Peanut water and fertilizer drip irrigation intelligent control method

Abstract

The application relates to the technical field of agricultural engineering, and discloses a peanut water-fertilizer drip irrigation intelligent regulation and control method.The present application constructs a self-adaptive closed loop based on thermodynamic deviation correction and porous medium volume balance, completely solves the serious agricultural pain points of shallow high-concentration fertilizer burn of fruit needles and long-term fertilizer deficiency of deep main root systems caused by blind water injection in traditional agricultural drip irrigation, performs temperature compensation on the original sensor signal in a pure physical dimension by using real-time temperature, filters out false high-salinity signal artifacts caused by the mulch greenhouse effect, and provides a deterministic physical scale for nutrient quantitative injection and deep research and judgment of the fertilizer front.

Description

Technical Field

[0001] This application relates to the field of agricultural engineering technology, and in particular to an intelligent control method for peanut drip irrigation. Background Technology

[0002] Peanuts, an important economic crop in my country, are widely cultivated in major producing areas such as Shandong using a planting model that combines plastic film mulching with drip irrigation. In the microclimate environment of plastic film mulching, peanut growth and development exhibit unique spatial stratification in terms of water and fertilizer requirements. Especially during the crucial flowering and pegging stage, which determines yield, the pods formed above ground need to penetrate into the shallow soil layer (0-10 cm below the surface) and develop into pods in a microenvironment with suitable moisture and shade. Simultaneously, the peanut's taproot system is primarily located in the deeper soil layer (15-30 cm below the surface), responsible for absorbing large amounts of nitrogen, phosphorus, and potassium nutrients for the plant. Because the physical barrier of the plastic film completely cuts off the natural rainfall supply path, the drip irrigation strip becomes the only physical channel for the plant to obtain water and fertilizer. This necessitates that the drip irrigation system simultaneously meet the dual spatial habitat requirements of promoting pegging development in the shallow layer and promoting root absorption in the deep layer.

[0003] However, existing agricultural fertilization control technologies cannot effectively address the misaligned distribution of water and fertilizer demands in three-dimensional space. Current automated drip irrigation technologies typically only bury temperature and humidity sensors at a single depth in the field, and their system control logic is mostly based on simultaneous water and fertilizer application at preset fixed times or single-point humidity thresholds. This extensive approach lacks the ability to perceive the three-dimensional transport gradients of water and fertilizer across different soil layers, resulting in a rigid, strongly coupled relationship between water supply and nutrient delivery. Specifically, when the control system performs short-term drip irrigation to maintain a moist microenvironment in the shallow soil, the water and the carried liquid fertilizer cannot penetrate to the taproot zone, directly causing the deep roots to be in a state of nutrient deficiency for a long time. Conversely, if the system performs long-term drip irrigation to ensure nutrient supply to the deep roots, the water-fertilizer mixture will inevitably leach into the deeper layers in large quantities. This not only leads to excessive accumulation of fertilizer in non-target soil layers but also causes the shallow soil to rapidly lose water and physically compact after drip irrigation. This phenomenon of shallow compaction and deep enrichment, caused by the single dimension of system perception and insufficient decoupling ability of control strategy, makes the new pods face great mechanical penetration resistance. Even if they manage to penetrate the soil, they will wither due to lack of suitable moisture conditions, ultimately leading to a sharp reduction in the number of pods per peanut plant and nutrient loss, which completely deviates from the original intention of modern agriculture to save water and fertilizer and achieve high yield. Summary of the Invention

[0004] This application proposes an intelligent control method for drip irrigation of peanut water and fertilizer to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this application adopts the following technical solution: an intelligent control method for peanut water and fertilizer drip irrigation, comprising the following steps:

[0006] Step S1: Obtain the real-time water content of the first depth and the second depth, as well as the first and second times when the water front reaches both depths. When the time difference between the first and second times is greater than a preset lower limit, calculate the infiltration velocity based on the depth difference and the time difference. When the real-time water content of the first depth reaches the saturation threshold, output the calibration status and the infiltration velocity.

[0007] Step S2: Receive the calibration status and the infiltration velocity, obtain the instantaneous flow rate, nutrient mass, mother liquor concentration, and the original conductivity and real-time temperature at the third depth, perform temperature compensation on the original conductivity based on the real-time temperature to obtain the standard conductivity, and calculate the fertilization duration from the nutrient mass, the mother liquor concentration, and the instantaneous flow rate. When the fertilization duration is reached, generate a first instruction to shut down the fertilization equipment while keeping the water supply equipment on.

[0008] Step S3: Receive the first instruction, obtain the pipeline volume, hysteresis factor, and real-time moisture content and water holding threshold at each depth, calculate the pore surplus term based on the water holding threshold and the real-time moisture content, calculate the jacking time by combining the pipeline volume, the hysteresis factor, the instantaneous flow rate and the infiltration velocity, generate a shutdown instruction after injecting water according to the instantaneous flow rate and the jacking time, and push the fertilizer to the third depth;

[0009] Step S4: Receive the shutdown command, and after resting, obtain the steady-state standard conductivity at the third depth. If the steady-state standard conductivity is lower than the target lower limit, increase the preset step size to update the hysteresis factor as the parameter benchmark for the next cycle.

[0010] Further, in step S1, the specific operation of obtaining the real-time moisture content at the first depth and the second depth, as well as the first and second times when the moisture front reaches both, is as follows: A composite sensor array is arranged below the drip irrigation point. The composite sensor array includes a first sensor located at the first depth, a second sensor located at the second depth, and a third sensor located at the third depth. The system receives real-time moisture content, raw conductivity, and real-time temperature collected by the first sensor, the second sensor, and the third sensor. It also reads the pipeline volume, sends an activation command to the water supply equipment, and receives the instantaneous flow rate collected by the flow meter. The system extracts the real-time moisture content at the first depth and the real-time moisture content at the second depth, records the moment when the real-time moisture content at the first depth reaches a data jump to generate the first time, and records the moment when the real-time moisture content at the second depth reaches a data jump to generate the second time.

[0011] Further, in step S1, the specific operation of calculating the infiltration velocity based on the depth difference and the time difference when the time difference between the first time and the second time is greater than a preset lower limit is as follows: subtract the first time from the second time to obtain the time difference; perform a comparison operation between the time difference and the preset lower limit; under the condition that the time difference is less than the preset lower limit, extract the saturated hydraulic conductivity pre-stored in the local database, and assign the saturated hydraulic conductivity as the infiltration velocity; under the condition that the time difference is greater than or equal to the preset lower limit, subtract the first depth from the second depth to obtain the depth difference, extract the depth difference as a numerator parameter, extract the time difference as a denominator parameter, and divide the numerator parameter by the denominator parameter to calculate the infiltration velocity.

[0012] Further, in step S2, the specific operation of obtaining the standard conductivity by temperature compensation of the original conductivity based on the real-time temperature is as follows: obtain the real-time temperature and subtract the standard constant 25 to obtain the physical temperature difference; obtain the conductivity temperature compensation coefficient and multiply the physical temperature difference by the conductivity temperature compensation coefficient to obtain the temperature compensation product; add a constant 1 to the temperature compensation product to obtain the correction denominator; divide the original conductivity by the correction denominator to obtain the standard conductivity.

[0013] Further, in step S2, the specific operation of calculating the fertilization duration from the nutrient mass, the mother liquor concentration, and the instantaneous flow rate is as follows: multiply the mother liquor concentration by the instantaneous flow rate to obtain the nutrient injection mass per unit time; divide the nutrient mass by the nutrient injection mass per unit time to obtain the fertilization duration; when the operating time of the fertilization equipment reaches the fertilization duration, generate the first instruction to shut down the fertilization equipment while keeping the water supply equipment on.

[0014] Further, in step S3, the specific operation of calculating the pore surplus term based on the water holding threshold and the real-time moisture content is as follows: obtain the water holding threshold at the first depth and the water holding threshold at the second depth; subtract the real-time moisture content at the first depth from the water holding threshold at the first depth to obtain the water content difference at the first depth; extract the maximum value between the water content difference at the first depth and zero to generate the pore surplus term at the first depth; subtract the real-time moisture content at the second depth from the water holding threshold at the second depth to obtain the water content difference at the second depth; extract the maximum value between the water content difference at the second depth and zero to generate the pore surplus term at the second depth.

