A method and system for reducing nitrogen control in rice fields

Abstract

The application discloses a kind of rice field reduction nitrogen control method and system, comprising the following steps: detection data acquisition step: the recharge water of reservoir is carried out online nitrogen monitoring, obtains the nitrogen concentration and water flow of recharge into farmland water body, and the nitrogen concentration and flow of drainage water are monitored in field outlet;Central control unit processes data step: the detection data obtained in the previous step is processed using central control unit, obtains the nitrogen flux of recharge into field and the nitrogen flux of field drainage, and obtains the recharge water nitrogen input / output load and recharge water nitrogen element utilization rate, combines with crop growth period nitrogen supply target and soil nitrogen supply estimate, calculates topdressing amount or postpones timing;According to topdressing amount, control fertilizing device and solenoid valve, realize chemical nitrogen fertilizer reduction and irrigation and drainage coordination.The application reduces nitrogen loss and end discharge load under the premise of guaranteeing yield and quality, realizes the efficient green use of water and fertilizer resources.

Description

Technical Field

[0001] This invention belongs to the field of agricultural technology, and specifically relates to a method for controlling nitrogen reduction in paddy fields. Background Technology

[0002] Currently, there are common problems in paddy fields such as excessive nitrogen application, extensive irrigation and drainage, and direct discharge of tailwater, which lead to low nitrogen utilization, strong nitrogen loss, and increased risk of eutrophication of end-water bodies.

[0003] Chinese patent CN109302874B discloses a method for reducing nitrogen loss from paddy fields. In this method, tap water is injected into an F-type variable frequency magnetized water generator to obtain magnetized water with a magnetic susceptibility of 200-1000 Gauss, which is then used to irrigate the paddy fields. This solution, by treating tap water with magnetization before using it to irrigate paddy fields, effectively reduces nitrogen loss from the soil and has achieved good results.

[0004] The patent publication document with publication number CN107646270A discloses a method for reducing nitrogen volatilization loss in double-cropping paddy fields, which includes paddy field fertilization control measures and irrigation water regulation measures; wherein the paddy field fertilization control measures refer to reducing the application of controlled-release nitrogen fertilizer, and the irrigation water regulation measures refer to adopting a light-dry-wet alternating irrigation mode.

[0005] However, existing precision irrigation schemes mainly optimize the timing of water release based on water level / flow and weather data, and lack online quantification and utilization assessment of nitrogen content in recharge water, making it difficult to incorporate "nitrogen in water" into the total fertilizer balance. Summary of the Invention

[0006] The purpose of this patent is to propose a method and system for controlling nitrogen reduction in paddy fields, in order to solve the problems existing in the prior art.

[0007] The purpose of this patent is achieved as follows: a method for controlling nitrogen reduction in paddy fields, comprising the following steps:

[0008] Data collection steps: Online nitrogen monitoring of the recharge water in the reservoir to obtain the nitrogen concentration and flow rate of the water recharged into the farmland; monitoring the nitrogen concentration and flow rate of the discharged water at the field outlet.

[0009] The steps for data processing by the central control unit are as follows: The central control unit processes the detection data obtained in the previous step to obtain the nitrogen flux of re-irrigation into the field and the nitrogen flux of field discharge, and obtains the nitrogen input / output load of re-irrigation water and the nitrogen element utilization rate of re-irrigation water. This data will be combined with the nitrogen supply target of crop growth period and the estimated nitrogen supply of soil to calculate the amount of topdressing or the time sequence of fertilization.

[0010] The fertilizer application device and solenoid valve are controlled according to the amount of topdressing fertilizer, so as to achieve coordinated regulation of chemical nitrogen fertilizer reduction, re-irrigation and drainage.

[0011] Furthermore, when the monitored values ​​and water volume meet the threshold, the recharge process is initiated, and the water in the reservoir is recharged back into the farmland.

[0012] Furthermore, the nitrogen input / output load of the recharged water, the nitrogen utilization rate of the recharged water, the crop growth period demand curve, and the estimated soil nitrogen supply are all used as inputs to the fertilizer control algorithm to dynamically correct the subsequent topdressing amount and link the execution process of the solenoid valve / fertilizer application device.

