that had passed through a 2 mm sieve. The phosphate fertilizer application rate was 0.23 g / kg P2O5, dissolved in 60 mL of water and evenly mixed into the soil. The plastic cups were then placed in a 25℃ incubator in the dark. During the culture process, water was added to the plastic cups by weighing to maintain a consistent soil moisture content. The fertilizer-grade polyphosphate (16-55-0) used was from Guizhou Wengfu Group Co., Ltd.: average degree of polymerization 2-3, polymerization rate 75.64%, nitrogen content 14%, total phosphorus content 58.5%, and total nutrients ≥71%.

[0063] 2. Soil samples were collected on days 7, 14, 21, 28, and 35 of cultivation. Each sample was 5–10 g, air-dried, sieved, and sealed in a resealable bag. Available phosphorus was determined by sodium bicarbonate extraction followed by a molybdenum-antimony colorimetric method.

[0064] Experimental results:

[0065] The effects of different phosphate fertilizer treatments on the available phosphorus content in tea garden soil are shown in Table 4 below:

[0066] Table 4. Effects of ammonium polyphosphate on available phosphorus content in Dianhong tea garden soil

[0067]

[0068] As shown in Table 4, with the increase of phosphate fertilizer application time, the effects of superphosphate (SSP), monoammonium phosphate (MAP), diammonium phosphate (DAP), and calcium magnesium phosphate (CMP) on the content of available phosphorus in Dianhong tea garden soil were significantly lower than those of polyphosphate (APP) treatment, indicating that polyphosphate can significantly increase the availability of phosphorus in Dianhong tea garden soil.

[0069] Experiment 3: Effects of the Special Fertilizer of the Present Invention on Improving the Quality of Dianhong Tea

[0070] Experimental locations: The experiment was conducted in three terraced tea gardens in Lincang City, Yunnan Province, designated as Location 1, Location 2, and Location 3. The soil physicochemical properties are shown in Table 5 below.

[0071] Table 5 Basic physical and chemical properties of soil in the test site

[0072]

[0073] As shown in Table 5, the soil organic matter in the tea gardens at all three test sites was relatively high, but the contents of available copper, zinc and molybdenum were all in the range of deficiency. Among them, the soil exchangeable magnesium content in the tea garden at site 2 was low, and the soil available phosphorus content in site 3 was low.

[0074] The experimental crops were large-leaf tea trees that were 8, 10, and 5 years old, respectively.

[0075] Test method:

[0076] 1. From February to October 2024, two fertilization treatments were conducted at three experimental sites: conventional fertilization (CK) and the application of the special compound fertilizer prepared in Example 1 (T). Each treatment was replicated four times. The middle 20 meters of the same terrace was divided into two sections, with the conventional fertilization treatment and the special fertilizer treatment applied to one section and the other to the other. The conventional fertilization treatment and the special fertilizer treatment were alternated between the upper and lower terraces. The conventional fertilization treatment involved applying 100 kg / mu of compound fertilizer with an N:P2O5:K2O ratio of 17:17:17 in strips (strip trenches) in February, followed by the application of 40 kg / mu of urea in late May and early August. The special fertilizer treatment involved applying 100 kg / mu of the special fertilizer prepared in Example 1 in strips throughout the year, with 40 kg / mu, 30 kg / mu, and 30 kg / mu applied in late February, late May, and early August, respectively.

[0077] 2. On April 3, 2024, samples of one bud and two leaves were collected. The samples were spread into a thin layer on a glass plate in a microwave oven and heated rapidly for 2 minutes at maximum power to kill cells. Intermittent heating (heating for 1 minute, cooling, and then heating again for 1 minute) was used. When the moisture content reached approximately 30%, the heat was reduced to medium, and the samples were heated intermittently for 30 seconds until they were dry and easily crumbled when squeezed. After cooling, the levels of tea polyphenols (GB / T8313-2018), amino acids (GB / T 8314-2013), caffeine (GB / T 8312-2013), and water extracts (GB / T 8305-2013) were determined. Simultaneously, the third-to-last intact leaf from the current year's new shoots was collected, washed, dried, and ground for mineral nutrient analysis.

