Camellia sinensis under-planting and water-fertilizer coupling soil improvement system and control method thereof

Abstract

This invention discloses a soil improvement system and control method for tea oil forest understory planting and water and fertilizer coupling, belonging to the field of soil improvement technology. The system includes a biological ecological layer, a three-dimensional interactive hardware layer, and a digital intelligent control layer. This invention constructs a soil improvement system that deeply integrates the biological ecological layer, the three-dimensional interactive hardware layer, and the digital intelligent control layer. Through the synergistic effect of understory vegetation cover and customized fertilizer and water supply, it effectively curbs soil erosion, achieves soil pH balance and increases organic matter content, significantly reduces soil bulk density and increases porosity. Addressing the differences in the vertical distribution of roots between tea oil and understory crops, a layered pipeline structure is adopted to achieve three-dimensional precise supply, eliminate nutrient competition, improve water and fertilizer utilization efficiency, and introduce multi-dimensional control logic to dynamically adjust the water and fertilizer coupling ratio, significantly increasing the fruit setting rate of tea oil. Combined with intercropping of economic crops under the forest, the total output value per unit area is significantly higher than that of the traditional model, achieving the goal of high yield, improved quality, and increased efficiency.

Description

Technical Field

[0001] This invention relates to the field of soil improvement technology, and in particular to a soil improvement system and control method that couples water and fertilizer for planting under Camellia oleifera forests. Background Technology

[0002] Camellia oleifera Abel. is an important woody oilseed tree species in southern my country, widely planted in hilly red soil areas such as Jiangxi, Hunan, Guangdong, and Guangxi. In recent years, to increase camellia oleifera yield, some regions have begun to promote the application of automated or semi-automated integrated water and fertilizer management systems. The closest existing technology usually adopts a monoculture intelligent irrigation system, the basic structure of which includes: a water source hub, a head pump station (including fertilizer tanks and a filtration system), a main water supply pipeline, branch pipelines, and drip irrigation tape or micro-sprinkler tape laid between the rows of camellia oleifera trees. This technology mainly uses a single-layer drip irrigation pipeline laid at the base of the tree trunk to deliver water and dissolved fertilizer based on preset timers or simple soil moisture sensor feedback.

[0003] However, the aforementioned existing technologies have the following significant drawbacks in practical applications, especially in acidic red soil hilly areas: (1) Poor soil improvement effect and fragile ecosystem. Existing technologies are mostly designed for "clean forests" (monoculture forests after weeding). Due to the lack of understory vegetation cover, the surface is directly exposed, resulting in serious soil erosion. Furthermore, long-term drip irrigation with single chemical fertilizers can easily lead to increased soil acidification and compaction, and cannot fundamentally improve the physical and chemical properties of red soil.

[0004] (2) Mismatch between water and fertilizer distribution and crop needs (low coupling). Existing irrigation pipelines are mostly single-layered and fixed. However, in complex understory planting patterns (such as intercropping camellia with legume green manure or medicinal herbs), the deep root system of camellia and the shallow root system of understory crops have different requirements for water and nutrients. Existing technology cannot achieve precise supply in layers and stages, which often leads to nutrient competition between understory crops and main trees, and even causes root rot or nutrient loss due to excessive water.

[0005] (3) Intelligent regulation lacks biological feedback. Existing digital management is mostly based on physical sensors (such as environmental temperature and humidity), without taking into account the impact of increased biomass on soil carbon and nitrogen cycles under the understory planting model. The system cannot automatically adjust the fertilizer and water ratio according to the phenological stage of the understory crops, resulting in resource waste and making it difficult to achieve the expected goals of high yield, improved quality and efficiency.

