Application method of nano-selenium fertilizer for tea garden

Abstract

The invention aims to provide a tea garden nano-selenium fertilizer application method, and relates to the technical field of agricultural fertilizer application, and the method comprises the following steps: (1) soil environment monitoring and basic fertility adjustment; (2) applying a nano-selenium fertilizer; (3) fertilization modes and matched management measures including root application, leaf surface spraying and matched management measures; and (4) monitoring and adjusting the selenium content of the tea leaves. The absorption and utilization rate of nano-selenium in the tea garden can be increased, the selenium content in the tea leaves is accurately regulated and controlled, it is ensured that the selenium-rich tea leaves are stable in quality and meet the safety standard, and meanwhile the soil ecological environment of the tea garden is protected.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural fertilizer application, in particular to a method for applying nano-selenium fertilizer in a tea garden. Background Art

[0002] Selenium is one of the essential trace elements for the human body and plays many important roles in human health, such as anti-oxidation, enhancing immunity, and preventing cancer. As a widely consumed beverage, tea enriched with selenium has broad market prospects. There are many problems with the application of traditional selenium fertilizers in tea gardens. For example, the absorption and utilization rate of ordinary selenium fertilizers is low, which easily causes the residue and loss of selenium in the soil, and it is difficult to accurately control the selenium content in tea, resulting in unstable quality of selenium-enriched tea. At the same time, excessive selenium may also have adverse effects on the ecological environment of tea garden soil. Nano-selenium has unique physical and chemical properties, with small particle size, high activity, and high bioavailability. Its application in the agricultural field has gradually attracted attention, but the scientific application and management technology of nano-selenium fertilizers in tea gardens still needs to be improved. Summary of the invention

[0003] The purpose of the present invention is to provide a method for applying nano-selenium fertilizer in a tea garden, which can improve the absorption and utilization rate of nano-selenium, accurately regulate the selenium content in tea leaves, and ensure that the quality of selenium-enriched tea leaves is stable and meets safety standards.

[0004] To this end, the technical solution of the present invention is: a method for applying nano-selenium fertilizer in a tea garden, comprising the following steps: (1) Soil environment monitoring and basic fertility regulation: Before applying nano-selenium fertilizer, conduct a comprehensive environmental monitoring of the tea garden soil, and adjust the basic soil fertility according to the soil monitoring results; if the soil is too acidic, apply an appropriate amount of lime to improve it; if the organic matter content is low, add organic fertilizer to create a soil environment suitable for tea tree growth and nano-selenium absorption; (2) Application of nano-selenium fertilizer: Determine the timing of applying nano-selenium fertilizer according to the growth cycle of tea trees; apply the first nano-selenium fertilizer to the roots 1-2 weeks before the tea trees sprout, and the application amount is calculated based on the original selenium content in the soil and the target selenium content in the tea leaves. Apply nano-selenium fertilizer to each tea tree, with 0.5-2 mg of selenium element; spray nano-selenium fertilizer on the leaves during the rapid growth stage after the spring tea is picked or during the growth period of summer tea. The concentration of foliar spraying is controlled at 50-200 mg / L. According to the growth status and leaf area of ​​the tea trees, the amount of solution sprayed per hectare is 300-600 liters, spraying every 7-10 days, and spraying continuously for 4-6 times; (3) Fertilization methods and supporting management measures: (3.1) When applying nano-selenium fertilizer to the roots, use the method of ring ditch application or strip ditch application. Dig a ring ditch or strip ditch with a depth of 15-20 cm 20-30 cm away from the trunk of the tea tree, evenly spread the nano-selenium fertilizer into the ditch, then cover it with soil and water it in time to promote the dissolution of nano-selenium in the soil and the absorption of the tea tree roots; (3.2) When spraying nano-selenium fertilizer on leaves, choose to do it between 9 and 11 am or 4 and 6 pm on a windless and sunny day; before spraying, stir the nano-selenium fertilizer solution thoroughly and use a spraying device with good atomization effect to ensure that both sides of the leaves are sprayed evenly. Avoid spraying during high temperatures, strong light periods or rainy days to prevent the nano-selenium solution from evaporating too quickly or being washed away by rain; (3.3) Supporting management measures: During the application of nano-selenium fertilizers, strengthen the water management of the tea garden, maintain the soil moisture content in the appropriate range of 60%-80%, and avoid the soil being too dry or too wet to affect the tea tree's absorption of nano-selenium; at the same time, reasonably prune the tea garden to enhance the ventilation and light transmittance of the tea trees, promote the growth and metabolism of the tea trees, and improve the absorption and conversion efficiency of nano-selenium; (4) Monitoring and adjustment of selenium content in tea: Before tea is picked, tea samples are collected regularly from different areas of the tea garden, and the selenium content in the tea is accurately determined by atomic fluorescence spectrometry or inductively coupled plasma mass spectrometry. According to the monitoring results of the selenium content in tea, compared with the target selenium content range, the dosage, number of applications or application time of nano-selenium fertilizer can be adjusted. If the selenium content in tea is lower than the target value, the application amount of nano-selenium fertilizer can be appropriately increased or the application interval can be shortened. If the selenium content in tea is close to or exceeds the upper limit of the target value, the application amount can be reduced or the application interval can be extended to ensure that the selenium content in tea is stable and in a safe range that meets the selenium-rich standard of 0.15 - 0.5 mg / kg.