[0015] Further, in step S3, the specific operation of calculating the jacking time by combining the pipeline volume, the hysteresis factor, the instantaneous flow rate, and the infiltration velocity is as follows: obtain the cross-sectional area of ​​the wetted ball, the first depth thickness, and the second depth thickness; divide the pipeline volume by the instantaneous flow rate to obtain the pipeline emptying compensation time; multiply the cross-sectional area of ​​the wetted ball by the first depth thickness to obtain the first volume base; multiply the first volume base by the first depth pore surplus term to obtain the first depth compensation volume; multiply the cross-sectional area of ​​the wetted ball by the second depth thickness to obtain the second volume base; multiply the second volume base by the second depth pore surplus term to obtain the second depth compensation volume; add the first depth compensation volume to the second depth compensation volume to obtain the total soil compensation volume; multiply the total soil compensation volume by the hysteresis factor to obtain the corrected compensation volume; divide the corrected compensation volume by the instantaneous flow rate to obtain the soil replacement time; add the pipeline emptying compensation time to the soil replacement time to obtain the jacking time.

[0016] Further, in step S3, the specific operation of generating a shutdown command after injecting water according to the instantaneous flow rate and the pushing duration, and pushing the fertilizer to the third depth, is as follows: under the condition of receiving the first command, keep the water supply equipment on; multiply the instantaneous flow rate by the pushing duration to obtain the target total amount of pure water pushed; obtain the cumulative volume of pure water output by the water supply equipment; under the condition that the cumulative volume of pure water is equal to the target total amount of pure water pushed, complete the pushing operation of the fertilizer to the third depth; when the pushing operation of the fertilizer to the third depth is completed, generate the shutdown command; and shut down the water supply equipment according to the shutdown command.

[0017] Further, in step S4, the specific operation of obtaining the steady-state standard conductivity of the third depth after settling is as follows: after generating the shutdown command, a settling operation lasting 120 minutes is performed; after completing the settling operation, the steady-state temperature and the steady-state original conductivity of the third depth are obtained; a constant of 25 is subtracted from the steady-state temperature of the third depth to obtain the steady-state temperature difference; a conductivity temperature compensation coefficient is obtained; the steady-state temperature difference is multiplied by the conductivity temperature compensation coefficient to obtain the steady-state temperature compensation product; a constant of 1 is added to the steady-state temperature compensation product to obtain the steady-state correction denominator; the steady-state original conductivity of the third depth is divided by the steady-state correction denominator to obtain the steady-state standard conductivity of the third depth.

[0018] Further, in step S4, the specific operation of updating the hysteresis factor by increasing the preset step size as the parameter benchmark for the next cycle if the steady-state standard conductivity is lower than the target lower limit is as follows: obtain the target lower limit; under the condition that the steady-state standard conductivity at the third depth is lower than the target lower limit, obtain the preset step size and the hysteresis factor; add the preset step size to the hysteresis factor to obtain the updated hysteresis factor; establish the updated hysteresis factor as the parameter benchmark for the next cycle.

[0019] The beneficial effects of this invention are as follows:

[0020] This invention, by constructing an adaptive closed loop based on thermodynamic correction and porous media volume balance, completely solves the serious agronomic problems of shallow high-concentration fertilizer burning of fruit pegs and long-term nutrient deficiency in deep taproots caused by indiscriminate water injection in traditional agricultural drip irrigation. It utilizes real-time temperature to perform purely physical temperature compensation on the original sensor signal, filtering out false high-salinity signal artifacts caused by the greenhouse effect of mulching, providing a deterministic physical benchmark for quantitative nutrient injection and precise determination of fertilizer front depth. Simultaneously, the method deeply integrates the law of conservation of mass for incompressible fluids and the dynamic absorption limit of soil pores, accurately outputting the top through anti-collapse volume boundary calculation. By extending the water injection time and utilizing the fluid piston effect generated by the continuous injection of pure water, the high-concentration fertilizer retained in the shallow fruit peg zone is forced and precisely pressed downwards to the deep main root enrichment zone. This achieves absolute habitat decoupling between shallow pure water without salt wetting and deep high-concentration targeted fertilization in a three-dimensional physical space. At the same time, an adaptive compensation feedback mechanism for the bottom fluid resistance parameters is introduced under the steady state of hydraulic redistribution in porous media. This mechanism can capture and dynamically correct the additional transport resistance caused by the physical aging of soil aggregate structure and the enhanced adsorption force of clay particles, thus preventing deep underground leakage pollution caused by excessive water injection and fruit rot caused by shallow water accumulation. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort:

[0022] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0023] 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.

[0024] Example

[0025] like Figure 1 As shown, this invention discloses an intelligent control method for peanut drip irrigation, comprising the following steps:

[0026] Step S1: Obtain the real-time water content of the first depth and the second depth, as well as the first and second times when the water front arrives at both depths. When the time difference between the first and second times is greater than a preset lower limit, calculate the infiltration velocity based on the depth difference and time difference. When the real-time water content of the first depth reaches the saturation threshold, output the calibration status and infiltration velocity.

[0027] Step S2: Receive calibration status and infiltration velocity, obtain instantaneous flow rate, nutrient quality, mother liquor concentration and original conductivity and real-time temperature at the third depth, perform temperature compensation on the original conductivity based on real-time temperature to obtain standard conductivity, and calculate fertilization time from nutrient quality, mother liquor concentration and instantaneous flow rate. When the fertilization time is reached, generate the first instruction to shut down the fertilization equipment and keep the water supply equipment on.

[0028] Step S3: Receive the first instruction, obtain the pipeline volume, hysteresis factor, and real-time moisture content and water holding threshold at each depth, calculate the pore surplus based on the water holding threshold and real-time moisture content, calculate the jacking time by combining the pipeline volume, hysteresis factor, instantaneous flow rate and infiltration velocity, generate a shutdown instruction after injecting water according to the instantaneous flow rate and jacking time, and push the fertilizer to the third depth.

[0029] Step S4: Receive the shutdown command, and after resting, obtain the steady-state standard conductivity at the third depth. If the steady-state standard conductivity is lower than the target lower limit, increase the preset step size update hysteresis factor as the parameter benchmark for the next cycle.

[0030] As can be seen from the above process, by constructing an adaptive closed loop based on thermodynamic correction and porous media volume balance, the serious agronomic problems of shallow high-concentration fertilizer burning of fruit pegs and long-term nutrient deficiency of deep taproots caused by blind water injection in traditional agricultural drip irrigation are completely solved. Real-time temperature compensation is applied to the original sensor signal using a purely physical dimension, filtering out false high-salinity signal artifacts caused by the greenhouse effect of mulching, providing a deterministic physical benchmark for quantitative nutrient injection and fertilizer front depth determination. Simultaneously, the method deeply integrates the law of conservation of mass for incompressible fluids and the dynamic absorption limit of soil pores, and accurately calculates the anti-collapse volume boundary. The quasi-output top-push water injection duration utilizes the fluid piston effect generated by the continuous injection of pure water to force and precisely press the high-concentration fertilizer retained in the shallow fruit peg zone downwards to the deep main root enrichment zone. In three-dimensional physical space, it achieves absolute habitat decoupling between shallow pure water salt-free wetting and deep high-concentration targeted fertilization. At the same time, under the steady state of hydraulic redistribution in porous media, an adaptive compensation feedback mechanism for bottom fluid resistance parameters is introduced. This mechanism can capture and dynamically correct the additional transport resistance caused by the physical aging of soil aggregate structure and the enhanced adsorption force of clay particles, thus preventing deep underground leakage pollution caused by excessive water injection and fruit rot caused by shallow water accumulation.

[0031] The following describes in detail each step of the above process and the effects that can be further produced, with reference to the embodiments.

[0032] First, the above step S1, namely, "obtaining the real-time water content of the first depth and the second depth, as well as the first time and the second time when the water front reaches the first and second depths, and calculating the infiltration velocity based on the depth difference and time difference when the time difference between the first and second times is greater than a preset lower limit, and outputting the calibration status and infiltration velocity when the real-time water content of the first depth reaches the saturation threshold", will be described in detail with reference to the embodiment.