[0006] The aforementioned shortcomings mainly stem from limitations in the structural design of existing technologies: First, the delivery structure is simplistic, possessing only a single-level water outlet device and lacking a layered, three-dimensional delivery structure to address the differences in root distribution across vertical spaces; second, the feedback control logic loop is incomplete, as the logic framework of existing controllers does not include a three-dimensional correlation model encompassing "understory vegetation - soil environment - main tree growth"; and third, there is a lack of bio-physical integration design, with existing systems completely separating water and fertilizer pipelines from the soil improvement process. Therefore, this invention proposes a soil improvement system and its control method that couples tea oil forest understory planting with water and fertilizer to address the problems existing in the prior art. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to propose a soil improvement system and its control method that couples planting under Camellia oleifera forests with water and fertilizer, in order to solve the problems of poor soil improvement effect, mismatch in spatial distribution of water and fertilizer, and lack of ecological synergistic feedback in intelligent regulation in the prior art.

[0008] To achieve the objectives of this invention, the invention is implemented through the following technical solution: a soil improvement system for tea oil forest understory planting coupled with water and fertilizer, comprising a biological ecological layer, a three-dimensional interactive hardware layer, and a digital intelligent control layer, wherein: The biological ecological layer consists of cover crops (such as legume green manure or Chinese herbal medicines) planted between the rows of camellia oleifera. Its main function is to improve soil compaction, reduce water evaporation, and prevent soil erosion. The 3D interactive hardware layer includes two types of core hardware: Multi-parameter soil monitor for collecting real-time soil parameters; The layered pipeline structure is used to transport water and fertilizer. Specifically, it includes a deep irrigation pipe for the main forest trees (buried in a deeper soil layer to specifically transport water and fertilizer to the deep root system of the camellia trees, avoiding competition with shallow-rooted crops) for transporting water and fertilizer to the second soil layer where the root system of the understory crops is located (buried in a shallower soil layer (second depth) to transport water and fertilizer to the shallow root system of the understory crops). The depth of the first soil layer is greater than the depth of the second soil layer. The digital intelligent control layer includes a controller and a cloud server. The controller generates differentiated water and fertilizer regulation instructions based on real-time soil parameters collected by a multi-parameter soil monitor and a preset water and fertilizer requirement coupling model of camellia oleifera-understory crops. It then drives the deep irrigation pipes of the main forest trees and the shallow irrigation pipes of the understory crops to perform stratified water and fertilizer supply. The cloud server is connected to the controller and is used for data storage and management.

[0009] Further improvements include: the first soil layer is 20cm to 30cm deep (the concentrated area of ​​Camellia oleifera root absorption), the second soil layer is from the surface to 5cm deep (the root zone of understory crops), the main tree deep irrigation pipe is equipped with pressure-compensating drippers (to ensure water supply balance for each tree), and the understory crop shallow irrigation pipe uses microporous seepage irrigation to deliver water and fertilizer (slow and even water supply, reducing surface evaporation).

[0010] A further improvement is that the multi-parameter soil monitor is used to collect soil parameters at depths of 10cm and 30cm in the vertical direction, respectively. The soil parameters include temperature, humidity, pH value, and nitrogen, phosphorus, and potassium (NPK) concentrations.

[0011] Further improvements are made in that: the controller is used to receive soil parameters transmitted by the multi-parameter soil monitor through a 4-20mA signal interface or an RS485 bus, calculate the water and fertilizer dilution ratio (e.g., 1:200 to 1:500) according to the water and fertilizer demand coupling model, and generate differentiated water and fertilizer control instructions based on the calculation results.

[0012] A further improvement is that the digital intelligent control layer also includes: The main hub, including an automatic fertilizer applicator, a multi-stage filtration device, a pressure compensation pump, and a fertilizer mixing tank, is used to receive control commands from the controller and adjust the fertilizer and water flow rate through pulse width modulation technology. The drone collaborative control module receives phenological periods (such as flowering period and fruit setting period) from the controller and automatically generates drone operation instructions. The drone operation instructions include starting the drone equipped with a centrifugal nozzle to spray in the early morning or evening when the wind speed is less than 3m / s, and controlling the particle size of the liquid to be between 100μm and 150μm.

