Saline-alkali soil improvement method

Abstract

The invention relates to the technical field of soil improvement, in particular to a saline-alkali soil improvement method which comprises the steps of dividing a to-be-improved saline-alkali soil area, detecting the saline-alkali distribution depth of the area and determining the ploughing depth by combining the depth of a target plant root system. Adjusting parameters of the ploughing device according to the difference between the depth and the soil permeability coefficient; setting initial leaching water pressure according to the ploughing parameters, detecting the concentration of sodium ions in discharged water, and adjusting the pressure according to the change curve of the period; when the slope of the curve reaches a preset value, measuring the proportion of sodium ions adsorbed by soil colloid, and comparing the proportion with a standard interval to judge whether continuous spraying is carried out or not. Whether the soil bulk density is detected or not is determined according to the result, ploughing parameters are fed back and adjusted according to the bulk density result, and the improvement requirement is met. According to the method, the ploughing parameters are adjusted through the target ploughing depth and the soil permeability coefficient difference value, and the leaching water pressure is adjusted according to the sodium ion change curve, so that the sodium ion removal efficiency is improved, and then the subsequent improvement efficiency of the saline-alkali soil is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil improvement, and particularly relates to a saline-alkali soil improvement method. BACKGROUND

[0002] The saline-alkali farmland has the characteristics of high salt content, soil compaction, poor aeration, low fertility level, poor water and fertilizer retention capacity, which is not conducive to the emergence and normal growth of crops, and most of the severe saline-alkali farmland has no any output and poor economic benefits.

[0003] Chinese patent publication No. CN107517613A discloses a saline-alkali soil improvement method, which comprises the following steps: filling the mixed drought-resistant grass seeds into the compression-molded carrier body in the long strip-shaped accommodation groove; arranging the compression-molded cover body at the opening of the long strip-shaped accommodation groove filled with the cultivation soil to obtain the improved body I with a nearly triangular transverse section; arranging a plurality of the improved body I in a staggered manner to form an improved body II; arranging the plurality of improved bodies II in the exposed layer of the soil to be improved; filling the soil improvement agent between the plurality of improved bodies II; covering the soil improvement agent on the plurality of improved bodies II; and spraying 0.5-2L / m2 of water on the soil improvement agent at one time. 2 The method can effectively improve the soil structure of the saline-alkali land in a short time, and has a significant water and fertilizer retention effect.

[0004] It can be seen that the prior art has the following problems: lacking adjustment of the plowing parameters based on the difference between the target plowing depth and the soil permeability coefficient, and lacking adjustment of the leaching water pressure according to the sodium ion change curve, which leads to incomplete leaching of the sodium ion content when the saline-alkali soil is leached, and reduces the subsequent improvement efficiency of the saline-alkali land. SUMMARY

[0005] Therefore, the present application provides a saline-alkali soil improvement method to overcome the problems in the prior art that lacking adjustment of the plowing parameters based on the difference between the target plowing depth and the soil permeability coefficient, and lacking adjustment of the leaching water pressure according to the sodium ion change curve, which leads to incomplete leaching of the sodium ion content when the saline-alkali soil is leached, and reduces the subsequent improvement efficiency of the saline-alkali land.

[0006] To achieve the above-mentioned purpose, the present application provides a saline-alkali soil improvement method, which comprises,

[0007] dividing the target saline-alkali land to be improved into regions to obtain regional saline-alkali lands, detecting the salt-alkali distribution depth of any regional saline-alkali land, determining the plowing depth based on the root penetration depth range of the target planting plant and the salt-alkali distribution depth to obtain the target plowing depth;

[0008] Adjust the plowing parameters of the plowing device based on the target plowing depth and the difference between the soil permeability coefficients;

[0009] Determine the initial leaching water pressure according to the plowing parameters, detect the sodium ion concentration of the discharged water after the regional saline-alkali soil is leached, obtain the actual sodium ion concentration, obtain a sodium ion change curve according to the actual sodium ion concentration and a detection period, and adjust the leaching water pressure based on the sodium ion change curve;

[0010] For a case where the sodium ion curve slope of the sodium ion change curve is a preset slope, detect the actual soil sodium ion proportion adsorbed by soil colloids, and determine whether to continue leaching the soil of the regional saline-alkali soil according to a comparison result of the actual soil sodium ion proportion and a standard soil sodium ion proportion interval;

[0011] Determine whether to detect the soil bulk density based on the comparison result of the soil sodium ion proportion, and determine whether to feed back and adjust the plowing parameters according to a soil bulk density detection result, so as to meet the saline-alkali soil improvement requirement;

[0012] The salinity distribution parameters include a salinity distribution depth and an actual salinity, the plowing parameters include a plowing intensity and a plowing speed, and the difference between the soil permeability coefficients is a difference between a target soil permeability coefficient and an actual soil permeability coefficient.

[0013] Further, the process of detecting the salinity distribution depth of any regional saline-alkali soil includes,

[0014] Randomly selecting salinity distribution depth detection points of a plurality of regional saline-alkali soils, detecting sampling salinity distribution depths of the salinity distribution depth detection points in a stratified soil sampling manner, and calculating an average value of the sampling salinity distribution depths as the salinity distribution depth of the corresponding regional saline-alkali soil;

[0015] The salinity distribution depth is a soil depth reaching a preset salinity.

[0016] Further, the process of determining the plowing depth based on the root system rooting depth range of the target planted plant and the salinity distribution depth includes,

[0017] For a case where the salinity distribution depth is less than a minimum value of the root system rooting depth range, determining that the minimum value of the root system rooting depth range is taken as a plowing base value of the plowing depth;

[0018] For a case where the salinity distribution depth is within the root system rooting depth range, determining that a maximum value of the root system rooting depth range is taken as a plowing target value of the plowing depth;

[0019] For a case where the salinity distribution depth is greater than the maximum value of the root system rooting depth range, determining that the maximum value of the root system rooting depth range is taken as the target plowing depth.

[0020] Further, the process of adjusting the ploughing parameters of the ploughing device based on the target ploughing depth and the soil permeability coefficient difference value comprises,

[0021] The ploughing intensity is determined according to the permeability level of the soil permeability coefficient difference value, and the ploughing speed is determined according to the target ploughing depth and the ploughing intensity.

[0022] The permeability level comprises a primary permeability level, a medium permeability level and a high permeability level.

[0023] Further, the process of determining the initial leaching water pressure according to the ploughing parameters comprises,

[0024] The ploughing leaching water influence parameter is obtained based on the determined ploughing intensity and ploughing speed, and the initial leaching water pressure is determined based on the ploughing leaching water influence parameter.

[0025] The ploughing leaching water influence parameter is the influence value of the ploughing parameter on the initial leaching water pressure.

[0026] Further, the process of adjusting the leaching water pressure based on the sodium ion change curve comprises,

[0027] The sodium ion change curve is segmented to obtain a plurality of sodium ion change segmented curves according to the inflection point, the slope of any sodium ion change segmented curve is obtained, and the actual sodium ion change segmented curve slope is obtained.

[0028] For the pre-inflexion actual sodium ion change segmented curve slope before the inflection point, the leaching water pressure is adjusted based on the comparison result of the pre-inflexion actual sodium ion change segmented curve slope and the first standard sodium ion change segmented curve slope to obtain the pre-inflexion leaching water pressure.

[0029] For the post-inflexion actual sodium ion change segmented curve slope after the inflection point, the leaching water pressure is adjusted based on the comparison result of the post-inflexion actual sodium ion change segmented curve slope and the second standard sodium ion change segmented curve slope to obtain the post-inflexion leaching water pressure.

[0030] The first standard sodium ion change segmented curve slope is determined according to the target desalination efficiency of the initial leaching stage, the second standard sodium ion change segmented curve slope is determined according to the stable efficiency of deep soil desalination, and the inflection point is the inflection point on the sodium ion change curve.

[0031] Further, for the case that the sodium ion curve slope of the sodium ion change curve is a preset slope, the process of detecting the actual soil sodium ion proportion adsorbed by soil colloids comprises,

[0032] For the case that the actual sodium ion change segmented curve slope after the inflection point is zero, the actual soil sodium ion proportion adsorbed by soil colloids is detected.

[0033] The preset slope is a slope of an actual sodium ion change segmented curve, and the slope is zero.

[0034] Further, the process of determining whether to continue leaching the soil of the regional saline-alkali land according to the comparison result of the actual soil sodium ion proportion and the standard soil sodium ion proportion interval includes,

[0035] For a case where the actual soil sodium ion proportion is less than a minimum value of the standard soil sodium ion proportion interval, it is determined to stop leaching the soil of the saline-alkali land.

[0036] For a case where the actual soil sodium ion proportion is in the standard soil sodium ion proportion interval, it is determined to suspend leaching the soil of the saline-alkali land, and the actual soil sodium ion proportion is continuously monitored.

[0037] For a case where the actual soil sodium ion proportion is greater than a maximum value of the standard soil sodium ion proportion interval, it is determined to adjust the leaching parameters according to an exceeding degree of the actual soil sodium ion proportion exceeding the maximum value of the standard soil sodium ion proportion interval.

[0038] The leaching parameters include a leaching interval and a leaching depth, and the exceeding degree includes slight exceeding, moderate exceeding, and severe exceeding.

[0039] Further, the process of adjusting the leaching parameters according to the exceeding degree of the actual soil sodium ion proportion exceeding the maximum value of the standard soil sodium ion proportion interval includes,

[0040] For a case where the exceeding degree of the actual soil sodium ion proportion exceeding the maximum value of the standard soil sodium ion proportion interval is slight exceeding, the original leaching interval is shortened according to a slight exceeding value, and the original leaching depth is maintained.

[0041] For a case where the exceeding degree of the actual soil sodium ion proportion exceeding the maximum value of the standard soil sodium ion proportion interval is moderate exceeding, the original leaching interval is shortened according to a moderate exceeding value, and the original leaching depth is deepened according to the moderate exceeding value.

[0042] For a case where the exceeding degree of the actual soil sodium ion proportion exceeding the maximum value of the standard soil sodium ion proportion interval is severe exceeding, the original leaching interval is shortened according to a severe exceeding value, and the original leaching depth is deepened according to the severe exceeding value.

[0043] The original leaching interval is determined according to a sodium ion concentration drop rate in an initial leaching stage, the original leaching depth is determined according to a target plowing depth, and the exceeding value is a difference between the actual soil sodium ion proportion and the maximum value of the standard soil sodium ion proportion interval.

[0044] Further, the process of determining whether to feed back and adjust the plowing parameters according to the soil bulk density detection result includes,

[0045] For the case that the actual soil sodium ion proportion is less than the maximum value of the standard soil sodium ion proportion interval, it is determined to detect the soil bulk density, and the plowing parameters are feedback adjusted according to the difference between the maximum value of the standard soil sodium ion proportion interval and the actual soil sodium ion proportion.