[0033] In a specific embodiment of the present invention, the system mainly acquires the real-time moisture content of the first and second depths through multi-layer soil data sensing terminals deployed in the drip irrigation area. When the water supply equipment is turned on and pure water is injected, the control system monitors the data dynamics of the aforementioned sensing terminals at high frequency to accurately capture the time node when the moisture front causes a step change in moisture content, thereby acquiring the first and second times. The reason why the present invention adopts the logic of comparing the time difference with a preset lower limit after acquiring the time is that the soil physical characteristics under peanut mulching planting scenarios are extremely complex. Under the long-term effects of high temperature and alternating wet and dry conditions under mulching, the soil in the field is prone to developing microscopic drought cracks; if the calculation is performed directly without verification, the large pore flow formed by the rapid leakage of water along the cracks will mislead the system into obtaining an abnormally high false infiltration velocity. By introducing a preset lower limit for anti-counterfeiting boundary verification, and when the time difference is greater than this lower limit (i.e., excluding the interference of direct leakage from cracks), the infiltration velocity is calculated using the absolute depth difference and the true time difference, which can accurately restore the true water kinematic parameters that conform to the fluid dynamics of porous media. Simultaneously, when the real-time moisture content at the first depth reaches the saturation threshold, the calibration status is output. This is significant because it pre-constructs a healthy initial habitat—purely moistened and free from high-concentration salt stress—for peanuts during the flowering and pegging stage, ensuring the pegs penetrate the soil and swell. This step revolutionizes the static empirical approach of traditional fertilization systems to dynamic anti-counterfeiting calibration based on in-situ physical laws. It effectively overcomes the technical shortcomings of existing technologies that rely solely on single-depth sensing or rigid timing logic, preventing the system from adaptively tracking the actual movement of water in three-dimensional space. It fundamentally solves the problem of water and fertilizer infiltration model failure caused by the time-varying decay of soil physical structure (such as local compaction and cracking), laying an absolutely reliable underlying data foundation for subsequent precise spatial separation of water and fertilizer between shallow and deep layers.

[0034] As an feasible approach, the specific operations for obtaining the real-time moisture content at the first and second depths, as well as the first and second times when the moisture front reaches both depths, are as follows: A composite sensor array is arranged below the drip irrigation point. The composite sensor array includes a first sensor at the first depth, a second sensor at the second depth, and a third sensor at the third depth. The system receives real-time moisture content, raw conductivity, and real-time temperature collected by the first, second, and third sensors. It also reads the pipeline volume, sends an activation command to the water supply equipment, and receives the instantaneous flow rate collected by the flow meter. The system extracts the real-time moisture content at the first and second depths, records the moment when the real-time moisture content at the first depth reaches a data jump to generate the first time, and records the moment when the real-time moisture content at the second depth reaches a data jump to generate the second time.

[0035] Specifically, a composite sensor array is arranged vertically below the drip irrigation point in the peanut planting mulch area. The first sensor in the composite sensor array is physically deployed in the shallow core area of ​​peg development 5 cm below the ground surface, the second sensor is physically deployed in the microenvironment transition zone 15 cm below the ground surface, and the third sensor is physically deployed in the deep area of ​​main root enrichment 30 cm below the ground surface.

[0036] After completing the above-mentioned physical hardware deployment, in order to ensure high-sensitivity capture of the internal water transport trajectory of the covered soil, the system synchronously and continuously receives real-time moisture content, raw conductivity, and real-time temperature collected by the first sensor, the second sensor, and the third sensor. The first, second, and third sensors preferably adopt sensing terminals based on the frequency domain reflection principle, and the data sampling frequency is set to no less than 1Hz to ensure that the physical accuracy of the captured first and second times reaches the second level.

[0037] Subsequently, when the system enters the dynamic calibration phase, the network volume of the drip irrigation system is read. The value of the network volume is based on the static volume constant determined according to the physical layout drawing of the drip irrigation network of the target planting plot. The purpose of reading the network volume is to eliminate the hydraulic delay error caused by the difference in the geometric length of the pipeline in subsequent calculations. Under the premise of clearly defining the physical volume boundary, an opening command is sent to the water supply equipment to inject pure water into the pores inside the mulched soil, and the instantaneous flow rate collected by the flow meter is received as the initial dynamic parameter of water movement.

[0038] Finally, as pure water seeps downwards through the soil pores under the combined physical forces of gravity and capillary tension, forming a water front, the system continuously extracts the real-time moisture content at the first and second depths. To eliminate random physical noise from the sensor caused by uneven soil particle distribution, the absolute value of the first derivative of the real-time moisture content is set to exceed a preset soil background fluctuation threshold as the physical criterion for a data jump. The system captures the moment when the real-time moisture content at the first depth experiences a step-like increase due to the water front reaching the infiltration point, and records the moment when the real-time moisture content at the first depth reaches this data jump, generating the first time. As the water front continues to physically advance downwards, the system accurately captures the moment when the real-time moisture content at the second depth experiences a step-like increase due to the water front reaching the infiltration point, and records the moment when the real-time moisture content at the second depth reaches this data jump, generating the second time.

[0039] As an feasible approach, when the time difference between the first and second times is greater than a preset lower limit, the specific operation for calculating the infiltration velocity based on the depth difference and time difference is as follows: subtract the first time from the second time to obtain the time difference; perform a comparison operation between the time difference and the preset lower limit; if the time difference is less than the preset lower limit, extract the saturated hydraulic conductivity pre-stored in the local database, assign the saturated hydraulic conductivity as the infiltration velocity; if the time difference is greater than or equal to the preset lower limit, subtract the first depth from the second depth to obtain the depth difference, extract the depth difference as the numerator parameter, extract the time difference as the denominator parameter, and divide the numerator parameter by the denominator parameter to calculate the infiltration velocity.

[0040] Specifically, after acquiring the first and second times, the process subtracts the first time from the second time to obtain the time difference. Subsequently, the time difference is compared with a preset lower limit. The preset lower limit is based on the theoretical shortest time required for pure water to penetrate the physical distance between the first and second depths in homogeneous target soil without physical cracks. The reason for setting the preset lower limit is that peanut planting plots are prone to microscopic physical cracks due to high temperature and drought under long-term mulching. The role of the preset lower limit is to construct a physical judgment boundary to filter out interference from artifacts of large pore flow.

[0041] Under physical conditions where the time difference is less than a preset lower limit, it is determined that the moisture front has passed through abnormal soil physical crack channels, i.e., abnormal large pore flow physical penetration has occurred. Under this extreme condition, the saturated hydraulic conductivity pre-stored in the local database is extracted. The value of the saturated hydraulic conductivity is based on a constant physical lookup table value pre-calibrated based on the soil texture of the target planting plot and stored in non-volatile memory. The saturated hydraulic conductivity is assigned as the infiltration velocity to ensure that a fluid kinematic benchmark with physical reference value can still be obtained when the soil structure is physically damaged.

[0042] Under physical conditions where the time difference is greater than or equal to a preset lower limit, it is determined that the water front is undergoing normal physical infiltration in the soil porous matrix. The depth difference is obtained by subtracting the first depth from the second depth. The depth difference is extracted as a numerator parameter, and the time difference is extracted as a denominator parameter. The numerator parameter is divided by the denominator parameter to calculate the true infiltration velocity that fully conforms to the hydrodynamic characteristics of porous media.

[0043] Through the branching operation processing based on physical boundary verification, the system completes the transformation from the time dimension signal collected by the bottom sensor to the spatial kinematic index. The above calculation logic not only realizes the adaptive elimination of complex physical interference in the mulched soil, but also provides reliable flow velocity parameters for the subsequent steps to accurately deduce the dynamic displacement path of the fertilizer front through the water-fertilizer coupling model.

[0044] The following describes in detail step S2 above, namely, "receiving the calibration status and infiltration velocity, obtaining the instantaneous flow rate, nutrient quality, mother liquor concentration, and the original conductivity and real-time temperature at the third depth, performing temperature compensation on the original conductivity based on the real-time temperature to obtain the standard conductivity, calculating the fertilization time from the nutrient quality, mother liquor concentration, and instantaneous flow rate, and generating a first instruction to shut down the fertilization equipment while keeping the water supply equipment on when the fertilization time is reached."

