A saline-alkali soil improvement method based on water, fertilizer and salt synergistic intelligent regulation

Abstract

The application discloses a saline-alkali soil improvement method based on water, fertilizer and salt synergic intelligent regulation and control, and relates to the technical field of saline-alkali soil improvement.The method comprises the following steps: screening crabapple salt-tolerant resources as rootstocks, cultivating the rootstock seedlings, grafting apple variety scions after gradient salt domestication, and obtaining apple salt-adapted grafted seedlings; deep ploughing is implemented on the saline-alkali soil planting site to construct a three-layer heterogeneous functional root zone structure; the grafted seedlings are planted in the structure center, an inner ring liquid supply ditch and an outer ring salt collection ditch are arranged on the periphery of the tree body, and corresponding flow guide mulching films are laid; water and fertilizer are supplied in batches through the inner ring liquid supply ditch, and according to the salt content characteristic value of the outer ring salt collection ditch, the water content of the rooting and stable fertilizer layer and the growth of the apple trees, the water irrigation amount, the fertilizer liquid concentration and the salt compression frequency are adjusted, so that the salt content continuously migrates away from the root zone of the tree body.Through the spatial separation and arrangement of the three-layer heterogeneous functional root zone structure and the inner and outer ring ditches, the growth of the root zone and the salt accumulation function are separated, and the secondary accumulation of the salt content in the root zone is avoided.

Description

Technical Field

[0001] This invention relates to the field of saline-alkali land improvement technology, and in particular to a method for saline-alkali land improvement based on intelligent regulation of water, fertilizer and salt synergy. Background Technology

[0002] Saline-alkali land, as a significant obstacle to agricultural production, has long been a focus of widespread attention. In fruit tree cultivation, conventional technical approaches for improving saline-alkali land mainly include engineering desalination, chemical improvement, and biological salt-tolerant breeding. Engineering desalination primarily reduces salt accumulation in the root zone through methods such as open ditch drainage and underground pipe drainage; chemical improvement relies on exogenous substances such as gypsum and organic fertilizers to regulate the composition of soil colloidal ions; biological salt-tolerant breeding focuses on screening salt-tolerant rootstock resources and supplementing them with grafting techniques to enhance the adaptability of fruit trees to saline environments. These methods have already been applied in the saline-alkali land cultivation of economic fruit trees such as apples, and some technologies, through the construction of root protective layers and the implementation of integrated water and fertilizer management, have provided basic support for fruit tree production in saline-alkali land.

[0003] However, existing methods for improving saline-alkali land often manage water supply, nutrient input, and salt migration as relatively independent processes, resulting in a lack of full realization of the synergistic relationship among water, fertilizer, and salt. Specifically, firstly, conventional water and fertilizer management models are mostly based on fixed schemes set according to the apparent water and fertilizer requirements of crops, lacking real-time response to the dynamics of salt in the root zone, thus failing to effectively leverage the functions of water and nutrients in driving salt migration outward; secondly, the spatial regulation pathway of salt is ambiguous. Although salt shifts under irrigation conditions, there is a lack of clear spatial separation structure, making it easy for salt to accumulate secondary near the root zone, and difficult to establish a stable salt outflow boundary under continuous irrigation conditions. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a method for improving saline-alkali land based on intelligent regulation of water, fertilizer and salt to solve the problems of lack of coordinated linkage between water, fertilizer and salt regulation and salt spatial migration path in the existing technology, as well as the problem that the accumulation of salt in the root zone and the growth space of the tree are highly overlapping, making it difficult to form a stable salt discharge boundary under continuous irrigation conditions.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] This invention provides a method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt synergy. The method includes: screening salt-tolerant crabapple resources as rootstocks, cultivating rootstock seedlings, and grafting apple scions onto the rootstock seedlings after gradient salt acclimatization to obtain apple salt-adapted grafted seedlings; deep tilling the planting site in the saline-alkali land to construct a three-layered heterogeneous functional root zone structure, consisting of a transpiration and salt-suppressing layer, a rooting and fertilization layer, and a sodium ion exchange and salt-conducting layer; planting the apple salt-adapted grafted seedlings at the center of the three-layered heterogeneous functional root zone structure; setting up an inner ring supply ditch and an outer ring salt collection ditch around the tree, and laying a flow-guiding mulch corresponding to the inner and outer ring supply ditches; supplying water and fertilizer in stages through the inner ring supply ditch, and adjusting the irrigation volume, fertilizer concentration, and salt suppression frequency based on the salt content of the outer ring salt collection ditch, the moisture content of the rooting and fertilization layer, and the growth of the apple trees, so that salt continuously migrates away from the near-root zone of the tree.

[0008] As a preferred embodiment of the saline-alkali land improvement method based on the intelligent regulation of water, fertilizer, and salt synergy described in this invention, the cultivation of rootstock seedlings includes: numbering crabapple germplasm from different sources and propagating each crabapple germplasm into crabapple seedlings; subjecting each crabapple seedling to uniform disease and pest control and root and leaf treatment, and restoring cultivation under clean water conditions; under the same salt stress conditions, collecting data on root vigor, new root development, leaf damage, and recovery growth after stress relief for each crabapple seedling, and screening salt-tolerant crabapple materials as salt-tolerant crabapple resources; and propagating the salt-tolerant crabapple resources into rootstock seedlings to obtain graftable rootstock seedlings.

[0009] As a preferred embodiment of the saline-alkali land improvement method based on the intelligent regulation of water, fertilizer, and salt synergy described in this invention, the step of obtaining apple salt-adapted grafted seedlings includes: placing the cultivated rootstock seedlings under salt acclimatization culture conditions, gradually increasing the intensity of the rhizosphere salt environment according to different gradients, and maintaining cultivation under each salt environment level; continuously observing the new root growth status, leaf retention status, and salt damage symptoms of the rootstock seedlings under each salt environment level; when the rootstock seedlings maintain normal activity under the current salt environment, they are moved to the next gradient salt environment; after the rootstock seedlings have completed gradient salt acclimatization, scions of the target apple variety are selected and grafted onto the rootstock seedlings to obtain grafted seedlings; the grafted seedlings are subjected to wound healing maintenance and pre-planting hardening treatment, and when the grafted seedlings have normal activity, apple salt-adapted grafted seedlings are obtained.

[0010] As a preferred embodiment of the saline-alkali land improvement method based on intelligent regulation of water, fertilizer and salt synergy described in this invention, the deep tillage of the planting site in the saline-alkali land includes: conducting an in-situ soil survey at the planting site to obtain the thickness of the surface salt crust, the distribution of salt content in different layers, the degree of soil compaction, and the soil permeability; clearing the surface salt crust of the planting site and stripping off the surface high-salt soil; and deep tilling the planting site to break up the compacted layer and establish a continuous permeability channel connecting the upper and lower layers.

[0011] As a preferred embodiment of the saline-alkali land improvement method based on intelligent regulation of water, fertilizer and salt synergy described in this invention, the sodium ion replacement salt-conducting layer includes: mixing the improvement component with sodium ion replacement function with the lower soil in the area below the planting site to form a sodium ion replacement salt-conducting layer; the rooting and fertilization stabilizing layer includes: mixing the middle soil and decomposed organic fertilizer above the sodium ion replacement salt-conducting layer to form a rooting and fertilization stabilizing layer.

[0012] As a preferred embodiment of the saline-alkali land improvement method based on intelligent regulation of water, fertilizer and salt synergy described in this invention, the three-layer heterogeneous functional root domain structure includes: laying refined and leveled topsoil above the rooting and fertilization stabilizing layer to form an anti-evaporation and salt-suppressing layer; shaping the sodium ion replacement salt-conducting layer, the rooting and fertilization stabilizing layer and the anti-evaporation and salt-suppressing layer, and forming a tree pit in the center for planting apple salt-adapted grafted seedlings.