[0046] Compared with the prior art, the beneficial effects of the present application are that, through such a regional division method, the improvement of saline-alkali soil is more targeted. The dominant factors of salinization in different regions include but are not limited to groundwater action, waterlogging influence and channel side seepage, etc. Appropriate improvement strategies can be developed for each region to avoid blind management in a "one-size-fits-all" manner. For example, the "near-river area" focuses on solving the problem of salt accumulation caused by groundwater uplift, and the "canal side area" focuses on handling the salt accumulation caused by side seepage, so that the improvement measures are accurately matched with the characteristics of the region, and the management efficiency is improved. At the same time, after regional division, resources can be concentrated to implement unified improvement programs for the same type of region, which is convenient for technology popularization and management, reduces the improvement cost, promotes the transformation of saline-alkali land management from decentralization to systematization, and improves the overall improvement effect.

[0047] Further, through the method of random point selection, stratified soil sampling and mean value calculation, the salt-alkali distribution depth can be detected to provide accurate basic data support for the improvement of saline-alkali soil, which is embodied in the following aspects: first, the objectivity and representativeness of the detection results are ensured. Randomly selecting multiple detection points and covering different micro-landforms in the region avoids the interference of local special plots on the results; stratified soil sampling accurately captures the distribution boundary of salt-alkali in the vertical direction, combined with the regionally adapted conductivity conversion formula, makes the core index of "the soil depth reaching the preset salinity" more in line with the actual situation, and provides a reliable basis for subsequent plowing depth determination. Second, the accurate landing of improvement measures is realized. After determining the salt-alkali distribution depth, the target plant root system requirements can be matched in a targeted manner to avoid the problem of shallow plowing that fails to reach the salt-alkali layer or deep plowing that causes resource waste. For example, when the salt-alkali distribution depth of a certain region is detected to be 62 cm, the depth that plowing needs to reach can be accurately judged to ensure that the improvement measures hit the core area of salt-alkali, improving the management efficiency. Third, data linkage basis is provided for regional improvement. The detection results correspond to the previous regional division, and the salt-alkali distribution characteristics in the same region are quantified, which facilitates the combination of "regional characteristics" and "depth data" to form a double-precision improvement scheme of "area + depth". At the same time, the standardized detection process (such as stratified sampling and formula conversion) can be popularized to different regions to ensure the comparability of data in each area, and provide a unified reference standard for the management of the whole saline-alkali land. In addition, the conversion formula is calibrated based on local historical data, which further improves the accuracy of salinity calculation and reduces errors caused by regional differences, so that the detection results can more directly serve subsequent leaching pressure adjustment, plowing parameter optimization and other links, and promote the transformation of improvement work from experience-driven to data-driven.

[0048] Further, determining the plowing depth according to the relationship between the root depth of the target plant and the distribution depth of the saline-alkali soil can make the plowing operation in saline-alkali soil improvement more scientific and effective, which is embodied in the following aspects. Firstly, the precise matching of the improvement measures and the plant requirements is achieved. By distinguishing the three relationships between the distribution depth of the saline-alkali soil and the root range, the plowing depth is strictly set around the core needs of plant growth. For example, when the saline-alkali soil is distributed shallowly, the minimum value of the root is taken as the basis for plowing, which meets the growth of the superficial root and avoids invalid deep plowing. When the saline-alkali soil invades the active area of the root, the maximum value of the root is taken as the target to ensure that the saline-alkali problem of the soil where the deep root is located is solved, so that the plowing operation directly serves the key area of plant growth. Secondly, the resource utilization efficiency is improved and the improvement cost is reduced. This method can avoid the energy consumption and cost waste caused by blind plowing. For example, when the distribution depth of the saline-alkali soil is deeper than the root range, the plowing is not pursued to the bottom of the saline-alkali layer, but only limited to the maximum value of the root, which reduces the mechanical operation amount and energy consumption. When the distribution depth of the saline-alkali soil is shallow, shallow plowing can meet the demand, which avoids the non-saline-alkali soil in the lower layer being turned to the surface to cause new saline-alkali problems, and realizes the reasonable allocation of resources while ensuring the improvement effect. Thirdly, it lays a good foundation for subsequent improvement steps. The accurate determination of the plowing depth makes the mixing and leaching of the saline-alkali layer and the surface soil more targeted. For example, plowing to 60 cm can fully expose the saline-alkali layer at 45 cm, which is convenient for the uniform penetration of leaching water and the removal of salt, improves the improvement quality of the entire root active area, and provides a healthy growth environment for the plant root, which promotes the transformation of saline-alkali soil improvement from "wide-area governance" to "precise cultivation".

[0049] Further, the plowing parameter adjustment method realizes scientific and efficient plowing operation in saline-alkali land improvement through explicit parameter setting basis and hierarchical regulation logic. The specific advantages are as follows: firstly, the parameter setting has scientificity and pertinence. The initial plowing speed, the compensation parameter of the penetration level to the intensity, and the compensation parameter of the intensity to the speed are determined according to the soil texture, regional penetration difference, and equipment resistance characteristics respectively, so that the parameters are highly adapted to the actual conditions of the saline-alkali land. For example, the initial speed is adjusted low for clay soil and high for sandy soil, ensuring that the parameters are consistent with the soil characteristics from the source and avoiding the lack of adaptability caused by universal setting. Secondly, the plowing intensity and speed are precisely regulated. Through the conduction logic of "penetration level-plowing intensity-plowing speed", different saline-alkali soils can obtain matched operation parameters: the primary penetration level adopts a 25° shallow angle and a 7.5km / h faster speed to avoid excessive turning; the advanced penetration level adopts a 60° large angle and a 4km / h slow speed to ensure that the hard soil is fully broken. This hierarchical regulation not only guarantees the soil improvement effect, but also avoids the waste of energy and time. Thirdly, the operation standardization and generalizability are improved. The explicit level division standard such as 0, 5m / d as the primary penetration level and the quantitative parameter calculation method plowing intensity = soil penetration coefficient difference x 5, plowing speed = 10-plowing intensity x 0.1 make the plowing operation free from dependence on experience, and the operator can directly apply the formula according to the test data, reducing the technical threshold and facilitating the large-scale application in different regions. Fourthly, the synergy with the subsequent improvement link is strengthened. The plowing intensity increases with the penetration coefficient difference, which can accurately open the soil penetration channel. The strong plowing intensity under the advanced penetration level creates conditions for the penetration of leaching water, and the light breaking under the primary level avoids the damage to the soil structure, which affects the water and fertilizer retention capacity, so that the plowing link and the subsequent leaching form an efficient linkage, and the overall improvement effect is improved.

[0050] Further, through the process of deriving the initial leaching water pressure by the plowing parameters, the scientific linkage of plowing and leaching is realized, providing precise initial conditions for salt leaching in saline-alkali soil. The specific advantages are as follows: first, the parameter setting logic is rigorous, ensuring the scientificity of pressure calculation. The weight coefficients of plowing intensity and plowing speed, 0.2 and 0.5, are set according to the actual influence of the two on soil permeability, which not only reflects the auxiliary role of plowing intensity in soil crushing, but also highlights the dominant influence of plowing speed on soil density, making the plowing leaching water influence parameter truly reflect the soil's acceptance ability after plowing; the pressure conversion coefficient 0.1 is determined based on regional historical test data, ensuring that the calculation results match the local soil characteristics and avoiding deviations caused by subjective experience. Second, the initial leaching water pressure accurately adapts to the soil state. Different plowing parameters correspond to pressure values that can meet the soil leaching needs: under the primary permeability level, 0.875 MPa pressure matches the loose surface layer after shallow plowing, which can uniformly penetrate and remove shallow salt; adjusting the upper limit pressure to 1.1 MPa for the intermediate permeability level and 1.2 MPa for the high-level permeability level can meet the permeability needs of deep soil after plowing, ensuring that leaching water fully contacts and dissolves deep salt. This precise matching not only avoids incomplete leaching due to insufficient pressure, but also prevents excessive pressure from damaging soil structure. Third, the linkage calculation of plowing parameters and leaching pressure realizes the synergistic effect of plowing and leaching. The linkage calculation of plowing parameters and leaching pressure makes the loose structure formed by plowing fully utilized by the leaching process. The greater the plowing intensity and the slower the speed, such as the high-level grade, the higher the soil porosity, and the higher the pressure of the matching leaching water, which can promote rapid water infiltration and remove more salt. The two form a virtuous cycle of "plowing creates conditions and leaching efficiently executes", improving the overall improvement efficiency. Fourth, the operation standardization improves the promotion applicability. The clear formula calculation method of plowing leaching water influence parameter = plowing intensity x 0.2 + speed x 0.5, initial leaching water pressure = plowing leaching water influence parameter x 0.1, and pressure range limit 0.3-1.2 MPa make the operator can directly derive the leaching pressure according to the plowing parameters, without relying on complex experience judgment, reducing the technical threshold, and facilitating large-scale application in different saline-alkali regions.

[0051] Further, by adjusting the leaching water pressure through phased comparison of the actual sodium ion change segment curve slope and the standard sodium ion change segment curve slope, the saline-alkali soil leaching process is more dynamically adaptive, significantly improving desalination efficiency and improvement quality, with the following specific advantages: First, precise dynamic regulation of leaching pressure is achieved. In the pre-inflexion stage, the first standard sodium ion change segment curve slope of -0.08% / h is used as a reference, and when the actual sodium ion change segment curve slope of -0.06% / h is slower, the pressure adjustment value is calculated by the quantitative formula (increment = slope difference x 10), and the pressure is increased from 0.875 MPa to 1.075 MPa, which accelerates the loss of surface salt. In the post-inflexion stage, the second standard sodium ion change segment curve slope of -0.02% / h is used as a reference, and the actual sodium ion change segment curve slope of -0.01% / h is fine-tuned, ensuring stable removal of deep salt. This "on-demand adjustment" mode avoids the problem of desalination being too fast or too slow under fixed pressure, making the sodium ion concentration decline pace and target efficiency highly matched. Second, balance desalination efficiency and soil protection. In the pre-inflexion stage, the pressure is moderately increased without exceeding the upper limit of 1.2 MPa, allowing rapid desalination while avoiding soil structure damage; in the post-inflexion stage, the pressure is only slightly increased from 1.0 MPa to 1.1 MPa to ensure continuous salt dissolution and prevent soil colloids loss or nutrient imbalance caused by high pressure flushing. This pre-fast and post-stable leaching water pressure adjustment strategy balances desalination speed and soil ecological protection. Third, improve the controllability and target achievement rate of the leaching process. The segmented adjustment based on the inflection point allows operators to clearly understand the characteristics of the leaching stage: before the inflection point, focus on rapid surface salt reduction to ensure that the sodium ion concentration is reduced from 0.6% to 0.45% within 20 hours; after the inflection point, turn to stable desalination of deep salt, finally reducing the concentration to below the upper limit of 0.3% for corn tolerance. Clear stage goals and quantitative adjustment methods significantly reduce the blindness of the leaching process and improve the achievement rate of the improvement target. Fourth, strengthen the scientific nature of data-driven. Through slope analysis of the sodium ion change curve, the desalination effect is converted into a quantifiable adjustment basis, breaking away from the traditional mode of judging pressure based on experience. Whether it is the slope difference calculation before the inflection point or the dynamic fine-tuning after the inflection point, it is based on measured data, making the leaching decision more objective and repeatable, facilitating replication and promotion in different saline-alkali regions.