[0078] Experimental results:

[0079] 1. The effects of different fertilization treatments on tea yield and quality at three experimental sites in the Dianhong tea garden are shown in Table 6 below:

[0080] Table 6. Effects of Special Fertilizer Application on Yield and Quality of Dianhong Black Tea

[0081]

[0082] As shown in Table 6, compared with conventional fertilization (CK), the special fertilizer of the present invention can significantly increase the yield of fresh leaves of Dianhong tea, as well as the content of free amino acids, tea polyphenols and caffeine, significantly reduce the content of water extract, and at the same time show a trend of increasing soluble sugars and total flavonoids.

[0083] 2. The effects of different fertilization treatments on the nutrient element content in tea leaves at three experimental sites in the Dianhong tea garden are shown in Table 7 below:

[0084] Table 7. Effects of Special Formula Fertilizer Treatment on Mineral Content of Spring Tea Leaves

[0085]

[0086] As shown in Table 7, compared with conventional fertilization (CK), the special fertilizer of the present invention can significantly increase the content of nutrients such as nitrogen, phosphorus, zinc, copper, boron and sulfur in tea, and significantly reduce the content of elemental aluminum.

[0087] 3. The effects of different fertilization treatments on soil microbial community diversity at three experimental sites in Dianhong tea gardens, such as... Figure 2 and Figure 3 As shown, by Figure 2 and Figure 3 It is known that, compared with conventional fertilization (CK), the special fertilizer of the present invention can increase the relative abundance of eutrophic microorganisms Actinobacteria and Verruciformis, and reduce the abundance of oligotrophic microorganisms, thereby improving the diversity and composition of the soil microbial community in tea gardens.

Claims

1. A special fertilizer for improving the quality of Dianhong tea, characterized in that The raw materials include the following quality parts: humic acid 9-11 parts, urea 48-50 parts, diammonium phosphate 8-12 parts, ammonium polyphosphate 1.5-2.5 parts, potassium sulfate 14-16 parts, magnesium oxide 1.5-2.5 parts, nano-magnesium oxide 0.8-1.2 parts, borax 0.2-0.3 parts, copper sulfate 0.1-0.2 parts, zinc sulfate 0.5-0.6 parts, ammonium molybdate 0.02-0.08 parts, and diatomite 5.62-16.38 parts.

2. The special fertilizer for improving the quality of Yunnan black tea according to claim 1, characterized in that: The particle size of the nano-magnesium oxide is 15-100 nm.

3. The special fertilizer for improving the quality of Yunnan black tea according to claim 1, characterized in that: The ammonium polyphosphate has an average polymerization degree of 2-3, a polymerization rate of 70-75%, a nitrogen content of 13-14%, a total phosphorus content of 57-59%, and a total nutrient content of ≥71%.

4. The special fertilizer for improving the quality of Yunnan black tea according to claim 1, characterized in that: The humic acid is mineral source humic acid.

5. The method for preparing the special fertilizer for improving the quality of Dianhong tea according to claim 1, characterized in that The method comprises the following steps: S1, uniformly mixing and crushing urea, ammonium polyphosphate, diammonium phosphate, and potassium sulfate to obtain core materials; S2, adding the core materials into a granulator to granulate to obtain cores; S3, while the cores are prepared by granulation, mixing and crushing humic acid, magnesium oxide, nano-magnesium oxide, borax, copper sulfate, zinc sulfate, ammonium molybdate, and diatomite to obtain a coating material; S4, after the core granulation is completed, adding the coating material into the granulator to continue granulation to obtain granular materials; S5, sequentially drying, screening, and cooling the granular materials to obtain the special fertilizer for improving the quality of Dianhong tea.

6. The method of applying the special fertilizer for improving the quality of Dianhong tea according to claim 1, characterized in that The method comprises the following steps: The special fertilizer for improving the quality of Dianhong tea in claim 1 is applied by a trenching method, and the application amount is 80-100 kg per mu, which is applied three times a year, and the three application times are early February, late May, and early August, respectively, and the proportions of the three application times are 40%, 30%, and 30% of the total annual fertilizer application amount.

7. The application method of the special fertilizer for improving the quality of Dianhong tea in claim 1, characterized in that: when the tea trees are tableland tea trees, a 20-30 cm deep strip-shaped trench is opened along the edge of the tableland tea tree crown, and the special fertilizer for improving the quality of Dianhong tea in claim 1 is applied in the strip-shaped trench; when the tea trees are ancient tea trees, a 20-30 cm deep fox-shaped trench is opened along the edge of the ancient tea tree crown, and the special fertilizer for improving the quality of Dianhong tea in claim 1 is applied in the fox-shaped trench.

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