[0013] A further improvement is that the drone collaborative control module is equipped with a foliar fertilizer formula, which is used by the drone collaborative control module during spraying and includes, by mass fraction: Urea, accounting for 0.3% to 0.5%; Potassium dihydrogen phosphate, accounting for 0.2% to 0.3%; Borax or boric acid, accounting for 0.1% to 0.15%; Magnesium sulfate, accounting for 0.05%; Trace element chelate solution, accounting for 0.02%; Water, remaining amount.

[0014] A method for controlling a soil improvement system that combines tea tree oleifera understory planting with water and fertilizer coupling includes the following steps: S1, Data Acquisition Real-time soil nitrogen, phosphorus, and potassium concentrations and pH values ​​are obtained using a multi-parameter soil monitoring instrument. S2, Decision Analysis Based on the preset water and fertilizer requirement coupling model of camellia oleifera-understory crops and the obtained soil nitrogen, phosphorus and potassium concentrations and pH values, the target water and fertilizer dilution ratio for the day is calculated. When the soil pH value is determined to be lower than the preset threshold, an instruction to add soil conditioner is automatically generated. S3, Layered Execution According to the target water and fertilizer dilution ratio and the instructions for adding soil conditioner, the deep irrigation pipes of the main forest trees are activated to deliver the first water and fertilizer, and the shallow irrigation pipes of the understory crops are activated to deliver the second water and fertilizer. The composition or concentration of the first water and fertilizer and the second water and fertilizer are different (the first water and fertilizer is supplied to camellia, and the second water and fertilizer is supplied to the understory crops). S4, Feedback Optimization After a preset observation period (e.g., 48 hours), the numerical changes of the multi-parameter soil monitoring instrument are acquired, and the fertilization plan for the next cycle is updated based on the changes, thus achieving closed-loop adaptive control.

[0015] Further improvements are made in S3, where the deep irrigation pipes of the main trees are activated first to deliver the first water and fertilizer, and then the shallow irrigation pipes of the understory crops are activated to deliver the second water and fertilizer. The mass fractions of phosphorus and potassium in the first water and fertilizer are greater than the mass fraction of nitrogen (to promote flowering and fruit setting). The second water and fertilizer is an organic nutrient solution (to prevent excessive growth and promote soil health).

[0016] A further improvement is made in S4, where the preset observation time is 48 hours, and the update of the fertilization plan for the next cycle includes: automatically adjusting the target water-fertilizer dilution ratio and the amount of soil conditioner added based on the numerical changes of the multi-parameter soil monitor.

[0017] The beneficial effects of this invention are as follows: This invention constructs a soil improvement system that deeply integrates a biological ecological layer, a three-dimensional interactive hardware layer, and a digital intelligent control layer. Through the synergistic effect of understory vegetation cover and customized fertilizer and water supply, it effectively curbs soil erosion in red soil hilly areas. It also utilizes the integration of biomass degradation and water and fertilizer regulation to achieve soil pH balance and continuous improvement of organic matter content, significantly reducing soil bulk density and significantly increasing porosity. At the same time, considering the vertical spatial distribution differences between the roots of Camellia oleifera and the roots of understory crops, a layered pipeline structure is used to provide a layered three-dimensional supply that takes into account both deep main trees and shallow intercrops, eliminating nutrient competition and improving fertilizer utilization and water production efficiency. In addition, a multi-dimensional control logic based on biofeedback and environmental monitoring is introduced, and the integration of mechanized production, digitalized management, and green prevention and control is achieved by dynamically adjusting the water and fertilizer coupling ratio. The fruit setting rate of Camellia oleifera is significantly higher than that of conventional single-layer irrigated forests. Finally, the additional economic value generated by understory intercropping crops, combined with the increased yield of Camellia oleifera, makes the total output value per unit area significantly higher than that of the control group, achieving the production goal of high yield, improved quality, and increased efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the framework structure of the soil improvement system for planting under Camellia oleifera forests and coupling water and fertilizer according to the present invention. Detailed Implementation

[0019] The technical solutions of 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.

[0020] It should be noted that the technical means not described in detail in the following embodiments are all conventional means in the art, are not the key points of the invention, and will not be elaborated upon.