[0052] Further, the detection process can accurately determine whether leaching needs to continue, avoiding false judgment of completion due to the stability of sodium ions in the solution, and ensuring that the sodium ion content in the soil colloidal layer meets the plant growth requirements. By comparing the actual soil sodium ion proportion with the standard soil sodium ion proportion interval, the precision start and stop of saline-alkali soil leaching and parameter optimization are achieved, significantly improving the improvement efficiency and resource utilization rate. The specific advantages are as follows: first, avoid insufficient or excessive leaching, balance the improvement effect and cost. When the actual soil sodium ion proportion is less than the minimum value of the standard soil sodium ion proportion interval, such as 12%<15%, timely stopping leaching can prevent the loss of soil nutrients such as potassium and calcium ions with water, reducing water and energy waste; when the actual soil sodium ion proportion is within the standard soil sodium ion proportion interval, such as 18%, the strategy of pausing and monitoring can avoid ineffective leaching and prevent secondary salinization caused by the rise of sodium ions through dynamic observation, ensuring stable improvement effect. Second, adjust according to the degree of exceeding, improve the pertinence of leaching. For cases exceeding the maximum value of the standard soil sodium ion proportion interval, adjust the leaching parameters according to the degree of exceeding, i.e. slight exceeding, moderate exceeding and severe exceeding, so that the treatment measures are accurately matched with the degree of sodium ion exceeding.

[0053] Further, the adjustment process realizes the precision and efficiency of desalination of saline-alkali soil by matching the leaching parameters with the sodium ion exceeding degree through hierarchical matching. The specific beneficial effects are as follows: firstly, the adjustment force and the precise adaptation of the exceeding degree improve the desalination pertinence. When the exceeding degree is slight, only the interval is shortened and the original depth is maintained to focus on the desalination of the surface soil, avoiding resource waste caused by excessive adjustment. When the exceeding degree is moderate, the interval and the depth are shortened and deepened simultaneously to precisely cover the deep area exceeding the standard. When the exceeding degree is severe, the parameters are adjusted by a larger margin, the interval is 15 hours, and the depth is 97.5 cm to deal with the serious exceeding problem of the whole soil layer. This gradient strategy of "the heavier the exceeding degree, the more thorough the adjustment" makes each parameter adjustment directly hit the core area of sodium ion aggregation, avoiding the inefficient problems of "using heavy medicine for light disease" or "using light medicine for heavy disease". Secondly, the desalination efficiency and soil protection are balanced to reduce the improvement cost. When the exceeding degree is slight, based on the judgment of "surface priority and deep stability", the original depth is maintained to reduce water resource consumption without additional leaching of deep soil not exceeding the standard. When the exceeding degree is moderate and severe, the deepening depth is linked to the exceeding degree, such as 72 cm for moderate and 97.5 cm for severe, which ensures the deep desalination effect and avoids the increase of energy consumption caused by blind deepening. At the same time, through the proportional calculation of "exceeding value ÷ denominator", the interval shortening margin is controllable, which balances the desalination efficiency and cost input while accelerating the desalination and avoiding excessive equipment wear caused by high-frequency operation. Thirdly, the desalination effect stability is improved by adapting to the soil colloid characteristics. According to the characteristic differences of soil colloid "low saturation adsorption 20%-25%, medium saturation adsorption 25%-30%, and high saturation adsorption >30%", the adjustment strategy is matched with the difficulty of desorption of colloid sodium ion: when the exceeding degree is slight, high-frequency leaching can quickly replace the easily desorbed surface colloid sodium ion; when the exceeding degree is moderate, the leaching intensity is strengthened to break the sodium ion embedded in the lattice; when the exceeding degree is severe, the deep and frequent leaching gradually breaks the close combination of colloid and sodium ion. This adjustment that adapts to the soil physicochemical characteristics makes the desalination process more in line with the migration law of sodium ion, avoiding the rebound problem after desalination and improving the stability of soil improvement effect. Fourthly, the adjusted leaching parameters can target to alleviate the influence of different degrees of exceeding on crops: when the exceeding degree is slight, the proportion of surface sodium ion is quickly reduced to avoid corn seedling leaf yellowing; when the exceeding degree is moderate, the deep desalination improves the root water absorption capacity to prevent plant dwarfing; when the exceeding degree is severe, the sodium ion concentration is maximally reduced to avoid crop death caused by root cell membrane damage.

[0054] Further, the plowing parameter adjustment process based on the difference between soil bulk density and sodium ion realizes the deep improvement of saline-alkali soil improvement from "chemical index standard" to "physical structure optimization", and the specific advantages are as follows: firstly, the soil physical structure is precisely improved to adapt to the growth needs of crops. By adjusting the plowing parameters, the exceeding bulk density is reduced to 1.4 g / cm 3To standard bulk density convergence: deepening the plowing depth by 3cm to 33cm can directly break the deep compacted soil layer, increase the soil penetration angle by 0.8°, strengthen the soil cutting and crushing, and reduce the speed by 0.32km / h to improve the crushing degree. The synergistic effect of the three makes the soil porosity increase and the bulk density decrease, providing a breathable and loose growth environment for the corn root system, and solving the hidden problem of "sodium ion reaching the standard but the soil being compacted". Second, it realizes "on-demand adjustment" and avoids invalid operation. The adjustment logic is directly linked to the sodium ion difference of 2 percentage points. The smaller the difference, the better the sodium ion control, and the adjustment range is more focused on soil structure improvement: since the 18% sodium ion proportion is close to the upper limit of 20%, there is no need to intervene excessively in the salt content, and instead, the parameters are fine-tuned, such as deepening the depth by only 3cm to optimize the bulk density, avoiding the waste of energy consumption or excessive disturbance of the soil caused by "blindly increasing the plowing intensity to reduce the bulk density". Third, the parameters are adjusted in stages to balance the improvement effect and operational feasibility. The setting of different adjustment coefficients of 5%, 3%, and 2% reflects the priority of the impact of parameters on the bulk density: the plowing depth coefficient is the largest, ensuring the improvement of deep soil structure; the soil penetration angle coefficient is moderate, enhancing the crushing effect while avoiding excessive load on the equipment; and the plowing speed coefficient is the smallest, ensuring the crushing degree on the premise of reducing the impact on operating efficiency. This staged adjustment not only guarantees the improvement effect of the bulk density, but also avoids the risk of excessive adjustment of a single parameter, such as the slow speed leading to a prolonged construction period. Fourth, it connects chemical and physical indicators to improve the overall quality of the soil. This process takes "sodium ion reaching the standard" as a prerequisite and focuses on the "bulk density exceeding the standard" problem, realizing the synergy of "desalination" to "salinization control + structure repair" in saline-alkali soil improvement: sodium ion ensures crop salt tolerance, and soil bulk density ensures root growth conditions, both of which make the soil reach a "double-standard" state, laying a solid foundation for subsequent crop planting. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 The flow chart of the saline-alkali soil improvement method in this embodiment;

[0056] Figure 2 The process flow chart of detecting the saline-alkali distribution depth in the saline-alkali soil improvement method in this embodiment;

[0057] Figure 3 The process flow chart of determining the plowing depth in the saline-alkali soil improvement method in this embodiment;

[0058] Figure 4 The soil leaching process flow chart of the saline-alkali soil improvement method in this embodiment. DETAILED DESCRIPTION

[0059] In order to make the purpose and advantages of the present application clearer and more apparent, the present application will be further described below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0060] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. Those skilled in the art will appreciate that the embodiments are only used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application.

[0061] It should be noted that, in the description of the present application, the terms indicating the direction or positional relationship of "upper", "lower", "left", "right", "inner", "outer" and the like are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0062] In addition, it should also be noted that, in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific circumstances.

[0063] Please refer to Figures 1-4 shown, Figure 1 is a flow chart of the saline-alkali soil improvement method in the embodiment; Figure 2 is a process flow chart of detecting the salt-alkali distribution depth of the saline-alkali soil improvement method in the embodiment; Figure 3 is a process flow chart of determining the plowing depth of the saline-alkali soil improvement method in the embodiment; Figure 4 is a soil leaching process flow chart of the saline-alkali soil improvement method in the embodiment.

[0064] The embodiment provides a saline-alkali soil improvement method, which comprises,

[0065] Step S1, dividing a target saline-alkali land to be improved into regions to obtain regional saline-alkali lands, detecting the salt-alkali distribution depth of any regional saline-alkali land, determining a plowing depth based on the root penetration depth range of a target planting plant and the salt-alkali distribution depth, and obtaining a target plowing depth;

[0066] Step S2, adjusting the plowing parameters of a plowing device based on the target plowing depth and the difference of soil permeability coefficients;

[0067] Step S3, determining an initial leaching water pressure according to the plowing parameters, detecting the sodium ion concentration of discharged water after leaching of the regional saline-alkali land to obtain an actual sodium ion concentration, obtaining a sodium ion change curve according to the actual sodium ion concentration and a detection period, and adjusting the leaching water pressure based on the sodium ion change curve.

[0068] In step S4, when the sodium ion curve slope of the sodium ion change curve is the preset slope, the actual soil sodium ion proportion adsorbed by the soil colloid is detected, and whether to continue leaching the soil of the regional saline-alkali land is determined according to the comparison result of the actual soil sodium ion proportion and the standard soil sodium ion proportion interval;

[0069] In step S5, whether to detect the soil bulk density is determined based on the comparison result of the soil sodium ion proportion, and whether to feedback adjust the plowing parameters is determined according to the soil bulk density detection result, so as to meet the improvement demand of the saline-alkali land.

[0070] The saline-alkali degree distribution parameters include a saline-alkali distribution depth and an actual saline-alkali degree, the plowing parameters include a plowing intensity and a plowing speed, and the soil permeability coefficient difference is the difference between a target soil permeability coefficient and an actual soil permeability coefficient.

[0071] In the embodiment, a regional division method is provided, for example, division according to topography and hydrological characteristics. A 2-kilometer range along the Yellow River is a "low-lying area near the river". In the embodiment, the underground water level of the defined region is 1-2 meters, and the saline-alkali degree is mainly heavy. A 3-5-kilometer range to the south is a "gentle slope transition area", the underground water level is 2-3 meters, and the saline-alkali degree is moderate. A higher area in the south is a "high and flat plain area", the underground water level is more than 4 meters, and the saline-alkali degree is lighter. In the embodiment, special large areas include abandoned pit pond areas and channel surrounding areas. The channel surrounding areas include but are not limited to a 100-meter range along the main irrigation canal. The channel surrounding areas are prone to salt accumulation due to lateral seepage, and the abandoned pit pond areas are prone to saline-alkali due to seasonal water accumulation. The specific regional division is performed according to the specific topography and geomorphology.

