A method for improving soil to overcome the obstacle of heavy cropping of fruit trees

Abstract

The application relates to the technical field of fruit tree planting, and particularly discloses a soil improvement method for overcoming heavy-crop obstacles of fruit trees. The method obtains basic soil data of heavy-crop soil to be improved and generates anaerobic treatment parameters; carbon source is added, water content is adjusted and covering treatment is carried out according to the anaerobic treatment parameters, so that anaerobic treatment soil is obtained; anaerobic suppression indexes and seedling root risk indexes are generated according to anaerobic state data, and reoxygenation treatment is controlled according to the indexes; basic re-colonization window indexes are generated according to reoxygenation state data, and the re-colonization window indexes are corrected in combination with soil water content to generate batch re-colonization results of beneficial microorganisms; rhizosphere safety indexes are generated according to rhizosphere safety data, and planting control results are generated according to the indexes. The application can improve the stage control precision of the heavy-crop soil improvement process, and reduce the rebound of pathogenic bacteria, the failure of microbial agent colonization and the risk of seedling planting.

Description

Technical Field

[0001] This invention relates to the field of fruit tree planting technology, and more specifically to a soil improvement method for overcoming the obstacle of continuous cropping of fruit trees. Background Technology

[0002] Replanting disorder in fruit trees refers to the phenomenon where, after continuously planting the same or closely related fruit trees on the same plot of land, the soil ecological environment deteriorates, leading to reduced survival rates of newly planted seedlings, poor root development, weakened tree growth, increased pests and diseases, and decreased yield and quality. This problem is particularly common in the renewal and reconstruction of old orchards of perennial fruit trees such as apples, pears, peaches, citrus, and grapes. With the increasing demand for the renovation of aging orchards, reconstruction on the original site has become an unavoidable application scenario in fruit tree production. Whether the soil from continuous planting can be effectively improved directly affects the quality of newly established orchards, the speed of seedling recovery, and the uniformity of early growth.

[0003] Replanting problems in fruit trees are usually not caused by a single factor, but rather by a combination of factors including soil microbial imbalance, accumulation of autotoxic substances, and deterioration of soil physicochemical properties. Specifically, long-term continuous cropping leads to the enrichment of pathogenic microorganisms such as Fusarium, Pythium, Phytophthora, and cladocerans in the replanted soil, while reducing the number of beneficial microorganisms, and the rhizosphere microecology gradually shifts from a disease-suppressing mode to a disease-promoting mode. At the same time, the decomposition of fruit tree root exudates and organic residues such as roots and fallen leaves releases phenolic acids, organic acids, or glycosides. The continuous accumulation of these autotoxic substances in the soil inhibits root elongation and white root formation in newly planted fruit tree seedlings. In addition, long-term cultivation may also cause a decrease in soil organic matter, compaction, acidification, salt accumulation, nitrogen form imbalance, and reduced aeration, placing the roots of newly planted fruit trees in an unfavorable growth environment. Therefore, overcoming replanting problems in fruit trees requires simultaneous attention to multiple aspects, including pathogen suppression, autotoxic substance transformation, restoration of beneficial microorganisms, and the safety of the rhizosphere physicochemical environment.

[0004] To address the problem of continuous cropping obstacles in fruit trees, existing technologies typically employ methods such as soil fumigation, strong oxidation treatment, organic fertilizer improvement, green manure rotation, biochar application, microbial inoculation, and anaerobic soil disinfection. Among these, soil fumigation and strong oxidation treatment can quickly reduce the number of some soil-borne pathogens, but they can easily damage beneficial soil microorganisms and have insufficient environmental friendliness. Organic fertilizers, green manure, and biochar can improve soil structure, increase organic matter content, and enhance soil water and fertilizer retention capacity, but their effects on continuous cropping pathogens and autotoxic substances are relatively indirect and have a long timeframe for effectiveness. Microbial inoculation can improve the soil microecology through antagonizing pathogens, promoting root growth, or degrading autotoxic substances, but its effectiveness is easily affected by soil redox status, moisture content, pH, salinity, and residual harmful substances, resulting in unstable colonization.

[0005] Anaerobic soil disinfection is a widely used soil ecological improvement method in recent years. It typically involves applying rice bran, molasses, crushed green manure, or other readily biodegradable carbon sources to the soil, combined with irrigation and mulching to create a low-oxygen or anaerobic environment within a certain timeframe. Under anaerobic conditions, soil microorganisms decompose the readily biodegradable carbon sources and produce reducing metabolites such as volatile fatty acids, thereby suppressing some soil-borne pathogens and promoting changes in the soil microbial community structure. This method is more eco-friendly than traditional chemical fumigation and is more suitable for large-scale soil improvement in the renewal of old orchards.

[0006] However, existing anaerobic soil improvement methods still have significant shortcomings in the application of replanted fruit tree soils. Firstly, current methods often use a fixed number of days of mulching or empirical judgment as the endpoint of anaerobic treatment, such as directly removing the film and reoxygenating after a certain number of days, lacking a comprehensive assessment of process data such as soil redox potential, volatile fatty acid concentration, soil temperature, and pathogen abundance. Because soil texture, organic matter content, moisture content, temperature conditions, and pathogen load vary significantly among different orchards, using a fixed treatment cycle can easily lead to insufficient or excessive anaerobic treatment. If anaerobic treatment is insufficient, replanted pathogens are not adequately suppressed, and a rapid rebound is likely after reoxygenation; if anaerobic treatment is excessive, volatile fatty acids, ammonium nitrogen, or other reducing metabolites may accumulate in the root zone, leading to browning of the roots, reduced white roots, or failure to establish seedlings.

[0007] Secondly, existing methods typically view "film removal and reoxygenation" as a simple aeration process following anaerobic treatment, lacking a window-based assessment of the reoxygenation state. In reality, anaerobic soil does not immediately return to a state suitable for beneficial microorganisms. In the initial stages of reoxygenation, the soil redox potential may still be low, volatile fatty acid residues may remain high, pH may fluctuate, and residual pathogens may rebound after oxygen recovery. If microbial agents are applied directly at this time, beneficial microorganisms may become largely inactive due to environmental unsuitability or be unable to compete with pathogens for rhizosphere niches, resulting in low colonization rates, unstable function, and recurrence of continuous cropping problems.