[0045] In a specific embodiment of the present invention, after receiving the calibration status and infiltration flow rate, the process enters the stage of quantitative nutrient injection and conductivity verification. The main control equipment simultaneously acquires instantaneous flow rate, nutrient mass, mother liquor concentration, and the original conductivity and real-time temperature at the third depth. It then uses the real-time temperature to perform standardized temperature compensation calculations on the original conductivity to obtain the standard conductivity, thereby eliminating the physical interference of high-temperature thermal disturbance under the mulch film on the accuracy of conductivity detection. Simultaneously, based on the law of conservation of mass, the main control equipment accurately calculates the fertilization duration using nutrient mass, mother liquor concentration, and instantaneous flow rate. When the fertilization equipment's operating time reaches the designated duration, it generates a first instruction to shut down the fertilization equipment while keeping the water supply equipment running. Step S2, while accurately delivering the target nutrients during the peanut growth period, maintains positive pressure within the pipeline network by keeping the water supply equipment running, providing a power reserve and signal benchmark for subsequent physical separation of the fertilizer front and shallow peg zone using clear water jacking.

[0046] As an feasible approach, the specific operation of obtaining the standard conductivity by temperature compensation of the original conductivity based on real-time temperature is as follows: obtain the real-time temperature and subtract the standard constant 25 to obtain the physical temperature difference; obtain the conductivity temperature compensation coefficient and multiply the physical temperature difference by the conductivity temperature compensation coefficient to obtain the temperature compensation product; add the constant 1 to the temperature compensation product to obtain the correction denominator; divide the original conductivity by the correction denominator to obtain the standard conductivity.

[0047] Specifically, during the quantitative nutrient injection process, in order to eliminate the interference of the severe thermodynamic disturbance caused by the greenhouse effect of the mulch film on the accuracy of the bottom layer ion concentration measurement in the case of peanut planting under mulch film, the real-time temperature of the third depth is obtained and the physical temperature difference is obtained by subtracting the standard constant 25. The standard constant 25 is based on the internationally accepted 25℃ soil conductivity calibration benchmark temperature. The purpose of subtracting the standard constant 25 is to accurately quantify the absolute physical deviation of the current mulched soil microenvironment from the 25℃ benchmark thermodynamic state.

[0048] Based on the obtained physical temperature difference, a pre-calibrated and stored conductivity temperature compensation coefficient is acquired, and the physical temperature difference is multiplied by the conductivity temperature compensation coefficient to obtain the temperature compensation product. The conductivity temperature compensation coefficient is a constant numerical coefficient (usually ranging from 0.019 to 0.021 / ℃) set according to the linear regression rate of ion activity in the soil pore solution of the target planting plot with physical thermodynamic changes. The temperature compensation product clearly reflects the absolute physical error drift of the original conductivity signal caused by thermodynamic disturbance.

[0049] After determining the physical boundary of the temperature compensation product, the temperature compensation product is added to a constant 1 to obtain the correction denominator. The constant 1 represents the basic physical proportion under the reference thermodynamic state at 25℃. The mathematical and physical dual role of adding the constant 1 is to ensure that the value of the correction denominator is constant at 1 under the physical condition that the real-time temperature is exactly equal to 25℃, thereby constructing a correction base that conforms to the derivation logic of the limit of porous media fluid mechanics.

[0050] After constructing the corrected denominator, the original conductivity is divided by the corrected denominator to calculate the standard conductivity. By obtaining the standard conductivity through the above division operation, the original conductivity, which is severely affected by surface thermodynamic and physical fluctuations, is precisely mapped to a 25°C isothermal physical reference coordinate system. This completely eliminates the false high salinity signal artifacts caused by high temperature, and provides a definite concentration scale for subsequent accurate determination of whether the high-concentration fertilizer front has physically reached the deep main root zone at the third depth.

[0051] As an feasible method, the specific operation of calculating the fertilization duration based on nutrient quality, mother liquor concentration, and instantaneous flow rate is as follows: multiply the mother liquor concentration by the instantaneous flow rate to obtain the nutrient injection mass per unit time; divide the nutrient quality by the nutrient injection mass per unit time to obtain the fertilization duration; when the fertilization equipment reaches the fertilization duration, generate a first instruction to shut down the fertilization equipment while keeping the water supply equipment running.

[0052] Specifically, after completing the benchmark calibration of standard conductivity, the preset mother liquor concentration and the real-time instantaneous flow rate are obtained. The value of the mother liquor concentration is based on the constant physical solubility of nutrients pre-configured in the storage tank of the fertilizer equipment. The unit of measurement for the mother liquor concentration is kg / L, and the unit of measurement for the instantaneous flow rate is L / h. The nutrient injection mass per unit time is obtained by multiplying the mother liquor concentration by the instantaneous flow rate. The nutrient injection mass per unit time accurately maps the absolute physical mass flow rate of the effective fertilizer components in the target pipeline in fluid mechanics, and the unit of measurement for the nutrient injection mass per unit time is derived as kg / h.

[0053] After obtaining the fluid physics mapping of nutrient injection mass per unit time, the nutrient mass pre-stored locally on the main control equipment is extracted. The nutrient mass value is based on the absolute total weight of the target formula, which is strictly calculated according to the physical area of ​​the target plot and the agronomic consumption model of the current flowering and pegging stage or the pod-filling stage of peanuts. The unit of measurement for nutrient mass is kg. The fertilization duration is calculated by dividing the nutrient mass by the nutrient injection mass per unit time. The fertilization duration in h or min is obtained by performing the division operation, which completely eliminates the agricultural accident risk of peanut seedling burn caused by insufficient or excessive physical fertilizer injection due to abnormal fluctuations in water pressure in the pipeline network in traditional drip irrigation systems.

[0054] Under the premise of precisely defining the physical time boundary of fertilization duration, the actual operating clock cycle of the fertilization equipment is continuously monitored. At the precise physical moment when the fertilization equipment's operating time reaches the fertilization duration, it is determined that the absolute quantitative fertilizer meeting the nutrient quality requirements has been fully physically injected into the drip irrigation main pipeline network and the shallow soil space of the peanut root system. This generates the first instruction to shut down the fertilization equipment while keeping the water supply equipment on. The physical function of generating the first instruction and strictly keeping the water supply equipment on is to maintain a positive fluid pressure physical state of greater than 0.1MPa inside the drip irrigation network using the pure water continuously injected by the water supply equipment. This lays an indispensable fluid dynamic foundation for the subsequent use of the fluid piston effect to physically push the high-concentration fertilizer front downwards and achieve the three-dimensional spatial physical separation of fertilizer between the 5cm shallow fruit peg zone and the 30cm deep main root zone.

[0055] The following describes in detail step S3 above, namely, "receiving the first instruction, obtaining the pipeline volume, hysteresis factor, and real-time moisture content and water holding threshold at each depth, calculating the pore surplus term based on the water holding threshold and real-time moisture content, calculating the jacking time in combination with the pipeline volume, hysteresis factor, instantaneous flow rate and infiltration velocity, generating a shutdown instruction after injecting water according to the instantaneous flow rate and jacking time, and pushing the fertilizer to the third depth".

[0056] In a specific embodiment of the present invention, under the physical state of receiving the first instruction to maintain the continuous operation of the water supply equipment, the pipeline volume, hysteresis factor, and real-time moisture content and water holding threshold at each depth are simultaneously acquired; the main control equipment calculates the pore surplus term based on the water holding threshold and real-time moisture content to dynamically quantify the actual absorption space of the soil and prevent physical water oversaturation; after clarifying the physical boundary of the pore surplus term, the main control equipment combines the pipeline volume, hysteresis factor, instantaneous flow rate and infiltration velocity to perform a volume balance deduction of porous media and accurately calculate the jacking time; the main control equipment continuously injects pure water according to the instantaneous flow rate and generates a shutdown instruction when the water injection time reaches the jacking time. Utilizing the physical piston effect generated by the continuous injection of pure water, the high-concentration fertilizer retained in the pipeline and shallow soil is forcibly and accurately pushed to the third depth, thereby completely realizing the absolute separation of pure water wetting of the shallow fruit needle area and high-concentration fertilization of the deep main root area in three-dimensional physical space.

[0057] As an feasible approach, the specific operation of calculating the pore surplus term based on the water holding threshold and real-time moisture content is as follows: obtain the water holding threshold at the first depth and the water holding threshold at the second depth; subtract the real-time moisture content at the first depth from the water holding threshold at the first depth to obtain the moisture content difference at the first depth; extract the maximum value between the moisture content difference at the first depth and zero to generate the pore surplus term at the first depth; subtract the real-time moisture content at the second depth from the water holding threshold at the second depth to obtain the moisture content difference at the second depth; extract the maximum value between the moisture content difference at the second depth and zero to generate the pore surplus term at the second depth.