[0005] The beneficial effects of the present invention are as follows: by adopting the nano-selenium fertilizer application method of the present invention, the color of fresh tea leaves becomes darker green, the freshness of tea leaves is improved, the bitterness is reduced, and the flavonoids, phenolic acids, vitamin C and other health-care functional substances are increased; the present invention can improve the absorption and utilization rate of nano-selenium, accurately control the selenium content in tea leaves, ensure that the quality of selenium-rich tea leaves is stable and meets safety standards; at the same time, the ecological environment of tea garden soil is protected. DETAILED DESCRIPTION

[0006] The present invention is described in detail below with reference to the embodiments.

[0007] Example 1 Preparation method of nano-selenium fertilizer: Sodium selenite is used as a selenium source, and an appropriate amount of sodium selenite is dissolved in deionized water to prepare a selenium source solution with a concentration of 10-50 mmol / L. A specific microbial strain (such as a Pseudomonas strain) or a plant extract (such as a garlic extract) is selected as a reducing agent, and the selenium source and the reducing agent are mixed evenly in a molar ratio of 1:2-1:5. The mixed solution is placed in a constant temperature oscillator and reacted for 2-6 hours at 25-35°C and 150-250 rpm to generate nano-selenium particles. After the reaction is completed, the nano-selenium particles are collected by centrifugation and repeatedly washed with deionized water for 3-5 times to remove impurities. Then the nano-selenium particles are dispersed in a solution containing 1%-3% chitosan or sodium alginate, and ultrasonically treated in an ultrasonic oscillator for 30-60 minutes to uniformly coat the surface of the nano-selenium particles with natural polymer materials to obtain a stable nano-selenium fertilizer.

