A method for non-destructive carbon sequestration and sink increase of tea trees in tea gardens

Abstract

The present application relates to the field of agricultural ecological environment management and carbon sink monitoring technology, and more particularly to a tea tree lossless tea garden carbon fixation and sink increase method, comprising: pyrolyzing agricultural waste to obtain biochar and making the biochar into a specific standard biochar-based fertilizer; determining tea garden soil organic matter, cation exchange capacity and soil bulk density, calculating soil quality comprehensive coefficient by using improved Nemerow comprehensive index method and dividing soil quality grades according to the soil quality comprehensive coefficient; applying the biochar-based fertilizer in a differentiated application amount according to the soil quality grades; determining tea tree aboveground biomass after fertilization and calculating tea tree carbon storage according to a corresponding carbon storage model selected according to the age of the tea tree; simultaneously determining soil parameters to calculate tea garden soil carbon storage; and finally taking the tea tree carbon storage and the soil carbon storage as the total carbon sink of the tea garden. The present application realizes systematic, accurate and lossless monitoring of tea garden carbon fixation and sink increase technology.

Description

Technical Field

[0001] This invention relates to the field of agricultural ecological environment management and carbon sequestration monitoring technology, and in particular to a method for carbon sequestration and enhancement in tea gardens without damaging tea trees. Background Technology

[0002] Tea gardens are important agricultural ecosystems and economic crop cultivation areas, and their carbon sequestration function is receiving increasing attention under the national dual-carbon strategy. Currently, the main technical approaches to enhancing the carbon sequestration capacity of tea garden soils include increasing the application of organic fertilizers and planting green manure. Among these, biochar has become a hot topic due to its stable carbon sequestration characteristics and soil improvement potential. Regarding carbon sequestration monitoring in tea gardens, traditional methods require excavating the tea tree root system to obtain underground biomass and then calculating vegetation carbon storage. This method is highly destructive, complex to operate, and difficult to promote and apply on a large scale in tea gardens.

[0003] However, existing carbon sequestration and enhancement technologies in tea gardens still suffer from a prominent technical problem: the lack of a systematic approach that combines soil carbon sequestration enhancement technologies with non-destructive and precise monitoring and assessment technologies for tea garden carbon sequestration. Specifically, existing technologies often focus on single soil improvement or single carbon storage estimation, failing to form a complete technical loop: targeted activation of inert and active carbon with specific functional fertilizers to improve soil, precise management based on soil conditions, and convenient quantitative assessment of carbon sequestration effects using non-destructive models. This results in problems such as extensive management practices, difficulty in accurately measuring effects, and weak operability for technology promotion in tea garden carbon sequestration and enhancement practices. Summary of the Invention

[0004] To overcome the above shortcomings, this invention provides a method for carbon sequestration and enhancement in tea gardens without damaging tea trees, aiming to improve the problem that existing tea garden management is unable to combine soil carbon sequestration technology, precision fertilization and non-destructive monitoring and assessment of carbon sequestration.

[0005] This invention provides the following technical solution: a method for carbon sequestration and enhancement in tea gardens without damaging tea trees, comprising the following steps: S1. Agricultural waste is pyrolyzed at 400-600℃ to obtain biochar, which is then formulated into a biochar-based fertilizer with a biochar content ≥30%, an organic matter content ≥30%, a pH value of 7.0-9.0, and a total nutrient content ≥8%. S2. Determine the soil organic matter, cation exchange capacity and soil bulk density of the tea garden to be applied, and calculate the comprehensive soil quality coefficient using the modified Nemerow comprehensive index method. Based on this coefficient, the soil quality is classified into general or poor grades. S3. Based on the soil quality grade classified in S2, apply at a rate of 6000-8500 kg / ha to tea gardens with average soil quality, or at a rate of 7000-9000 kg / ha to tea gardens with poor soil quality. S4. During the monitoring period following fertilization, measure the aboveground biomass of the tea trees. Based on the aboveground biomass And calculate the carbon storage of tea trees by selecting the appropriate carbon storage model based on the age of the tea trees: If the tea tree is a young tea tree, a model is used. calculate; If the tea tree is a mature tea tree, a model is used. calculate; Among them, young tea trees refer to tea trees with an age of 0-2 years, and mature tea trees refer to tea trees with an age of 3-25 years; S5. Measure the soil bulk density, soil depth, soil organic carbon content and gravel content of the tea garden, and calculate the soil carbon storage of the tea garden based on the soil bulk density, soil depth, soil organic carbon content and gravel content. S6. The carbon storage of tea trees calculated in S4 is converted into the carbon storage of a specified unit area or the total carbon storage of the entire tea garden according to the number of tea trees or the area of ​​the tea garden. Then, it is added to the carbon storage of the tea garden soil calculated in S5 and converted to the same unit standard to obtain the total carbon storage of the tea garden.