[0008] Furthermore, current technologies for applying microbial agents often involve a single application, failing to adequately consider the varying adaptations of different functional microorganisms to soil reoxygenation environments. For instance, hypoxia-tolerant antagonistic bacteria can exert their inhibitory effect under the low redox potential conditions of the initial reoxygenation stage, while growth-promoting bacteria, autotoxic substance-degrading bacteria, or mycorrhizal fungi typically require a more stable pH, lower volatile fatty acid residues, and more suitable soil moisture content. Applying agents in a single application without distinguishing between the reoxygenation stage and the microbial growth window can easily lead to the inactivation of some functional bacteria, making it difficult to form a stable beneficial microbial community.

[0009] Furthermore, existing soil improvement methods for fruit tree replanting typically lack a pre-planting rhizosphere safety assessment. In production, the suitability for planting fruit tree seedlings is often determined based on mulching time, odor changes, or the number of days of reoxygenation. However, the completion of anaerobic treatment and inoculant application does not necessarily mean the soil meets the conditions for safe seedling planting. If problems such as residual volatile fatty acids, high salinity, ammonium nitrogen accumulation, unstable pH, insufficient soil respiration activity, or residual biological toxicity in the seedling roots still exist in the soil, direct planting may still lead to slow seedling recovery, root tip damage, or even seedling death. Therefore, relying solely on a single treatment measure or empirical judgment is insufficient to guarantee the stability of soil improvement effects for fruit tree replanting. Summary of the Invention

[0010] To solve the above-mentioned technical problems, the present invention provides a soil improvement method to overcome the obstacle of continuous planting of fruit trees.

[0011] The technical solution adopted in this invention is as follows: A soil improvement method for overcoming the obstacle of continuous cropping of fruit trees, the method comprising: S1. Obtain basic soil data of the replanted soil to be improved, and generate anaerobic treatment parameters based on the basic soil data; S2. Apply carbon source, adjust moisture content and cover the replanted soil to be improved according to the anaerobic treatment parameters to obtain anaerobic treated soil. S3. Obtain anaerobic state data of the anaerobic treated soil, and generate anaerobic suppression index and seedling root risk index based on the anaerobic state data. Step S4: Generate anaerobic stage control results based on the anaerobic suppression index and the seedling root risk index, and when the anaerobic stage control results meet the reoxygenation start-up conditions, perform reoxygenation treatment on the anaerobic soil to obtain reoxygenated soil. S5. Obtain the reoxygenation status data of the soil treated with reoxygenation, generate a basic repopulation window index based on the reoxygenation status data, correct the basic repopulation window index based on the soil moisture content of the reoxygenation stage in the reoxygenation status data to obtain a corrected repopulation window index, and generate the batch repopulation results of beneficial microorganisms based on the corrected repopulation window index. S6. Obtain rhizosphere safety data after the completion of the batch repopulation results of the beneficial microorganisms, generate a rhizosphere safety index based on the rhizosphere safety data, and generate planting control results based on the rhizosphere safety index.

[0012] Further, S1 includes: The soil redox potential, soil moisture content, soil temperature, soil pH, soil EC, soil organic matter content, initial abundance of pathogens, initial concentration of volatile fatty acids, initial concentration of ammonium nitrogen, initial concentration of nitrate nitrogen, and target fruit tree type of the soil to be improved are obtained to form the basic soil data. Based on the soil organic matter content, soil moisture content, soil temperature, initial abundance of pathogens, and initial concentration of volatile fatty acids, the amount of easily degradable carbon source to be applied, the target moisture content, the initial value of the mulch treatment duration, and the data collection interval are generated. The anaerobic treatment parameters are formed by combining the amount of readily degradable carbon source applied, the target moisture content, the initial value of the coverage treatment duration, and the data acquisition interval.

[0013] Further, S2 includes: The readily degradable carbon source is applied to the replanted soil to be improved according to the specified amount of readily degradable carbon source to obtain carbon source-treated soil. The carbon source-treated soil is irrigated or replenished with water according to the target moisture content to obtain moisture-conditioned soil. The moisture-conditioning soil is covered and sealed according to the initial value of the covering treatment time to obtain the anaerobic soil. The readily biodegradable carbon source includes at least one of rice bran, molasses, crushed green manure, and fermented fruit tree waste.

[0014] Further, S3 includes: According to the data acquisition interval, the soil redox potential, volatile fatty acid concentration, soil temperature, pathogen abundance, soil EC, ammonium nitrogen concentration, and pH of the anaerobic soil in the anaerobic stage are acquired to form the anaerobic state data. The anaerobic suppression index is generated based on the soil redox potential, volatile fatty acid concentration, soil temperature, and pathogen abundance during the anaerobic stage. The seedling root risk index is generated based on the volatile fatty acid concentration, soil EC, ammonium nitrogen concentration, and pH of the anaerobic stage.

[0015] Furthermore, the anaerobic suppression index API satisfies the following relationship: ; in, This represents the cumulative decrease in soil redox potential during the anaerobic stage. This represents the effective cumulative value of the volatile fatty acid concentration during the anaerobic phase. The percentage decrease in pathogen abundance during the anaerobic phase. The temperature-time product of the soil temperature during the anaerobic stage. , , , Preset anaerobic suppression weighting coefficients; The seedling root risk index RRI satisfies the following relationship: ; in, This represents the residual value of the volatile fatty acid concentration during the anaerobic stage. For the anaerobic stage soil EC, The concentration of ammonium nitrogen during the anaerobic stage. The pH stability during the anaerobic phase. , , , The seedling root risk weight coefficient is preset.

[0016] Further, step S4 includes: When the anaerobic suppression index The preset anaerobic suppression threshold is reached and the seedling root risk index is... When the risk level is below the preset seedling root risk threshold, a reoxygenation initiation result is generated; When the anaerobic suppression index The preset anaerobic suppression threshold was not reached and the seedling root risk index was not met. When the risk level is below the preset seedling root risk threshold, an anaerobic maintenance result is generated, and the anaerobic soil is covered and sealed according to the anaerobic maintenance result. When the seedling risk index When the risk threshold for seedling roots is reached or exceeded, a risk reoxygenation result is generated. Based on the reoxygenation initiation results or the risk reoxygenation results, the anaerobic soil is subjected to methods such as removing the film, opening and ventilating, tilling and ventilating, or intermittent aeration to obtain the reoxygenated soil.