[0013] As a preferred embodiment of the saline-alkali land improvement method based on the intelligent regulation of water, fertilizer, and salt synergy described in this invention, the step of setting up an inner ring supply ditch and an outer ring salt collection ditch around the tree body includes: taking the trunk of an apple salt-adapted grafted seedling planted in the center of a three-layer heterogeneous functional root zone as the center, and opening an inner ring supply ditch around the root zone of the tree body; the bottom of the inner ring supply ditch is connected to the upper part of the rooting and fertilization layer; an outer ring salt collection ditch is opened at intervals outside the inner ring supply ditch; a continuous soil zone is maintained between the outer ring salt collection ditch and the inner ring supply ditch; the inner ring supply ditch forms a continuous supply path around the tree body; and the outer ring salt collection ditch forms a continuous salt collection boundary around the tree body.

[0014] As a preferred embodiment of the saline-alkali land improvement method based on intelligent regulation of water, fertilizer, and salt synergy described in this invention, the guiding mulch includes: laying a guiding mulch on the surface of the tree basin to cover the central area of ​​the tree, the inner ring slurry supply ditch, and the soil area between the inner ring slurry supply ditch and the outer ring salt collection ditch; the guiding mulch and the evaporation-inhibiting and salt-suppressing layer are attached to each other; slurry supply openings are set at positions corresponding to the inner ring slurry supply ditch, through which irrigation water and fertilizer solution enter the inner ring slurry supply ditch and extend towards the rooting and fertilization stabilizing layer; a salt release observation area is set at positions corresponding to the outer ring salt collection ditch to observe the salt accumulation state in the outer ring salt collection ditch; the edges of the guiding mulch are compacted and fixed to reduce evaporation in the central area of ​​the tree and maintain the controlled salt collection boundary of the outer ring salt collection ditch.

[0015] As a preferred embodiment of the saline-alkali land improvement method based on intelligent regulation of water, fertilizer, and salt as described in this invention, the specific steps for adjusting irrigation volume, fertilizer concentration, and salt suppression frequency based on the salinity characterization value of the outer ring salt collection ditch, the moisture content of the rooting and fertilization stabilization layer, and the growth status of apple trees are as follows: At the beginning of each regulation cycle, the salinity characterization value of the outer ring salt collection ditch, the moisture content of the rooting and fertilization stabilization layer, and the growth status characterization value of apple trees are collected; based on the salinity characterization value of the outer ring salt collection ditch, the moisture content of the rooting and fertilization stabilization layer, and the growth status characterization value of apple trees, the single supply volume and fertilizer concentration of the current regulation cycle are determined; water and fertilizer are supplied in stages through the inner ring supply ditch, so that water and nutrients preferentially enter the rooting and fertilization stabilization layer; after the supply, the salinity characterization value of the outer ring salt collection ditch is collected again, and combined with the changes in apple tree growth and the changes in the moisture content of the rooting and fertilization stabilization layer, the salt suppression frequency of the current regulation cycle is determined.

[0016] As a preferred embodiment of the saline-alkali land improvement method based on intelligent regulation of water, fertilizer, and salt synergy described in this invention, determining the single-time liquid supply volume and fertilizer concentration for the current regulation cycle includes: obtaining the actual root zone horizontal area controlled by the inner ring liquid supply ditch, the target wetting layer depth, the current moisture content of the rooting and fertilization stabilization layer, the target upper limit moisture content, the salinity characterization value of the outer ring salt collection ditch, and the apple tree growth characterization value within the current regulation cycle; and determining the current regulation based on the difference between the actual root zone horizontal area, the target wetting layer depth, the current moisture content of the rooting and fertilization stabilization layer, and the target upper limit moisture content. The single-time supply volume for each cycle is determined based on the salt content characterization value of the outer ring salt collection ditch and the apple tree growth characterization value. When the salt content characterization value of the outer ring salt collection ditch increases and the apple tree growth weakens, the fertilizer concentration is reduced and the single-time supply volume is decreased. When the salt content characterization value of the outer ring salt collection ditch increases and the apple tree growth stabilizes, the fertilizer concentration is maintained and the single-time supply volume is kept constant. When the salt content characterization value of the outer ring salt collection ditch decreases and the apple tree growth improves, the fertilizer concentration is increased, and the single-time supply volume is adjusted according to the difference between the current moisture content of the rooting and stabilizing fertilizer layer and the target upper limit moisture content.

[0017] The beneficial effects of this invention are as follows: By separating the three-layer heterogeneous functional root zone structure from the inner and outer ring ditches, the functions of root zone growth and salt accumulation are separated, avoiding secondary accumulation of salt in the near-root zone; by adjusting the irrigation volume, fertilizer concentration, and frequency of application in real time, dynamic synergistic regulation of water, fertilizer, and salt is achieved; by selecting salt-tolerant crabapple rootstocks and grafting after gradient salt acclimatization, combined with the three-layer root zone structure to directionally optimize the rhizosphere environment, the root vitality and growth stability of grafted seedlings under saline-alkali conditions are improved; by using the outer ring salt collection ditch and the guiding membrane to form a stable salt collection boundary, and with the sodium ion replacement salt guiding layer to promote the downward migration of salt, the salt is continuously moved away from the near-root zone, enhancing the long-term effectiveness of the improvement. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Fig. 1 This is a flowchart of a method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt synergy.

[0020] Fig. 2 A flowchart for adapting apple seedlings to salt-tolerant grafted seedlings.

[0021] Fig. 3 A flowchart for constructing a three-layer heterogeneous functional root domain structure.

[0022] Fig. 4 This is a flowchart of the closed-loop regulation of water, fertilizer, and salt based on the response of the inner ring supply ditch and the outer ring collection ditch. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0026] Reference Figs. 1-4 This is one embodiment of the present invention, which provides a method for improving saline-alkali land based on intelligent regulation of water, fertilizer and salt synergy, comprising the following steps:

[0027] S1. Select salt-tolerant crabapple resources as rootstocks, cultivate rootstock seedlings, and graft apple scions onto the rootstock seedlings after implementing gradient salt acclimatization to obtain apple salt-adapted grafted seedlings.

[0028] Furthermore, we collected crabapple germplasm materials from different sources, numbered each crabapple germplasm material, and used them as salt-tolerant crabapple resources to be screened.

[0029] All salt-tolerant crabapple resources to be screened were propagated in a unified manner to obtain crabapple seedlings with consistent growth stages.

[0030] Preferably, crabapple seedlings are cultivated using the same seedling substrate, the same container specifications, and the same water and fertilizer management conditions, so that each crabapple seedling has the same seedling age, plant height, and root system integrity before entering the salt tolerance screening.

[0031] The crabapple seedlings that entered the screening stage underwent standardized pretreatment.

[0032] The standardized pretreatment includes removing diseased and weak seedlings, retaining seedlings with intact root systems, controlling the number of leaves on the above-ground parts to be within a consistent range, and allowing each crabapple seedling to recover its growth for a predetermined time under clean water conditions, so as to eliminate short-term physiological fluctuations caused by transportation, seedling division, and transplanting.

[0033] Furthermore, the standardized pretreated crabapple seedlings were grouped and planted in the same containers, with each group corresponding to a different type of crabapple material, and salt tolerance screening was conducted under the same environment.

[0034] During the screening, the crabapple seedlings of each group were simultaneously placed in a salt stress culture solution with the same salt concentration for treatment, and the salt stress intensity was gradually increased according to a fixed salt concentration gradient, such as a 30 mmol / L gradient. Under each salt concentration condition, the crabapple seedlings of each group were treated with the same salt concentration, the same treatment time and the same culture environment, so that the salt tolerance of different crabapple materials could be compared under the same salt stress level.