[0006] Preferably, the agricultural waste is at least one of tea branches, mulberry branches, or sugarcane leaves.

[0007] Preferably, in S2, the standard for classifying the soil quality based on the comprehensive soil quality coefficient P is as follows: When the p-value is between 1.8 and 0.9, it is classified as a general level; When the P-value is less than 0.9, it is classified as poor.

[0008] Preferably, in S3, the application time of the biochar-based fertilizer is: It can be applied as a base fertilizer during the autumn dormancy period of tea trees or before the spring budding, and as a top dressing fertilizer after the spring tea harvest or the summer tea harvest.

[0009] Preferably, the biochar-based fertilizer is applied by trenching or hole application, with the trench or hole being 15-20 cm deep, and then covered with soil after application.

[0010] Preferably, in S4, the carbon storage model for young tea trees coefficient of determination ; Carbon storage model of mature tea trees coefficient of determination 95.

[0011] Preferably, in S5, the soil carbon storage Calculated using the following formula: =[V×H×O×(1-G)]×S; Where V is the soil bulk density, H is the soil depth, O is the soil organic carbon content, G is the gravel content, and S is the tea garden area.

[0012] Preferably, the monitoring cycle is once a year, or once every 3-5 years.

[0013] Preferably, the method further includes supporting management steps: In tea gardens, implement grass cultivation and intercropping with green manure, while maintaining soil moisture content at 70%-80% of field capacity.

[0014] Preferably, the method further includes a security monitoring step: The biochar-based fertilizer was tested for heavy metals, and the pH value and heavy metal content of the tea garden soil were monitored regularly.

[0015] The present invention has the following beneficial effects: 1. In this invention, the precise application technology of biochar-based fertilizer, the soil quality diagnosis technology based on the improved Nemerow index, and the non-destructive carbon sequestration accounting technology of tea trees based on aboveground biomass are systematically integrated to form a complete technical system from soil carbon sequestration capacity improvement to carbon sequestration effect quantitative evaluation, preventing the disconnect between improvement measures and effect evaluation.

[0016] 2. In this invention, by establishing and applying experimentally verified mathematical models of carbon storage for tea trees of different ages, vegetation carbon storage can be accurately calculated simply by measuring the aboveground biomass. It is easy to operate, low in cost, and highly repeatable, providing a feasible technical means for the routine and large-scale monitoring of carbon sequestration in large-area tea gardens.

[0017] 3. In this invention, through scientific soil quality evaluation and grading, differentiated biochar-based fertilizer application rates are matched for tea garden soils with different degrees of degradation. This achieves precise management of inputs and targeted activation of inert and activated carbon resources for efficient utilization, avoiding blind fertilization and optimizing carbon sequestration while improving soil quality.