[0017] Further, S5 includes: The soil redox potential rise value, volatile fatty acid decrease rate, pH stability, pathogen rebound rate, and soil moisture content during the reoxygenation stage of the soil under reoxygenation treatment were obtained to form the reoxygenation status data. The basic repopulation window index is generated based on the soil redox potential rise during the reoxygenation stage, the volatile fatty acid decline rate during the reoxygenation stage, the pH stability during the reoxygenation stage, and the pathogen rebound rate during the reoxygenation stage. A moisture content correction coefficient is determined based on the soil moisture content during the reoxygenation stage, and the basic repopulation window index is corrected based on the moisture content correction coefficient to obtain the corrected repopulation window index. The beneficial microorganisms were repopulated in batches based on the modified repopulation window index.

[0018] Furthermore, the basic repopulation window index RWI satisfies the following relationship: ; in, This refers to the increase in soil redox potential during the reoxygenation stage. The rate of decrease in volatile fatty acids during the reoxygenation phase. This refers to the pH stability during the reoxygenation phase. The pathogen rebound rate during the reoxygenation phase. , , , The pre-defined repopulation window weight coefficient; The modified repopulation window index The following relationship must be satisfied: ; in, This is the moisture content correction factor; When the modified repopulation window index When the first repopulation threshold is reached, the first beneficial microbial agent is applied; When the modified repopulation window index When the second repopulation threshold is reached, a second beneficial microbial agent is applied to obtain the batch repopulation results of the beneficial microorganisms. Wherein, the second repopulation threshold is greater than the first repopulation threshold.

[0019] Furthermore, the first beneficial microbial agent includes hypoxia-resistant antagonistic bacteria, and the second beneficial microbial agent includes growth-promoting bacteria, autotoxic substance-degrading bacteria, or mycorrhizal fungi; After the first beneficial microbial agent is applied, first repopulation monitoring data is obtained, which includes the colonization rate of the first beneficial microorganism, the abundance of the first pathogenic bacteria, and the residual value of the first volatile fatty acid. A repopulation feedback coefficient is generated based on the colonization rate of the first beneficial microorganism, the residual abundance of the first pathogen, and the residual value of the first volatile fatty acid. The modified repopulation window index is then adjusted based on the repopulation feedback coefficient. The update is performed to obtain the updated and corrected repopulation window index; The timing of application of the second beneficial microbial agent is determined based on the updated and corrected repopulation window index; After the second beneficial microbial agent is applied, second recolonization monitoring data is obtained, and the batch recolonization results of the beneficial microorganisms are generated based on the second recolonization monitoring data. The second recolonization monitoring data includes the colonization rate of the second beneficial microorganisms and the abundance of residual pathogens.

[0020] Further, S6 includes: The following data were obtained after the completion of the batch reclamation of the beneficial microorganisms: soil redox potential, residual value of volatile fatty acids, soil EC, pH, ratio of ammonium nitrogen to nitrate nitrogen, soil respiration rate and seedling root elongation rate, to form the rhizosphere safety data. The root zone security index is generated based on the root zone security data; When the rhizosphere safety index reaches the preset planting safety threshold, a planting permission result is generated; When the rhizosphere safety index does not reach the preset planting safety threshold, a temporary planting delay result is generated, and a reoxygenation correction parameter is generated based on the rhizosphere safety data.

[0021] The beneficial effects of this invention are: This invention generates anaerobic treatment parameters using basic soil data and introduces an anaerobic suppression index and a seedling root risk index during the anaerobic treatment process. This allows for quantitative control of the timing of anaerobic termination, preventing pathogen rebound due to insufficient treatment or seedling root damage due to excessive treatment. Simultaneously, it generates and corrects the re-colonization window index using reoxygenation status data to control the phased application of beneficial microbial agents, thereby improving the colonization stability of beneficial microorganisms. Furthermore, it uses a rhizosphere safety index to determine planting conditions, reducing the impact of volatile fatty acid residues, salt risk, and ammonium nitrogen accumulation on fruit tree seedlings. This improves the stability of soil improvement for continuous cropping, seedling survival rate, and orchard establishment consistency. Attached Figure Description

[0022] Figure 1 This is an overall flowchart of the soil improvement method for overcoming the obstacle of continuous planting of fruit trees according to an embodiment of the present invention; Figure 2 A flowchart illustrating the dual-exponential coordinated control of anaerobic termination according to an embodiment of the present invention; Figure 3 This is a flowchart illustrating the reoxygenation window identification and batch recolonization of beneficial microorganisms according to an embodiment of the present invention; Figure 4 This is a flowchart illustrating the rhizosphere safety acceptance and planting control according to an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figures 1-4 As shown, an embodiment of the present invention provides a soil improvement method for overcoming the obstacle of continuous cropping of fruit trees, comprising the following steps: In the scenario of renovating an old open-field orchard, this invention can be implemented after the removal of old trees, clearing of residual roots, and leveling of the site, but before the planting of new fruit tree seedlings. By performing anaerobic treatment, reoxygenation regulation, phased re-inoculation of beneficial microorganisms, and rhizosphere safety inspection on the original reconstruction site, it reduces the impact of pathogen accumulation, autotoxic substance residues, and deterioration of physicochemical properties in the old orchard soil on newly planted fruit tree seedlings. In the scenario of greenhouse fruit tree cultivation, this invention can be implemented after clearing the greenhouse orchard, but before the planting of the next batch of fruit tree seedlings or container seedlings. Since rainfall, temperature, and moisture conditions are relatively controllable in the greenhouse environment, it facilitates covering and sealing, anaerobic fermentation, and the determination of the reoxygenation window. In the scenario of crop rotation in fruit tree nurseries, this invention can be implemented after the previous batch of seedlings has left the nursery, but before the sowing, cutting, or transplanting of the next batch of fruit tree seedlings, to reduce the risk of pathogen accumulation and rhizosphere environment deterioration caused by continuous seedling cultivation in the nursery soil.

[0025] It should be noted that for perennial fruit trees that have already been planted and have formed stable root systems, it is not advisable to directly apply the overall anaerobic treatment process of this invention to cover and seal the entire root zone of the fruit trees. This is because the anaerobic treatment stage of this invention requires carbon source application, moisture content adjustment, and covering and sealing. During this process, the soil redox potential decreases, and reducing metabolites such as volatile fatty acids may be generated. If this treatment is applied to the entire main root zone of the fruit trees while they are already planted, it may cause root hypoxia, root tip damage, or mechanical damage to the roots. Therefore, the method described in this invention is preferably used for soil pretreatment before planting fruit trees, rather than as a conventional treatment method for the root zone soil of planted fruit trees during their growth period.