[0072] Through such a regional division method, the saline-alkali land improvement can be more targeted. The dominant factors of saline-alkali in different regions include but are not limited to underground water action, water accumulation influence, and channel lateral seepage. Accordingly, appropriate improvement strategies can be developed for each region to avoid "one-size-fits-all" blind management. For example, the "near-river area" focuses on solving the salt accumulation problem caused by underground water lifting, and the "channel edge area" focuses on handling the salt accumulation caused by lateral seepage, so that the improvement measures are accurately connected to the regional characteristics and the management efficiency is improved. At the same time, after regional division, resources can be concentrated to implement unified improvement schemes for the same type of region, which is convenient for technology popularization and management, reduces the improvement cost, promotes the transformation of saline-alkali land management from decentralization to systematization, and improves the overall improvement effect.

[0073] Specifically, the process of detecting the saline-alkali distribution depth of any regional saline-alkali land includes,

[0074] Randomly select several salt-alkali distribution depth detection points of the salt-alkali land in the region, detect the sampling salt-alkali distribution depth of the salt-alkali distribution depth detection points by the layered soil sampling method, calculate the average value of the sampling salt-alkali distribution depth as the salt-alkali distribution depth of the corresponding region salt-alkali land;

[0075] The salt-alkali distribution depth is the soil depth reaching the preset salt-alkali degree.

[0076] The salt-alkali distribution depth of the region is detected by the layered soil sampling method, and the average value of the sampling salt-alkali distribution depth is calculated as the salt-alkali distribution depth of the corresponding region salt-alkali land. Figure 2 The salt-alkali distribution depth of the region is detected by the layered soil sampling method, and the average value of the sampling salt-alkali distribution depth is calculated as the salt-alkali distribution depth of the corresponding region salt-alkali land.

[0077] Step S11, according to the standard of setting 3 detection points per 100 mu, 18 random detection points are set in the 600 mu area. The coordinates are randomly generated by GPS positioning to ensure that the point spacing is not less than 50 meters, covering the high points, low points and flat areas in the area;

[0078] Step S12, using the soil sampling drill, the sampling diameter is set to 5 cm in this embodiment, and the soil is taken in layers, with a depth of 20 cm each, and the sampling range is 0-120 cm. The specific operation is as follows: for each detection point, 0-20 cm, 20-40 cm, 40-60 cm, 60-80 cm, 80-100 cm and 100-120 cm soil layer samples are collected in turn, and the soil conductivity of each layer is measured on site with a portable salinity meter. The soil conductivity is converted into salinity, and the preset salinity threshold is 2 ‰. When the soil salinity is ≤2 ‰, it is determined that it is not a salt-alkali layer.

[0079] Step S13, if the salinity data of each layer of a detection point is: 0-20 cm (4.5 ‰), 20-40 cm (3.8 ‰), 40-60 cm (2.1 ‰), 60-80 cm (1.8 ‰), the salt-alkali distribution depth of the point is 60 cm, and the sampling depth of the 18 detection points is respectively: 60 cm, 70 cm, 55 cm, 65 cm, 75 cm, 50 cm, 60 cm, 65 cm, 70 cm, 55 cm, 60 cm, 65 cm, 70 cm, 55 cm, 60 cm, 65 cm, 70 cm, 50 cm.

[0080] Step S14, sum the 18 sampling depths (60+70+55+…+50=1110 cm), and the average value is 1110 / 18=61.67 cm.

[0081] The soil conductivity is converted into salinity, the soil salinity refers to the total soluble salt content, the unit is % or ‰, and the conductivity EC, the unit is mS / cm, is positively correlated. The higher the salt content, the stronger the solution conductivity, and the larger the conductivity value;

[0082] The formula for converting the soil conductivity of saline-alkali soil into salinity-alkalinity is: total salt content (‰) = 0.046 x EC (mS / cm), which is applicable to most saline-alkali soils in North China and Northwest China with an EC value range of 1-30 mS / cm,

[0083] Different regions need to be calibrated, such as the clayey saline-alkali soil in the Hetao Plain of Inner Mongolia, which can be adjusted to: total salt content (‰) = 0.052 x EC (mS / cm). This example only provides one conversion method, and the specific conversion parameters need to be determined according to the historical data of local salinity-alkalinity.

[0084] The detection of saline-alkali distribution depth through random point selection, stratified soil sampling, and mean value calculation can provide accurate basic data support for saline-alkali soil improvement, which is reflected in the following aspects: first, the objectivity and representativeness of the detection results are ensured. Randomly selecting multiple detection points and covering different microtopographies in the region avoids the interference of local special plots on the results; stratified soil sampling accurately captures the distribution boundary of saline-alkali in the vertical direction, combined with the regionally adapted conductivity conversion formula, makes the core index of "the depth of soil reaching the preset salinity-alkalinity" more in line with the actual situation, and provides a reliable basis for subsequent plowing depth determination. Second, the accurate landing of improvement measures is realized. After determining the distribution depth of saline-alkali, the target plant root system requirements can be matched in a targeted manner, avoiding the problem of shallow plowing that fails to reach the saline-alkali layer or deep plowing that causes resource waste. For example, when the distribution depth of saline-alkali in a certain region is detected to be 62 cm, the depth that plowing needs to reach can be accurately judged, ensuring that the improvement measures hit the core area of saline-alkali and improve the efficiency of governance. Third, it provides a data linkage basis for regional improvement. The detection results are in line with the previous regional division, and the distribution characteristics of saline-alkali in the same region are quantified, which facilitates the combination of "regional characteristics" and "depth data" to form a double-precision improvement scheme of "area + depth". At the same time, the standardized detection process (such as stratified sampling and formula conversion) can be promoted to different regions, ensuring the comparability of data in each area, and providing a unified reference standard for the governance of saline-alkali soil in the whole region. In addition, the calibration of the conversion formula based on local historical data further improves the accuracy of salinity-alkalinity calculation, reduces errors caused by regional differences, and makes the detection results more directly serve subsequent leaching pressure regulation, plowing parameter optimization, and other links, promoting the improvement work from experience-driven to data-driven.

[0085] Specifically, the process of determining the plowing depth based on the root penetration depth range of the target planting plant and the saline-alkali distribution depth includes,

[0086] For the case where the saline-alkali distribution depth is less than the minimum value of the root penetration depth range, the minimum value of the root penetration depth range is determined as the plowing base value of the plowing depth;

[0087] For the case that the salt and alkali distribution depth is within the root system rooting depth range, it is determined that the maximum value of the root system rooting depth range is the plowing target value of the plowing depth;

[0088] For the case that the salt and alkali distribution depth is greater than the maximum value of the root system rooting depth range, it is determined that the maximum value of the root system rooting depth range is the target plowing depth.

[0089] In this embodiment, the target planting plant is corn, and the root system rooting depth range is 30-60 cm. The plowing depth is determined in three cases:

[0090] For the case that the salt and alkali distribution depth is less than the minimum value of the root system rooting depth range, for example, the salt and alkali distribution depth detected in a certain area is 25 cm, which is less than 30 cm. It is determined that the plowing base value is the minimum value of the root system rooting depth range, which is 30 cm. At this time, plowing to 30 cm can meet the growth needs of the corn superficial layer root system 0-30 cm. Since the salt and alkali below 25 cm does not invade the root system active area, there is no need for deep plowing, which can reduce energy consumption and avoid the lower non-salt and alkali soil being turned to the surface;

[0091] For the case that the salt and alkali distribution depth is within the root system rooting depth range, for example, the salt and alkali distribution depth detected is 45 cm, which is within the corn root system rooting depth range. It is determined that the plowing target value is the maximum value of the root system rooting depth range, which is 60 cm. Plowing to 60 cm can mix the salt and alkali layer at a depth of 45 cm with the surface soil, and cooperate with subsequent leaching to reduce the salt and alkali concentration in the root system active area 30-60 cm, providing a suitable environment for the development of corn deep root system;

[0092] For the case that the salt and alkali distribution depth is greater than the maximum value of the root system rooting depth range, when the salt and alkali distribution depth is 70 cm, the maximum value of the root system rooting depth range, which is 60 cm, is determined as the target plowing depth. At this time, plowing to 60 cm can ensure that the soil structure in the corn main root system distribution area 30-60 cm is improved, and the salt and alkali layer below 70 cm is not included in the plowing range because it does not touch the root system, avoiding excessive work and increasing cost.

[0093] According to the relationship between the root depth of the target plant and the distribution depth of the saline-alkali soil, the plowing depth is determined, which can make the plowing operation in the saline-alkali soil improvement more scientific and effective. Specifically, first, the precise matching of the improvement measures and the plant requirements is realized. By distinguishing the three relationships between the distribution depth of the saline-alkali soil and the root range, the plowing depth is strictly set around the core needs of plant growth. For example, when the saline-alkali soil is distributed shallowly, the minimum value of the root is taken as the basis for plowing, which not only meets the growth of the superficial root, but also avoids invalid deep plowing. When the saline-alkali soil invades the active area of the root, the maximum value of the root is taken as the target, which ensures that the problem of the saline-alkali soil in the deep layer where the deep root is located is solved, and the plowing operation directly serves the key area of plant growth. Second, the resource utilization efficiency is improved, and the improvement cost is reduced. This method can avoid the energy consumption and cost waste caused by blind plowing. For example, when the distribution depth of the saline-alkali soil is deeper than the root range, the plowing is not pursued to the bottom of the saline-alkali layer, but only limited to the maximum value of the root, which reduces the mechanical operation amount and energy consumption. When the saline-alkali soil is distributed shallowly, shallow plowing can meet the requirements, which avoids the new saline-alkali problem caused by the non-saline-alkali soil in the lower layer being turned to the surface, and realizes the reasonable allocation of resources while ensuring the improvement effect. Third, a good foundation is laid for the subsequent improvement steps. The precise determination of the plowing depth makes the subsequent steps such as mixing and leaching of the saline-alkali layer and the surface soil more targeted. For example, plowing to 60 cm can fully expose the saline-alkali layer at 45 cm, which is convenient for the uniform penetration of leaching water and the removal of salt, improves the improvement quality of the entire root active area, provides a healthy growth environment for the plant root, and promotes the transformation of the saline-alkali soil improvement from "wide-area governance" to "precise cultivation".

[0094] Specifically, the process of adjusting the plowing parameters of the plowing device based on the difference between the target plowing depth and the soil permeability coefficient includes,

[0095] The plowing intensity is determined according to the permeation level of the difference between the soil permeability coefficients, and the plowing speed is determined according to the target plowing depth and the plowing intensity.

[0096] The permeation level includes a primary permeation level, an intermediate permeation level, and a high-level permeation level.

[0097] Taking a saline-alkali soil improvement area in the Hetao Plain of Inner Mongolia as an example, the target soil permeability coefficient is set to 15 m / d in this embodiment, and the difference between the soil permeability coefficients is the difference between the target soil permeability coefficient and the actual soil permeability coefficient, which determines the permeation level. The plowing device takes a hydraulic driven plow as an example, the plowing intensity is reflected by the plow blade angle range of 30°-40°, the larger the angle, the stronger the intensity; the plowing speed is reflected by the equipment travel speed range of 3-8 km / h.