[0018] 4. In this invention, by setting flexible monitoring periods, the total carbon sequestration of tea gardens at different time points can be conveniently obtained. By comparing the difference in total carbon sequestration before and after the application of biochar-based fertilizer or in different monitoring periods, the net carbon sequestration rate or increase in carbon sequestration of the tea garden during that period can be directly quantified. This allows for an objective and dynamic assessment of the actual effect and contribution of this carbon sequestration and increase method, providing a reliable data foundation for carbon trading and ecological compensation. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating a method for carbon sequestration and enhancement in tea gardens without damaging tea trees, as proposed in this invention. Figure 2This is a schematic diagram showing the relationship between the total biomass of tea trees of two different ages and the age of the tea trees in a non-destructive carbon sequestration and enhancement method for tea gardens proposed in this invention. Figure 3 This is a schematic diagram showing the relationship between the total biomass of tea trees of two different ages and the aboveground biomass in a non-destructive carbon sequestration and enhancement method for tea gardens proposed in this invention. Figure 4 This is a schematic diagram showing the relationship between carbon storage of young tea trees (a) and mature tea trees (b) as a function of tree age or aboveground biomass in a non-destructive carbon sequestration and enhancement method for tea gardens proposed in this invention. Figure 5 This is a scatter plot of measured and predicted values ​​of carbon storage in tea trees of two different ages as a function of aboveground biomass, based on a non-destructive carbon sequestration and enhancement method for tea gardens proposed in this invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] This invention provides a method for carbon sequestration and enhancement in tea gardens without damaging tea trees, such as... Figures 1-5 As shown, it includes the following steps: Agricultural waste is pyrolyzed at 400-600℃ to produce biochar, which is then formulated into a biochar-based fertilizer with a biochar content ≥30%, an organic matter content ≥30%, a pH value of 7.0-9.0, and a total nutrient content ≥8%.

[0022] Furthermore, the agricultural waste is at least one of tea branches, mulberry branches, or sugarcane leaves.

[0023] Specifically, firstly, the raw material for preparing biochar-based fertilizer is agricultural waste. Specifically, agricultural waste includes at least one of tea branches, mulberry branches, or sugarcane leaves. The selected raw materials should be free from pollution and mold. The aforementioned agricultural waste is placed in a high-temperature pyrolysis device. This pyrolysis process is carried out under anaerobic or oxygen-limited conditions. The pyrolysis temperature is controlled between 400°C and 600°C. The high-temperature pyrolysis device is equipped with a flue gas purification treatment device. The flue gas purification treatment device typically includes, but is not limited to, one or more combinations of cyclone dust collectors, spray towers, or activated carbon adsorption equipment, used to treat the flue gas generated during the pyrolysis process for dust removal, deacidification, and removal of harmful gas components to ensure that the production process meets environmental emission requirements. After pyrolysis, a solid product, biochar, is obtained. This biochar has a porous structure, high carbon content, and stable properties. Subsequently, biochar-based fertilizer is formulated. The obtained biochar is mixed with appropriate amounts of organic and / or inorganic nutrients. Organic nutrients can be derived from well-rotted organic fertilizer, and inorganic nutrients include, but are not limited to, nitrogen, phosphorus, potassium, and necessary trace element fertilizers. The purpose of mixing is to ensure that the final product meets specific nutrient ratio requirements to suit the nutrient needs of tea trees. The above formulation process yields a finished biochar-based fertilizer. This finished product must meet the following quality standards: biochar content not less than 30%, organic matter content not less than 30%, pH value between 7.0 and 9.0, and total nutrient content not less than 8%. Total nutrients refer to the sum of nitrogen, phosphorus pentoxide, and potassium oxide content. Furthermore, the moisture content of this biochar-based fertilizer should not exceed 20%.

[0024] S2. Determine the soil organic matter, cation exchange capacity and bulk density of the tea garden to be treated, and calculate the comprehensive soil quality coefficient using the modified Nemerow comprehensive index method. Based on this coefficient, the soil quality is classified into general or poor grades.

[0025] Furthermore, in S2, the standard for grading based on the comprehensive soil quality coefficient P is as follows: When the p-value is between 1.8 and 0.9, it is classified as a general level; When the P-value is less than 0.9, it is classified as poor.