[0058] Specifically, in the scenario of high-frequency drip irrigation for mulched peanuts, in order to completely prevent the high concentration of fertilizer from penetrating downwards or causing waterlogging and oxygen deficiency in the shallow soil due to blind watering, the water-holding thresholds at the first and second depths are obtained before performing the piston-like water-pushing physical action with anti-collapse boundaries. The water-holding thresholds at the first and second depths are uniformly calibrated using the international standard unit of volumetric water content (m³ / m³) in terms of physical dimensions. The effect of obtaining the water-holding thresholds at the first and second depths is to pre-set an insurmountable maximum water-holding volume percentage boundary between the shallow core area of ​​fruit peg development (5cm below the surface) and the microenvironment transition zone (15cm below the surface).

[0059] Under the basic boundary condition of setting the upper limit of physical volume, considering the severe spatiotemporal fluctuations in water content caused by the alternating effects of surface evaporation and root water absorption in the shallow fruit needle area, the real-time water content of the first depth, which is measured in m³ / m³, is obtained. The water holding threshold of the first depth is subtracted from the real-time water content of the first depth to obtain the water content difference of the first depth. The effect of the water content difference of the first depth in physical space is to accurately map and quantify the absolute volume percentage of pure water that the pores inside the soil 5cm below the current surface can safely absorb.

[0060] In the context of fluid physics mapping for extracting the difference in water content at the first depth, for extreme cases where the real-time water content at the first depth may exceed the water-holding threshold due to local microclimate condensation or rainfall exceeding the water-holding threshold at the first depth, resulting in a negative value for the difference in water content at the first depth, the maximum value between the difference in water content at the first depth and the value of 0 is extracted to generate the first depth porosity surplus term. The mathematical operation of extracting the maximum value constructs an absolute lower limit interception safety mechanism in the physical scenario, forcibly locking the calculation result of the first depth porosity surplus term to the value of 0, completely preventing the subsequent porous media volume balance equation from crashing due to the substitution of negative parameters, and at the same time, from a physical perspective, avoiding the agricultural disaster of anaerobic rotting of peanut roots due to the output of erroneous excessive water injection commands.

[0061] With the safety defense line of locking the lower limit of the first depth pore surplus term completed, in order to simultaneously control the true absorption potential of the main channel for downward water and fertilizer transport, namely the microenvironment transition zone, the real-time water content of the second depth (in units of m³ / m³) is obtained. The water holding threshold of the second depth is subtracted from the real-time water content of the second depth to obtain the water content difference of the second depth. It is clear that the water content difference of the second depth physically characterizes the remaining volume of pure water allowed to be physically pushed and injected downwards in the three-dimensional pores of the soil 15cm below the surface.

[0062] Given a clear understanding of the physical properties of the second depth moisture content difference, and considering the risk of localized overwatering in deeper layers, the system extracts the maximum value between the second depth moisture content difference and 0 to generate a second depth porosity surplus term. By performing a bottom-level mathematical constant anti-collapse interception action on the second depth moisture content difference that is completely consistent with that on the first depth, the system generates a second depth porosity surplus term. In terms of overall effect, the system achieves precise three-dimensional quantification of the dynamic absorption limit of pores at different physical depths of the covered soil.

[0063] As an feasible method, the specific operation for calculating the jacking time by combining the pipeline volume, hysteresis factor, instantaneous flow rate, and infiltration velocity is as follows: Obtain the cross-sectional area of ​​the wetted ball, the thickness of the first depth, and the thickness of the second depth; divide the pipeline volume by the instantaneous flow rate to obtain the pipeline emptying compensation time; multiply the cross-sectional area of ​​the wetted ball by the thickness of the first depth to obtain the first volume base; multiply the first volume base by the first depth pore surplus term to obtain the first depth compensation volume; multiply the cross-sectional area of ​​the wetted ball by the thickness of the second depth to obtain the second volume base; multiply the second volume base by the second depth pore surplus term to obtain the second depth compensation volume; add the first depth compensation volume to the second depth compensation volume to obtain the total soil compensation volume; multiply the total soil compensation volume by the hysteresis factor to obtain the corrected compensation volume; divide the corrected compensation volume by the instantaneous flow rate to obtain the soil replacement time; add the pipeline emptying compensation time to the soil replacement time to obtain the jacking time.

[0064] Specifically, in scenarios where fertilization equipment is shut down and the drip irrigation system switches to the pure water injection stage, the fluid dynamics challenges are addressed by the inevitable physical residue of high-concentration liquid mother liquor inside the drip irrigation network, and the physical diffusion of pure water in the membrane porous soil due to capillary force and gravity coupling to form a three-dimensional ellipsoidal wetted area. The cross-sectional area of ​​the wetted sphere with a spatial mapping relationship to the infiltration velocity and a unit of m² is obtained, and the first depth thickness with a physical value of 0.05m and the second depth thickness with a physical value of 0.15m are obtained. The main control equipment divides the pipe network volume (physical dimension m³) by the instantaneous flow rate (physical dimension m³ / h) to obtain the pipe network purging compensation time (physical dimension h). The resulting pipe network purging compensation time accurately quantifies the pure fluid dynamic prerequisite time required for the system to completely squeeze out the residual fertilizer liquid in the ground physical pipes before pushing the high-concentration fertilizer in the shallow soil downwards. The obtained wet sphere cross-sectional area provides an absolutely accurate three-dimensional spatial physical boundary for the subsequent porous media volume balance equation.

[0065] Based on the calculation foundation of the clear drainage time of the ground pipeline network and the three-dimensional physical boundary of the soil, and considering the physical differences in water absorption volume between the shallow core area of ​​peanut peg development and the microenvironment transition zone, the cross-sectional area of ​​the wetting bulb is multiplied by the thickness of the first depth to obtain the first volume base with physical dimensions of m³. The first volume base is multiplied by the dimensionless first depth pore surplus term to obtain the first depth compensation volume with the same dimension unit of m³. For the microenvironment transition zone, the same geometric formula is applied, and the cross-sectional area of ​​the wetting bulb is multiplied by the thickness of the second depth to obtain the second depth compensation volume with the same dimension unit of m³. The volume base is multiplied by the dimensionless second depth porosity surplus term to obtain the second depth compensation volume with a dimension unit of m³. The first depth compensation volume is added to the second depth compensation volume and then aggregated to obtain the total soil compensation volume with a physical dimension of m³. The total soil compensation volume is calculated to completely upgrade the one-dimensional depth water physical surplus parameter to the absolute volume parameter in three-dimensional space in terms of core physical effect. The total absolute pure water physical volume required to just fill the soil physical pores of the shallow core area and the microenvironment transition zone is derived.

[0066] Given an ideal hydrodynamic volumetric model for the total soil compensation volume, the tortuous capillary network within the covered soil presents a significant physical frictional resistance and dynamic hysteresis effect on the downward penetration of pure water. Directly using the ideal physical volume would inevitably lead to a serious engineering error risk, where the actual pure water penetration depth falls far short of the target. Therefore, a dimensionless hysteresis factor, pre-calibrated based on the target soil texture, is obtained. Multiplying the total soil compensation volume by the hysteresis factor yields a corrected compensation volume with the actual physical characteristics of porous media resistance. Dividing the corrected compensation volume by the instantaneous flow rate yields the soil replacement time in hours (h). Finally, the soil replacement time is added to the pipeline drainage compensation time. The replacement time is finally calculated by adding the time dimension to obtain the jacking time with the total physical dimension h. This jacking time action abandons the extensive management mode of blindly setting flushing time in traditional agricultural drip irrigation systems. The system introduces a hysteresis factor to correct the porous media resistance of the ideal fluid dynamics volume model and superimposes the physical residual time of the pipeline network. The output has an absolute volume balance boundary, which ensures that the pure water continuously injected according to the jacking time can not only push the shallow high-concentration fertilizer downwards to the deep enrichment zone of the main root system, but also completely eliminate the agricultural environmental disaster caused by the fertilizer front penetrating the bottom soil layer and leaking into the groundwater due to excessive injection of pure water.

[0067] As an feasible approach, after injecting water based on the instantaneous flow rate and jacking duration, a shutdown command is generated to push the fertilizer to the third depth. The specific operation is as follows: upon receiving the first command, keep the water supply equipment running; multiply the instantaneous flow rate by the jacking duration to obtain the target total volume of pure water to be pushed; obtain the cumulative volume of pure water output by the water supply equipment; under the condition that the cumulative volume of pure water equals the target total volume of pure water to be pushed, complete the pushing operation to the third depth; upon completing the pushing operation to the third depth, generate a shutdown command; and shut down the water supply equipment according to the shutdown command.