[0013] As another aspect of the present invention, a system is proposed, comprising:

[0014] Central control unit;

[0015] Detection combination;

[0016] The detection combination includes:

[0017] Nitrogen concentration detector A is used to detect nitrogen concentration in farmland drainage.

[0018] Nitrogen concentration detector B is used to detect the nitrogen concentration in the water inside a reservoir.

[0019] A flow detector A, installed in a drainage channel, is used to detect the flow rate of drainage from farmland.

[0020] A flow detector B, installed in the recharge channel, is used to detect the recharge water flow rate.

[0021] A level gauge installed in a water storage tank to detect the water level inside the tank;

[0022] In addition, the central control unit is electrically connected to each component in the detection assembly.

[0023] Furthermore, it also includes an external fertilization device, controlled by a central control unit and independent of the farmland, for supplementing fertilizer to the farmland.

[0024] Furthermore, the external fertilization device includes:

[0025] The variable frequency pump is electrically connected to and controlled by the central control unit.

[0026] The fertilizer tank is connected to the input end of a variable frequency pump via a pipeline, and the input end of the variable frequency pump is also connected to an external water source.

[0027] The output end of the variable frequency pump is connected to the farmland through the fertilizer pipeline.

[0028] Furthermore, the external fertilization device also includes a fertilization solenoid valve, which is electrically connected to the central control unit. When the nitrogen concentration in the farmland water is insufficient, the fertilization solenoid valve and the frequency converter pump are in the open state.

[0029] Furthermore, the system also includes a drainage electric actuator and a recharge electric actuator, which are used to perform drainage and recharge actions respectively, and are respectively located in the drainage channel and the recharge channel.

[0030] Compared to existing technologies, the beneficial effects of this patent are as follows:

[0031] The invention involves online monitoring of total nitrogen, ammonium nitrogen, and nitrate nitrogen in the recharge water in the terminal storage tank. By combining the inflow and outflow rates, the nitrogen input and output of the recharge water are calculated. Based on the mass balance, the nitrogen utilization rate of the recharge water is obtained and used as an input variable for fertilizer control decision-making. The target nitrogen application rate for each growth stage is dynamically adjusted to achieve precise reduction of chemical nitrogen fertilizer application. Therefore, this invention reduces nitrogen loss and terminal discharge load while ensuring yield and quality, and achieves efficient and green utilization of water and fertilizer resources.

[0032] This invention achieves integrated monitoring, calculation, and control through online nitrogen monitoring in the terminal reservoir, mass balance calculation, and fertilizer control linkage algorithm. It can form a closed loop between monitoring results and the next round of fertilization decisions, which can significantly improve the utilization rate of nitrogen resources. Attached Figure Description

[0033] Figure 1 This is a schematic diagram illustrating the control system setup principle for nitrogen reduction in paddy fields.

[0034] Figure 2 This is a schematic diagram illustrating the core steps of nitrogen reduction control methods in paddy fields. Detailed Implementation

[0035] The following will refer to the appendices in the embodiments of the present invention. Figure 1-2 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] To address the shortcomings of existing technologies, an intelligent method for paddy field irrigation and fertilizer control is proposed, such as... Figure 1 As shown, the basic architecture upon which this method is based includes the following parts:

[0037] Farmland 1;

[0038] Water storage tank 2;

[0039] Drainage channel 3 connects the field drainage outlet 7 of farmland 1 and the inlet of reservoir 2;

[0040] The recharge channel 4 connects the drainage outlet of the reservoir 2 and the water inlet of the farmland 1.

[0041] like Figure 2 As shown, based on the above-described farmland-reservoir basic architecture, the method includes the following steps:

[0042] Install terminal water storage tank 2 at the drainage location of the paddy field;

[0043] Online nitrogen monitoring was performed on the recharge water of reservoir 2 to obtain data such as nitrogen concentration and flow rate of the recharge water;

[0044] Online nitrogen monitoring was conducted at field outlet 7 to obtain data such as nitrogen concentration and flow rate in the discharged water.