[0035] During the screening process, root vigor retention rate, new root development retention rate, leaf damage index, and recovery growth rate after stress relief were continuously collected from crabapple seedlings. A crabapple salt tolerance evaluation index was constructed to characterize the comprehensive salt tolerance level of each crabapple material, expressed as:

[0036] ;

[0037] in, Indicates the first Salt tolerance evaluation index of crabapple materials Indicates the first Root activity of crabapple trees after salt stress was measured. This represents the root activity test value of the corresponding crabapple material under the clear water control condition. Indicates the first Measurement of new root development in crabapple trees after salt stress. This represents the measured value of new root development for the corresponding crabapple material under the clear water control condition. Indicates the first Recovery growth of crabapple trees after relief of salt stress. This represents the measured recovery growth value of the corresponding crabapple material under the clear water control condition. Indicates the first Leaf damage measurements of crabapple varieties under salt stress This indicates the maximum calibrated value for leaf damage measurement. , , , All of these represent weighting coefficients, and all are positive values.

[0038] It should be noted that the root vigor measurement value can be obtained by collecting crabapple roots, performing a colorimetric reaction using root vigor detection reagent, and then calculating the absorbance; the new root growth measurement value can be obtained by statistically analyzing the number, total length, or total mass of new roots of crabapple seedlings per unit time; the recovery growth measurement value can be obtained by recording the elongation of new shoots, the increase in plant height, or the amount of biomass recovery of crabapple seedlings; and the leaf damage measurement value can be obtained by statistically analyzing the percentage of chlorosis, scorched edges, curling, and necrosis areas on the leaves.

[0039] It should be noted that the weighting coefficients of the crabapple salt tolerance evaluation index... , , , The values ​​are determined by principal component analysis or multi-index regression fitting method based on the collected salt tolerance test sample data of crabapple materials. The values ​​are usually between 0 and 1, and the sum of each weight is 1.

[0040] Furthermore, the salt tolerance evaluation index of crabapple trees was sorted from high to low, and the crabapple materials with the highest ranking were selected for the re-selection stage.

[0041] During the second selection, the crabapple materials that entered the second selection stage were placed in cultivation conditions that were closer to the actual environment of saline-alkali land for verification. The focus was on examining the root stability, aboveground growth continuity, and regeneration ability of the crabapple materials in a continuous saline environment.

[0042] When the same crabapple material maintains the highest crabapple salt tolerance evaluation index in both the preliminary and secondary selection stages, and exhibits continuous and stable growth, intact root system, and no obvious irreversible damage to the above-ground parts, the current crabapple material is identified as a crabapple salt-tolerant resource and used as a subsequent apple rootstock cultivation target.

[0043] Furthermore, the propagation materials identified as salt-tolerant crabapple resources will be propagated to obtain rootstock seedlings. During the cultivation of rootstock seedlings, uniform container specifications, uniform seedling substrate, and uniform fertilizer and water management will be maintained to ensure that the rootstock seedlings have a consistent growth state before entering the gradient salt acclimatization process.

[0044] The criteria for determining whether rootstock seedling cultivation is complete include: the rootstock seedlings have reached the required degree of lignification for grafting; the root system is intact; the taproot and lateral roots are continuously developed; the rootstock seedlings are free of disease spots and mechanical damage; and the above-ground buds are plump.

[0045] Furthermore, the obtained rootstock seedlings were placed under salt acclimatization culture conditions to implement gradient salt acclimatization.

[0046] Gradient salt acclimatization refers to not directly applying a high-intensity salt environment to the rootstock seedlings, but gradually increasing the intensity of the rhizosphere salt environment according to a fixed gradient, and maintaining the same culture time in each level of salt environment, so that the rootstock seedling roots can complete the transition from adaptation to stable growth before entering the next level of salt environment.

[0047] It should be noted that salt acclimatization gradients are typically set as salt concentration gradients that increase gradually from low to high, with a fixed or approximately fixed increment between adjacent levels. For example, salt treatment gradients of 0, 30, 60, 90, and 120 mmol / L are set, and each level is maintained for a fixed time before moving to the next level.

[0048] At each level of salinity, the status parameters of the rootstock seedlings were continuously monitored.

[0049] The state parameters include the retention of white roots, the extension of new roots, the degree of leaf chlorosis, the uprightness of stems and leaves, and the growth recovery rate. A gradient salt acclimatization advancement judgment coefficient is set to determine whether the rootstock seedling can be transferred from the current salt environment to the next level of salt environment, expressed as:

[0050] ;

[0051] in, Indicates the first The determination coefficient for the advancement of gradient salt domestication in a salt-gradient environment. Indicates the first Measurement values ​​of continuous new root growth in rootstock seedlings under saline conditions. Indicates the first Determination of normal leaf retention rate of rootstock seedlings under saline conditions. Indicates the first Measured values ​​of salt damage symptoms in rootstock seedlings under high-salt conditions. Represents a very small positive number, and .

[0052] It should be noted that the continuous growth of new roots in rootstock seedlings under saline conditions can be obtained by continuously recording the number of new roots during each level of saline treatment; the normal retention rate of leaves in rootstock seedlings under saline conditions can be obtained by statistically analyzing the proportion of leaves that remain green, without obvious chlorosis or wilting, and have not fallen off after treatment to the total number of leaves before treatment; and the salt damage symptoms of rootstock seedlings under saline conditions can be obtained by scoring the salt damage manifestations such as leaf yellowing, scorching, curling, wilting, and necrosis, and then normalizing the average of the total scores.

[0053] The criteria for determining whether rootstock seedlings have completed gradient salt acclimatization include that, during the continuous observation period, the root system of the rootstock seedlings maintains continuous growth, the leaves do not show continuously deteriorating salt damage symptoms, the above-ground growth points remain active, and they can still maintain normal growth after recovery culture under the current gradient.

[0054] Furthermore, robust one-year-old branches of the target apple variety are selected as scions, and the scions are uniformly cut and preserved.

[0055] Among them, the scion should meet the requirements of plump buds, free from pests and diseases, free from mechanical damage, and with a moderate degree of lignification.

[0056] Subsequently, after the rootstock seedlings have completed gradient salt acclimatization and their growth status has been confirmed to be stable, the scions are grafted onto the rootstock seedlings.

[0057] During grafting, ensure precise alignment of the cambium layers of the scion and rootstock, fix the graft union, and keep the graft union moist and clean to promote callus formation.

[0058] After grafting, place the grafted seedlings in a suitable environment for maintenance, control the water supply and environmental fluctuations, and prevent the graft union from losing water and causing secondary damage.

[0059] After grafting is completed, the grafted seedlings undergo graft union healing and maintenance.

[0060] During the maintenance period, it is important to keep the graft union stable, the scion buds fresh, and the rootstock roots continuously watered without excessive salt damage.

[0061] After the graft union has healed, continue to cultivate the grafted seedlings to establish a stable root-stem-leaf transport relationship.

[0062] The conditions for determining whether apple seedlings are suitable for salt adaptation include: continuous healing of the graft union without obvious cracks or necrosis; normal budding or shoot growth of the scion; continued activity of the rootstock root system after salt adaptation; and no obvious wilting, chlorosis, or persistent salt damage symptoms in the overall grafted seedling.

[0063] After obtaining apple salt-adapted grafted seedlings, the grafted seedlings were hardened off before transplanting.

[0064] During the hardening-off process, the intensity of external environmental fluctuations is gradually increased, allowing the apple salt-adapted grafted seedlings to gradually adapt to changes in temperature, light, and water supply in the subsequent saline-alkali land planting environment.

[0065] S2. Deeply till the planting site in saline-alkali land to construct a three-layer heterogeneous functional root domain structure, consisting of an anti-evaporation and salt-suppressing layer, a root-promoting and fertilizer-stabilizing layer, and a sodium ion-displacement and salt-conducting layer, from top to bottom.