[0021] The organic nutrient solution used in this invention refers to a water-soluble liquid fertilizer containing organic matter, including but not limited to humic acid solution, alginic acid solution, amino acid solution, molasses fermentation solution, etc. The specific dilution ratio of each type of organic nutrient solution can be adjusted according to the crop type, growth stage and soil fertility status, which can be achieved without creative labor.

[0022] Example 1 according to Figure 1 As shown, this embodiment provides a soil improvement system that couples water and fertilizer for understory planting of Camellia oleifera. Taking a Camellia oleifera planting base in Meizhou City, Guangdong Province as an example, the Camellia oleifera varieties are Cenruan No. 2 and Cenruan No. 3, and the planting density is 3m×3m, as detailed below: 1. Establishment of the biological ecosystem Leave a working strip approximately 1.5m to 2m wide between the rows of camellia oleifera trees. Plant leguminous green manure (such as white clover) or economically valuable Chinese medicinal herbs (such as coralberry) within the working strip. The root exudates of the cover crops can degrade soil compaction, and the plant cover can reduce water evaporation and soil erosion.

[0023] 2. Deployment of the 3D Interactive Hardware Layer First, topographic mapping is carried out: for hilly terrain, a digital elevation model (DEM) is established by scanning with drones to determine the layout and direction of the main and branch pipes.

[0024] The layered piping structure is laid out as follows: Deep irrigation pipes for main trees: Buried 20cm-30cm underground along the planting rows of camellia trees, with a pipe diameter of 16mm. Each camellia tree is equipped with a pressure-compensating dripper with a flow rate of 2L / h. This depth corresponds to the soil layer where the absorbing roots of the camellia trees are concentrated.

[0025] Shallow irrigation pipes for understory crops: These pipes are laid on the ground or buried 5cm deep, with a diameter of 16mm. They are microporous drip irrigation pipes with a pore size of 0.5μm and a seepage rate of 5L / h per meter. This method ensures moisture in the root zone of understory crops while reducing surface evaporation.

[0026] Multi-parameter soil monitoring instruments are arranged in a quincunx pattern, with each 667m² section containing one or more soil samples. 2 Five monitoring points were set up. The probe of each monitoring instrument was inserted vertically into the soil to collect temperature, humidity, pH value, and nitrogen, phosphorus, and potassium (NPK) concentrations at depths of 10 cm and 30 cm, respectively. The sensor data was transmitted to the controller via an RS485 bus.

[0027] The main control unit is installed in the pump house and includes an automatic fertilizer applicator (fertilizer pump flow rate 5-50 L / h), a disc filter (120 mesh), a pressure compensation pump (60 m head), and a fertilizer mixing tank (200 L capacity). The fertilizer applicator receives PWM (pulse width modulation) signals from the controller to adjust the fertilizer solution injection ratio.

[0028] 3. Configuration of the digital intelligent control layer The controller uses a Siemens S7-1200 PLC, equipped with a 4G communication module, and establishes an MQTT connection with a cloud server (Alibaba Cloud). The controller incorporates a coupled water and fertilizer requirement model for camellia oleifera and its understory crops. The specific implementation of this model is as follows: The model is a decision-making algorithm based on multi-factor weighted fusion. Input parameters include: soil moisture content (%) at depths of 10cm and 30cm, soil pH, available nitrogen (mg / kg), available phosphorus (mg / kg), and available potassium (mg / kg), as well as pre-calibrated phenological parameters (flowering, fruit setting, oil accumulation, and dormancy stages, with corresponding weight coefficients of 0.8, 1.2, 1.0, and 0.5, respectively). Model output parameters include: target fertilization rate (L / tree / application) for deep irrigation pipes in main forest trees and target fertilization rate (L / m²) for shallow irrigation pipes in understory crops. 2 / time), the target water-fertilizer dilution ratio (1:X) in the fertilizer mixing tank.

[0029] Example of a decision rule: When the soil pH is below 5.0, physiological alkaline fertilizer (such as calcium nitrate) will be added automatically. The amount added (kg / mu) will be calculated according to the following formula: Amount added = 2.5 × (5.0 - current soil pH).