[0026] In practical applications, when the soil to be improved is open-field soil, the anaerobic treatment parameters can be adaptively adjusted according to rainfall, drainage conditions, and soil temperature. For example, drainage ditches can be set up during the rainy season to avoid excessive moisture content, and the duration of the covering treatment or the frequency of data collection can be extended during the cold season. When the soil to be improved is greenhouse soil, the target moisture content, the initial value of the covering treatment duration, and the reoxygenation and aeration method can be adjusted in conjunction with the temperature, humidity, and irrigation conditions inside the greenhouse. All of the above adaptive adjustments do not change the core technical process of this invention: generating anaerobic treatment parameters from basic soil data, controlling reoxygenation through the anaerobic suppression index and seedling root risk index, controlling the phased re-colonization of beneficial microorganisms through the modified re-colonization window index, and controlling the planting timing through the rhizosphere safety index.

[0027] Step S1: Obtain basic soil data of the replanted soil to be improved, and generate anaerobic treatment parameters based on the basic soil data.

[0028] In this invention, step S1 generates personalized initial parameters for anaerobic treatment by collecting multi-dimensional background characteristics of the replanted soil to be improved. This solves the common problems of "insufficient treatment - pathogen residue" or "overtreatment - root toxicity" caused by the use of fixed parameters in existing technologies. The heterogeneity of replanted fruit tree soils is extremely high; the abundance of pathogens in different areas of the same orchard can differ by 10%. 2 -10 4 The organic matter content can vary by 3-10 times. Fixed carbon source application and treatment time cannot accommodate this difference. This step transforms traditional empirical operations into quantitative calculations through a multi-factor correlation model, ensuring the accuracy and stability of anaerobic treatment from the source.

[0029] In one embodiment of the present invention, step S1 specifically includes: The soil redox potential, soil moisture content, soil temperature, soil pH, soil EC, soil organic matter content, initial abundance of pathogens, initial concentration of volatile fatty acids, initial concentration of ammonium nitrogen, initial concentration of nitrate nitrogen, and target fruit tree type of the soil to be improved are obtained to form basic soil data.

[0030] Based on soil organic matter content, soil moisture content, soil temperature, initial abundance of pathogens, and initial concentration of volatile fatty acids, the amount of easily degradable carbon source to be applied, the target moisture content, the initial value of the mulch treatment duration, and the data collection interval are generated.

[0031] The parameters for anaerobic treatment are combined by the amount of readily degradable carbon source applied, the target moisture content, the initial value of the coverage treatment duration, and the data acquisition interval.

[0032] In this step, basic soil data was collected from the 0-30cm topsoil layer (the main active layer of fruit tree seedling roots) of the plot to be improved using a five-point mixed sampling method. This data, obtained through a combination of in-situ field measurements and laboratory analysis, includes 11 indicators, comprehensively covering three dimensions: soil physicochemical properties, biological characteristics, and planting objectives. Specifically, the initial soil redox potential (RPP) was obtained by in-situ measurement at a depth of 10cm using platinum electrodes. This reflects the initial RRP state of the soil; the lower the initial RRP, the faster the anaerobic environment forms and the less exogenous carbon source is required. Soil temperature, the daily average at a depth of 10cm over three consecutive days, directly determines the metabolic rate of anaerobic microorganisms and is a key environmental factor affecting treatment duration. The initial abundance of pathogens was determined using qPCR combined with target fruit tree-specific primers, such as measuring *Fusarium oxysporum* apple-specific type in apple orchards, *Phytophthora infestans* in peach orchards, and *Phytophthora infestans* in citrus orchards. These values ​​directly reflect the biological severity of continuous cropping obstacles and are the core basis for calculating carbon source application. In addition, basic soil data also include soil moisture content, pH, electrical conductivity (EC), organic matter content, initial concentration of volatile fatty acids, initial concentration of ammonium nitrogen, initial concentration of nitrate nitrogen, and target fruit tree type. When the initial soil EC exceeds 2.0 mS / cm, leaching treatment is required to reduce EC to below 1.5 mS / cm. When the initial soil pH is below 5.5 or above 8.0, the pH must be adjusted to the range of 6.0-7.5 before subsequent parameter calculations are performed.

[0033] Based on the aforementioned basic soil data, this invention generates four anaerobic treatment parameters—the amount of readily degradable carbon source applied, the target moisture content, the initial value of the mulch treatment duration, and the data acquisition interval—using a multi-factor correlation model. Among these, the amount of readily degradable carbon source applied is a key parameter determining the intensity of anaerobic fermentation and the suppression effect on pathogens; its model formula is as follows: ; In the formula, This refers to the application rate of readily biodegradable carbon sources, expressed in t / hm², typically ranging from 1 to 10 t / hm². 2 ; The contribution weighting coefficient for organic matter is dimensionless and ranges from 0.05 to 0.15. It can be determined by response surface methodology, with the upper limit for sandy soil and the lower limit for clayey soil. Soil organic matter content, expressed in g / kg; The contribution weighting coefficient to pathogen abundance is dimensionless and ranges from 0.2 to 0.8. The more sensitive the pathogen is to volatile fatty acids, the lower the value. This is a commonly used logarithmic value for the initial abundance of pathogens. It is dimensionless and uses logarithmic transformation to adapt to the exponential distribution characteristics of pathogen abundance. The weighting coefficient for initial volatile fatty acids is dimensionless and ranges from -0.001 to -0.005. A negative sign indicates that the higher the initial volatile fatty acid content, the less exogenous carbon source is required. This represents the initial concentration of volatile fatty acids, expressed in mg / L. The correction factor for nitrate nitrogen is dimensionless and ranges from 0.01 to 0.03, reflecting the carbon source consumption during denitrification. The nitrate nitrogen content exceeding 50 mg / kg, expressed in mg / kg, is... When that time, the value of this item is 0.

[0034] This model comprehensively considers soil basic carbon source reserves, pathogen killing requirements, initial reducing substance content, and denitrification carbon source consumption. The calculated carbon source application rate is typically 1-10 t / hm. 2 This ensures that enough volatile fatty acids are produced during anaerobic fermentation to kill the target pathogens.