[0026] Specifically, representative soil samples were collected from the target tea gardens where biochar-based fertilizer was planned to be applied, following the soil sampling methods specified in national or industry standards. Three key indicators were measured on the collected soil samples: first, soil organic matter content, expressed in grams per kilogram; second, cation exchange capacity, expressed in centimoles per kilogram; and third, soil bulk density, expressed in grams per cubic centimeter. Based on the above three measurement results, the comprehensive quality coefficient P of the tea garden soil was calculated using the improved Nemerow comprehensive index method. The specific calculation process is as follows: First, the sub-quality coefficient of each measurement index was calculated. For the two indicators of soil organic matter content and cation exchange capacity, based on their measured values... Compared with the preset lower limit of nutrient grading standards With upper limit Perform the calculation: When measured value Less than or equal to the lower limit value When, the fractional quality coefficient of this indicator equal Divide by When the measured value Greater than and less than When, the fractional quality coefficient of this indicator =1 plus reduce Difference divided by reduce The difference; when the measured value Greater than or equal to When, the fractional quality coefficient of this indicator Equals 3; where the grading standard for soil organic matter content refers to: It is 20 grams per kilogram. The standard is 30 grams per kilogram; the grading standard for cation exchange capacity is as follows: It is 10.5 centimoles per kilogram. It is 15.4 centimoles per kilogram; For soil bulk density index, based on its measured value Perform the calculation: when the soil bulk density When it is less than 1.0 g per cubic centimeter, its partial mass coefficient Equals 3; when soil bulk density When it is greater than 1.6 grams per cubic centimeter, its partial mass coefficient Equals Cᵢ divided by 1.6; when the soil bulk density When its concentration is between 1.0 g / cm³ and 1.6 g / cm³, its partial mass coefficient is... It equals 1 plus 1.6 minus Divide the difference by 0.6; The partial mass coefficients of soil organic matter content, cation exchange capacity, and soil bulk density were calculated separately. Then, the comprehensive soil quality coefficient P is calculated using the following formula: The comprehensive soil quality coefficient P is equal to the average of the three sub-quality coefficients. The square of the fraction and the minimum of the three fractional mass coefficients. Add the squares of the results, then divide by two, take the square root of the result, and finally multiply the square root by the number of evaluation indicators n minus one, then divide the result by the quotient of n. The number of evaluation indicators n is 3. Based on the calculated comprehensive soil quality coefficient P, the soil quality of the tea garden is classified into grades: when the P value is between 1.8 and 0.9, the soil quality of the tea garden is classified as general grade; when the P value is less than 0.9, the soil quality of the tea garden is classified as poor grade.

[0027] S3. Based on the soil quality grade classified in S2, apply at a rate of 6000-8500 kg / ha to tea gardens with average soil quality, or at a rate of 7000-9000 kg / ha to tea gardens with poor soil quality.

[0028] Furthermore, in S3, the application time of biochar-based fertilizer is as follows: It can be applied as a base fertilizer during the autumn dormancy period of tea trees or before the spring budding, and as a top dressing fertilizer after the spring tea harvest or the summer tea harvest.

[0029] Furthermore, biochar-based fertilizers are applied by trenching or hole application, with a trench or hole depth of 15-20 cm, and then covered with soil after application.

[0030] Specifically, based on the tea garden soil quality grades obtained above, determine the precise application rate of biochar-based fertilizer. If the soil quality is classified as average, apply biochar-based fertilizer at a rate of 6,000 to 8,500 kg per hectare. If the soil quality is classified as poor, apply biochar-based fertilizer at a rate of 7,000 to 9,000 kg per hectare. Regarding the timing of application, it should be arranged according to the growth and development patterns of tea trees. Biochar-based fertilizer can be applied as a base fertilizer, specifically after the tea trees enter dormancy in autumn, usually between October and November; or before the tea trees begin to sprout in spring, usually between February and March. Alternatively, biochar-based fertilizer can be applied as a top dressing, specifically after the spring tea harvest, usually between May and June; or after the summer tea harvest, usually between July and August. Base fertilizer and top dressing can be applied individually or in combination. Regarding application methods, either trench application or hole application can be used. When using trench application, dig trenches along the direction of the tea rows. When using hole application, dig holes around the tea plants. Regardless of whether trench or hole application is used, the depth of the trench or hole should be controlled between 15 and 20 centimeters. After evenly applying the pre-weighed biochar-based fertilizer of the corresponding amount into the trench or hole, immediately cover it with soil, completely covering the fertilizer and compacting it to avoid nutrient loss.

[0031] S4. During the monitoring period following fertilization, measure the aboveground biomass of the tea trees. Based on aboveground biomass And calculate the carbon storage of tea trees by selecting the appropriate carbon storage model based on the age of the tea trees: If the tea tree is a young tea tree, a model is used. calculate; If the tea tree is a mature tea tree, a model is used. calculate; Among them, young tea trees refer to tea trees with an age of 0-2 years, and mature tea trees refer to tea trees with an age of 3-25 years.