[0045] Calculate the nitrogen flux into the field after recharge, the nitrogen flux discharged from the field, and the nitrogen utilization rate of the recharge water;

[0046] The amount of topdressing or the timing of fertilization will be calculated by combining the nitrogen supply target during the crop growth period and the estimated soil nitrogen supply.

[0047] Based on the above calculation results, the central control unit 15 generates corresponding control commands to control the external fertilization device and the corresponding solenoid valve according to the amount of topdressing, so as to realize the reduction of chemical nitrogen fertilizer application and the coordination of irrigation and drainage.

[0048] The preferred specific process scheme is described below:

[0049] Set up an end-point water storage tank 2, and equip it with an online water quality monitoring unit (at least one of total nitrogen TN / nitrate nitrogen NO3-N / ammonium nitrogen NH4-N), sampling and automatic cleaning components, flow colorimetric cell / electrode, flow meter and level gauge, etc.

[0050] Establish a reinjection operation strategy: Initiate reinjection when the monitoring values ​​and water volume meet the thresholds (nitrogen concentration ≥ Cmin and water storage ≥ Vmin);

[0051] The program of the central control unit 15 is used to calculate the nitrogen input / output load and nitrogen element utilization rate of the reinjection water;

[0052] The nitrogen utilization rate of recharged water, the crop growth period demand curve, and the soil nitrogen supply estimate are used as inputs to the fertilizer control algorithm, which dynamically corrects the subsequent topdressing amount and links the execution of the solenoid valve / fertilizer application device.

[0053] The first key computational model is as follows:

[0054] Discrete-time integration is performed over a control period Δt (e.g., 5–15 min): Nitrogen flux reinjected into the field (kg):

[0055] ;

[0056] Field nitrogen flux (kg):

[0057] ;

[0058] In the two formulas above: the symbol Q represents the volumetric flow rate (m³), the symbol C represents the nitrogen concentration (mg / L), and " / 1000" is a combination of conversion factors from mg to g to kg.

[0059] Nitrogen utilization rate of reinjection water (%):

[0060] ;

[0061] In the above formula for calculating nitrogen utilization rate in recharge water, the relevant symbols are explained as follows:

[0062] “ "This represents the nitrogen load that entered the paddy field but was not discharged with the outflow, including the crop."

[0063] The contributions of absorption, soil fixation, and system purification can be used as effective items in fertilizer control calculations.

[0064] Based on the nitrogen utilization rate of the recharge water obtained in the above calculation process, calculate the linkage reduction application rate (calculated as pure nitrogen, kg):

[0065] Choose one of the following two strategies or use them in combination:

[0066] A. Supply-side equilibrium method:

[0067] ;

[0068] in, To meet the target nitrogen supply during this reproductive period, For soil nitrogen supply estimation, This represents the current nitrogen flux injected into the field. To determine the current nitrogen utilization rate of the reinjected water, and This is the reduction factor (empirical or calibration), and its value range can be (0,1).

[0069] Dynamically adjust subsequent topdressing amount and link solenoid valve / fertilizer application device: based on dynamic values ​​obtained from the supply balance method. The process of controlling the solenoid valve / fertilizer applicator is adjusted to correct the amount of subsequent topdressing, that is, subtracting the amount of fertilizer from the original amount. .

[0070] B. Direct reduction method based on utilization rate:

[0071] ;

[0072] This is the amount of nitrogen fertilizer obtained from the recharge water; it's a dynamic value. It's obtained using the direct deduction method based on utilization rate. The process of controlling the solenoid valve / fertilizer applicator is adjusted to correct the amount of subsequent topdressing, that is, subtracting the amount of fertilizer from the original amount. .

[0073] initial value =0.60-0.85 (based on field measurements and regression calibration), setting a minimum safe fertilization limit to ensure yield.

[0074] The second key computational model is as follows:

[0075] Based on the existing nitrogen quality balance of the end-of-pipe reservoir and the nitrogen utilization rate of the recharge water, a comprehensive optimization concept is introduced to unify crop nitrogen supply demand, tailwater nitrogen discharge, water layer control, fertilization cost and fertilization smoothness into the same objective function, so as to achieve multi-objective coordinated control of "ensuring yield and quality, reducing nitrogen fertilizer application and reducing non-point source emissions".