[0030] Flowering period (October-November): The application rate of potassium dihydrogen phosphate is increased to 0.3%-0.5%, and foliar fertilizer is sprayed by drone module at the same time.

[0031] During the fruit-setting period (May-June): prioritize the deep irrigation pipes for the main trees, and start the shallow irrigation pipes for the understory crops after a 2-hour interval.

[0032] The controller implements the above rules through a ladder logic program. The cloud server is used to store historical data, remotely monitor, and update model parameters.

[0033] Drone Collaborative Control Module: Equipped with a DJI T30 agricultural drone and a centrifugal spray nozzle. The controller automatically sends operation instructions to the drone's ground base station based on the phenological period (e.g., the overlapping flowering and fruiting period from October 20th to November 10th of the current year). The drone sprays foliar fertilizer at a low volume (8L / acre) in the early morning (6:00-8:00) or late afternoon (17:30-19:00) when the wind speed is less than 3m / s, with a flight altitude of 1.5m-2m, a spray width of 5m, and a pesticide particle size of 100-150μm.

[0034] The foliar fertilizer formula, by mass fraction, is as follows: urea 0.4%, potassium dihydrogen phosphate 0.25%, borax 0.12%, magnesium sulfate 0.05%, trace element chelate solution (containing Zn=5%, Mo=0.5%) 0.02%, with the balance being water. Dissolve the above components in water before use.

[0035] Example 2 This embodiment provides a control method for a soil improvement system that combines camellia oleifera understory planting with water and fertilizer coupling. During the overlapping period of camellia oleifera flowering and fruiting (late October), the system operation steps are as follows: S1, Data Acquisition The multi-parameter soil monitor collects data every 2 hours. The data obtained at 8:00 on the same day are as follows: soil moisture content at 10cm depth 18.6%, soil moisture content at 30cm depth 15.2%, pH at 10cm depth 4.8, pH at 30cm depth 5.0, available nitrogen 85mg / kg, available phosphorus 12mg / kg, and available potassium 90mg / kg.

[0036] S2, Decision Analysis The controller invokes the coupled model. Because the pH value is below 5.0, the model automatically generates an instruction to add soil conditioner (physiologically alkaline fertilizer) at a rate of 3.5 kg / acre. Based on the phenological period (overlapping flowering and fruiting period) and soil phosphorus and potassium levels, the model calculates the target water-fertilizer dilution ratio to be 1:300 (i.e., adding 3.33 g of mixed fertilizer per liter of water). The fertilizer formula for deep irrigation pipes in the main forest is a water-soluble compound fertilizer with a high phosphorus and potassium ratio (N:P2O5:K2O=15:30:15), while the fertilizer formula for shallow irrigation pipes in understory crops is a low-concentration organic nutrient solution (alginic acid + humic acid, diluted 1:500).

[0037] S3, Layered Execution At 9:00, the controller sends a command to the head hub to start the main forest deep irrigation pipe system. The pressure compensation pump starts, the fertilizer mixing tank mixes fertilizer at a ratio of 1:300, and drips 5L of fertilizer water onto each camellia tree through the main forest deep irrigation pipe, which takes 40 minutes.

[0038] At 10:00, the deep irrigation pipes for the main trees were closed.

[0039] At 10:30, the controller activated the shallow irrigation pipes for understory crops, delivering organic nutrient solution at a ratio of 1:500. Irrigation lasted 30 minutes, with a total water consumption of 1.5 cubic meters per acre. 3 .

[0040] Simultaneously, the controller sent an operation command to the drone module at 17:30 that day. The drone took off automatically and sprayed the foliar fertilizer described in Example 1 at a dosage of 8L / acre according to the planned route, ensuring that the leaves of each camellia oleifera plant were evenly coated on both sides.