[0032] Furthermore, in S4, the carbon storage model for young tea trees... coefficient of determination ; Carbon storage model of mature tea trees coefficient of determination 95.

[0033] Specifically, within one monitoring cycle following the application of biochar-based fertilizer, representative quadrats or sample plants are selected from the target tea garden. The aboveground biomass is measured based on the actual growth of the tea trees. Aboveground biomass includes all living tissues of the tea tree above ground, including stems and leaves, but excludes litter. The measured aboveground biomass is recorded as follows: For young tea trees, their aboveground biomass The unit is usually grams per plant; for mature tea trees, the aboveground biomass The unit is usually tons per hectare; Based on the planting age of the tea trees, a corresponding carbon storage mathematical model is selected for calculation. Tea trees aged 0 to 2 years are defined as young tea trees, and tea trees aged 3 to 25 years are defined as mature tea trees. If the tea tree being measured is a young tea tree, the young tea tree carbon storage model is used. This model is a linear model, and its specific formula is as follows: , in the formula The carbon storage of young tea trees is estimated, expressed in grams per tree. This model is based on the analysis of historical measured biomass data from zero- to two-year-old tea trees, and its coefficient of determination for goodness of fit is [value missing]. Not less than 0.989; If the tea trees being measured are mature tea trees, then the carbon storage model for mature tea trees is used. This model is a quadratic nonlinear model, and its specific formula is as follows: , in the formula The carbon storage of mature tea trees is estimated, in tons per hectare. Indicates aboveground biomass The square of the value. This model is based on the analysis of historical measured data on the biomass of tea trees aged three to twenty-five years, and its coefficient of determination for goodness of fit is... Not less than 0.995; The construction and validation of the two carbon storage models mentioned above are based on publicly available research literature and experimental data. The establishment of the young tea tree model and the mature tea tree model comprehensively referenced measured biomass data from multiple papers, including "Preliminary Report on the Growth Dynamics of One-Year-Old Seedling Tea," "Correlation between Root and Crown Growth of Tea Trees and Its Practical Significance," and the paper "Study on the Accumulation of Aboveground Biomass and Nutrient Requirement Patterns of Tea Trees under Field Conditions," which recorded biomass data from tea trees of different ages. Furthermore, the model validation also utilized field monitoring data from the Guangxi Tea Experiment Station on tea varieties such as Guiqing, Lingyun Baihao, and Meizhan. Thirty-three measured samples were used for the validation of the young tea tree model, and six measured samples were used for the validation of the mature tea tree model. Validation showed that the coefficient of determination, root mean square error, and mean absolute error of the models all met the accuracy requirements, enabling non-destructive and accurate estimation of tea tree carbon storage based on aboveground biomass.

[0034] S5. Measure the soil bulk density, soil depth, soil organic carbon content, and gravel content of the tea garden. Based on the soil bulk density, soil depth, soil organic carbon content, and gravel content, calculate the soil carbon storage of the tea garden.

[0035] Furthermore, in S5, soil carbon storage Calculated using the following formula: =[V×H×O×(1-G)]×S; Where V is the soil bulk density, H is the soil depth, O is the soil organic carbon content, G is the gravel content, and S is the tea garden area.

[0036] Specifically, within the target tea garden, select the same sampling points as S2 or representative new sampling points to conduct soil profile surveys and sampling to obtain the parameters needed to calculate soil carbon storage. First, determine the soil bulk density, denoted as V, in kilograms per cubic meter. Then, determine the soil depth to be calculated, denoted as H, in meters. Typically, the soil depth considered when calculating soil carbon storage is 0 to 30 centimeters, or determined according to actual needs. Next, determine the soil organic carbon content within this soil layer, denoted as O, in kilograms per kilogram. Simultaneously, determine the gravel volume percentage content within this soil layer, denoted as G, in percentage. After obtaining the above parameters, the soil carbon storage in the tea garden is calculated using the following formula. : Tea garden soil carbon storage The product is equal to the soil bulk density V multiplied by the soil depth H multiplied by the soil organic carbon content O multiplied by one minus the gravel content G, and finally multiplied by the total tea garden area S, i.e.: ; Wherein, the total tea garden area S is in square meters, and the calculated soil carbon storage is... The unit is kilogram; By following the steps above, the soil carbon storage at a specific soil depth within a designated tea garden area can be calculated based on the measured soil physical and chemical properties.