[0076] Within the discrete time period k and the prediction time domain length H, the comprehensive performance index function J is defined as follows:

[0077] Formula 1:

[0078] J = Σ k=t t+H [α (N target (k) - N sup (k)) 2 + β (C out (k) - C std ) 2 + γ (H(k) -H set (k)) 2 + ρ u(k) 2 + λ (u(k) - u(k-1)) 2 ];

[0079] Where: N target (k): The target nitrogen supply at time k or on day k is obtained by subdividing the stage nitrogen supply target N_target(stage) determined in advance according to the rice variety and growth process by time.

[0080] N sup(k): The actual comprehensive nitrogen supply at time k, which is composed of nitrogen supply from soil, nitrogen supply from recharge water, and nitrogen supply from chemical nitrogen fertilizer;

[0081] C out (k): The nitrogen concentration (e.g., total nitrogen) in the water body measured at the end discharge outlet at time k;

[0082] C std : Environmental emission standards or the end-of-pipe nitrogen concentration control threshold set by this invention;

[0083] H(k): The water depth of the paddy field at time k, obtained by a water level sensor;

[0084] H set (k): The target water layer depth trajectory set for the current reproductive stage;

[0085] u(k): The controlled amount of chemical nitrogen fertilizer applied at time k (calculated as pure nitrogen), which is the control variable for optimization in this invention;

[0086] α, β, γ, ρ, λ: These are the weighting coefficients used to balance crop nitrogen demand, tailwater discharge constraints, water regulation, fertilization costs, and control smoothness.

[0087] The actual comprehensive nitrogen supply N sup (k) is obtained by summing the estimated nitrogen supply from the soil, the available nitrogen in the irrigation water, and the amount of fertilizer applied in the current application, and can be expressed as:

[0088] Formula 2:

[0089] N sup (k) = N soil (k) + k rw × M in,eff (k) + u(k);

[0090] Where, N soil (k) is the estimated soil nitrogen supply at time k, which can be determined based on local empirical models or soil nutrient monitoring results; M in,eff (k) represents the nitrogen flux "effectively utilized" in the reinjection water within the time window. rw The reduction factor for effective utilization of reinjected nitrogen.

[0091] The effective nitrogen flux in the reinjection water can be estimated from the results of online monitoring of the end-of-pipe tailwater, for example:

[0092] Formula 3:

[0093] M in,eff (k) = η rw (k) · M in (k);

[0094] Among them, M in (k) represents the nitrogen flux re-injected into the field within the time window, and η rw (k) represents the nitrogen utilization rate of the reinjected water during this time window, which can be calculated based on the mass balance relationship according to the measurement results of the inflow and outflow of water and nitrogen concentration in the terminal reservoir.

[0095] By minimizing the comprehensive performance index J, the optimal fertilization control sequence in the prediction time domain is obtained. This sequence is defined as u. * (k). To facilitate project implementation, this sequence can be converted into the target topdressing amount N for the corresponding growth stage. fert * (stage):

[0096] Formula 4:

[0097] N fert * (stage) = Σ k=t t+H u * (k) · Δt;

[0098] Where Δt is the control cycle length. Further, N fert * (stage) can be integrated with the topdressing formula based on supply balance to correct the traditional topdressing amount calculation results and achieve the unity of "nitrogen quality balance + recharge water nitrogen utilization rate + comprehensive optimization control".

[0099] For example, in one embodiment, the original topdressing amount based on nitrogen supply and demand balance can be expressed as:

[0100] Formula 5:

[0101] N fert (stage) = k s ×[ N target (stage)-N soil,total (stage)-k rw ×M in,eff,total (stage)];

[0102] Where, N soil,total (stage) refers to the total amount of nitrogen supplied to the soil during this growth stage;

[0103] M in,eff,total (stage) represents the total effective nitrogen supply from the recharge water during this stage, k s This is a safety reduction factor.