[0068] Specifically, in the scenario of water and fertilizer regulation for mulched peanuts entering the clear water space replacement stage, addressing the engineering pain points of fluid depressurization and backflow easily occurring inside the drip irrigation network after the fertilization equipment stops, and the inability of traditional agriculture to achieve three-dimensional spatial depth of fertilizer through blind flushing, the hardware logic, upon receiving the first instruction, forces the water supply equipment to remain in the physical state of water injection. The main control equipment multiplies the instantaneous flow rate (in m³ / h) by the jacking duration (in h) to obtain the target jacking pure water volume (in m³). The resulting target jacking pure water volume not only maintains the positive pressure fluid dynamic state inside the drip irrigation network to prevent mother liquor backflow by continuously injecting pure water, but also establishes a three-dimensional hydraulic piston volume boundary with an absolutely quantitative measurement scale for the subsequent porous media piston replacement action.

[0069] Based on the established three-dimensional hydraulic piston volume boundary, and considering the physical reality that pure water propels fertilizer downwards within porous soil media, which is an invisible underground fluid black box movement, the main control equipment acquires the cumulative pure water volume output by the water supply equipment flow meter in real time, with the physical dimension being m³. Under the physical condition that the cumulative pure water volume is numerically equal to the target total amount of pure water pushed, the system determines that the fluid physical piston composed of pure water has completely squeezed all the high-concentration mother liquor in the shallow pores downwards. The physical system then confirms the completion of the pushing operation that completely pushes the high-concentration fertilizer to the third depth of 30cm below the surface. The effect of confirming the completion of the pushing operation that pushes the fertilizer to the third depth is that the three-dimensional movement trajectory of the complex underground fertilizer front, which is invisible, is transformed and locked into a digital index of cumulative pure water volume that can be accurately measured by the surface water supply equipment, realizing the complete white-box digital monitoring of the underground space stripping action on the surface.

[0070] Upon confirming the completion of the fertilizer-pushing operation to the third depth at the full-capacity limit, to completely prevent excessive injection of pure water that could cause high-concentration fertilizer to continue penetrating the root zone and trigger non-point source pollution in deep underground waters, the main control equipment immediately generates a shutdown command when the cumulative pure water volume equals the target total volume of pure water pushed in. Based on the shutdown command, the main control equipment rigidly cuts off the power output of the water supply equipment to shut it down. The ultimate physical effect and agricultural engineering value of shutting down the water supply equipment according to the shutdown command lies in forcibly stopping all fluid input power within the drip irrigation network, thus solidifying in three-dimensional physical space an absolute spatial-temporal decoupling habitat where pure water 5cm below the surface of the mulched peanut field promotes peg development, and high-concentration fertilizer 30cm below the surface promotes strong root systems.

[0071] The following describes in detail step S4, namely, "receiving a shutdown command, obtaining the steady-state standard conductivity at the third depth after resting, and if the steady-state standard conductivity is lower than the target lower limit, increasing the preset step size to update the hysteresis factor as the parameter benchmark for the next cycle," with reference to the embodiments.

[0072] In a specific embodiment of the present invention, after receiving a shutdown command, the system enters a physical static state to ensure that the hydraulic redistribution and ion diffusion inside the porous soil covered with the membrane are completely completed. After the static state is completed, the main control device obtains the steady-state standard conductivity at the third depth and compares the steady-state standard conductivity with the preset target lower limit. Under physical conditions where the steady-state standard conductivity is lower than the target lower limit, the system determines that the actual physical displacement distance of the high-concentration fertilizer front has not reached the deep main root zone. The main control device then adds a preset step size to the hysteresis factor to generate a new hysteresis factor. The main control device extracts the new hysteresis factor as the parameter benchmark for the next cycle. By introducing an adaptive compensation mechanism for fluid resistance parameters based on physical feedback, the calculation error of deep transport resistance caused by soil aggregate aging or enhanced clay adsorption is corrected, thereby constructing a closed loop with self-learning and targeted depth-based iteration capabilities.

[0073] As an feasible method, the specific operation for obtaining the steady-state standard conductivity of the third depth after settling is as follows: After generating the shutdown command, perform a settling operation lasting 120 minutes; after completing the settling operation, obtain the steady-state temperature and the steady-state original conductivity of the third depth; subtract a constant of 25 from the steady-state temperature of the third depth to obtain the steady-state temperature difference; obtain the conductivity temperature compensation coefficient; multiply the steady-state temperature difference by the conductivity temperature compensation coefficient to obtain the steady-state temperature compensation product; add a constant of 1 to the steady-state temperature compensation product to obtain the steady-state correction denominator; divide the steady-state original conductivity of the third depth by the steady-state correction denominator to obtain the steady-state standard conductivity of the third depth.

[0074] Specifically, after the piston-type clear water jacking is completed and the water supply equipment is completely shut down, there is a strong hydrodynamic time lag in the downward movement of gravity water and capillary water carrying high concentrations of liquid fertilizer inside the porous soil. If the sensor signal sampling is performed immediately at the moment the water supply equipment stops, it will inevitably collect erroneous fluid ion data in a state of violent dynamic fluctuation. After generating the shutdown command, the main control equipment forces a static operation with a duration of 120 minutes. The reason for the duration of 120 minutes is to be the average hydraulic redistribution time benchmark required for the gravity water inside the porous medium of typical sandy loam soil in the target planting plot to decay from the saturated transient infiltration physical state and completely transform into the capillary steady-state retention physical state. This provides sufficient physical relaxation time that conforms to the fluid decay law for the hydraulic redistribution and three-dimensional diffusion of solutes within the microenvironment of the covered soil, ensuring that the entire underground porous media physical system is completely calmed down from the violent fluid transient movement and enters a physical steady-state environment with an absolutely balanced ion concentration distribution, thus completely preventing signal overload artifacts caused by the failure to drain the gravity water in the large pores.

[0075] Given that the entire underground porous media physical system has entered a physically stable environment with an absolutely balanced ion concentration distribution, and considering the objective agronomical fact that deep soil thermodynamic fluctuations have a strong physical interference with the ion conductivity of porous media pore liquid and are prone to generating false high salinity signals, the steady-state temperature at the third depth (unit: °C) and the steady-state original conductivity at the third depth (unit: mS / cm) were obtained. The main control equipment subtracted the steady-state temperature at the third depth from the physical constant 25 °C, which represents the internationally accepted thermodynamic benchmark, to obtain the steady-state temperature difference. The effect of obtaining the steady-state temperature difference is that it accurately quantifies the absolute physical environment deviation of the microenvironment in the deep root-rich zone 30 cm below the surface from the 25 °C benchmark thermodynamic state.

[0076] Based on the measurement base for quantifying the absolute physical environment deviation, considering the physical differences in the sensitivity of different soil textures to thermodynamic disturbances, a conductivity temperature compensation coefficient is obtained, which is pre-calibrated based on the physical decay law of ion activity in the pore solution of the target plot and has a physical value range of 0.0191 / ℃ to 0.0211 / ℃. The main control equipment multiplies the steady-state temperature difference by the conductivity temperature compensation coefficient to obtain a dimensionless steady-state temperature compensation product. At the mathematical limit of the steady-state temperature compensation product, the main control equipment adds the physical constant 1 to the steady-state temperature compensation product to obtain a dimensionless steady-state correction denominator. The effect of obtaining the dimensionless steady-state correction denominator is that, by adding the physical constant 1 as a fallback mathematical action, it ensures that under the ideal, interference-free physical condition where the steady-state temperature at the third depth is exactly equal to the reference physical constant 25℃, the steady-state correction denominator is forcibly locked to a constant 1 in value, thus constructing a correction condition that conforms to the dual physical laws of fluid mechanics and thermodynamics for subsequent elimination of extreme thermal noise.

[0077] Under the corrected conditions that conform to both fluid mechanics and thermodynamics, the main control equipment performs a final pure text division operation by dividing the steady-state original conductivity (in mS / cm) of the third depth by the dimensionless steady-state corrected denominator to obtain the steady-state standard conductivity (in mS / cm) of the third depth. The obtained steady-state standard conductivity of the third depth eliminates false salinity detection artifacts caused by abnormal fluctuations in deep geothermal temperature. It maps the steady-state original conductivity of the third depth, which is severely affected by geothermal temperature, to a 25℃ constant-temperature physical reference coordinate system. This provides a high-fidelity scale signal with absolute physical certainty for the next step of accurately judging whether the target fertilizer front has truly moved to the deep root zone of the third depth.