[0035] Target moisture content The water content of soil pores is used to control the degree of water filling, which is a necessary condition for the formation of an effective anaerobic environment. The model formula is as follows: ; In the formula, The target moisture content is dimensionless and expressed as a proportion of field capacity. This refers to the field water holding capacity of the soil, which is dimensionless and can be determined by the ring cutter method. The value is approximately 0.25-0.35 for sandy soil, approximately 0.35-0.45 for loamy soil, and approximately 0.45-0.55 for clay soil. This is the maximum allowable water content. Exceeding this value will cause the soil pores to be completely filled with water, producing highly toxic substances such as hydrogen sulfide, while inhibiting the activity of beneficial anaerobic microorganisms such as methanogens. The initial soil moisture content is dimensionless. The maximum allowable water replenishment is dimensionless and is usually taken as 0.2, which means that the maximum water replenishment is 20% higher than the initial moisture content, in order to avoid excessive irrigation that could lead to nutrient leaching and soil structure damage.

[0036] During implementation, when the initial soil moisture content is When the maximum allowable moisture content has been reached or exceeded, no additional water is needed before covering. If the initial moisture content is still below 60% of the field capacity after the maximum water replenishment, water needs to be replenished in multiple stages and allowed to stand still until the moisture content reaches above 60%, otherwise a stable anaerobic environment cannot be formed.

[0037] Initial value of overlay processing time The reference duration for anaerobic treatment is calculated based on the average daily anaerobic suppression effect of the same season and soil type in the local area. The model formula is as follows: ; In the formula, This is the initial value for the coverage processing time, in days (d), and typically ranges from 10 to 40 days. The preset anaerobic suppression threshold is dimensionless and usually 80-100. The upper limit is used for plots with high pathogen pressure. The initial value represents the average daily anaerobic suppression index increment (dimensionless / d) for the same season and soil type in the local area. This value can be obtained through statistical analysis of historical experimental data and is positively correlated with soil temperature. In summer, it is typically 4-8 dimensionless / d, and in winter, it is typically 1-3 dimensionless / d. It should be noted that this initial value is only a reference for starting the anaerobic treatment. The actual treatment duration will be dynamically adjusted in step S4 based on the real-time monitored anaerobic suppression index and seedling root risk index to achieve precise termination.

[0038] Data collection interval The model formula used to determine the monitoring frequency of anaerobic state data is as follows: ; In the formula The data collection interval is expressed in days (d). To ensure a minimum data collection interval of 1 day, and to avoid missing critical nodes due to sparse data collection; The function is rounded up, and the calculated acquisition interval is usually 1-3 days. The shorter the processing time, the higher the acquisition frequency, in order to avoid missing the key reoxygenation start-up node.

[0039] The complete implementation process of this step is as follows: First, topsoil samples from the plot to be improved are collected using a five-point mixed sampling method, while soil redox potential and ground temperature are measured in situ. Then, soil physicochemical and biological indicators are measured in the laboratory to obtain all basic soil data. The basic soil data is then input into the above parameters to generate a model, and the weighting coefficients are fine-tuned according to soil texture (sandy / loamy / clay) and local climate. , , , Ultimately, personalized anaerobic treatment parameters (easily degradable carbon source application rate) are generated. Target moisture content Initial value of overlay processing time Data collection interval This parameter is used to guide the implementation of anaerobic treatment in step S2. Through the above-described quantitative parameter generation process, this invention achieves personalized customization of anaerobic treatment, laying the foundation for precise control of the entire subsequent process.

[0040] Step S2: Apply carbon source, adjust moisture content, and cover the soil to be improved according to the anaerobic treatment parameters to obtain anaerobic treated soil.

[0041] This step, through the synergistic operation of carbon source supply, water regulation, and airtight sealing, artificially creates and maintains a strongly reducing soil environment (oxidation-reduction potential ≤ -100mV). This induces the rapid proliferation and fermentation of indigenous anaerobic microorganisms, which then decompose easily degradable carbon sources, producing volatile fatty acids (VFAs) such as acetic acid, propionic acid, and butyric acid, as well as other reducing metabolites. This achieves non-specific killing of replanting pathogens (Fusarium, Pythium, Phytophthora, etc.) while simultaneously degrading some soil autotoxic substances. The difference between this step and existing technologies lies in the fact that all operational parameters are precisely calculated from the baseline soil data in step S1, rather than using industry-standard fixed values ​​(such as uniformly applying 2t / acre of organic fertilizer and mulching for 20 days). This addresses the problems of existing technologies, such as "insufficient treatment leading to pathogen residues and excessive treatment leading to root toxicity," from an implementation perspective.

[0042] In one embodiment of the present invention, step S2 specifically includes: The carbon source was applied to the continuously cropped soil to be improved according to the amount of easily degradable carbon source applied, and the carbon source treated soil was obtained.

[0043] The carbon source-treated soil is irrigated or replenished with water according to the target moisture content to obtain moisture-conditioned soil.

[0044] The moisture-conditioned soil was covered and sealed according to the initial value of the covering treatment time to obtain anaerobic soil. The readily degradable carbon source included at least one of rice bran, molasses, crushed green manure, and fermented fruit tree waste.

[0045] In this embodiment of the invention, the first step involves applying an easily degradable carbon source. The selection and precise application of the carbon source directly determine the rate of anaerobic fermentation and the effect on pathogen suppression. This invention limits the easily degradable carbon source to at least one of rice bran, molasses, crushed green manure, and fermentation broth from fruit tree waste. The selection criteria are a suitable carbon-to-nitrogen ratio (C / N) (20:1-30:1), easy decomposition by anaerobic microorganisms, rapid production of high-concentration volatile fatty acids, wide availability, and low cost.

[0046] Among them, rice bran has a carbon-to-nitrogen ratio of 20:1-25:1, a high yield of volatile fatty acids with acetic acid accounting for over 60%, and a decomposition cycle of 10-20 days, making it suitable for all soil types; molasses has the fastest decomposition rate, reaching bactericidal concentration in 5-10 days, making it suitable for sandy soils and plots requiring rapid treatment; crushed green manure can replenish soil organic matter, making it suitable for plots with extremely low organic matter content; and fermented fruit tree waste liquid can realize the resource utilization of orchard self-produced waste. To balance decomposition rate and bactericidal spectrum, a composite carbon source of "rice bran + molasses" (mass ratio 7:3) can be used, which improves pathogen suppression effect by 15%-20% compared to a single carbon source.

[0047] In this embodiment of the invention, the amount of readily degradable carbon source applied is calculated according to step S1. The execution is allowed within a ±5% error range, and adaptive fine-tuning can be made for different soil textures. Specifically, for sandy soils where carbon sources are easily leached by water, adjustments can be made... Increase by 10% on the basis; clay soil has poor air permeability and slow microbial decomposition rate, and can be used to... Reduce by 10% based on the original amount; loam soils require no adjustment, proceed directly according to... Apply.