[0066] Furthermore, the planting locations for apple trees were determined in the saline-alkali land where the orchard was to be established.

[0067] The planting locations are set based on the orchard design spacing and row spacing, and are planned in a coordinated manner in combination with changes in ground elevation, drainage direction of the plot, and distribution of salt crust on the ground surface, so that each planting location forms a relatively independent root zone space that is easy to improve later.

[0068] After the planting sites are determined, an in-situ soil survey is conducted at each planting site.

[0069] In-situ soil surveys mainly involve stratified analysis of the surface, middle, and lower layers of the planting site to obtain information such as the thickness and coverage of the surface salt crust, the salt distribution in different layers, the degree of soil compaction, soil permeability, soil texture, and the trend of shallow underground salt accumulation, thereby forming the initial soil data for the planting site.

[0070] After completing the in-situ soil survey, the surface of the planting site was pretreated to remove the visible salt crust and crystalline salt-rich layer. Then, the obviously high-salt soil on the surface of the planting site was peeled off and transferred out of the central area of ​​the planting site to avoid some of the high-salt soil from being mixed back into the root zone during deep tillage.

[0071] Furthermore, after completing the surface cleaning, deep tilling is carried out at the planting site.

[0072] During deep tillage, the soil is loosened from the surface downwards, using the planting center as a reference, breaking up the original compacted and dense layers, so as to form a continuous permeation channel between the surface, middle and lower layers.

[0073] The conditions to be met during deep tillage include: breaking up the original compacted layer at the planting site that hinders water infiltration; creating a continuous porous connection between the middle root zone soil and the lower salt-conducting soil; avoiding the re-mixing of the stripped topsoil with high salinity into the center of the planting site; and preliminarily shaping the loosened soil to ensure clear boundaries for the functional construction of different layers.

[0074] Furthermore, a root domain hierarchical adaptation coefficient is set to characterize the degree of adaptation of the planting site to construct a three-layered heterogeneous functional root domain structure after deep tillage, expressed as:

[0075] ;

[0076] in, Indicates the first Root zone stratification fit coefficient at each planting site Indicates the first Soil permeability measurements after deep tillage at each planting site. Indicates the first Measurement values ​​of connectivity between upper and lower layers after deep tillage at each planting site. Indicates the first The residual compaction measured after deep tillage at each planting site.

[0077] It should be noted that the soil permeability measurement value after deep plowing at the planting site can be obtained by quantitatively irrigating the planting site and measuring the water infiltration rate per unit time; the connectivity measurement value between the upper and lower layers after deep plowing at the planting site can be obtained by applying tracer water or dye solution to the surface layer of the planting site and observing its continuous downward movement depth between the surface, middle and lower layers; the residual compaction measurement value after deep plowing at the planting site can be obtained by using soil penetration resistance measurement to detect the resistance of soil layers at different depths after deep plowing, and using the resistance magnitude to characterize the degree of residual compaction.

[0078] Furthermore, after deep tilling to form continuous permeation channels, a sodium ion-displacement salt-conducting layer is constructed in the lower layer area below the planting site.

[0079] The sodium ion replacement salt-conducting layer is set below the main active layer of the root system. During irrigation, it is used to receive salts migrating downward from the upper soil, promote the replacement of sodium ions in the soil, and provide a conduit for the continued downward movement of salts.

[0080] Therefore, when constructing a sodium ion-exchange salt-conducting layer, the modified component with sodium ion exchange function is uniformly mixed with the deep-turned subsoil so that the subsoil has both a certain ion exchange capacity and maintains good permeability and bearing capacity.

[0081] Meanwhile, during the construction of the sodium ion-replaced salt-conducting layer, the following a1-a4 relationships need to be controlled:

[0082] a1. The sodium ion replacement salt-conducting layer should be located below the rooting and fertilizer-stabilizing layer.

[0083] a2. The sodium ion-displaced salt-conducting layer should form a continuous interface with the upper middle soil layer.

[0084] a3. Sodium ion replacement of the salt conduction layer must not form a new dense barrier layer.

[0085] a4. Sodium ion-displaced salt-conducting layers should maintain water conductivity that allows the moist front to advance downwards.

[0086] Similarly, to determine whether the sodium ion-replaced salt-conducting layer has achieved its intended function, a salt-conducting construction determination coefficient is set, denoted as:

[0087] ;

[0088] in, Indicates the first The salt-conducting construction determination coefficient of each planting site Indicates the first Ion exchange measurements of the lower layer of the plant site Indicates the first Hydraulic conductivity measurements of the lower layer area of ​​each planting site Indicates the first Salt retention values ​​in the lower layer of the planted area.

[0089] It should be noted that the ion exchange value of the lower layer area of ​​the planting site can be obtained by collecting soil samples from the lower layer and measuring the decrease in exchangeable sodium content or displaceable sodium ions before and after the replacement treatment; the water conductivity value of the lower layer area of ​​the planting site can be obtained by applying a fixed amount of water to the constructed lower layer area and measuring the infiltration flux per unit time; the salt retention value of the lower layer area of ​​the planting site can be obtained by collecting soil samples from the lower layer area after a fixed amount of irrigation and measuring the cumulative degree of soluble salt content.

[0090] Furthermore, after the sodium ion replacement salt-conducting layer is constructed, a rooting and fertilizer-stabilizing layer is constructed above the sodium ion replacement salt-conducting layer.

[0091] Among them, the rooting and fertilization stabilization layer is located in the middle of the three-layer heterogeneous functional root domain structure. It is the area where the main root and lateral root of the apple salt-adapted grafted seedlings preferentially grow after transplanting, and it is also the main functional layer for the inner ring liquid supply ditch to input water and fertilizer solution.

[0092] In this embodiment, the in-situ intermediate soil and fully decomposed organic fertilizer are evenly mixed to form a root-promoting and fertilizer-stabilizing layer.

[0093] Meanwhile, during the construction of the rooting and fertilization stabilization layer, the following b1-b4 relationship needs to be controlled:

[0094] b1. The rooting and stabilizing fertilizer layer should be in continuous contact with the sodium ion replacement salt-conducting layer below, but without forming a collapsed interface.

[0095] b2. The rooting and fertilization layer should have a good granular structure to ensure air permeability and water retention.

[0096] b3. The organic components in the rooting and stabilizing fertilizer layer should be evenly distributed to avoid local over-fertilization or local gaps.

[0097] b4. The rooting and fertilization layer should be located within the root extension area of ​​the apple salt-adapted grafted seedling, so that new roots can preferentially expand in the layer after transplanting.

[0098] Furthermore, after the rooting and fertilization stabilization layer is constructed, an anti-evaporation and salt-suppressing layer is constructed above it.

[0099] Among them, the evaporation-inhibiting and salt-suppressing layer is located at the top of the three-layer heterogeneous functional root domain structure. It has the functions of reducing surface evaporation; weakening the tendency of salt return caused by the migration of deep water to the surface; providing a flat and adhesive base for the laying of the diversion membrane; and making the water input from the inner ring liquid supply ditch more inclined to expand downward and outward, rather than directly evaporate and be lost to the surface.

[0100] In this embodiment, the evaporation and salt suppression layer is constructed using refined topsoil, and the evaporation and salt suppression layer is leveled and shaped to give the upper surface of the evaporation and salt suppression layer good continuity and film adhesion.

[0101] It should be noted that during construction, the high-salt topsoil should not be remixed into the anti-evaporation and salt-suppressing layer to prevent salt accumulation under the membrane after covering.

[0102] Furthermore, after the evaporation-inhibiting and salt-suppressing layer, the root-promoting and fertilizer-stabilizing layer, and the sodium ion-displacement salt-conducting layer are constructed in sequence, the entire planting site is shaped so that the three-layer heterogeneous functional root domain structure has a clear upper and lower layer relationship and a central planting space.