[0098] In this embodiment, the soil permeability coefficient difference is set to be in [0 m / d, 5 m / d] as a primary permeation level, in [6 m / d, 10 m / d] as a medium permeation level, and greater than 11 m / d as a high permeation level; the initial plowing speed is 10 km / h; the influence compensation parameter of the permeation level on the plowing intensity is 5; the influence compensation parameter of the plowing intensity on the plowing speed is 0.1; wherein, the initial plowing speed is determined according to the soil texture of the saline-alkali land; the influence compensation parameter of the permeation level on the plowing intensity is determined according to different soil permeability coefficient differences in the region; the influence compensation parameter of the plowing intensity on the plowing speed is set based on the correlation between the plowing intensity, i.e., the angle of entry into the soil, and the operation resistance, the greater the intensity, the greater the angle, and the greater the resistance of the device;

[0099] The plowing intensity is determined according to the permeation level and the influence compensation parameter of the permeation level on the plowing intensity, and the plowing speed is determined according to the initial plowing intensity and the influence compensation parameter of the plowing intensity on the plowing speed;

[0100] If the actual soil permeability coefficient is 10 m / d, the soil permeability coefficient difference is 15-10=5 m / d, which is recorded as a primary permeation level, and the target plowing depth is set to 30 cm, because the soil permeability and the target difference are small, the angle of entry into the soil is 5x5=25°, mainly light soil crushing is avoided to prevent excessive turning from causing structure damage; combined with the 30 cm plowing depth, the plowing speed is 10-25x0.1=7.5 km / h, which improves the operation efficiency while ensuring the soil looseness;

[0101] If the actual soil permeability coefficient is 7 m / d, the soil permeability coefficient difference is 15-7=8 m / d, which is recorded as a medium permeation level, and the target plowing depth is set to 60 cm, because the soil is somewhat hardened, it needs to be broken with moderate intensity, the angle of entry into the soil is 8x5=40°, mainly light soil crushing is avoided to prevent excessive turning from causing structure damage; combined with the 60 cm plowing depth, the plowing speed is 10-40x0.1=6 km / h, which improves the operation efficiency while ensuring the soil looseness;

[0102] If the actual soil permeability coefficient is 3 m / d, the soil permeability coefficient difference is 15-3=12 m / d, which is recorded as a high permeation level, and the target plowing depth is set to 60 cm, because the soil is severely hardened, the permeability is far lower than the target, the angle of entry into the soil is 12x5=60°, strong intensity is needed to break the hard soil layer and open the deep permeation path; combined with the 60 cm plowing depth, the plowing speed is 10-60x0.1=4 km / h, considering the high intensity breaking and 60 cm depth requirement, the speed is reduced to 4 km / h, ensuring that every inch of soil can be fully turned to create conditions for subsequent leaching water penetration.

[0103] The plowing parameter adjustment method realizes scientific and efficient plowing operation in saline-alkali land improvement through clear parameter setting basis and hierarchical control logic. The specific advantages are as follows: first, the parameter setting has scientificity and pertinence. The initial plowing speed, the compensation parameter of the penetration level to the intensity, and the compensation parameter of the intensity to the speed are determined according to the soil texture, regional penetration difference, and equipment resistance characteristics respectively, so that the parameters are highly adapted to the actual conditions of the saline-alkali land. For example, the initial speed is adjusted low for clay soil and high for sandy soil, which ensures that the parameters are consistent with the soil characteristics from the source and avoids the lack of adaptability caused by universal setting. Second, the plowing intensity and speed are precisely controlled. Through the transmission logic of “penetration level-plowing intensity-plowing speed”, soils with different degrees of salinization can obtain matched operation parameters: the primary penetration level adopts a shallow angle of 25° and a faster speed of 7.5 km / h to avoid excessive turning; the advanced penetration level adopts a large angle of 60° and a slow speed of 4 km / h to ensure that the hardened soil is fully broken. This hierarchical control not only guarantees the soil improvement effect, but also avoids the waste of energy and time. Third, the operation standardization and generalizability are improved. Clear classification standards such as 0, 5 m / d for the primary penetration level and quantitative parameter calculation methods such as plowing intensity = soil penetration coefficient difference x 5 and plowing speed = 10-plowing intensity x 0.1 make the plowing operation independent of experience, so that the operator can directly apply the formula according to the test data, reduce the technical threshold, and facilitate large-scale application in different regions. Fourth, the synergy between the plowing and subsequent improvement links is strengthened. The plowing intensity increases with the penetration coefficient difference, which can accurately open the soil penetration channel. The strong plowing intensity under the advanced penetration level creates conditions for the penetration of leaching water, and the light breaking under the primary level avoids the damage to the soil structure, which affects the water and fertilizer retention capacity, so that the plowing link and the subsequent leaching form an efficient linkage, and the overall improvement effect is improved.

[0104] Specifically, the process of determining the initial leaching water pressure according to the plowing parameters includes,

[0105] Based on the determined plowing intensity and plowing speed, the plowing leaching water influence parameter is obtained, and the initial leaching water pressure is determined based on the plowing leaching water influence parameter;

[0106] Wherein, the plowing leaching water influence parameter is the influence value of the plowing parameter on the initial leaching water pressure.

[0107] Taking a saline-alkali land improvement area in Hetao Plain of Inner Mongolia as an example, in the embodiment, the plowing leaching water influence parameter is set as plowing intensity x weight coefficient of plowing intensity + plowing speed (km / h) x weight coefficient of plowing speed, and the initial leaching water pressure (unit: MPa) is set as plowing leaching water influence parameter x pressure conversion coefficient, wherein the weight coefficient of plowing intensity is set as 0.2, based on the influence degree of plowing intensity on soil looseness, the greater the angle of entering the soil, the more sufficient the soil crushing, the higher the porosity, and the easier the leaching water to penetrate, but its influence is weaker than that of plowing speed, and the increase of the angle has a marginal decreasing effect on the improvement of porosity, so the coefficient is set as 0.2, which reflects the auxiliary role of plowing intensity on leaching; the weight coefficient of plowing speed is 0.5, based on the influence of plowing speed on soil compactness, the slower the speed, the more uniform the soil plowing, avoiding local compaction caused by rapid operation, which is more beneficial to the uniform penetration of leaching water, and its influence on leaching effect is more significant, so the coefficient is set as 0.5, which is higher than the coefficient of plowing intensity, highlighting the dominant role of speed on leaching; the pressure conversion coefficient is 0.1, which is determined according to the historical data of regional soil leaching test;

[0108] The plowing leaching water influence parameter is set as plowing intensity x 0.2 + plowing speed (km / h) x 0.5, and the initial leaching water pressure (unit: MPa) is set as plowing leaching water influence parameter x 0.1, and the leaching water pressure range is set between 0.3-1.2 MPa, wherein the leaching water pressure range is determined comprehensively according to soil structure protection, leaching efficiency and actual operation feasibility;

[0109] Case 1, the primary penetration level corresponds to the plowing parameters,

[0110] The plowing intensity is 25°, and the plowing speed is 7.5 km / h,

[0111] The plowing leaching water influence parameter is 25 x 0.2 + 7.5 x 0.5 = 8.75;

[0112] The initial leaching water pressure is 8.75 x 0.1 = 0.875 MPa;

[0113] This pressure is suitable for the soil after light plowing, and shallow angle plowing makes the surface soil loose, and 7.5 km / h speed does not excessively damage the soil structure, and 0.875 MPa pressure can promote the uniform penetration of leaching water and remove the shallow layer salt.

[0114] Case 2: the intermediate penetration level corresponds to the plowing parameters,

[0115] The plowing intensity is 40°, and the plowing speed is 6 km / h,

[0116] The plowing leaching water influence parameter is 40 x 0.2 + 6 x 0.5 = 11;

[0117] Initial leaching water pressure = 11 x 0.1 = 1.1 MPa;

[0118] 40° angle plowing makes the soil break more fully, 6 km / h speed ensures deep (60 cm) soil looseness, 1.2 MPa high pressure can ensure that the leaching water penetrates to the deep layer, and matches the leaching requirements of the soil with medium permeability.

[0119] Case 3: High permeability level corresponds to plowing parameters,

[0120] The plowing intensity is 60°, and the plowing speed is 4 km / h,

[0121] Plowing leaching water influence parameter = 60 x 0.2 + 4 x 0.5 = 14;

[0122] Initial leaching water pressure = 14 x 0.1 = 1.4 MPa, adjusted to 1.2 MPa upper limit.

[0123] 60° large angle plowing breaks hard soil layer, 4 km / h slow speed ensures soil fully loose, 1.2 MPa pressure can maximize the leaching effect, help deep salt with water discharge.

[0124] Through the linkage calculation of plowing parameters and leaching water pressure, the initial pressure accurately matches the soil state after plowing, laying the foundation for subsequent salt leaching.

[0125] The process of deriving the initial leaching water pressure through the plowing parameter realizes the scientific linkage of plowing and leaching links, provides precise initial conditions for salt leaching in saline-alkali soil, and has the following advantages: first, the parameter setting logic is rigorous, ensuring the scientificity of pressure calculation. The weight coefficients of plowing intensity and plowing speed, 0.2 and 0.5, are set according to the actual influence of the two on soil permeability, which not only reflects the auxiliary role of plowing intensity in soil crushing, but also highlights the dominant influence of plowing speed on soil density, so that the plowing and leaching water influence parameter can truly reflect the soil's acceptance ability after plowing; the pressure conversion coefficient 0.1 is determined based on regional historical test data, which ensures that the calculation results match the local soil characteristics and avoids deviations caused by subjective experience. Second, the initial leaching water pressure accurately matches the soil state. Different plowing parameters correspond to pressure values that can meet the soil leaching needs: under the primary permeability level, the 0.875 MPa pressure matches the loose surface layer after shallow plowing, which can uniformly penetrate and remove shallow salt; the upper limit pressure of 1.1 MPa for the intermediate permeability level and 1.2 MPa for the high-level permeability level can meet the permeability needs of deep soil after plowing, ensuring that the leaching water fully contacts and dissolves the deep salt. This precise matching not only avoids incomplete leaching caused by insufficient pressure, but also prevents excessive pressure from damaging the soil structure. Third, it realizes the synergistic effect of plowing and leaching. The linkage calculation of plowing parameters and leaching pressure makes the loose structure formed by plowing fully utilized by the leaching link, and the higher the plowing intensity and the slower the speed, the higher the soil porosity, so matching higher pressure leaching water can promote rapid water infiltration and remove more salt, forming a virtuous cycle of "plowing creating conditions and leaching efficiently executing" to improve the overall improvement efficiency. Fourth, the standardized operation improves the applicability. The clear formula calculation method of plowing and leaching water influence parameter = plowing intensity × 0.2 + speed × 0.5, initial leaching water pressure = plowing and leaching water influence parameter × 0.1, and pressure range limit 0.3-1.2 MPa make the operator can directly derive the leaching pressure according to the plowing parameters, without relying on complex experience judgment, reducing the technical threshold and facilitating large-scale application in different saline-alkali regions.