[0041] S4, Feedback Optimization Forty-eight hours later (8:00 AM on the fourth day), sensor data showed that the pH value at a depth of 10cm rose to 5.2, and the pH value at a depth of 30cm rose to 5.3. Available phosphorus and available potassium increased to 15mg / kg and 98mg / kg, respectively. Based on the difference between the two data points, the controller automatically learned and adjusted the fertilization plan for the next cycle: the soil conditioner dosage was adjusted to 2.8kg / acre, the phosphorus-potassium ratio in the deep irrigation fertilizer for main trees was slightly reduced (N:P2O5:K2O adjusted to 15:28:15), and the concentration of organic nutrient solution in the shallow irrigation pipes for understory crops remained unchanged. The adjusted parameters were automatically uploaded to the cloud server and implemented in the next irrigation cycle (5 days later).

[0042] Comparative Example In a camellia oleifera planting base in Meizhou City, Guangdong Province, an experimental group (using the system of this invention) and a control group (using conventional single-layer drip irrigation and clean cultivation management) were set up. Each group covered an area of ​​1 mu (approximately 0.16 acres), and all camellia oleifera trees were of the Cenruan No. 3 variety, with an age of 8 years. The experimental period was one growing season (January 2023 to December 2023). The experimental results are as follows: (1) Soil physical properties: The soil bulk density in the experimental group was initially 1.45 g / cm³. 3 Reduced to 1.22 g / cm³ 3 The total porosity of the soil increased from 48% to 63%; the bulk density of the control group soil only increased from 1.46 g / cm³. 3 Reduced to 1.41 g / cm³ 3 The porosity did not change significantly.

[0043] (2) Soil chemical properties: The pH value of the experimental group increased from 4.7 to 5.3, and the organic matter content increased from 1.2% to 1.8%; the pH value of the control group decreased from 4.7 to 4.5, and the organic matter content decreased from 1.2% to 1.1%.

[0044] (3) Yield and quality of camellia: The average fruit setting rate of camellia in the experimental group was 22.5%, which was 23.6% higher than that of the control group (18.2%); the yield of fresh fruit per mu was 485 kg in the experimental group and 398 kg in the control group, which was 21.8% higher; the oil content of dried seeds was 42.5% in the experimental group and 40.1% in the control group.

[0045] (4) Comprehensive economic benefits: The experimental group's intercropping of *Gnaphalium affine* yielded 300 kg of fresh fruit per mu, increasing income by 1,800 yuan; the increased production of *Camellia oleifera* resulted in an additional income of 950 yuan; after deducting the new system costs (head unit, pipeline, drone services, etc., totaling 380 yuan / year), the net increase in income per mu was 2,370 yuan, which is 27.9% higher than the control group (conventional management yields approximately 8,500 yuan per mu).

[0046] The above experimental data fully demonstrate the significant effects of the system and method of this invention on soil improvement, efficient water and fertilizer utilization, and increased yield and income.

[0047] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A soil improvement system for under-planting of oil tea camellia with water and fertilizer coupling, characterized in that, include: The biological ecological layer consists of cover crops planted between the rows of camellia oleifera; The three-dimensional interactive hardware layer includes a multi-parameter soil monitor for collecting real-time soil parameters and a layered pipeline structure for transporting water and fertilizer. The layered pipeline structure includes a deep irrigation pipe for transporting water and fertilizer to the main forest trees in the first soil layer where the roots of the camellia oleifera trees are located, and a shallow irrigation pipe for transporting water and fertilizer to the understory crops in the second soil layer where the roots of the understory crops are located. The depth of the first soil layer is greater than the depth of the second soil layer. The digital intelligent control layer includes a controller and a cloud server. The controller generates differentiated water and fertilizer regulation instructions based on real-time soil parameters collected by a multi-parameter soil monitor and a preset water and fertilizer requirement coupling model of camellia oleifera-understory crops. It then drives the deep irrigation pipes of the main forest trees and the shallow irrigation pipes of the understory crops to perform stratified water and fertilizer supply. The cloud server is connected to the controller and is used for data storage and management.