[0103] During the shaping process, a tree pit is formed in the center of the three-layered heterogeneous functional root domain structure.

[0104] When the tree pit is formed, the following requirements c1-c4 should be met:

[0105] c1. The tree pit is located in the central region of the three-layered heterogeneous functional root domain structure.

[0106] c2. The lower part of the tree pit and the rooting and fertilization layer are continuously connected.

[0107] c3. The bottom of the tree pit does not disrupt the integrity of the sodium ion-displaced salt-conducting layer.

[0108] c4. The top of the tree pit and the anti-evaporation and salt-suppressing layer are smoothly connected.

[0109] S3. Plant the apple salt-adapted grafted seedlings in the center of the three-layer heterogeneous functional root zone structure, set up an inner ring supply ditch and an outer ring salt collection ditch around the tree, and lay a drainage mulch corresponding to the inner ring supply ditch and the outer ring salt collection ditch.

[0110] Furthermore, the tree pit formed at the center of the three-layered heterogeneous functional root domain structure was remodeled.

[0111] During the restoration process, the inner wall and bottom of the tree pit are lightly loosened and arranged to ensure continuous connection between the bottom of the tree pit and the rooting and fertilization layer. At the same time, the integrity of the sodium ion replacement salt-conducting layer below is avoided.

[0112] It should be noted that any localized collapses, hardening, or salt accumulation in the tree pit should be promptly removed or dispersed to ensure that the roots of the apple seedlings can continuously expand along the rooting and fertilization layer after transplanting.

[0113] After the tree pit is prepared, a pre-planting re-inspection is carried out on the apple salt-adapted grafted seedlings to be planted.

[0114] The re-inspection includes the following: the healing status of the grafting interface, the germination status of the scion, the integrity of the root system, the salt adaptation status, and the completion status of hardening off.

[0115] Only apple salt-adapted grafted seedlings that meet the planting conditions will be used for planting.

[0116] If the graft union is not fully healed, the root system is severely damaged, or the leaves show persistent salt damage, then planting should not be carried out.

[0117] Furthermore, place the apple salt-adapted grafted seedling in the center of the tree pit, allowing the seedling's roots to spread out naturally in all directions, and ensuring that the main roots are distributed within the rooting and fertilization layer.

[0118] When planting, first cover the space around the roots with finely refined low-salt backfill soil to make the roots and the surrounding soil form close contact, and then continue to backfill in layers up to the opening of the tree hole.

[0119] During backfilling, light pressure should be applied while filling to ensure that the backfill soil adheres to the root system, but it should not be compacted to the point of affecting aeration and water seepage.

[0120] After planting, the apple tree should be adapted to the following conditions: the grafted seedling should be kept upright, the grafting interface should be at an appropriate height, the main root system should be located in the rooting and fertilization layer, the root system and the sodium ion replacement salt-conducting layer should maintain a continuous water-conducting relationship, and the surface of the planting hole and the evaporation and salt-inhibiting layer should be smoothly connected.

[0121] Immediately after transplanting the apple salt-adapted grafted seedlings, implement initial root stabilization solution supply.

[0122] The purpose of the initial root stabilization slurry supply is not to replenish a large amount of water, but to make the backfill soil around the roots settle quickly and form a continuous moist body in the center of the tree pit, so as to establish a stable water connection between the roots and the rooting and fertilization layer.

[0123] When initially supplying liquid to stabilize the roots, the intensity of the liquid supply should be controlled so that the liquid can preferentially seep into the center of the tree pit and the adjacent rooting and fertilization layer, rather than excessively scouring the surface soil of the tree pit, thus avoiding tree pit collapse or local water accumulation.

[0124] After the initial root stabilization and sap supply is completed, observe whether the tree remains upright, whether there is obvious collapse on the surface of the tree pit, and whether the central moist area is continuous.

[0125] If local collapse occurs, add low-salt fine soil and then lightly apply liquid to restore the planting area to a flat state.

[0126] Furthermore, after completing the initial root stabilization and sap supply, an inner ring sap supply trench is constructed around the grafted seedling, centered on the trunk of the apple salt-adapted grafted seedling.

[0127] The inner ring liquid supply ditch is located at the outer edge of the tree near the root zone. It is used to receive subsequent water and fertilizer supply in stages, so that the input liquid can spread along the rooting and fertilization layer first, rather than being concentrated directly at the base of the trunk.

[0128] When constructing the inner ring slurry supply trench, the inner ring slurry supply trench and the tree trunk should be arranged in a ring shape that is basically consistent in circumference, and the bottom of the inner ring slurry supply trench should be located below the evaporation and salt suppression layer and above the rooting and fertilization stabilization layer.

[0129] When the inner ring liquid supply channel is formed, the following requirements d1-d4 should be met:

[0130] d1. The inner ring sap supply trench forms a continuous sap supply path around the tree.

[0131] d2. The bottom of the inner ring liquid supply trench should not damage the integrity of the rooting and fertilization layer.

[0132] d3. Retain stable soil near the root zone between the inner ring sap supply ditch and the trunk.

[0133] d4. When supplying liquid, the inner ring liquid supply channel can form a moistening front starting point that extends downward, inward, and outward.

[0134] After the inner ring supply ditch is constructed, the outer ring salt collection ditch is constructed outside the inner ring supply ditch.

[0135] The outer ring salt collection ditch is located outside the inner ring liquid supply ditch and is spaced apart from the inner ring liquid supply ditch.

[0136] The outer ring salt collection ditch is used to collect the salt that migrates outward after the liquid is input from the inner ring liquid supply ditch, and serves as an area for subsequent observation of the controlled accumulation state of the salt.

[0137] When constructing the outer ring salt collection ditch, it should be ensured that the outer ring salt collection ditch forms a continuous outer ring boundary around the tree body, and that the salt ditch is located in the corresponding area of ​​the outer edge of the diversion mulch.

[0138] When the outer ring salt collection ditch is formed, the following requirements e1-e4 should be met:

[0139] e1. The outer ring salt collection ditch is located outside the inner ring liquid supply ditch, and a continuous soil zone is maintained between the two.

[0140] e2. The outer ring salt collection ditch receives salt that migrates from the near-root area of ​​the tree to the outer periphery.

[0141] e3. The outer ring salt collection ditch is not directly connected to the central root activity area of ​​the tree.

[0142] e4. In a preferred embodiment, the outer ring salt collection ditch is shallowly repaired to facilitate observation of changes in salt content.

[0143] It should be noted that the construction of the outer ring salt collection ditch transfers the controlled salt accumulation area from the near-root area of ​​the trunk to the outer boundary area, so that the central area of ​​the tree undertakes the growth function and the outer area undertakes the salt collection function, thus forming a spatial functional separation within the same planting location.

[0144] After the inner ring supply ditch and the outer ring salt collection ditch were constructed, the double-ring ditch structure was tested for compatibility.

[0145] The adaptation test includes checking the continuity of the inner ring supply ditch, the integrity of the outer ring salt collection ditch, the stability of the soil zone between the two, and the relative positional relationship between the centers of the double-ring ditch and the three-layer heterogeneous functional root domain structure.

[0146] In this embodiment, to determine whether the planting center of the apple salt-adapted grafted seedling and the double-ring ditch drainage relationship are matched, a planting drainage matching coefficient is set, which is expressed as:

[0147] ;

[0148] in, Indicates the first Planting flow matching coefficient for each planting site Indicates the first The measured values ​​of the central position of the apple salt-adapted grafted seedlings and the circumferential consistency of the inner ring slurry in each planting location. Indicates the first The connectivity between the inner ring slurry supply trench and the rooting and fertilization stabilization layer was measured at each planting site. Indicates the first Measurement values ​​of sap flow near the root zone of the tree at each planting location.