[0048] Before application, it is necessary to remove residual fruit tree roots, dead branches and leaves, and weeds from the plot to prevent them from consuming the carbon source and affecting the formation of the anaerobic environment. During application, mechanical or manual spreading should be used to ensure even distribution of the carbon source on the soil surface. For liquid carbon sources (molasses, fermented fruit tree waste liquid), sprinkler or drip irrigation can be used for even application. Immediately after application, the soil should be tilled to a depth of 20-30cm (the main active layer of the fruit tree seedling roots) using a rotary tiller, with at least two tilling operations to ensure thorough mixing of the carbon source with the soil. During acceptance testing, 10 random sampling points should be selected to measure the carbon source content in the 0-30cm soil layer, with a mixing uniformity requirement of a coefficient of variation ≤15%. It should be noted that the uniformity of carbon source mixing with the soil directly determines the homogeneity of the anaerobic environment. Uneven mixing can lead to insufficient local carbon source, preventing the redox potential from decreasing to the bactericidal threshold and resulting in pathogen residues; excessive local carbon source can lead to excessively high concentrations of volatile fatty acids, resulting in an excessive risk index for subsequent seedling roots.

[0049] After carbon source application, soil moisture content adjustment is performed, as moisture content is a key factor determining whether an anaerobic environment can be formed. This step calculates the target moisture content based on step S1. (Percentage of field capacity) Implementation. This invention limits the target moisture content to 60%~85% of field capacity. The scientific basis is as follows: When the moisture content is below 60% of field capacity, the air content in the soil pores exceeds 40%, making it impossible to form a strictly anaerobic environment. The oxidation-reduction potential is difficult to drop below -100mV, and pathogen suppression fails. When the moisture content is between 60% and 85% of field capacity, the soil pores are filled with water at 60%~85%, and the oxygen in the remaining pores is rapidly consumed by microorganisms. A strong reducing environment can be formed within 2~3 days, and the yield of volatile fatty acids is the highest. When the moisture content exceeds 85% of field capacity, the soil pores are almost completely filled with water. Toxic substances such as hydrogen sulfide and methane produced by microbial respiration cannot be discharged, which will inhibit the activity of anaerobic fermentation microorganisms and increase the difficulty of subsequent reoxygenation, significantly increasing the risk to seedling roots.

[0050] Based on the initial soil moisture content With target moisture content The difference can be adjusted using different methods. Specifically, when When additional water is needed (i.e., when more than 10% of field capacity is required), drip irrigation or micro-sprinkler irrigation can be used for slow and even watering. Irrigation should be slow and even to avoid flooding, which can lead to carbon leaching and soil compaction. When the required water replenishment is no more than 10% of field capacity, manual watering or spraying can be used, focusing on replenishing dry areas of the surface. In this embodiment of the invention, the uniformity of moisture content control requires setting up one measuring point every 5 mu (approximately 0.33 hectares). At each measuring point, the moisture content of three soil layers (0-10cm, 10-20cm, and 20-30cm) is measured. Specifically, a portable soil moisture meter can be used for on-site measurement, or the drying method (105℃, 8h) can be used for laboratory verification. The coefficient of variation of moisture content at different measuring points within the same plot should be ≤10%, and the difference in moisture content between different soil layers at the same measuring point should be ≤5%. If these requirements are not met, the dry areas need to be re-irrigated. Meanwhile, adjustments need to be made according to the season and climate: In summer (temperature ≥25℃), the evaporation rate is fast, so the target moisture content can be increased by 5% and the mulch film should be covered immediately after irrigation; in winter (temperature ≤10℃), the evaporation rate is slow, so the target moisture content can be reduced by 5% to avoid soil freezing and affecting anaerobic fermentation; if it rains within 24 hours after irrigation, the moisture content needs to be re-measured. If it exceeds 85% of field capacity, the mulch film should be removed and the water drained for 1-2 days.

[0051] Within two hours of completing the moisture content adjustment, the soil must be immediately covered and sealed to prevent external oxygen from entering and maintain an anaerobic environment. Specifically, a black polyethylene film with a thickness of ≥0.08mm can be used as the covering material. Its light transmittance is less than 5%, effectively absorbing solar energy to raise the soil temperature by 2-5℃, accelerating the metabolism of anaerobic microorganisms, and it also has high tensile strength, good sealing effect, and stable chemical properties. It should be noted that ultra-thin films with a thickness <0.06mm (easily damaged and leaking air), transparent films (weed growth consumes oxygen), and biodegradable films (the degradation process consumes oxygen and the sealing time cannot be guaranteed) should not be used.

[0052] When covering, ensure the mulch film completely covers the entire plot to be improved, including the edges and ditches. The overlap between adjacent mulches should be at least 20cm, and the overlap should be compacted with soil. Mulch film at the edges of the plot should be buried 10-15cm deep in the soil to ensure a tight seal. Every 5-10m, press a strip of soil onto the film to prevent it from being blown away by the wind. The initial covering time is as generated in step S1. The actual coverage time is determined by the anaerobic suppression index in step S4. and seedling root risk index The joint judgment and dynamic adjustment should be made. It should be noted that the integrity of the mulch film should be inspected daily during the mulching period. If any damage is found, it should be repaired immediately with special mulch film tape. The repair area should be more than twice the size of the damaged area. It is strictly forbidden for people and animals to step on the mulch film or to pile heavy objects on it. A ground thermometer can be buried 10cm deep under the mulch film to record the soil temperature every day, which will provide a basis for subsequent anaerobic state data analysis.

[0053] After step S2 is completed, the quality acceptance standards must be met before proceeding to step S3, anaerobic state monitoring. Specifically, the carbon source application rate error should be ≤ ±5%, the coefficient of variation for mixing uniformity should be ≤ 15%, and the soil moisture content should reach the target moisture content. Uniformity variation coefficient ≤10%; full coverage of the mulch film without damage, with tight compaction at the edges and an overlap width ≥20cm; within 3 days after covering, the soil redox potential drops to below -50mV.