[0078] As an feasible approach, if the steady-state standard conductivity is lower than the target lower limit, the hysteresis factor is updated by increasing the preset step size as the parameter benchmark for the next cycle. The specific operation is as follows: obtain the target lower limit; under the condition that the steady-state standard conductivity at the third depth is lower than the target lower limit, obtain the preset step size and hysteresis factor; add the preset step size to the hysteresis factor to obtain the updated hysteresis factor; establish the updated hysteresis factor as the parameter benchmark for the next cycle.

[0079] Specifically, given the high-fidelity scale signal of the steady-state standard conductivity at the third depth, and addressing the issue that the true three-dimensional spatial retention depth of fertilizer fronts cannot be directly observed in the underground black box environment of porous media, this invention first obtains a target lower limit with the same physical dimension as mS / cm. The target lower limit is the empirical threshold of the minimum absolute ion concentration required to maintain the normal physiological metabolism of the deep main root system of peanuts at the current specific growth stage. The main control device compares the steady-state standard conductivity at the third depth with the target lower limit. Using the dimensionlessly uniform standard conductivity parameter, the invisible spatial distribution of underground fluids is accurately transformed into a deterministic digital truth judgment logic executable by the surface system.

[0080] Given that the steady-state standard conductivity at the third depth is lower than the target lower limit, and considering the physical aging of the soil aggregate structure with increasing irrigation frequency and the dynamic enhancement of the physical adsorption force of soil clay particles on nutrient ions, which leads to the actual porous media transport resistance of pure water pushing fertilizer downwards being much greater than the theoretically calculated resistance, resulting in insufficient fertilizer pushing distance and deep nutrient depletion, a dimensionless preset step size and a previously preset dimensionless hysteresis factor were obtained. The preset step size was pre-set based on the soil clay aging law of the target plot. The resistance compensation fine-tuning constant is set to a physical value of 0.05 for the preset step size; the hysteresis factor is the reciprocal of the ratio of the solute transport velocity in the target soil pores to the pure water carrier velocity, and the initial value range of the hysteresis factor is set to 1.1 to 1.5; the main control equipment adds the hysteresis factor to the preset step size to obtain the updated hysteresis factor; the effect of obtaining the updated hysteresis factor is that, by forcibly increasing the system resistance boundary parameters according to the underlying logic of fluid transport resistance mechanics, the true cause of the fluid dynamic resistance failure that led to the fertilizer jacking failure is accurately anchored and corrected.

[0081] Under the adaptive compensation control state where the update lag factor is confirmed, the main control device establishes the update lag factor as the parameter benchmark for the next cycle. The next cycle is defined as the next spatial allocation task of water or nutrients immediately following the current water and fertilizer scheduling event. When the system triggers the water and fertilizer irrigation task of the next cycle again, the main control device will automatically retrieve the update lag factor that has been corrected for resistance compensation from the local register in the push duration calculation program of step S3. This will ensure that the system calculates a longer push duration and a larger target push pure water volume, thereby using more abundant pure water piston kinetic energy to strongly overcome the additional physical transport resistance caused by soil aging and solve the agricultural disaster of long-term nutrient deficiency in the deep taproot zone.

[0082] To further illustrate the technical effects achievable by the proposed solution, a specific implementation method is given below, along with the results of porous media fluid dynamics simulation and field verification of the specific implementation method.

[0083] In this embodiment, the method is applied to a typical sandy loam soil peanut planting field in Shandong Province. The hardware system includes a distributed multi-depth soil sensor array (deployed at depths of 5cm, 15cm, and 30cm below the soil surface), a high-frequency flow meter with a range of 0-500L / h, and a main control fertilization device supporting variable frequency and constant pressure. The main control device is implemented based on a PLC+DSP dual-core hardware platform, and the sensor data sampling frequency is 1Hz. The implementation steps are as follows: Under the physical reference conditions of obtaining the calibration state and infiltration velocity, the main control equipment obtains the real-time temperature and performs nonlinear mapping on the original conductivity to obtain the standard conductivity, and strictly calculates the fertilization time according to the law of conservation of mass to perform quantitative nutrient injection; under the volume state of completing quantitative nutrient injection, the pipeline volume, the pore surplus at depths of 5cm and 15cm below the surface, and the pre-set hysteresis factor are obtained. Based on the volume balance equation of porous media, the jacking time is deduced, and the fluid piston effect generated by the continuous injection of pure water is used to physically push the shallow high-concentration mother liquor to the deep root zone 30cm below the surface; after stopping and forcibly settling for 120 minutes to achieve hydraulic redistribution steady state, the steady-state standard conductivity at a depth of 30cm below the surface is compared with the target lower limit. Under the condition that the target is not met, the hysteresis factor is updated by addition with a preset step size of 0.05 and written to the local register as the control reference for the next cycle.

[0084] To verify the effectiveness of the control method, a three-dimensional equivalent model of solute transport in sandy loam was constructed on the COMSOL Multiphysics simulation platform, and time-domain simulation and field measurement were combined using a field micro lysimeter. The benchmark test scenario was that the covered soil entered an extreme high-temperature period (the temperature 30 cm below the surface suddenly increased to 38 °C) and the soil aggregate structure underwent mid-term physical aging (the clay adsorption resistance increased by 30%). Under the traditional timed and quantitative drip irrigation control mode without thermodynamic correction, the test system was affected by deep high temperature interference, resulting in extreme false high salinity detection artifacts. This caused the fertilizer application equipment to prematurely trigger a shutdown command (the absolute nutrient injection amount was only 72% of the formula target value). At the same time, due to the lack of piston-type clear water pushing and resistance adaptive mechanism in the traditional benchmark mode, up to 68% of the high-concentration fertilizer remained in the shallow space of 0-15cm below the surface, causing the conductivity of the shallow microenvironment to surge to 3.8mS / cm, resulting in large-scale salt damage and burns to peanut pegs (the rotten fruit rate in the test area was as high as 14%). The effective conductivity of the deep root zone 30cm below the surface was only 1.1mS / cm (far below the agronomic target lower limit of 2.0mS / cm), and the deep damping nutrient depletion time exceeded 15 days. The overall system voltage qualification rate (which maps to the fertilizer spatial distribution qualification rate in this field) was only 61%.

[0085] After adopting the method proposed in this application, the main control equipment thoroughly filters out high-temperature thermal noise by performing standard conductivity temperature compensation calculation in step S2, ensuring that the absolute nutrient injection amount is restored to 99.5% of the formula target value; after performing the piston-type clear water jacking operation with anti-collapse boundary in step S3, the pure water piston kinetic energy is precisely applied, and the conductivity of the shallow fruit needle zone 0-10cm below the ground surface rapidly drops and stabilizes at 0.6mS / cm within a safe pure water salt-free stress microenvironment within 2 hours after the water injection ends. The steady-state standard conductivity of the deep main root zone 30cm below the ground surface precisely jumps to the optimal physiological absorption range of 2.2mS / cm, realizing the absolute separation of water and fertilizer in three-dimensional space. Further, in scenarios involving soil aging and a surge in resistance, the control method relies on the closed-loop self-checking mechanism of step S4 to maintain on-site optimal control. The main control equipment accurately captures weak signals indicating that the fertilizer front has not met the standards, triggering adaptive updates of the hysteresis factor (automatically iterating from the initial 1.2 to 1.3) for two consecutive irrigation cycles. By utilizing the physically increased correction and compensation volume, the system forcibly overcomes the clay adsorption resistance barrier, preventing shallow seedling burn or deep leakage. Multiple Monte Carlo equivalent simulations (covering 100 combinations of random rainfall and waterlogging with different texture aging fluctuations) show that the safe peeling rate in the shallow fruit peg zone remains stable above 99.2%, the target-based fertilization compliance rate in the deep main root zone increases to 98.8%, and the average fruit rot rate drops sharply to below 0.8%, providing highly intuitive verification of the fluid dynamics robustness and spatiotemporal distribution control superiority of the control method.