[0037] Furthermore, the monitoring cycle is once a year, or once every 3-5 years.

[0038] Specifically, to systematically evaluate the carbon sequestration and carbon sink enhancement effects of biochar-based fertilizer application, a periodic monitoring and evaluation system needs to be established. The monitoring and evaluation cycle should be set based on management needs and the rate of carbon sink change. In practice, a short-term assessment cycle can be selected. The short-term assessment is conducted annually. At the same time each year, steps S4 and S5 are repeated: measuring the aboveground biomass of the tea trees and calculating the carbon storage of the tea trees, simultaneously measuring soil parameters and calculating soil carbon storage, and then calculating the total annual carbon sequestration of the tea garden to track annual carbon sequestration dynamics. Alternatively, a medium- to long-term assessment cycle can be selected. The medium- to long-term assessment is conducted every three to five years. Within this cycle, at the end of the third or fifth year, all measurements and calculations in steps S4 and S5 are performed, and the total carbon sequestration of the tea garden within this three- to five-year cycle is calculated to assess the long-term effects and trends of carbon sequestration technology. The choice of monitoring cycle depends on specific management objectives. Short-term assessments are suitable for refined management and annual carbon sequestration measurement needs; medium- and long-term assessments focus more on evaluating the sustainability and stability of carbon sequestration measures and reducing the cost of frequent monitoring. By implementing the aforementioned periodic monitoring, total carbon sequestration data of tea gardens over time can be obtained. By calculating the difference in total carbon sequestration between adjacent monitoring periods, the net carbon sequestration of the tea garden during that period can be determined, i.e., the carbon sequestration increment, which is used to assess the actual carbon sequestration and enhancement benefits of biochar-based fertilizer application and other management measures.

[0039] S6. The carbon storage of tea trees calculated in S4 is converted into the carbon storage per unit area or the total carbon storage of the entire tea garden according to the number of tea trees or area of ​​the tea garden. Then, it is added to the carbon storage of the tea garden soil calculated in S5 and converted to the same unit standard to obtain the total carbon sink of the tea garden.

[0040] Specifically, for young tea gardens, their carbon storage is determined by the model. The calculation yields the carbon storage per individual plant, expressed in grams of carbon per plant. This needs to be converted to a total amount or unit area comparable to soil carbon storage. The conversion is done by multiplying this value by the total number of tea plants N in the tea garden, and then dividing by... This yields the total carbon storage of young tea trees in "tons of carbon." If a value per unit area is required, divide the total by the tea garden area S; for mature tea gardens, the carbon storage is determined by the model. The calculated result is the carbon storage per unit area, expressed in tons of carbon per hectare. This value can be directly used in subsequent calculations. Regarding soil carbon storage: Soil carbon storage Calculations show that the initial result is in kilograms of carbon, when S is in square meters. To standardize the process, it is necessary to... Divide by 1000 to convert to the total amount in "tons of carbon". If you need the value per unit area, divide this total amount by the tea garden area S to get the soil carbon storage per hectare in tons of carbon. After converting both tea tree carbon storage and soil carbon storage to the same unit of measurement, such as expressing them both as "tons of carbon" or "tons of carbon per hectare," the two are arithmetically added together to obtain the total carbon sequestration of the tea garden. The general formula for calculation is: ; in, and These are the tea tree carbon storage value and soil carbon storage value, respectively, after the standardized conversion in the first step mentioned above, with consistent units. Through the standardization and summation operations described above, the final value obtained is the total carbon sequestration of the target tea garden ecosystem at a specific monitoring time point. This total carbon sequestration comprehensively reflects the total carbon sequestration of the two major carbon pools: tea tree vegetation and tea garden soil, and is a core indicator for assessing the overall carbon sequestration and enhancement effect of the tea garden. Furthermore, by comparing the total carbon sequestration calculated for different monitoring periods, the difference represents the net carbon sequestration of the tea garden during that period, which can be directly used to assess the actual carbon sequestration enhancement effect of this method and its supporting management measures.