[0054] During implementation, if the oxidation-reduction potential decreases slowly (not dropping to -50mV within 3 days), the sealing of the mulch film needs to be checked and any damage repaired. If the moisture content is too low, water should be added to the target value. If the carbon source is insufficient, the film should be removed, reapplied, and then re-covered. If black sludge-like substances appear in local areas and are accompanied by a rotten egg smell, it indicates that hydrogen sulfide has been produced locally. The mulch film in that area should be removed immediately and ventilated for 1-2 days. During the subsequent reoxygenation stage, the number of times the area is tilled should be increased. If a large number of weeds grow under the mulch film, the weeds need to be removed manually and the damaged areas should be compacted. If necessary, the mulch film can be replaced with black mulch film.

[0055] Step S3: Obtain anaerobic state data of the anaerobic treated soil, and generate anaerobic suppression index and seedling root risk index based on the anaerobic state data.

[0056] The anaerobic treatment process of soils with continuous fruit tree planting is a nonlinear dynamic process that is affected by multiple factors such as soil background, temperature, moisture, and microbial community. The initial value of the covering treatment duration generated in step S1 is only a historical experience estimate, and the actual treatment effect may deviate from the expectation.

[0057] This step utilizes high-frequency, multi-dimensional real-time monitoring of soil conditions to construct two independent and complementary models: the Anaerobic Suppression Index (API) and the Seedling Root Risk Index (RRI). The API quantifies the overall pathogen-killing effect, while the RRI quantifies the potential damage risk of anaerobic metabolites to the subsequent fruit tree roots. Compared to the empirical judgment of "fixed mulching days" in existing technologies, this invention achieves dual quantitative control of "sufficient sterilization" and "root safety," solving the problems of "insufficient treatment leading to pathogen rebound and excessive treatment leading to root toxicity."

[0058] Specifically, in one embodiment of the present invention, step S3 specifically includes: According to the data collection interval, the soil redox potential, volatile fatty acid concentration, soil temperature, pathogen abundance, soil EC, ammonium nitrogen concentration, and pH of the anaerobic treatment soil during the anaerobic stage were obtained to form anaerobic state data.

[0059] The anaerobic suppression index is generated based on the soil redox potential, volatile fatty acid concentration, soil temperature, and pathogen abundance during the anaerobic stage.

[0060] A seedling root risk index is generated based on the concentrations of volatile fatty acids, soil EC, ammonium nitrogen, and pH during the anaerobic stage.

[0061] Specifically, the anaerobic suppression index The following relationship must be satisfied: ; in, This represents the cumulative decrease in soil redox potential during the anaerobic stage. This represents the effective cumulative value of volatile fatty acid concentration during the anaerobic phase. The rate of decrease in pathogen abundance during the anaerobic phase. The temperature-time product of soil temperature during the anaerobic stage. , , , This is the preset anaerobic suppression weighting coefficient.

[0062] Specifically, the seedling root risk index RRI satisfies the following relationship: ; in, This represents the residual value of volatile fatty acid concentration during the anaerobic stage. For soil EC during the anaerobic stage, This represents the ammonium nitrogen concentration during the anaerobic stage. For pH stability during the anaerobic phase, , , , The seedling root risk weight coefficient is preset.

[0063] In this embodiment of the invention, the anaerobic state data is collected according to the data acquisition interval generated in step S1. Continuous sampling was conducted until step S4 generated the reoxygenation initiation result or risk reoxygenation result. All data were collected from the 0-30cm topsoil layer using a five-point mixed sampling method. This soil layer is the main active layer of the fruit tree seedling root system, and its condition directly determines the subsequent planting effect. It should be noted that sampling should avoid areas with damaged mulch, waterlogged areas, and plot edges to ensure sample representativeness. Soil redox potential and daily average soil temperature at a depth of 10cm were measured in situ to avoid data distortion caused by environmental changes during sample transportation. Volatile fatty acid concentration, pathogen abundance, soil EC, ammonium nitrogen concentration, and soil pH should be analyzed in the laboratory within 24 hours after sampling. Volatile fatty acids, ammonium nitrogen, and other variable indicators should be pretreated within 4 hours. Among the above indicators, soil redox potential directly reflects the strength and stability of the anaerobic environment; volatile fatty acid concentration is not only the core source of anaerobic sterilization but also the main factor for subsequent root toxicity; pathogen abundance is the gold standard for judging the effectiveness of anaerobic treatment; and soil EC, ammonium nitrogen concentration, and pH jointly determine the physicochemical safety of the soil for seedling roots.

[0064] This step first constructs an Anaerobic Suppression Index (API) model to quantify the overall suppression effect of anaerobic treatment on replant pathogens; a higher API value indicates more thorough pathogen eradication. This model comprehensively considers four dimensions: anaerobic environment intensity, accumulation of bactericidal substances, direct pathogen-killing effect, and temperature contribution. The model formula is as follows: In the formula , is the anaerobic suppression index (dimensionless). , , , To predetermine the anaerobic suppression weighting coefficients (dimensionless), they can be optimized using response surface methodology with "pathogen kill rate ≥ 90%" as the objective function. The values ​​can range from 0.1-0.3, 0.2-0.4, 0.3-0.5, and 0.05-0.2, respectively, where the pathogen reduction rate is... The highest weight reflects the core position of the direct bactericidal effect; This represents the cumulative decrease in soil redox potential during the anaerobic stage (unit: mV·d), reflecting the intensity and duration of the strong reducing environment. A higher cumulative value indicates a more stable anaerobic environment and better sterilization effect. , This represents the current number of days of anaerobic treatment. Let be the soil redox potential on day t. The initial redox potential is measured in step S1.

[0065] Effective cumulative value of volatile fatty acid concentration during the anaerobic phase (unit: mg·L) -1•d), reflecting the total exposure to volatile fatty acids with bactericidal activity, is a core contributing factor to pathogen killing, among which... , The effective bactericidal threshold for volatile fatty acids (dimensionless, usually 50 mg / L) is defined as the concentration below which volatile fatty acids have no significant bactericidal effect.

[0066] The percentage decrease in pathogen abundance during the anaerobic phase (in %) directly reflects the actual pathogen eradication rate and is the parameter with the highest weight in the API model. , The initial abundance of pathogens determined in step S1. for The abundance of pathogens in a day.

[0067] The temperature-time product of soil temperature during the anaerobic stage (unit: °C·d) reflects the total energy input of anaerobic microbial metabolism. The larger the temperature-time product, the more complete the microbial fermentation and the higher the yield of volatile fatty acids. , Let t be the daily average soil temperature at a depth of 10 cm on day t.