2. The soil improvement system for underplanting Camellia oleifera with water and fertilizer coupling according to claim 1, characterized in that: The first soil layer has a depth of 20cm to 30cm, the second soil layer has a depth of 5cm from the ground surface, the main forest deep irrigation pipe is equipped with pressure-compensating drippers, and the understory crop shallow irrigation pipe uses microporous seepage irrigation to deliver water and fertilizer.

3. The soil improvement system for underplanting Camellia oleifera with water and fertilizer coupling according to claim 1, characterized in that: The multi-parameter soil monitoring instrument is used to collect soil parameters at depths of 10cm and 30cm in the vertical direction, respectively. The soil parameters include temperature, humidity, pH value, and nitrogen, phosphorus, and potassium concentrations.

4. The soil improvement system for underplanting Camellia oleifera with water and fertilizer coupling according to claim 1, characterized in that: The controller is used to receive soil parameters transmitted by the multi-parameter soil monitor, calculate the water and fertilizer dilution ratio according to the water and fertilizer demand coupling model, and generate differentiated water and fertilizer regulation instructions based on the calculation results.

5. The soil improvement system for tea oil forest understory planting and water and fertilizer coupling according to claim 1, characterized in that: The digital intelligent control layer also includes: The main hub, including an automatic fertilizer applicator, a multi-stage filtration device, a pressure compensation pump, and a fertilizer mixing tank, is used to receive control commands from the controller and adjust the fertilizer and water flow rate through pulse width modulation technology. The drone collaborative control module receives the phenological period prompt from the controller and automatically generates drone operation instructions. The drone operation instructions include starting the drone equipped with a centrifugal nozzle to spray in the early morning or evening when the wind speed is less than 3m / s, and controlling the particle size of the liquid to be between 100μm and 150μm.

6. The soil improvement system for underplanting Camellia oleifera with water and fertilizer coupling according to claim 5, characterized in that: The drone collaborative control module is equipped with a foliar fertilizer formula, which is used by the drone collaborative control module to apply the fertilizer during spraying. By mass fraction, the foliar fertilizer formula includes: 0.3%–0.5% urea, 0.2%–0.3% potassium dihydrogen phosphate, 0.1%–0.15% borax or boric acid, 0.05% magnesium sulfate, and 0.02% trace element chelate solution, with the balance being water.

7. The control method of a soil improvement system for under-planting Camellia oleifera with water and fertilizer coupling according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Real-time acquisition of soil nitrogen, phosphorus, potassium concentrations and pH value using a multi-parameter soil monitoring instrument; S2. Based on the preset water and fertilizer requirement coupling model of camellia oleifera-understory crops and the obtained soil nitrogen, phosphorus and potassium concentrations and pH values, calculate the target water and fertilizer dilution ratio for the day. When it is determined that the soil pH value is lower than the preset threshold, automatically generate an instruction to add soil conditioner. S3. Based on the target water and fertilizer dilution ratio and the instruction to add soil conditioner, start the deep irrigation pipes of the main forest trees to deliver the first water and fertilizer, and start the shallow irrigation pipes of the understory crops to deliver the second water and fertilizer. S4. After the preset observation time, acquire the numerical changes of the multi-parameter soil monitoring instrument, and update the fertilization plan for the next cycle based on the changes.

8. The control method for a soil improvement system with tea oleifera understory planting and water-fertilizer coupling according to claim 7, characterized in that: In step S3, the deep irrigation pipes for the main trees are first activated to deliver the first water and fertilizer, and then the shallow irrigation pipes for the understory crops are activated to deliver the second water and fertilizer. The mass fractions of phosphorus and potassium in the first water and fertilizer are both greater than the mass fraction of nitrogen. The second water and fertilizer is an organic nutrient solution.

9. The control method for a soil improvement system with tea oleifera understory planting and water-fertilizer coupling according to claim 7, characterized in that: In S4, the preset observation time is 48 hours, and the update of the fertilization plan for the next cycle includes: automatically adjusting the target water and fertilizer dilution ratio and the amount of soil conditioner added based on the numerical changes of the multi-parameter soil monitoring instrument.

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