[0126] Specifically, the process of adjusting the leaching water pressure based on the sodium ion change curve includes,

[0127] According to the inflection point, a plurality of sodium ion change segment curves are obtained by segmenting the sodium ion change curve, the slope of any sodium ion change segment curve is obtained, and the actual sodium ion change segment curve slope is obtained.

[0128] For the pre-inflection actual sodium ion change segment curve slope before the inflection point, the leaching water pressure is adjusted based on the comparison result of the pre-inflection actual sodium ion change segment curve slope and the first standard sodium ion change segment curve slope to obtain the pre-inflection leaching water pressure.

[0129] a post-inflexion actual sodium ion change segment curve slope, adjusting the leaching water pressure based on a comparison result of the post-inflexion actual sodium ion change segment curve slope and a second standard sodium ion change segment curve slope to obtain a post-inflexion leaching water pressure;

[0130] The first standard sodium ion change segment curve slope is determined according to a target desalination efficiency of an initial leaching stage; the second standard sodium ion change segment curve slope is determined according to a stable desalination efficiency of deep soil; and the inflection point is an inflection point on a sodium ion change curve.

[0131] Taking a saline-alkali land improvement area in Hetao Plain, Inner Mongolia as an example, the target planting plant is corn, the upper limit of the sodium ion concentration tolerated by the root system is 0.3%, the first standard sodium ion change segment curve slope is set to -0.08% / h in this embodiment, the sodium ion concentration decreases by 0.08% per hour, which corresponds to the rapid desalination target of the initial leaching stage; the second standard sodium ion change segment curve slope is -0.02% / h, which decreases by 0.02% per hour, which corresponds to the deep stable desalination target; and the inflection point is determined as the time when the slope suddenly changes from >-0.05% / h to ≤-0.05% / h,

[0132] In the pre-inflexion stage, the initial leaching is 0-20 hours, the actual sodium ion change curve slope is -0.06% / h, which is less than the first standard sodium ion change segment curve slope -0.08% / h, and the decrease speed is relatively slow, so the leaching water pressure needs to be increased to accelerate the salt loss,

[0133] Specific operation: the initial leaching water pressure is 0.875 MPa, the leaching water pressure increment = (the first standard sodium ion change segment curve slope-the pre-inflexion actual sodium ion change segment curve slope) × 10, the leaching water pressure increment = (-0.08+0.06) × 10 =-0.2 MPa, the negative sign indicates that the pressure needs to be increased, so the pre-inflexion leaching water pressure is adjusted to 0.875+0.2 = 1.075 MPa,

[0134] In the post-inflexion stage, the inflection point appears after 20 hours of leaching is detected,

[0135] The actual sodium ion change curve slope is -0.01% / h, which is greater than the second standard sodium ion change segment curve slope -0.02% / h, and the decrease speed is too slow, so the leaching efficiency of deep salt is insufficient, and the pressure needs to be appropriately increased, but excessive flushing is avoided,

[0136] Specific operation: the pre-inflexion pressure is 1.0 MPa, the elution water pressure increment = (the second standard sodium ion change segment curve slope - the actual sodium ion change segment curve slope after inflexion) x 20 calculation, the elution water pressure increment = (-0.02 + 0.01) x 20 = -0.2 MPa, so the elution water pressure after inflexion is adjusted to 1.0 + 0.1 = 1.1 MPa to stabilize the push of deep salt dissolution.

[0137] By comparing the actual sodium ion change segment curve slope with the standard sodium ion change segment curve slope in stages, the elution water pressure is adjusted, the saline-alkali soil elution process is more dynamic and adaptive, and the desalination efficiency and improvement quality are significantly improved. The specific advantages are as follows: first, the precise dynamic regulation of elution pressure is realized. In the pre-inflexion stage, the first standard sodium ion change segment curve slope of -0.08% / h is taken as the reference, when the actual sodium ion change segment curve slope of -0.06% / h is slow, the pressure adjustment value is calculated by the quantitative formula (increment = slope difference x 10), the pressure is increased from 0.875 MPa to 1.075 MPa, and the surface salt loss is accelerated; in the post-inflexion stage, the second standard sodium ion change segment curve slope of -0.02% / h is referred to, and the actual sodium ion change segment curve slope of -0.01% / h is fine-tuned, and the deep salt is removed stably. This "on-demand adjustment" mode avoids the problem of desalination being too fast or too slow under fixed pressure, and makes the sodium ion concentration decline pace and target efficiency highly matched. Second, balance desalination efficiency and soil protection. In the pre-inflexion stage, the pressure is moderately increased without exceeding 1.2 MPa, which avoids damaging the soil structure while quickly desalinating; in the post-inflexion stage, the pressure is slightly increased from 1.0 MPa to 1.1 MPa according to the characteristics of the difficulty of deep salt elution, which ensures the continuous dissolution of salt and prevents soil colloids loss or nutrient imbalance caused by high pressure flushing. This pre-fast and post-stable elution water pressure adjustment strategy takes into account the desalination speed and soil ecological protection. Third, improve the controllability and target achievement rate of the elution process. The segmented adjustment based on the inflection point enables the operator to clearly understand the characteristics of the elution stage: before the inflection point, focus on rapid desalination of the surface layer to ensure that the sodium ion concentration is reduced from 0.6% to 0.45% within 20 hours; after the inflection point, turn to stable desalination of the deep layer to finally reduce the concentration to below the upper limit of 0.3% for corn tolerance. The clear stage target and quantitative adjustment method greatly reduce the blindness of the elution process and improve the achievement rate of the improvement target. Fourth, strengthen the scientificity of data-driven. Through the slope analysis of the sodium ion change curve, the desalination effect is converted into a quantifiable adjustment basis, which breaks away from the traditional mode of judging pressure by experience. Whether it is the slope difference calculation before the inflection point or the dynamic fine-tuning after the inflection point, it is based on measured data, making the elution decision more objective and repeatable, and facilitating replication and promotion in different saline-alkali regions.

[0138] Specifically, for the case that the sodium ion curve slope of the sodium ion change curve is the preset slope, the process of detecting the actual soil sodium ion proportion adsorbed by the soil colloid includes,

[0139] For the case that the actual sodium ion change segment curve slope is zero after the inflection point, the actual soil sodium ion proportion adsorbed by the soil colloid is detected.

[0140] The preset slope is that the actual sodium ion change segment curve slope is zero.

[0141] After 40 hours of leaching into the inflection point, the sodium ion change curve slope is 0% / h, that is, the preset slope, indicating that the free sodium ion concentration in the soil solution has stabilized and no longer decreases with the leaching time. At this time, the actual sodium ion proportion adsorbed by the soil colloid needs to be detected. The detection method: In this embodiment, the ammonium acetate exchange method is used, and mixed soil samples are taken from the 0-60 cm soil layer of the region, one sub-sample every 20 cm, a total of 3, the soil colloid is separated by centrifugation, and the proportion of sodium ion content in the colloid to the total soil sodium ion content is measured. The detection results: the actual sodium ion proportions of the three sub-samples are 28%, 30% and 26% respectively, and the average value is 28%. Although the free sodium ion in the leaching water no longer decreases, the soil colloid still adsorbs a large amount of sodium ion 28%>20%, and further leaching is needed to reduce the sodium ion proportion adsorbed by the colloid until it meets the standard.

[0142] Specifically, according to the actual soil sodium ion proportion and the standard soil sodium ion proportion interval comparison result, the process of determining whether to continue leaching the saline-alkali soil of the region includes,

[0143] For the case that the actual soil sodium ion proportion is less than the minimum value of the standard soil sodium ion proportion interval, it is determined to stop leaching the saline-alkali soil;

[0144] For the case that the actual soil sodium ion proportion is in the standard soil sodium ion proportion interval, it is determined to pause leaching the saline-alkali soil, and the actual soil sodium ion proportion is continuously monitored;

[0145] For the case that the actual soil sodium ion proportion is greater than the maximum value of the standard soil sodium ion proportion interval, it is determined to adjust the leaching parameters according to the extent of the actual soil sodium ion proportion exceeding the maximum value of the standard soil sodium ion proportion interval.

[0146] The leaching parameters include leaching interval and leaching depth; the exceeding degree includes slight exceeding, moderate exceeding and severe exceeding.

[0147] In this embodiment, the standard soil sodium ion proportion interval is set to 15%-20%, below 15% is up to standard, 15%-20% is to be observed, and above 20% needs to continue leaching,

[0148] For example, if the actual soil sodium ion proportion is detected to be 12% < 15%, it is determined to stop leaching. At this time, the sodium ions adsorbed by the soil colloids are at a low level, and continuing to leach will cause soil nutrients such as potassium and calcium ions to be lost with water, and the sodium ion environment for corn root growth has reached the standard, so further treatment is not needed.

[0149] If the actual soil sodium ion proportion is detected to be 18%, it is within the standard soil sodium ion proportion interval, and it is determined to suspend leaching and continue monitoring. After suspending leaching, the actual soil sodium ion proportion is detected every 3 days, and continuous monitoring is performed for 2 weeks. If the actual soil sodium ion proportion is stable at about 18% or decreases to below 15%, it is confirmed that leaching does not need to continue. If the proportion rebounds to above 20%, leaching is restarted to avoid wasting resources due to over-leaching, and to prevent sodium ions from re-aggregating due to evaporation through monitoring.

[0150] If the actual soil sodium ion proportion is greater than the maximum value of the standard soil sodium ion proportion interval, it is determined to adjust the leaching parameters according to the extent to which the actual soil sodium ion proportion exceeds the maximum value of the standard soil sodium ion proportion interval.

[0151] This detection process can accurately determine whether leaching needs to continue, avoiding misjudgment that the improvement is complete due to stable sodium ions in the solution, and ensuring that the sodium ion content on the soil colloidal layer meets the needs of plant growth. By comparing the actual soil sodium ion proportion to the standard soil sodium ion proportion interval, the precise start and stop of saline-alkali soil leaching and parameter optimization are achieved, significantly improving the improvement efficiency and resource utilization rate. The specific advantages are as follows: first, leaching is balanced to avoid under-leaching or over-leaching, and the improvement effect and cost are balanced. When the actual soil sodium ion proportion is less than the minimum value of the standard soil sodium ion proportion interval, such as 12% < 15%, timely stopping of leaching can prevent soil nutrients such as potassium and calcium ions from being lost with water, reducing water resource and energy waste. When the actual soil sodium ion proportion is within the standard soil sodium ion proportion interval, such as 18%, the strategy of suspending and monitoring can avoid ineffective leaching and prevent secondary salinization due to a rebound in sodium ions through dynamic observation, ensuring stable improvement effects. Second, the adjustment is graded according to the extent of the excess, improving the targeting of leaching. For cases where the actual soil sodium ion proportion exceeds the maximum value of the standard soil sodium ion proportion interval, the leaching parameters are adjusted according to the extent of the excess, such as mild excess, moderate excess, and severe excess, to precisely match the treatment measures with the extent of the sodium ion excess.