[0008] Example 2 A method for applying nano-selenium fertilizer in a tea garden comprises the following steps: (1) Soil environment monitoring and basic fertility adjustment: In the tea garden, select 10-20 sampling points according to the chessboard sampling method and collect soil samples at a depth of 0-20 cm. After the soil samples are air-dried, ground and sieved, the soil acidity and alkalinity are measured using a pH meter, the organic matter content is measured using the potassium dichromate oxidation method, the soil texture type is determined using a soil texture analyzer, the soil selenium content is measured using atomic fluorescence spectroscopy, and the nitrogen, phosphorus, potassium and other nutrient contents are measured using conventional chemical analysis methods. If the soil pH value is less than 4.5, apply lime at a rate of 1-2 tons per hectare to adjust the soil pH value to the appropriate range of 5.0-6.5. If the soil organic matter content is less than 2%, apply 15-30 tons of decomposed farmyard manure or commercial organic fertilizer per hectare to improve soil fertility and water and fertilizer retention capacity; (2) Application of nano-selenium fertilizer: Determine the timing of nano-selenium fertilizer application based on the growth cycle of tea trees; apply the first nano-selenium fertilizer to the roots 1-2 weeks before the tea trees sprout. The application amount is calculated based on the original selenium content in the soil and the target selenium content in the tea leaves. Each tea tree is applied with nano-selenium fertilizer, calculated as 1.5 mg of selenium; during the rapid growth stage after the spring tea is picked, spray nano-selenium fertilizer on the leaves to supplement the leaves; the concentration of foliar spraying is controlled at 100 mg / L. Based on the growth status and leaf area of ​​the tea trees, the amount of solution sprayed per hectare is 450 liters, spraying once every 7 days for 6 consecutive times; (3) Fertilization methods and supporting measures: (3.1) When applying nano-selenium fertilizer to the roots, dig a circular trench with a depth of 18 cm at a distance of 25 cm from the trunk of the tea tree; evenly spread the prepared nano-selenium fertilizer into the trench, then cover it with soil and immediately irrigate it thoroughly to make the soil moisture content reach about 70%; (3.2) When spraying nano-selenium fertilizer on the leaves, choose 10 a.m. on a windless and sunny day during the rapid growth stage after the spring tea is picked, and use a backpack sprayer to evenly spray the solution on both sides of the tea leaves; (3.3) Supporting management measures: Water management: Install soil moisture sensors in the tea garden to monitor soil moisture in real time; when the soil moisture content is lower than 60%, irrigate to restore the soil moisture content to the appropriate range of 60% - 80%; when the soil moisture content is higher than 80%, drain water in time to prevent soil waterlogging; Tea garden pruning: After picking spring tea and picking autumn tea, tea trees are lightly pruned and deep pruned. Light pruning removes 3-5 cm branches and leaves on the surface of the tea tree crown, and deep pruning removes 10-15 cm branches and leaves in the middle and lower part of the crown to improve the ventilation and light transmission conditions of the tea trees, promote the growth of new shoots of the tea trees and the absorption and conversion of nano-selenium; (4) Monitoring and adjustment of selenium content in tea: One week before tea picking, collect tea samples in different areas of the tea garden (such as the top of the mountain, the middle of the mountain, the foot of the mountain, etc.). After drying and crushing the collected tea samples, use atomic fluorescence spectrometry to determine the selenium content in the tea. If the test results show that the selenium content of the tea is 0.1 mg / kg, which is lower than the target value (0.2-0.5 mg / kg), the application amount of nano-selenium fertilizer to each tea tree will be increased to 2 mg of selenium when the nano-selenium fertilizer is applied to the roots next time. If the selenium content of the tea is 0.4 mg / kg, which is close to the upper limit of the target value, the concentration of nano-selenium fertilizer sprayed on the leaves will be reduced to 50 mg / L, and the spraying interval will be extended to 10 days. Through the implementation of the above tea garden nano-selenium fertilizer application management technology, the utilization efficiency of nano-selenium in the tea garden can be effectively improved, the selenium content in the tea can be accurately controlled, and selenium-rich tea with stable quality, safety and health can be produced. At the same time, the ecological environment of the tea garden soil can be protected, providing strong technical support for the sustainable development of the tea garden and the development of the selenium-rich tea industry.

[0009] The method for applying nano-selenium fertilizer in a tea garden of the present invention is not limited to Example 2, and is further described in detail by Example 3.