[0104] In this invention, N fert (stage) can directly replace or be used to correct the above N.fert * (stage), thereby introducing a high-level control mechanism for multi-objective optimization without changing the existing management experience framework.

[0105] To implement the above method, a control system is proposed to execute the above-described method for nitrogen reduction in paddy fields, comprising the following components:

[0106] Central control unit 15;

[0107] Detection combination;

[0108] The detection combination includes:

[0109] A nitrogen concentration detector A14 is used to detect the nitrogen concentration in farmland drainage. The detector can be equipped with an electric pump A13. The electric pump A13 is used to draw water samples into the nitrogen concentration detector A14 for detection. The nitrogen concentration detector A14 sends the detection results to the central control unit 15.

[0110] The nitrogen concentration detector B12 is used to detect the nitrogen concentration in the water inside the reservoir. The detector can be equipped with an electric pump B11. The electric pump B11 draws the water sample into the nitrogen concentration detector B12 for detection. The nitrogen concentration detector B12 sends the detection result to the central control unit 15.

[0111] A flow detector A6 is installed in the drainage channel 3 to detect the drainage flow rate;

[0112] A flow detector B9, installed in the recharge channel 4, is used to detect the recharge water flow rate.

[0113] A level gauge 10 installed in the water storage tank 2 for detecting the water level inside the water storage tank 2;

[0114] In addition, the central control unit 15 is electrically connected to each component in the detection assembly.

[0115] The system also includes an external fertilization device, which is set up independently of the farmland 1 and is controlled by the central control unit 15. The external fertilization device is used to supplement fertilizer to the farmland 1.

[0116] The aforementioned external fertilization device includes:

[0117] The variable frequency pump 18 is electrically connected to and controlled by the central control unit 15.

[0118] Fertilizer tank 16 is connected to the input end of variable frequency pump 18 via a pipeline;

[0119] External water source 17 is connected to the input end of the variable frequency pump via a pipeline;

[0120] The output end of the variable frequency pump 18 is connected to the inside of the farmland 1 through the fertilizer pipeline;

[0121] The fertilization solenoid valve 19 is electrically connected to the central control unit 15, and when the nitrogen concentration in the water of farmland 1 is insufficient, the fertilization solenoid valve 19 and the variable frequency pump 18 are in the open state.

[0122] The system also includes a drainage electric actuator 5 and a recharge electric actuator 8, which are used to perform drainage and recharge actions, respectively. The drainage electric actuator 5 and the recharge electric actuator 8 are respectively located in the drainage channel 3 and the recharge channel 4. The drainage electric actuator 5 is configured as an electric pump and / or an electric valve, and the recharge electric actuator 8 is configured as an electric pump and / or an electric valve. The drainage electric actuator 5, the recharge electric actuator 8, the variable frequency pump 18, and the fertilizer solenoid valve 19 can all adjust their opening degree / flow rate according to the control commands of the central control unit 15, thus forming a coordinated control system.

[0123] As can be seen from the above description, the system needs to have the following functional units:

[0124] The nitrogen online monitoring unit is located in the terminal water storage tank 2. This unit contains an online sensor and uses the online sensor to dynamically detect TN in the water sample.

[0125] The flow and level monitoring unit has flow meters installed at the inlet and outlet of the water storage tank, and level gauge 10 inside the tank is used to trigger recharge.

[0126] The central control unit 15 uses an edge controller (supporting Modbus / 4-20mA / 485 / Ethernet / cellular) and is linked with the cloud model service;

[0127] The actuator is equipped with adjustable solenoid valves / frequency converters / fertilizer tanks, supporting automatic fertilizer mixing and irrigation / drainage linkage according to the target formula;

[0128] The safety and maintenance unit includes a bypass manual valve, overflow port, sensors, sun protection / lightning protection, abnormal data rejection, and calibration scheduling functions.

[0129] The nitrogen online monitoring module communicates with the central control unit 15, which is equipped with a program for calculating and determining the amount of topdressing and issuing fertilizer control / irrigation and drainage instructions to the executing agency.

[0130] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In this invention, it should also be noted that the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an integrally formed connection, a mechanical connection, or an indirect connection through intermediate connecting parts. The specific meaning of the terms in this utility model can be understood according to the specific circumstances.