[0152] Specifically, the process of adjusting the leaching parameters according to the extent to which the actual soil sodium ion proportion exceeds the maximum value of the standard soil sodium ion proportion interval includes,

[0153] For cases where the extent to which the actual soil sodium ion proportion exceeds the maximum value of the standard soil sodium ion proportion interval is mild excess, the original leaching interval is shortened according to the mild excess value, and the original leaching depth is maintained.

[0154] For the case that the actual soil sodium ion proportion exceeds the maximum value of the standard soil sodium ion proportion interval by a moderate excess, the original leaching interval is shortened according to the moderate excess value, and the original leaching depth is deepened according to the moderate excess value;

[0155] For the case that the actual soil sodium ion proportion exceeds the maximum value of the standard soil sodium ion proportion interval by a severe excess, the original leaching interval is shortened according to the severe excess value, and the original leaching depth is deepened according to the severe excess value;

[0156] Wherein, the original leaching interval is determined according to the sodium ion concentration reduction rate of the initial leaching stage; the original leaching depth is determined according to the target plowing depth; the excess value is the difference between the actual soil sodium ion proportion and the maximum value of the standard soil sodium ion proportion interval.

[0157] In this embodiment, the excess degree is divided into: mild excess 20%-25%, moderate excess 25%-30%, severe excess >30%, which is determined comprehensively in combination with the target crop growth requirements and the soil colloid adsorption characteristics. For example, taking corn planted in the improved area as an example, the upper limit of the tolerance of its root growth to the soil colloid adsorption of sodium ions is 20%, that is, the maximum value of the standard soil sodium ion proportion interval. When the proportion exceeds 20%, sodium ions will affect the absorption of water and nutrients by the roots: when it is 20%-25%, corn seedlings may have slight growth retardation and yellow leaves, but this can be quickly alleviated by adjusting the leaching parameters; when it is 25%-30%, the root water absorption capacity decreases significantly, and the plant tends to be dwarfed, and leaching measures need to be strengthened; when it exceeds 30%, sodium ions will damage the root cell membrane structure, causing crop wilting and even death, and emergency intervention is needed; the soil colloid of the Hetao Plain saline-alkali soil is mainly montmorillonite and illite, and its saturated capacity for adsorbing sodium ions is about 35%-40%. When the actual proportion is 20%-25%, the soil colloid is in a state of "low saturation adsorption", and the sodium ions are easily replaced by calcium and magnesium ions, so the leaching difficulty is low, and it is mild; when it is 25%-30%, the soil colloid enters a state of "medium saturation adsorption", and part of the sodium ions are embedded in the colloid lattice, so a stronger leaching intensity is needed for desorption; when it exceeds 30%, the colloid is close to "high saturation adsorption", and the sodium ions are combined with the colloid closely, so the leaching difficulty is significantly increased.

[0158] The actual soil sodium ion proportion detected is 23%, and the excess value = 23%-20% = 3 percentage points, which is a mild excess, indicating that the sodium ions adsorbed by the surface soil colloid are relatively high, but the deep layer is not significantly affected, and only the leaching frequency needs to be increased to accelerate the surface desalination. According to the excess value of 3 percentage points, the shortening ratio = excess value ÷ 5, the original leaching interval of 24 hours is shortened by 3 / 5, that is, the shortened leaching interval = 24×(1-3 / 5) = 24×0.4 = 9.6 hours, and the original leaching depth of 60 cm is maintained, as the deep soil is not significantly over-standard, and there is no need for additional deepening;

[0159] The actual soil sodium ion proportion detected is 28%, the excess value = 28% - 20% = 8 percentage points (moderate excess), moderate excess indicates that there are also more sodium ions in the deep soil colloid, and it is necessary to shorten the leaching interval to increase the frequency and deepen the depth to cover the deep area. According to the excess value of 8 percentage points, the shortening ratio = excess value ÷ 10, shorten the original leaching interval of 24 hours by 4 / 5, that is, the shortened leaching interval = 24 x (1-4 / 5) = 24 x 0.2 = 4.8 hours, the leaching depth deepening amplitude is 60 + [60 x (1-4 / 5)] = 72 cm, through the denominator corresponding to the maximum value of the interval, it is ensured that the moderate adjustment amplitude is significantly greater than the light one, which embodies the gradient logic of "the more serious the over-standard is, the greater the adjustment intensity is"; wherein, the light and moderate excess values are divided by the maximum value corresponding to the over-standard;

[0160] The interval definition of severe over-standard is that the excess value > 10 percentage points, and the denominator is selected as 15 or 20 in combination with the common over-standard range in the region, such as the reasonable threshold set in the actual heavy over-standard of 10-20 percentage points, and the excess value of 15 percentage points is selected in this embodiment for example,

[0161] The actual soil sodium ion proportion detected is 35%, the excess value = 35% - 20% = 15 percentage points of severe over-standard, the sodium ion in the whole soil layer, the surface layer to the deep layer is seriously over-standard, and the parameter needs to be adjusted with the maximum amplitude, according to the excess value of 15 percentage points, the shortening ratio = excess value ÷ 40, shorten the original leaching interval of 24 hours by 3 / 8, that is, the shortened leaching interval = 24 x (1-3 / 8) = 24 x 0.625 = 15 hours, the leaching depth deepening amplitude is 60 + [60 x (1-3 / 8)] = 97.5 cm.

[0162] The adjustment process realizes the precision and efficiency of desalination of saline-alkali soil by matching the leaching parameters with the sodium ion exceeding degree in stages. The specific beneficial effects are as follows: first, the adjustment strength and the exceeding degree are accurately matched to improve the desalination pertinence. When the exceeding degree is slight, only the interval is shortened and the original depth is maintained to focus on the desalination of the surface soil, avoiding resource waste caused by excessive adjustment. When the exceeding degree is moderate, the interval and the depth are simultaneously shortened and deepened to accurately cover the deep area exceeding the standard. When the exceeding degree is severe, the parameters are adjusted by a larger margin, the interval is 15 hours, and the depth is 97.5 cm to deal with the serious exceeding problem of the whole soil layer. This gradient strategy of "the more severe the exceeding, the more thorough the adjustment" enables each parameter adjustment to directly hit the core area of sodium ion aggregation, avoiding the inefficient problems of "using heavy medicine for light disease" or "using light medicine for severe disease". Second, the desalination efficiency and soil protection are balanced to reduce the improvement cost. When the exceeding degree is slight, based on the judgment of "mainly in the surface layer and stable in the deep layer", the original depth is maintained to reduce water resource consumption without additional leaching of the deep soil not exceeding the standard. When the exceeding degree is moderate and severe, the deepening depth is linked to the exceeding degree, such as deepening to 72 cm for moderate exceeding and to 97.5 cm for severe exceeding, which ensures the deep desalination effect and avoids the increase of energy consumption caused by blind deepening. At the same time, through the proportional calculation of "exceeding value ÷ denominator", the interval shortening margin is controllable, which balances the desalination efficiency and cost input while accelerating the desalination and avoiding excessive equipment wear caused by high-frequency operation. Third, the desalination effect stability is improved by matching the soil colloid characteristics. According to the characteristics of soil colloid "low saturation adsorption 20%-25%, medium saturation adsorption 25%-30%, and high saturation adsorption >30%", the adjustment strategy is matched with the difficulty of desorption of colloid sodium ions: when the exceeding degree is slight, high-frequency leaching can quickly replace the easily desorbed surface colloid sodium ions; when the exceeding degree is moderate, the leaching strength is strengthened to break the sodium ions embedded in the crystal lattice; when the exceeding degree is severe, the deep and frequent leaching gradually breaks the close combination of colloid and sodium ions. This adjustment matching the soil physicochemical characteristics makes the desalination process more in line with the migration law of sodium ions, avoiding the rebound problem after desalination and improving the stability of soil improvement effect. Fourth, the adjusted leaching parameters can targetedly alleviate the influence of different degrees of exceeding on crops: when the exceeding degree is slight, the proportion of surface sodium ions is quickly reduced to avoid corn seedling leaf yellowing; when the exceeding degree is moderate, the deep desalination improves the root water absorption capacity to prevent plant dwarfing; when the exceeding degree is severe, the sodium ion concentration is maximally reduced to avoid crop death caused by root cell membrane damage.

[0163] Specifically, the process of determining whether to feedback adjust the plowing parameters according to the soil bulk density detection result comprises,

[0164] For the comparison result of the proportion of soil sodium ions, if the actual proportion of soil sodium ions is less than the maximum value of the standard soil sodium ion proportion interval, it is determined to detect the soil bulk density, and the plowing parameters are feedback adjusted according to the difference between the maximum value of the standard soil sodium ion proportion interval and the actual proportion of soil sodium ions.

[0165] In this embodiment, the standard soil bulk density is set to 1.3 g / cm 3 According to the growth needs of the target crop,

[0166] The actual proportion of soil sodium ions is detected to be 18%, at which time the soil bulk density of the 0-60 cm soil layer needs to be further detected to determine whether the soil physical structure after plowing is suitable for crop growth. The actual soil bulk density is 1.4 g / cm 3 Greater than the standard soil bulk density, indicating that the soil is still tight and compact, and the loosening degree after plowing is insufficient, and the plowing parameters need to be feedback adjusted and optimized,

[0167] The difference between the maximum value of the standard soil sodium ion proportion interval 20% and the actual proportion of soil sodium ions 18% is 20%-18%=2 percentage points. The smaller the difference, the better the sodium ion control effect, and the more focused on soil structure improvement,

[0168] Based on the difference, the plowing parameter feedback adjustment process is as follows: according to the logic that the smaller the difference, the greater the adjustment range of soil loosening degree needs to be strengthened, since the sodium ion has reached the standard, the core target is to optimize the soil physical structure, and the specific adjustment is as follows:

[0169] Plowing depth adjustment:

[0170] Adjustment formula: adjusted plowing depth = original depth × (1+difference × plowing depth adjustment coefficient), 30 cm × (1+2 × 5%) = 30 × 1.1 = 33 cm, deepened by 3 cm, and the crushing range of tight soil layer is enhanced; wherein, the plowing depth is the most core parameter for improving the soil bulk density, which directly determines the crushing range and depth of the tight soil layer. When the soil bulk density is too high, deepening the plowing depth can directly break the plow pan and increase the soil porosity, thereby rapidly reducing the bulk density;

[0171] Soil entry angle adjustment:

[0172] Adjustment formula: adjusted plowing angle = original angle x (1 + difference x soil penetration angle adjustment coefficient), 30° x (1 + 2 x 3%) = 30 x 1.06 = 31.8°, increase angle by 0.8°, increase the cutting force of the plow on the soil, reduce the bulk density, wherein the soil penetration angle adjustment coefficient is determined according to the soil penetration angle to determine the cutting angle and force of the plow on the soil: the greater the angle, the greater the contact area of the plow with the soil, the stronger the cutting and crushing effect, which can help reduce the bulk density, especially for the top 10 cm of soil, but the effect of angle adjustment is weaker than depth, cannot directly affect the deep compacted layer, and too large angle will increase the load of the equipment such as tractor power consumption,

[0173] Plowing speed adjustment:

[0174] Adjustment formula: adjusted plowing speed = original speed x (1 - difference x plowing speed adjustment coefficient), 8 km / h x (1 - 2 x 2%) = 8 x 0.96 = 7.68 km / h, reduce speed by 0.32 km / h, ensure that the soil is broken more fully after the angle is increased; wherein the plowing speed is negatively related to the degree of soil crushing: the slower the speed, the more time the plow has to cut and turn the soil, the more thorough the crushing, especially for heavy clay soil, but too slow speed will reduce the work efficiency;

[0175] Wherein, each adjustment coefficient is sorted according to the priority and sensitivity of the plowing parameters to the improvement of soil bulk density.