[0041] Furthermore, the method also includes supporting management steps: In tea gardens, implement grass cultivation and intercropping with green manure, while maintaining soil moisture content at 70%-80% of field capacity.

[0042] Specifically, in order to optimize the application environment of biochar-based fertilizers and synergistically enhance the carbon sequestration and absorption capacity of the tea garden ecosystem, it is necessary to implement supporting measures for tea garden soil management and water regulation. In terms of soil management, the practice of using ground cover in tea gardens is implemented. Specifically, suitable herbaceous plants are artificially sown or naturally preserved in the bare open spaces between tea rows to form a living ground cover. Simultaneously, the intercropping technique of green manure in tea gardens is promoted, which involves selectively intercropping specific green manure crops in the tea garden. Green manure crops should ideally be varieties with strong nitrogen-fixing capacity and a high carbon-to-nitrogen ratio, such as legume green manure or cruciferous green manure. The cultivation and management of green manure crops should be carried out in accordance with the Guangxi local standard DB45 / T 2247 "Technical Regulations for Green Manure Cultivation in Organic Tea Gardens". In terms of water management, water-saving irrigation is implemented based on the water requirements of tea trees, climatic conditions, and soil moisture. The specific goal is to maintain the soil moisture content in the tea garden at 70% to 80% of field capacity. By maintaining appropriate soil moisture, the needs of normal tea tree growth and the release of nutrients from biochar-based fertilizers are met, while also promoting the full integration and interaction between biochar-based fertilizers and the tea garden soil, thereby enhancing the soil's water retention and fertilizer retention capacity and carbon sequestration potential. The aforementioned supporting management measures, together with the application of biochar-based fertilizers, constitute a complete agronomic technology system to promote carbon sequestration and carbon sink enhancement in tea gardens.

[0043] Furthermore, the method also includes security monitoring steps: Heavy metal testing was conducted on the biochar-based fertilizer, and the pH value and heavy metal content of the tea garden soil were monitored regularly.

[0044] Specifically, to ensure that the long-term application of biochar-based fertilizers will not have a negative impact on the ecological environment of tea gardens, an ecological safety monitoring procedure needs to be established and implemented. This procedure includes two aspects: product safety monitoring and soil environmental monitoring. Regarding product safety monitoring, each batch of biochar-based fertilizer prepared for application must be tested for heavy metal content and other potentially harmful substances in accordance with relevant fertilizer safety standards. Only batches whose test results meet the national or industry standards for heavy metal limits in fertilizers can be used in tea gardens. Simultaneously, product quality records are established to achieve quality traceability from raw materials to finished products. Regarding soil environmental monitoring, a regular soil environmental monitoring plan needs to be developed for tea gardens that have applied biochar-based fertilizers. According to the plan, soil samples should be collected regularly from the tea gardens to monitor changes in key soil environmental indicators. Key indicators should include at least soil pH and the content of heavy metals such as lead, cadmium, chromium, arsenic, and mercury. By comparing monitoring data before and after application, the impact of biochar-based fertilizer application on the soil pH balance and heavy metal accumulation in tea gardens can be assessed to ensure soil environmental health and the safety of tea products. To ensure a healthy growing environment for tea trees, soil pH control is also necessary: ​​regularly monitor the soil pH after applying biochar-based fertilizer. When the soil pH continuously rises and exceeds 6.0 or 6.5, control measures should be taken, including but not limited to: reducing the amount of biochar-based fertilizer applied by 20%-30% in the next fertilization cycle; adding appropriate amounts of physiologically acidic substances, such as sulfur or ammonium sulfate, to the subsequently prepared biochar-based fertilizer for neutralization pretreatment; or increasing the application of acidic organic fertilizer to stabilize the soil pH within the suitable range for tea tree growth, between pH 4.5 and 5.5.