[0149] It should be noted that the circumferential consistency measurement value is obtained by measuring the radial distance from the center of the trunk of the apple salt-adapted grafted seedling to each circumferential position of the inner ring supply trench, and calculating the degree of distance deviation in each direction; the connectivity measurement value is obtained by detecting the infiltration depth and expansion range of the tracer solution into the rooting and stabilizing fertilizer layer after the tracer solution is introduced into the inner ring supply trench; the liquid deviation measurement value is obtained by monitoring the difference in the advancement of the soil wetting front in each direction near the root zone of the tree after the solution is supplied.

[0150] Furthermore, after the double-ring trench structure was inspected, a drainage mulch was laid on the surface of the tree basin.

[0151] The drainage mulch covers the central area of ​​the tree, the inner ring slurry supply ditch, and the main soil area between the inner and outer ring ditches. Slurry supply openings are set at the positions corresponding to the inner ring slurry supply ditch, and salt release observation areas are set at the positions corresponding to the outer ring salt collection ditch.

[0152] When laying the flow-guiding membrane, ensure that the flow-guiding membrane and the surface of the anti-evaporation and salt-inhibiting layer are in contact, and press and fix the edges of the membrane to reduce disordered evaporation of moisture under the membrane.

[0153] When the diversion membrane is laid, the following requirements f1-f4 should be met:

[0154] f1. The position of the liquid supply opening corresponds to the inner ring liquid supply groove, so that the liquid can be directed into the inner ring liquid supply groove.

[0155] f2. The location of the salt release observation area corresponds to the outer ring salt collection ditch, so as to observe the degree of salt accumulation.

[0156] f3. Drainage mulch covers the central area near the roots of the tree to reduce central evaporation.

[0157] f4. Maintain a clear boundary between the outer edge of the diversion membrane and the outer ring salt collection ditch to facilitate controlled salt collection in the periphery.

[0158] After the drainage membrane is laid, a drainage test is carried out.

[0159] During the flow test, a small amount of test liquid is introduced into the inner ring supply channel through the supply opening. It is observed whether the liquid can seep down along the inner ring supply channel and form a continuous wet expansion under the membrane. At the same time, it is observed whether the outer ring salt collection channel area maintains a relatively clear outer boundary.

[0160] Furthermore, after the diversion inspection and salt collection boundary confirmation are completed, the seedling establishment phase begins.

[0161] During the seedling establishment stage, low-intensity, multi-stage liquid supply is applied to the inner ring supply trench through the liquid supply openings on the drainage film to maintain a stable and moist state in the rooting and stabilizing fertilizer layer, and to allow the new roots of the apple salt-adapted grafted seedlings to gradually recover and elongate.

[0162] During the seedling establishment phase, high-intensity fertilization should not be carried out; instead, the focus should be on stabilizing the roots, maintaining moisture, and mildly suppressing salt levels.

[0163] During the seedling establishment stage, continuous observation should be made of the uprightness of the apple salt-adapted grafted seedlings; the stability of the graft union; the moisture retention of the central mulch area; whether the boundary of the outer ring salt collection ditch is clear; and whether there are signs of salt return in the near-root area.

[0164] When the new roots of the apple seedlings adapted to salt have recovered, the leaves are in stable condition, the tree's growth points remain active, and there is no significant instability at the boundary of the outer ring salt collection ditch, the seedling recovery stage is considered complete, and the closed-loop water, fertilizer, and salt regulation stage begins.

[0165] S4. Water and fertilizer are supplied in stages through the inner ring supply ditch. Based on the salt content of the outer ring salt collection ditch, the moisture content of the rooting and stabilizing fertilizer layer, and the growth of the apple trees, the irrigation volume, fertilizer concentration, and salt suppression frequency are adjusted to ensure that salt continuously migrates away from the root zone of the tree.

[0166] Furthermore, after the closed-loop water, fertilizer and salt regulation is initiated, the apple tree growth period is divided into continuous regulation cycles, each of which includes four stages: monitoring, judgment, liquid supply and verification.

[0167] At the beginning of each regulation cycle, the following data were collected: salt content of the outer ring salt collection ditch, moisture content of the rooting and fertilization layer, growth status of apple trees, integrity of the drainage mulch, and stability of the outer ring salt collection ditch boundary.

[0168] Among them, the salt content characterization value of the outer ring salt collection ditch is used to reflect whether salt is accumulating towards the periphery; the water content of the rooting and fertilization stabilization layer is used to reflect the current water status of the root activity layer; and the apple tree growth characterization value is used to reflect the tree's comprehensive response to the current water, fertilizer and salt environment.

[0169] In this embodiment, the apple tree growth characterization values ​​preferably include comprehensive indicators such as the extension status of new shoots, the color retention status of leaves, the degree of leaf edge scorching, the activity status of buds, and the uprightness of the tree.

[0170] It should be noted that the extension status of new shoots is obtained by measuring the increase in the length of new shoots of apple trees within the current regulation cycle; the leaf color retention status is obtained by collecting leaf surface color parameters; the degree of leaf margin scorch is obtained by statistically analyzing the percentage of area with water loss, yellowing, or brown necrosis at the leaf margins; the bud activity status is obtained by observing the fullness, color, and sprouting of buds, combined with the freshness of tissue after cutting and inspection; and the tree uprightness is obtained by measuring the degree of inclination of the trunk relative to the vertical direction. Finally, the comprehensive indicators are normalized and the average value is taken as the characterization value of apple tree growth.

[0171] Furthermore, after obtaining the monitoring data for the current regulation cycle, the current water, fertilizer, and salt synergy status of the root zone is determined.

[0172] In this embodiment, the water-fertilizer-salt synergistic regulation coefficient is used to characterize the first... The overall regulatory state of the root domain system in each regulatory cycle is represented as follows:

[0173] ;

[0174] in, Indicates the first The water-fertilizer-salt synergistic regulation coefficient for each regulation cycle Indicates the first The volumetric moisture content of the rooting and fertilization stabilization layer within each regulation cycle, Indicates the first The planned input of effective nutrient concentration into the inner ring supply ditch within each control cycle Indicates the first Apple tree growth characteristics within a single regulation cycle Indicates the first The salinity characterization values ​​of the inner and outer ring salt collection ditch during each regulation cycle.

[0175] Furthermore, after determining the synergistic state of water, fertilizer, and salt, the first... The amount of liquid supplied per cycle in a single control period.

[0176] Since this embodiment uses a multi-stage water and fertilizer supply, the amount of liquid supplied at one time should be determined based on the current water shortage level of the rooting and fertilization layer, the target moistening depth, and the current salt conduction demand.

[0177] In this embodiment, the first The single liquid supply volume for each control cycle is expressed as:

[0178] ;

[0179] in, Indicates the first The single liquid supply volume per control cycle, Indicates the first The actual root domain horizontal area controlled by the inner ring liquid supply channel in each regulation cycle Indicates the first The target wetting layer depth for each regulation cycle This indicates the target upper limit of moisture content for the rooting and fertilization layer. Indicates the first The current measured volumetric moisture content of the rooting and fertilization stabilization layer during each regulation cycle. Indicates the first The liquid supply correction coefficient for each control cycle.

[0180] It should be noted that the target upper limit moisture content is obtained by pre-determining the suitable moisture content range of the rooting and fertilization layer when it meets the requirements for normal root growth of apple trees and does not cause waterlogging stress, and selecting the upper limit value of the current range; the liquid supply correction coefficient is obtained by comprehensively considering the changes in the salinity characterization value of the outer ring salt collection ditch, the degree of deviation of the current moisture content of the rooting and fertilization layer, and the growth response of the apple trees, and correcting the basic liquid supply volume.

[0181] Furthermore, after determining the volume of liquid supplied in a single operation, the first... The concentration of fertilizer solution in each regulation cycle.