[0176] The plowing parameter adjustment process based on soil bulk density and sodium ion difference realizes the deep improvement of saline-alkali land improvement from "chemical index standard" to "physical structure optimization", and the specific advantages are as follows: first, precise improvement of soil physical structure, adaptation to crop growth needs. By adjusting the plowing parameters, the soil bulk density of the top 10 cm of soil is reduced by 1.4 g / cm 3To standard bulk density convergence: deepening the plowing depth by 3cm to 33cm can directly break the deep hard soil layer, increase the soil angle by 0.8°, strengthen the soil cutting and crushing, and reduce the speed by 0.32km / h to improve the crushing degree. The synergistic effect of the three makes the soil porosity increase and the bulk density decrease, providing a breathable and loose growth environment for corn roots and solving the hidden problem of "sodium ion reaching the standard but soil hardening". Second, realize "on-demand adjustment" and avoid invalid operation. The adjustment logic is directly linked to the sodium ion difference of 2 percentage points. The smaller the difference, the better the sodium ion control, and the adjustment range is more focused on soil structure improvement: since the 18% sodium ion proportion is close to the upper limit of 20%, there is no need to intervene too much in the salt, and instead, the parameters are fine-tuned, such as deepening the depth by only 3cm to optimize the bulk density, avoiding the waste of energy consumption or excessive disturbance of the soil caused by "blindly increasing the plowing intensity to reduce the bulk density". Third, grade the control parameters to balance the improvement effect and operational feasibility. The setting of different adjustment coefficients of 5%, 3%, and 2% reflects the priority of the impact of parameters on the bulk density: the plowing depth coefficient is the largest, ensuring the improvement of deep soil structure; the soil angle coefficient is moderate, enhancing the crushing effect while avoiding excessive load on the equipment; and the plowing speed coefficient is the smallest, ensuring the crushing degree while reducing the impact on operating efficiency. This graded control not only ensures the improvement effect of the bulk density, but also avoids the risk of excessive adjustment of a single parameter, such as slow speed leading to prolonged construction period. Fourth, link chemical and physical indicators to improve soil quality. This process takes "sodium ion reaching the standard" as the premise and focuses on the "bulk density exceeding the standard" problem, realizing the synergy of "single desalination" to "salinization control + structure repair" in saline-alkali land improvement: sodium ion ensures crop salt tolerance, and soil bulk density ensures root growth conditions, both of which make the soil reach the "double standard" state, laying a solid foundation for subsequent crop planting.

[0177] Thus far, the technical solutions of the present application have been described in connection with the preferred embodiments shown in the drawings, but those skilled in the art will readily understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the relevant technical features without departing from the principles of the present application, and the technical solutions after such changes or replacements will all fall within the scope of protection of the present application.

[0178] The above description is only the preferred embodiments of the present application and is not intended to limit the present application; for those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for improving saline-alkali soil, characterized in that: include, Divide the target saline-alkali land to be improved into regions to obtain regional saline-alkali land, detect the saline-alkali distribution depth of any regional saline-alkali land, determine the plowing depth based on the rooting depth range of the target plant and the saline-alkali distribution depth, and obtain a target plowing depth; adjusting the tillage parameters of the tillage device based on the target tillage depth and the difference in soil permeability coefficient; Determine the initial leaching water pressure according to the tillage parameters, detect the sodium ion concentration of the discharged water after leaching of the saline-alkali land in the area to obtain the actual sodium ion concentration, obtain a sodium ion change curve according to the actual sodium ion concentration and the detection period, and adjust the leaching water pressure based on the sodium ion change curve; When the slope of the sodium ion curve of the sodium ion change curve is a preset slope, the actual soil sodium ion ratio adsorbed by the soil colloid is detected, and according to the comparison result between the actual soil sodium ion ratio and the standard soil sodium ion ratio interval, it is determined whether to continue leaching the saline-alkali land soil in the area; Based on the comparison results of the proportion of sodium ions in the soil, it is determined whether the soil bulk density should be tested, and based on the soil bulk density test results, it is determined whether the tillage parameters should be adjusted to meet the needs of saline-alkali land improvement; Among them, the salinity distribution parameters include salinity distribution depth and actual salinity; the tillage parameters include tillage intensity and tillage speed, and the soil permeability coefficient difference is the difference between the target soil permeability coefficient and the actual soil permeability coefficient.

2. The saline-alkali soil improvement method according to claim 1, wherein The process of detecting the depth of salinity distribution in saline-alkali land in any area includes: Randomly select several saline-alkali distribution depth detection points in saline-alkali land in different regions, detect the sampling saline-alkali distribution depths of the saline-alkali distribution depth detection points by layered soil sampling, and calculate the average value of the sampling saline-alkali distribution depths as the saline-alkali distribution depth of the saline-alkali land in the corresponding region; The salinity distribution depth is the soil depth at which the preset salinity is reached.

3. The saline-alkali soil improvement method according to claim 2, characterized in that: The process of determining the tillage depth based on the rooting depth range of the target plant and the saline-alkali distribution depth includes: If the depth of salt-alkali distribution is less than the minimum value of the rooting depth range, the minimum value of the rooting depth range shall be determined as the basic value of the tillage depth; When the depth of salt-alkali distribution is within the rooting depth range, the maximum value of the rooting depth range is determined as the target tillage depth. When the depth of salt-alkali distribution is greater than the maximum value of the rooting depth range, the maximum value of the rooting depth range is determined as the target tillage depth.

4. The saline-alkali soil improvement method according to claim 3, characterized in that: The process of adjusting the tillage parameters of the tillage device based on the target tillage depth and the difference in soil permeability coefficient includes: Determine the tillage intensity based on the permeability level of the soil permeability coefficient difference, and determine the tillage speed based on the target tillage depth and the tillage intensity; The penetration levels include primary penetration level, intermediate penetration level and advanced penetration level.

5. The saline-alkali soil improvement method according to claim 4, characterized in that: The process of determining the initial leaching water pressure based on tillage parameters includes: Obtaining a plowing and rinsing water influencing parameter based on the determined plowing force and plowing speed, and determining an initial rinsing water pressure based on the plowing and rinsing water influencing parameter; The plowing and leaching water influencing parameter is the influence value of the plowing parameter on the initial leaching water pressure.

6. The saline-alkali soil improvement method according to claim 5, characterized in that: The process of adjusting the elution water pressure based on the sodium ion change curve includes: The sodium ion change curve is segmented according to the inflection point to obtain several sodium ion change segmented curves, and the slope of any sodium ion change segmented curve is obtained to obtain the slope of the actual sodium ion change segmented curve. For a pre-inflection actual sodium ion change segmented curve slope before the inflection point, adjusting the rinse water pressure based on a comparison result of the pre-inflection actual sodium ion change segmented curve slope and the first standard sodium ion change segmented curve slope to obtain the pre-inflection rinse water pressure; For the slope of the actual sodium ion change segmented curve after the inflection point, adjusting the elution water pressure based on a comparison result of the slope of the actual sodium ion change segmented curve after the inflection point and the slope of the second standard sodium ion change segmented curve to obtain the elution water pressure after the inflection point; Among them, the slope of the first standard sodium ion change segmented curve is determined according to the target desalination efficiency in the initial leaching stage; the slope of the second standard sodium ion change segmented curve is determined according to the stable efficiency of deep soil desalination; and the inflection point is the inflection point on the sodium ion change curve.

7. The saline-alkali soil improvement method according to claim 6, characterized in that: When the slope of the sodium ion curve of the sodium ion change curve is a preset slope, the process of detecting the actual soil sodium ion ratio adsorbed by the soil colloid includes: For the case where the slope of the segmented curve of actual sodium ion change after the inflection point is zero, the actual proportion of soil sodium ions adsorbed by soil colloids is detected; The preset slope is that the slope of the actual sodium ion change segmented curve is zero.

8. The saline-alkali soil improvement method according to claim 7, characterized in that: The process of determining whether to continue leaching the saline-alkali soil in the region according to the comparison result between the actual soil sodium ion ratio and the standard soil sodium ion ratio range includes: If the actual soil sodium ion ratio is less than the minimum value of the standard soil sodium ion ratio, it is determined to stop leaching the saline-alkali soil; If the actual soil sodium ion ratio is within the standard soil sodium ion ratio range, it is decided to suspend leaching of saline-alkali soil and continue to monitor the actual soil sodium ion ratio; In the case where the actual soil sodium ion ratio is greater than the maximum value of the standard soil sodium ion ratio interval, the leaching parameters are adjusted according to the degree to which the actual soil sodium ion ratio exceeds the maximum value of the standard soil sodium ion ratio interval; The elution parameters include elution interval and elution depth; the degree of excess includes mild excess, moderate excess and severe excess.

9. The saline-alkali soil improvement method according to claim 8, characterized in that: The process of adjusting the leaching parameters according to the degree to which the actual soil sodium ion ratio exceeds the maximum value of the standard soil sodium ion ratio range includes: If the actual soil sodium ion ratio exceeds the maximum value of the standard soil sodium ion ratio range to a slightly excessive degree, the original leaching interval shall be shortened according to the slightly excessive value and the original leaching depth shall be maintained; If the actual soil sodium ion ratio exceeds the maximum value of the standard soil sodium ion ratio by a moderate degree, the original leaching interval is shortened according to the moderate excess value and the original leaching depth is deepened according to the moderate excess value; If the actual soil sodium ion ratio exceeds the maximum value of the standard soil sodium ion ratio, which is a severe excess, the original leaching interval shall be shortened according to the severe excess value, and the original leaching depth shall be deepened according to the severe excess value; Among them, the original leaching interval is determined according to the rate of decrease of sodium ion concentration in the initial leaching stage; the original leaching depth is determined according to the target plowing depth; and the excess value is the difference between the actual soil sodium ion ratio and the maximum value of the standard soil sodium ion ratio interval.

10. The saline-alkali soil improvement method according to claim 9, characterized in that: The process of determining whether to make feedback adjustments to tillage parameters based on soil bulk density test results includes: When the comparison result of the soil sodium ion ratio is that the actual soil sodium ion ratio is less than the maximum value of the standard soil sodium ion ratio interval, it is determined that the soil bulk density is to be tested, and the tillage parameters are feedback-adjusted according to the difference between the maximum value of the standard soil sodium ion ratio interval and the actual soil sodium ion ratio.

Images