[0010] Example 3 A method for applying nano-selenium fertilizer in a tea garden comprises the following steps: (1) Soil environment monitoring and basic fertility regulation: Before applying nano-selenium fertilizer, conduct a comprehensive environmental monitoring of the tea garden soil, including soil acidity (pH value), organic matter content, soil texture, existing selenium content, and other major nutrient (nitrogen, phosphorus, potassium, etc.) content. According to the soil monitoring results, adjust the basic soil fertility; if the soil is too acidic, apply an appropriate amount of lime to improve it; if the organic matter content is low, add organic fertilizers (such as decomposed farmyard manure, commercial organic fertilizers, etc.) to create a soil environment suitable for tea tree growth and nano-selenium absorption; (2) Application of nano-selenium fertilizer: Determine the timing of applying nano-selenium fertilizer according to the growth cycle of tea trees; apply the first nano-selenium fertilizer to the roots 1-2 weeks before the tea trees sprout, and the application amount is calculated based on the original selenium content in the soil and the target selenium content in the tea leaves. Apply nano-selenium fertilizer to each tea tree, 0.5-2 mg in terms of selenium element; for example, for tea gardens with low soil selenium content and target tea selenium content of 0.2-0.5 mg / kg, the application of nano-selenium particles (in terms of selenium element) to each tea tree can be controlled at 1-2 mg; spray nano-selenium fertilizer on the leaves during the rapid growth stage after spring tea picking or during the growth period of summer tea. The concentration of foliar spraying is controlled at 50-200 mg / L. According to the growth status and leaf area of ​​the tea trees, the amount of solution sprayed per hectare is 300-600 liters, spraying every 7-10 days, and spraying continuously for 4-6 times; (3) Fertilization methods and supporting management measures: (3.1) When applying nano-selenium fertilizer to the roots, use the method of ring ditch application or strip ditch application. Dig a ring ditch or strip ditch with a depth of 15-20 cm 20-30 cm away from the trunk of the tea tree, evenly spread the nano-selenium fertilizer into the ditch, then cover it with soil and water it in time to promote the dissolution of nano-selenium in the soil and the absorption of the tea tree roots; (3.2) When spraying nano-selenium fertilizer on leaves, choose to do it between 9 and 11 am or 4 and 6 pm on a windless and sunny day; before spraying, stir the nano-selenium fertilizer solution thoroughly and use a spraying device with good atomization effect to ensure that both sides of the leaves are sprayed evenly. Avoid spraying during high temperatures, strong light periods or rainy days to prevent the nano-selenium solution from evaporating too quickly or being washed away by rain; (3.3) Supporting management measures: During the application of nano-selenium fertilizers, strengthen the water management of the tea garden, maintain the soil moisture content in the appropriate range of 60%-80%, and avoid the soil being too dry or too wet to affect the tea tree's absorption of nano-selenium; at the same time, reasonably prune the tea garden to enhance the ventilation and light transmittance of the tea trees, promote the growth and metabolism of the tea trees, and improve the absorption and conversion efficiency of nano-selenium; (4) Monitoring and adjustment of selenium content in tea: Before tea is picked, tea samples are collected regularly from different areas of the tea garden, and the selenium content in the tea is accurately determined by atomic fluorescence spectrometry or inductively coupled plasma mass spectrometry. According to the monitoring results of the selenium content in tea, compared with the target selenium content range, the dosage, number of applications or application time of nano-selenium fertilizer can be adjusted. If the selenium content in tea is lower than the target value, the application amount of nano-selenium fertilizer can be appropriately increased or the application interval can be shortened. If the selenium content in tea is close to or exceeds the upper limit of the target value, the application amount can be reduced or the application interval can be extended to ensure that the selenium content in tea is stable and in a safe range that meets the selenium-rich standard of 0.15 - 0.5 mg / kg.

[0011] The test results of the nano-selenium material of Example 2 are as follows: In general, the color of tea leaves treated with nano-selenium is darker green, the freshness of tea leaves is improved, the bitterness is reduced, and flavonoids, phenolic acids, and vitamin C are beneficial to the improvement of health-care functional substances. 1. Changes in the appearance of fresh leaves and dried tea From the perspective of fresh leaves, the leaves are larger and greener after being treated with nano-selenium fertilizer, which means that the biomass of one bud and two leaves is increased, promoting photosynthesis of tea trees; the color of dry tea is darker green after nano-selenium is applied;

[0012] 2. Changes in the internal components of fresh leaves and dried tea (1) Flavonoid phenolic acid compounds The results of the selenium enrichment test showed that nano-selenium fertilizer effectively increased the content of flavonoid compounds in fresh tea leaves, including 341.5% of rutin, 10.3% of myricetin, 65.9% of luteolin, 50.8% of quercetin, 114% of apigenin, 13.9% of kaempferol, and 23.5% of phenolic acid compound chlorogenic acid. (2) Ratio of tea polyphenols, theanine and phenolamine The results of the selenium enrichment test showed that after selenium enrichment treatment, the theanine content of fresh green tea leaves increased by 0.5%, the amino acid content in dry tea significantly increased by 6%, the tea phenol-ammonia ratio in dry tea significantly decreased by 1.4, and the freshness of the tea leaves was improved. (3) Changes in bitterness Selenium enrichment tests show that after applying nano-selenium fertilizer, the content of non-ester catechins with a relatively softer taste increased by 0.4-211% in fresh leaves and 3.2-92% in dry tea; the content of ester catechins with high bitterness decreased by 22.3% in fresh leaves and 15.8-28.4% in dry tea; on the premise of providing effective health value, the taste of tea is improved and the bitterness is reduced; (4) Vitamin C The results of the selenium-enriched experiment show that the application of nano-selenium can significantly increase the vitamin C content in fresh leaves and dry tea (7% for fresh leaves, 2.9% for dry tea), thereby improving the health quality of tea.