[0045] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for carbon sequestration and enhancement in tea gardens without damaging tea trees, characterized in that, Includes the following steps: S1. Agricultural waste is pyrolyzed at 400-600℃ to obtain biochar, which is then formulated into a biochar-based fertilizer with a biochar content ≥30%, an organic matter content ≥30%, a pH value of 7.0-9.0, and a total nutrient content ≥8%. S2. Determine the soil organic matter, cation exchange capacity and soil bulk density of the tea garden to be applied, and calculate the comprehensive soil quality coefficient using the modified Nemerow comprehensive index method. Based on this coefficient, the soil quality is classified into general or poor grades. S3. Based on the soil quality grade classified in S2, apply at a rate of 6000-8500 kg / ha to tea gardens with average soil quality, or at a rate of 7000-9000 kg / ha to tea gardens with poor soil quality. S4. During the monitoring period following fertilization, measure the aboveground biomass of the tea trees. Based on the aboveground biomass And calculate the carbon storage of tea trees by selecting the appropriate carbon storage model based on the age of the tea trees: If the tea tree is a young tea tree, a model is used. calculate; If the tea tree is a mature tea tree, a model is used. calculate; Among them, young tea trees refer to tea trees with an age of 0-2 years, and mature tea trees refer to tea trees with an age of 3-25 years; S5. Measure the soil bulk density, soil depth, soil organic carbon content and gravel content of the tea garden, and calculate the soil carbon storage of the tea garden based on the soil bulk density, soil depth, soil organic carbon content and gravel content. S6. The carbon storage of tea trees calculated in S4 is converted into the carbon storage of a specified unit area or the total carbon storage of the entire tea garden according to the number of tea trees or the area of ​​the tea garden. Then, it is added to the carbon storage of the tea garden soil calculated in S5 and converted to the same unit standard to obtain the total carbon storage of the tea garden.

2. The method for carbon sequestration and enhancement in tea gardens without damaging tea trees according to claim 1, characterized in that, The agricultural waste is at least one of tea branches, mulberry branches, or sugarcane leaves.

3. The method for carbon sequestration and enhancement in tea gardens without damaging tea trees according to claim 1, characterized in that, In S2, the standard for classifying soil grades based on the comprehensive soil quality coefficient P is as follows: When the p-value is between 1.8 and 0.9, it is classified as a general level; When the P-value is less than 0.9, it is classified as poor.

4. The method for carbon sequestration and enhancement in tea gardens without damaging tea trees according to claim 1, characterized in that, In S3, the application time of the biochar-based fertilizer is as follows: It can be applied as a base fertilizer during the autumn dormancy period of tea trees or before the spring budding, and as a top dressing fertilizer after the spring tea harvest or the summer tea harvest.

5. The method for carbon sequestration and enhancement in tea gardens without damaging tea trees according to claim 1, characterized in that, The biochar-based fertilizer is applied by trenching or hole application, with a trench or hole depth of 15-20 cm, and then covered with soil.

6. The method for carbon sequestration and enhancement in tea gardens without damaging tea trees according to claim 1, characterized in that, Carbon storage model for young tea trees in S4 coefficient of determination ; Carbon storage model of mature tea trees coefficient of determination 95.

7. The method for carbon sequestration and enhancement in tea gardens without damaging tea trees according to claim 1, characterized in that, In S5, the soil carbon storage Calculated using the following formula: =[V×H×O×(1-G)]×S; Where V is the soil bulk density, H is the soil depth, O is the soil organic carbon content, G is the gravel content, and S is the tea garden area.

8. A method for carbon sequestration and enhancement in tea gardens without damaging tea trees, as described in claim 1, characterized in that, The monitoring cycle is once a year, or once every 3-5 years.

9. A method for carbon sequestration and enhancement in tea gardens without damaging tea trees, as described in claim 1, characterized in that, The method also includes supporting management steps: In tea gardens, implement grass cultivation and intercropping with green manure, while maintaining soil moisture content at 70%-80% of field capacity.

10. A method for carbon sequestration and enhancement in tea gardens without damaging tea trees, as described in claim 1, characterized in that, The method also includes a security monitoring step: The biochar-based fertilizer was tested for heavy metals, and the pH value and heavy metal content of the tea garden soil were monitored regularly.

Images