[0086] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for intelligent control of drip irrigation for peanuts, characterized in that, Includes the following steps: Step S1: Obtain the real-time water content of the first depth and the second depth, as well as the first and second times when the water front reaches both depths. When the time difference between the first and second times is greater than a preset lower limit, calculate the infiltration velocity based on the depth difference and the time difference. When the real-time water content of the first depth reaches the saturation threshold, output the calibration status and the infiltration velocity. Step S2: Receive the calibration status and the infiltration velocity, obtain the instantaneous flow rate, nutrient mass, mother liquor concentration, and the original conductivity and real-time temperature at the third depth, perform temperature compensation on the original conductivity based on the real-time temperature to obtain the standard conductivity, and calculate the fertilization duration from the nutrient mass, the mother liquor concentration, and the instantaneous flow rate. When the fertilization duration is reached, generate a first instruction to shut down the fertilization equipment while keeping the water supply equipment on. Step S3: Receive the first instruction, obtain the pipeline volume, hysteresis factor, and real-time moisture content and water holding threshold at each depth, calculate the pore surplus term based on the water holding threshold and the real-time moisture content, calculate the jacking time by combining the pipeline volume, the hysteresis factor, the instantaneous flow rate and the infiltration velocity, generate a shutdown instruction after injecting water according to the instantaneous flow rate and the jacking time, and push the fertilizer to the third depth; Step S4: Receive the shutdown command, and after resting, obtain the steady-state standard conductivity at the third depth. If the steady-state standard conductivity is lower than the target lower limit, increase the preset step size to update the hysteresis factor as the parameter benchmark for the next cycle.

2. The intelligent control method for peanut water and fertilizer drip irrigation according to claim 1, characterized in that, In step S1, the specific operations for obtaining the real-time water content at the first depth and the second depth, as well as the first and second times when the moisture front arrives at both depths, are as follows: A composite sensor array is arranged below the drip irrigation point. The composite sensor array includes a first sensor located at the first depth, a second sensor located at the second depth, and a third sensor located at the third depth. The system receives real-time moisture content, raw conductivity, and real-time temperature data collected by the first sensor, the second sensor, and the third sensor. Read the pipeline volume, send an opening command to the water supply equipment, and receive the instantaneous flow rate collected by the flow meter; Extract the real-time moisture content at the first depth and the real-time moisture content at the second depth, record the moment when the real-time moisture content at the first depth reaches a data jump to generate the first time, and record the moment when the real-time moisture content at the second depth reaches a data jump to generate the second time.

3. The intelligent control method for peanut water and fertilizer drip irrigation according to claim 2, characterized in that, In step S1, the specific operation of calculating the infiltration velocity based on the depth difference and the time difference when the time difference between the first time and the second time is greater than a preset lower limit is as follows: The time difference is obtained by subtracting the first time from the second time. Perform a comparison operation between the time difference and the preset lower limit; Under the condition that the time difference is less than the preset lower limit, the saturated hydraulic conductivity stored in the local database is extracted, and the saturated hydraulic conductivity is assigned as the infiltration velocity. Under the condition that the time difference is greater than or equal to the preset lower limit, the depth difference is obtained by subtracting the first depth from the second depth, the depth difference is extracted as a numerator parameter, the time difference is extracted as a denominator parameter, and the infiltration velocity is calculated by dividing the numerator parameter by the denominator parameter.

4. The intelligent control method for peanut water and fertilizer drip irrigation according to claim 3, characterized in that, In step S2, the specific operation of deriving the standard conductivity by temperature compensation of the original conductivity based on the real-time temperature is as follows: The physical temperature difference is obtained by subtracting the standard constant 25 from the real-time temperature. Obtain the conductivity temperature compensation coefficient and multiply the physical temperature difference by the conductivity temperature compensation coefficient to obtain the temperature compensation product; Adding a constant to the temperature compensation product yields the corrected denominator term. The standard conductivity is obtained by dividing the original conductivity by the corrected denominator.

5. The intelligent control method for peanut water and fertilizer drip irrigation according to claim 4, characterized in that, In step S2, the specific operation of calculating the fertilization duration from the nutrient mass, the mother liquor concentration, and the instantaneous flow rate is as follows: Multiplying the concentration of the mother liquor by the instantaneous flow rate yields the nutrient injection mass per unit time; The fertilization duration is obtained by dividing the nutrient mass by the nutrient injection mass per unit time. When the operating time of the fertilization equipment reaches the fertilization duration, a first instruction is generated to shut down the fertilization equipment while keeping the water supply equipment on.

6. The intelligent control method for peanut water and fertilizer drip irrigation according to claim 5, characterized in that, In step S3, the specific operation of calculating the pore surplus term based on the water holding threshold and the real-time moisture content is as follows: Obtain the water holding threshold at the first depth and the water holding threshold at the second depth, and subtract the real-time water content at the first depth from the water holding threshold at the first depth to obtain the water content difference at the first depth; The maximum value between the difference in water content at the first depth and zero is extracted to generate the porosity surplus term at the first depth. The difference in water content at the second depth is obtained by subtracting the real-time water content at the second depth from the water holding threshold at the second depth. The maximum value between the difference in water content at the second depth and zero is extracted to generate the second depth porosity surplus term.

7. The intelligent control method for peanut water and fertilizer drip irrigation according to claim 6, characterized in that, In step S3, the specific operation of calculating the jacking time by combining the pipeline volume, the hysteresis factor, the instantaneous flow rate, and the infiltration velocity is as follows: Obtain the cross-sectional area, first depth thickness, and second depth thickness of the wetted sphere; Divide the pipeline volume by the instantaneous flow rate to obtain the pipeline emptying compensation time; multiply the cross-sectional area of ​​the wetted bulb by the first depth thickness to obtain the first volume base; multiply the first volume base by the first depth pore surplus term to obtain the first depth compensation volume; multiply the cross-sectional area of ​​the wetted bulb by the second depth thickness to obtain the second volume base; multiply the second volume base by the second depth pore surplus term to obtain the second depth compensation volume; add the first depth compensation volume to the second depth compensation volume to obtain the total soil compensation volume. Multiply the total soil compensation volume by the hysteresis factor to obtain the corrected compensation volume, divide the corrected compensation volume by the instantaneous flow rate to obtain the soil replacement duration, and add the pipeline emptying compensation duration to the soil replacement duration to obtain the jacking duration.

8. The intelligent control method for peanut water and fertilizer drip irrigation according to claim 7, characterized in that, In step S3, the specific operation of generating a shutdown command after injecting water according to the instantaneous flow rate and the jacking duration, and pushing the fertilizer to the third depth, is as follows: Upon receiving the first instruction, keep the water supply equipment running; Multiply the instantaneous flow rate by the jacking duration to obtain the target total amount of pure water jacked; Obtain the cumulative volume of pure water output by the water supply equipment; Under the condition that the cumulative volume of pure water is equal to the total volume of the target jacking pure water, the pushing operation of moving the fertilizer to the third depth is completed; The stop command is generated when the pushing operation of moving the fertilizer to the third depth is completed; The water supply equipment is shut down according to the shutdown command.

9. The intelligent control method for peanut water and fertilizer drip irrigation according to claim 8, characterized in that, In step S4, the specific operation of obtaining the steady-state standard conductivity at the third depth after settling is as follows: After the shutdown command is generated, a static operation is performed for 120 minutes. After completing the settling operation, the steady-state temperature and the steady-state original conductivity of the third depth are obtained. The steady-state temperature difference is obtained by subtracting a constant of 25 from the steady-state temperature at the third depth. Obtain the temperature compensation coefficient for conductivity; Multiplying the steady-state temperature difference by the conductivity temperature compensation coefficient yields the steady-state temperature compensation product; Adding a constant to the product of steady-state temperature compensations yields the steady-state correction denominator. The steady-state standard conductivity of the third depth is obtained by dividing the steady-state original conductivity by the steady-state correction denominator.

10. The intelligent control method for peanut water and fertilizer drip irrigation according to claim 1, characterized in that, In step S4, the specific operation of updating the hysteresis factor by increasing the preset step size if the steady-state standard conductivity is lower than the target lower limit, and using it as the parameter benchmark for the next cycle, is as follows: Obtain the target lower limit. Under the condition that the steady-state standard conductivity at the third depth is lower than the target lower limit, obtain the preset step size and the hysteresis factor. The hysteresis factor is obtained by adding the preset step size to the hysteresis factor. The update lag factor is established as the parameter benchmark for the next cycle.

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