[0013] In general, after the application of nano-selenium fertilizer, the color of the fresh leaves of the tea tree becomes darker green, the freshness of the tea leaves is improved, the bitterness is reduced, and the health-promoting functional substances such as flavonoids, phenolic acids, and vitamin C are increased.

Claims

1. A method for applying nano-selenium fertilizer in a tea garden, comprising the following steps: (1) Soil environment monitoring and basic fertility regulation: Before applying nano-selenium fertilizer, conduct a comprehensive environmental monitoring of the tea garden soil, and adjust the basic soil fertility according to the soil monitoring results; if the soil is too acidic, apply an appropriate amount of lime to improve it; if the organic matter content is low, add organic fertilizer to create a soil environment suitable for tea tree growth and nano-selenium absorption; (2) Application of nano-selenium fertilizer: Determine the timing of applying nano-selenium fertilizer according to the growth cycle of tea trees; apply the first nano-selenium fertilizer to the roots 1-2 weeks before the tea trees sprout, and the application amount is calculated based on the original selenium content in the soil and the target selenium content in the tea leaves. Apply nano-selenium fertilizer to each tea tree, with 0.5-2 mg of selenium element; spray nano-selenium fertilizer on the leaves during the rapid growth stage after the spring tea is picked or during the growth period of summer tea. The concentration of foliar spraying is controlled at 50-200 mg / L. According to the growth status and leaf area of ​​the tea trees, the amount of solution sprayed per hectare is 300-600 liters, spraying every 7-10 days, and spraying continuously for 4-6 times; (3) Fertilization methods and supporting management measures: (3.1) When applying nano-selenium fertilizer to the roots, use the method of ring ditch application or strip ditch application. Dig a ring ditch or strip ditch with a depth of 15-20 cm at a distance of 20-30 cm from the trunk of the tea tree, evenly spread the nano-selenium fertilizer into the ditch, then cover it with soil and water it in time to promote the dissolution of nano-selenium in the soil and the absorption of the tea tree roots; (3.2) When spraying nano-selenium fertilizer on leaves, choose to do it between 9 and 11 am or 4 and 6 pm on a windless and sunny day; before spraying, stir the nano-selenium fertilizer solution thoroughly and use a spraying device with good atomization effect to ensure that both sides of the leaves are sprayed evenly. Avoid spraying during high temperatures, strong light periods or rainy days to prevent the nano-selenium solution from evaporating too quickly or being washed away by rain; (3.3) Supporting management measures: During the application of nano-selenium fertilizers, strengthen the water management of the tea garden, maintain the soil moisture content in the appropriate range of 60%-80%, and avoid the soil being too dry or too wet to affect the tea tree's absorption of nano-selenium; at the same time, reasonably prune the tea garden to enhance the ventilation and light transmittance of the tea trees, promote the growth and metabolism of the tea trees, and improve the absorption and conversion efficiency of nano-selenium; (4) Monitoring and adjustment of selenium content in tea: Before tea is picked, tea samples are collected regularly from different areas of the tea garden, and the selenium content in the tea is accurately determined by atomic fluorescence spectrometry or inductively coupled plasma mass spectrometry. According to the monitoring results of the selenium content in tea, compared with the target selenium content range, the dosage, number of applications or application time of nano-selenium fertilizer can be adjusted. If the selenium content in tea is lower than the target value, the application amount of nano-selenium fertilizer can be appropriately increased or the application interval can be shortened. If the selenium content in tea is close to or exceeds the upper limit of the target value, the application amount can be reduced or the application interval can be extended to ensure that the selenium content in tea is stable and in a safe range that meets the selenium-rich standard of 0.15 - 0.5 mg / kg.