[0182] The concentration of fertilizer solution should be set according to the principle of stabilizing roots first and then promoting growth; controlling salt first and then increasing fertilizer. That is, when the salt content of the outer ring salt collection ditch is high or the apple tree shows mild salt damage, the fertilizer solution concentration should be maintained at a low level. When the salt content of the outer ring salt collection ditch tends to stabilize, the moisture content of the rooting and fertilization layer is appropriate, and the apple tree is growing normally, the fertilizer solution concentration can be appropriately increased.

[0183] In this embodiment, the first Fertilizer concentration in each regulation cycle And apple tree growth characterization values Salt content characterization value of outer ring salt collection ditch and the moisture content of the rooting and fertilization layer Linkage confirmed.

[0184] Specifically, when the apple tree growth indicator value The salinity of the outer ring salt collection ditch decreased and the salinity characterization value was lowered. When the concentration of fertilizer solution increases, decrease the concentration of fertilizer solution. When the apple tree growth indicator value Stable and outer ring salt collection ditch salinity characterization value Maintain fertilizer concentration within the controlled aggregation range of the outer ring. Stable; when the apple tree growth indicator value Moisture content of rising, rooting and stabilizing fertilizer layer Suitable and outer ring salt collection ditch salinity characterization value When the temperature drops, appropriately increase the fertilizer solution concentration. .

[0185] It should be noted that the controlled accumulation zone of the outer ring refers to the target range in which the salt content characterization value of the outer ring salt collection ditch is within a range that indicates that the salt has stably migrated from the near-root zone to the periphery, without causing a significant weakening of the apple tree's growth, and can continue to maintain the current strategy of partial liquid supply and salt suppression.

[0186] Furthermore, after determining the single supply volume and fertilizer concentration, the frequency of salt pressing is determined.

[0187] Among them, the salt pressure frequency refers to the number of times the liquid is supplied within a control cycle in order to promote the continuous migration of salt to the outer ring salt collection ditch and sodium ion replacement salt guiding layer.

[0188] The frequency of salt pressing is not fixed, but should be adjusted according to the changing trends of the salt content in the outer ring salt collection ditch, the changing trends of the moisture content in the rooting and fertilization layer, and the changing trends of apple tree growth.

[0189] In this embodiment, through the first The salt pressure frequency correction value for each regulation cycle is adjusted and expressed as follows:

[0190] ;

[0191] ;

[0192] in, Indicates the first Adjustment amount of salt pressure frequency per regulation cycle Indicates the first The frequency correction value for salt pressure in each regulation cycle Indicates the frequency of basic salt pressure. Indicates the first The change in salinity of the outer ring salt collection ditch in each regulation cycle relative to the previous regulation cycle. This indicates the baseline value of salinity in the outer ring salt collection ditch. Indicates the first The change in apple tree growth in one regulation cycle relative to the previous regulation cycle. This indicates the target moisture content benchmark value for the rooting and fertilization stabilization layer. This indicates the current volumetric moisture content of the rooting and fertilization layer. , , These represent the adjusted weights, This indicates the integer part.

[0193] It should be noted that the correction weight for the salt pressure frequency correction value is... , , The correlation analysis and regression calibration were performed on historical data on changes in salinity in the outer ring salt collection ditch, fluctuations in water content of the rooting and fertilization layer, and the growth response of apple trees under different saline-alkali land conditions. The values ​​are usually in the range of 0 to 1, and the sum of each correction weight is 1.

[0194] Furthermore, after determining the single supply volume, fertilizer concentration, and salt pressing frequency, water and fertilizer are supplied in stages to the inner ring supply ditch through the supply openings on the guide membrane.

[0195] During the liquid supply process, the liquid should first enter the inner ring supply trench and then extend from the inner ring supply trench to the rooting and fertilization layer.

[0196] When implementing phased water and fertilizer supply, a continuous moist zone should be formed in the root-stabilizing fertilizer layer after each supply, but prolonged water accumulation should be avoided. The supplied liquid should not be directly concentrated and seeped down from the base of the trunk. An observation interval should be left between each supply to judge the trend of salt changes in the outer ring salt collection ditch. The technical requirements are that fertilizer should be supplied first when the apple tree is growing steadily and the salt in the near-root zone is moving outward in a controlled manner, and the intensity of fertilizer supply should be reduced when the salt disturbance is strong.

[0197] Furthermore, after completing one supply cycle, the salinity characterization value of the outer ring salt collection ditch is retested, and combined with the growth of apple trees and the changes in the moisture content of the rooting and fertilization layer, it is determined whether the current control strategy needs to be switched.

[0198] In this embodiment, the following g1-g4 strategy switching rules are preferably adopted:

[0199] g1. When the salt content of the outer ring salt collection ditch increases and the apple trees grow steadily, it is determined that the controlled salt collection in the periphery is effective, and the current strategy of partial liquid supply and salt suppression continues.

[0200] g2. When the salt content of the outer ring salt collection ditch increases and the growth of apple trees weakens, it is determined that the current salt migration is accompanied by tree stress. The fertilizer solution concentration should be reduced and the intensity of each application should be decreased. Instead, a more frequent application of small amounts of solution should be used.

[0201] g3. When the salt content of the outer ring salt collection ditch decreases and the growth of apple trees improves, it is determined that the salt content in the near-root zone has been effectively reduced. The concentration of fertilizer solution should be appropriately increased and the frequency of salt pressure should be maintained at a moderate level.

[0202] g4. When the salinity characterization value of the outer ring salt collection ditch does not change significantly but there are signs of salt return in the near root zone, it is determined that the outer salt collection path is blocked. Priority should be given to checking the flow guiding membrane and the boundary of the outer ring salt collection ditch before deciding whether to replenish hydraulic salt.

[0203] Furthermore, during continuous regulation, if local collapse of the outer ring salt collection ditch boundary, lifting of the membrane edge, displacement of the liquid supply opening, or blurring of the salt release observation area is found, maintenance should be carried out on the outer ring salt collection ditch and the guiding membrane.

[0204] The maintenance includes: shallow repair of the outer ring salt collection ditch to restore its continuous boundary; re-pressing or partially replacing the guide membrane to restore its correspondence with the double ring ditch; correcting the position of the liquid supply opening to make it correspond to the inner ring liquid supply ditch again; and applying light liquid salt to the near-root area where salt return occurs, while maintaining a low fertilizer concentration until the outer salt collection boundary returns to stability.

[0205] In summary, this invention achieves separation of root growth and salt accumulation functions through the spatial separation of a three-layered heterogeneous functional root zone structure and inner and outer ring ditches, preventing secondary salt accumulation in the near-root zone. It achieves dynamic and synergistic regulation of water, fertilizer, and salt by real-time adjustment of irrigation volume, fertilizer concentration, and application frequency. Through the selection of salt-tolerant crabapple rootstocks and grafting after gradient salt acclimatization, combined with the three-layered root zone structure, the rhizosphere environment is optimized, enhancing the root vitality and growth stability of grafted seedlings under saline-alkali conditions. Furthermore, by utilizing the outer ring salt collection ditch and the guiding membrane to form a stable salt collection boundary, and with the sodium ion replacement salt-guiding layer promoting downward salt migration, salt continuously migrates away from the near-root zone, enhancing the long-term effectiveness of the improvement.