[0131] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0132] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for controlling nitrogen reduction in paddy fields, characterized in that, Includes the following steps: Data collection steps: Online nitrogen monitoring of the recharge water in the reservoir (2) is carried out to obtain the nitrogen concentration and flow rate of the water body recharged into the farmland. The nitrogen concentration and flow rate of the outflow are monitored at the field outlet (7). The steps of the central control unit to process data are as follows: The central control unit (15) processes the detection data obtained in the previous step to obtain the nitrogen flux of the re-irrigation into the field and the nitrogen flux discharged from the field, and obtains the nitrogen input / output load of the re-irrigation water and the nitrogen element utilization rate of the re-irrigation water. It is then combined with the nitrogen supply target of the crop growth period and the soil nitrogen supply estimate to calculate the amount of topdressing or the delayed timing. The fertilizer application device and solenoid valve are controlled according to the amount of topdressing fertilizer to achieve coordinated regulation of chemical nitrogen fertilizer reduction, re-irrigation and drainage. When the monitored values ​​and water volume meet the threshold, the recharge process is initiated, and the water in the reservoir is recharged into the farmland. The nitrogen input / output load of the recharge water, the nitrogen utilization rate of the recharge water, the crop growth period demand curve, and the estimated amount of soil nitrogen supply are used as inputs to the fertilizer control algorithm to dynamically correct the subsequent topdressing amount and link the execution process of the solenoid valve / fertilizer device. The calculation process for the data processing steps in the central control unit follows the following pattern: The discrete integral over time t is performed over the control period Δt, where Δt is in minutes. Nitrogen flux injected into the field after recharge is measured in kg. ； Field nitrogen flux, expressed in kg: ； In the two formulas above: the symbol Q represents the volumetric flow rate, with the unit being m³; the symbol C represents the nitrogen concentration, with the unit being mg / L; Nitrogen utilization rate of recharge water, expressed as a percentage (%): ； In the above formula for calculating nitrogen utilization rate in recharge water, the relevant symbols are explained as follows: This represents the nitrogen load that did not flow away with the outflow after entering the paddy field.

2. The method for controlling nitrogen reduction in paddy fields according to claim 1, characterized in that, The system settings for this method include: Central control unit (15); Detection combination; The detection combination includes: Nitrogen concentration detector A (14) is used to detect nitrogen concentration in farmland drainage. Nitrogen concentration detector B (12) is used to detect the nitrogen concentration in the water inside the reservoir (2). A flow detector A (6) is installed in the drainage channel (3) to detect the flow rate of drainage outside the farmland. A flow detector B (9) is installed in the recharge channel (4) to detect the recharge water flow rate. A level gauge (10) installed in the water storage tank (2) for detecting the water level inside the water storage tank (2); In addition, the central control unit (15) is electrically connected to each component in the detection assembly.

3. The method according to claim 2, characterized in that, It also includes an external fertilization device, which is independent of the farmland and is controlled by a central control unit (15), for supplementing the farmland with fertilizer.

4. The method according to claim 3, characterized in that, The external fertilization device includes: The variable frequency pump (18) is electrically connected to the central control unit (15) and controlled by the central control unit (15); The fertilizer tank (16) is connected to the input end of the variable frequency pump (18) via a pipe, and the input end of the variable frequency pump (18) is also connected to an external water source (17); The output end of the variable frequency pump (18) is connected to the farmland (1) through the fertilizer pipeline.

5. The method according to claim 4, characterized in that, The external fertilization device also includes a fertilization solenoid valve (19), which is electrically connected to the central control unit (15). When the nitrogen concentration in the water in the farmland (1) is insufficient, the fertilization solenoid valve (19) and the frequency converter pump (18) are in the open state.

6. The method according to claim 2, characterized in that, It also includes a drainage electric actuator (5) and a recharge electric actuator (8), which are used to perform drainage and recharge actions respectively. The drainage electric actuator (5) and the recharge electric actuator (8) are respectively located in the drainage channel (3) and the recharge channel (4).

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