[0206] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt synergy, characterized in that, include: Salt-tolerant crabapple resources were selected as rootstocks, rootstock seedlings were cultivated, and apple scions were grafted onto the rootstock seedlings after gradient salt acclimatization to obtain apple salt-adapted grafted seedlings. Deep plowing was carried out at the planting site in saline-alkali land to construct a three-layer heterogeneous functional root domain structure from top to bottom, consisting of an anti-evaporation and salt-suppressing layer, a root-promoting and fertilizer-stabilizing layer, and a sodium ion-displacement and salt-conducting layer. Apple salt-adapted grafted seedlings were planted in the center of a three-layer heterogeneous functional root zone structure. An inner ring slurry supply ditch and an outer ring salt collection ditch were set up around the tree, and a flow-guiding mulch corresponding to the inner ring slurry supply ditch and the outer ring salt collection ditch was laid. Water and fertilizer are supplied in stages through the inner ring supply ditch, and the amount of irrigation water, fertilizer concentration and frequency of salt suppression are adjusted according to the salt content of the outer ring salt collection ditch, the moisture content of the root stabilization layer and the growth of the apple trees, so that the salt can be continuously moved away from the root zone of the tree.

2. The method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt as described in claim 1, characterized in that, The cultivated rootstock seedlings include: The crabapple germplasm from different sources was numbered, and each crabapple germplasm was propagated into crabapple seedlings; All crabapple seedlings were treated uniformly for diseases, pests, and plant roots and leaves, and then restored to cultivation under clean water conditions. Under the same salt stress conditions, the root activity, new root development, leaf damage, and recovery growth of each crabapple seedling were collected to screen salt-tolerant crabapple materials as salt-tolerant crabapple resources. Salt-tolerant crabapple resources were propagated and cultivated into rootstock seedlings to obtain graftable rootstock seedlings.

3. The method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt as described in claim 2, characterized in that, The obtained apple salt-adapted grafted seedlings include: The cultivated rootstock seedlings were placed under salt acclimatization culture conditions, and the intensity of the rhizosphere salt environment was gradually increased according to different gradients, and the cultivation was maintained under each level of salt environment. The growth status of new roots, leaf retention status and salt damage symptoms of rootstock seedlings were continuously observed under various salt environments. When the rootstock seedlings maintain normal activity under the current salinity environment, they are moved to the next salinity gradient environment; After the rootstock seedlings have completed gradient salt acclimatization, scions of the target apple variety are selected and grafted onto the rootstock seedlings to obtain grafted seedlings. The grafted seedlings were treated with wound healing and hardening-off treatment before transplanting. Once the grafted seedlings were of normal activity, apple salt-adapted grafted seedlings were obtained.

4. The method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt as described in claim 1, characterized in that, The deep tillage of the planting site in saline-alkali land includes: In-situ soil surveys were conducted at the planting sites in saline-alkali land to obtain information on the thickness of the surface salt crust, the distribution of salt in different layers, the degree of soil compaction, and the soil permeability. Clean the surface salt crust at the planting site and peel off the top layer of highly saline soil; Deeply till the planting site to break up the hardened layer and establish a continuous infiltration channel connecting the upper and lower layers.

5. The method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt as described in claim 4, characterized in that, The sodium ion-displaced salt-conducting layer comprises: In the lower area below the planting site, the improved components with sodium ion replacement function are mixed with the lower soil to form a sodium ion replacement salt-conducting layer. The rooting and fertilization stabilization layer consists of a middle layer of soil and well-rotted organic fertilizer mixed above the sodium ion exchange salt-conducting layer to form the rooting and fertilization stabilization layer.

6. The method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt as described in claim 4 or 5, characterized in that, The three-layer heterogeneous functional root domain structure includes: A finely prepared and leveled topsoil layer is laid on top of the rooting and fertilizing layer to form an anti-evaporation and salt-suppressing layer. The three heterogeneous functional root zone structures—the sodium ion exchange salt-conducting layer, the root-promoting and fertilizer-stabilizing layer, and the evaporation-inhibiting and salt-suppressing layer—are shaped, and a tree pit for planting salt-adapted apple seedlings is formed in the center.

7. The method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt as described in claim 1, characterized in that, The construction of an inner ring slurry supply ditch and an outer ring salt collection ditch around the tree includes: Centered on the trunk of the apple salt-adapted grafted seedling planted in the center of the three-layer heterogeneous functional root zone structure, a ring-shaped inner ring liquid supply ditch is opened around the periphery of the tree near the root zone. The bottom of the inner ring liquid supply trench is connected to the upper part of the rooting and stabilizing fertilizer layer; An outer ring salt collection ditch is opened at intervals outside the inner ring supply ditch; A continuous soil zone is maintained between the outer ring salt collection ditch and the inner ring liquid supply ditch; The inner ring of the sap supply trench forms a continuous sap supply path around the tree; The outer ring of salt collection ditches forms a continuous salt collection boundary around the tree.

8. The method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt as described in claim 7, characterized in that, The flow-guiding coating includes: Lay a drainage mulch on the surface of the tree basin, covering the central area of ​​the tree, the inner ring sap supply ditch, and the soil area between the inner ring sap supply ditch and the outer ring salt collection ditch; The flow-guiding coating and the anti-evaporation and salt-suppressing layer are bonded together on the surface; A liquid supply opening is set at the position corresponding to the inner ring liquid supply trench. Irrigation water and fertilizer solution enter the inner ring liquid supply trench through the liquid supply opening and extend to the rooting and fertilizer stabilizing layer. A salt release observation area was set up at a location corresponding to the outer ring salt collection ditch to observe the salt accumulation state in the outer ring salt collection ditch; The edges of the drainage mulch are compacted and fixed to reduce evaporation in the central area of ​​the tree and maintain the controlled salt collection boundary of the outer ring salt collection ditch.

9. The method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt as described in claim 1, characterized in that, The specific steps for adjusting irrigation volume, fertilizer concentration, and salt suppression frequency based on the salinity characterization value of the outer ring salt collection ditch, the moisture content of the rooting and fertilization layer, and the growth of apple trees are as follows: At the beginning of each regulation cycle, the salt content of the outer ring salt collection ditch, the moisture content of the rooting and fertilization layer, and the growth characteristics of the apple trees were collected. Based on the salt content characterization value of the outer ring salt collection ditch, the moisture content of the rooting and fertilization stabilization layer, and the growth characterization value of the apple trees, the single supply volume and fertilizer concentration of the current regulation cycle are determined. Water and fertilizer are supplied in stages through the inner ring liquid supply ditch, so that water and nutrients can preferentially enter the rooting and fertilization layer. After the solution was supplied, the salt content of the outer ring salt collection ditch was collected again. Combined with the changes in apple tree growth and the changes in the moisture content of the rooting and fertilization layer, the frequency of salt suppression in the current regulation cycle was determined.

10. The method for improving saline-alkali land based on intelligent regulation of water, fertilizer, and salt as described in claim 9, characterized in that, The determination of the single-time liquid supply volume and fertilizer concentration for the current regulation cycle includes: The actual root zone horizontal area controlled by the inner ring liquid supply ditch, the target moist layer depth, the current moisture content of the rooting and fertilization layer, the target upper limit moisture content, the salt content characterization value of the outer ring salt collection ditch, and the apple tree growth characterization value are obtained within the current regulation cycle. The single liquid supply volume for the current regulation cycle is determined based on the difference between the actual root zone horizontal area, the target moist layer depth, the current moisture content of the rooting and fertilization layer, and the target upper limit moisture content. The concentration of fertilizer solution for the current regulation cycle is determined based on the salinity characterization value of the outer ring salt collection ditch and the growth characterization value of apple trees. When the salinity level of the outer ring salt collection ditch increases and the growth of apple trees weakens, reduce the concentration of fertilizer solution and decrease the amount of solution supplied at one time. When the salinity index of the outer ring salt collection ditch increases and the apple tree growth is stable, maintain the fertilizer solution concentration and maintain the single supply volume. When the salinity index of the outer ring salt collection ditch decreases and the growth of apple trees improves, increase the concentration of fertilizer solution and adjust the single supply volume according to the difference between the current moisture content of the rooting and stabilizing fertilizer layer and the target upper limit moisture content.

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