[0068] In a specific embodiment of the present invention, the pathogen suppression effect can be divided into three levels according to the API value. Specifically, when When the oxygen supply is severely insufficient, the pathogen eradication rate is less than 50%, and a large rebound is likely after reoxygenation, leading to recurrence of continuous cropping problems; when Sometimes the anaerobic treatment is insufficient, with a pathogen kill rate of 50%~90%, leaving a significant amount of pathogen residue, necessitating a longer anaerobic treatment time; when At that time, the pathogens were fully suppressed, the pathogen killing rate was ≥90%, the pathogens were completely killed, and the basic conditions for reoxygenation were met.

[0069] While quantifying the sterilization effect, this step constructs a root risk index (RRI) model to quantify the potential damage risk to the roots of fruit tree seedlings from residual harmful substances in the soil after anaerobic treatment. A higher RRI value indicates a greater risk of root damage. This model comprehensively considers four risk factors: volatile fatty acid residues, salt accumulation, ammonium nitrogen toxicity, and pH stability. The model formula is as follows: In the formula Seedling root risk index (dimensionless). To preset the root risk weight coefficient (dimensionless), it can be determined through a seedling root elongation experiment with "root elongation rate ≥ 80%" as the objective function. The values ​​can be ranged from m = 0.001 to 0.005, n = 0.5 to 2, p = 0.002 to 0.01, and q = 1 to 5. For fruit trees sensitive to volatile fatty acids (such as peaches and plums), the values ​​can be appropriately increased. For fruit trees sensitive to salt (such as grapes), the value can be appropriately increased. The value of .

[0070] This represents the residual concentration of volatile fatty acids during the anaerobic stage (unit: mg / L), i.e., the concentration at the current anaerobic stage. The total concentration of volatile fatty acids per day, i.e. ,when A concentration of mg / L can cause severe damage to the root system of fruit tree seedlings. Soil EC (unit: mS / cm) during the anaerobic stage; current anaerobic treatment stage The soil electrical conductivity of the day, i.e. ,when A salt concentration of mS / cm can cause obvious salt damage symptoms in fruit tree seedlings. The concentration of ammonium nitrogen during the anaerobic stage (unit: mg / kg) is the current concentration during the anaerobic treatment. The soil ammonium nitrogen content of the day, i.e. ,when Ammonia levels of mg / kg can cause ammonia poisoning in the roots of fruit tree seedlings, reducing the occurrence of white roots by more than 70%. This represents the stability of pH during the anaerobic phase (dimensionless), reflecting the degree of fluctuation in soil pH. A higher value indicates a more stable pH level and a safer root growth environment. , The coefficient of variation of soil pH during the last 3 days of anaerobic treatment. This is the average pH value over the last 3 days. This represents the standard deviation of pH over the last 3 days.

[0071] In a specific embodiment of the present invention, root risk can be divided into three levels based on the RRI value. Specifically, when When the risk is low, the seedling root elongation rate is ≥80%, the root system grows normally, and the transplant survival rate is ≥95%; At the medium-risk level, the seedling root elongation rate is 60%-80%, and the seedling recovery time is extended by 3-5 days; when If the risk level is high and the root elongation rate of the seedlings is below 60%, the risk reoxygenation procedure must be initiated immediately.

[0072] The implementation process of this step is as follows: Five-point mixed sampling is carried out from 9:00 to 11:00 am on each sampling day. Soil redox potential and soil temperature are measured and recorded on-site. Soil samples are brought back to the laboratory, and volatile fatty acids, pathogen abundance, soil EC, ammonium nitrogen concentration and pH are measured according to the standard method. Three parallel samples are set for all indicators. The relative deviation of parallel samples must be ≤10%. Otherwise, the measurement is repeated. All measurement data are entered, and the sub-parameters of API and RRI are calculated respectively. The anaerobic suppression index and seedling root risk index of the day are obtained by substituting them into the above formula. All raw data and calculation results are recorded and saved, and uploaded to the control module of step S4 for reoxygenation timing judgment. If API increases slowly during implementation (daily increment <2 for 3 consecutive days), it is usually caused by insufficient carbon source, poor sealing, or low temperature. The sealing of the mulch film needs to be checked and damaged areas repaired. When the temperature is below 15℃, an insulation layer can be placed on the film. If the carbon source is insufficient, the film needs to be removed, replenished, and then re-covered. If RRI increases too quickly (daily increment >1 for 2 consecutive days), it is usually caused by excessive carbon source, high moisture content, or excessively long anaerobic time. The sampling frequency needs to be immediately increased to once a day. The risk reoxygenation procedure can be initiated in advance.

[0073] Step S4: Generate anaerobic stage control results based on the anaerobic suppression index and seedling root risk index. When the anaerobic stage control results meet the reoxygenation start-up conditions, reoxygenate the anaerobic soil to obtain reoxygenated soil.

[0074] In one embodiment of the present invention, step S4 specifically includes: When the anaerobic suppression index The preset anaerobic suppression threshold and seedling root risk index were reached. When the risk level is below the preset seedling root risk threshold, a reoxygenation initiation result is generated.

[0075] When the anaerobic suppression index The preset anaerobic suppression threshold was not reached and the seedling root risk index was low. When the risk level falls below the preset seedling root risk threshold, an anaerobic maintenance result is generated, and the anaerobic soil is covered and sealed based on the anaerobic maintenance result.

[0076] When the seedling risk index When the risk threshold for seedling roots is reached or exceeded, a risk reoxygenation result is generated.

[0077] Based on the results of reoxygenation initiation or risk reoxygenation, the anaerobic soil is subjected to methods such as removing the film, opening and closing the ventilation channel, tilling and aerating, or intermittent aeration to obtain reoxygenated soil.

[0078] This step resolves the inherent contradiction between "sufficient sterilization" and "root safety" in anaerobic soil treatment for fruit trees in continuous cropping: extending the anaerobic time can increase the pathogen killing rate, but it leads to excessive accumulation of reducing metabolites such as volatile fatty acids (VFA) and ammonium nitrogen; shortening the anaerobic time can reduce the risk of root toxicity, but it results in pathogen residues and a significant rebound after reoxygenation. Existing technologies generally use empirical reoxygenation with a "fixed number of mulching days" (such as uniformly removing the mulch after 20 days), which cannot adapt to the differences in soil conditions in different plots and seasons, resulting in "undertreatment" or "overtreatment" in about 30% of plots. This step achieves precise dynamic control of the timing of anaerobic termination through a quantitative decision-making mechanism linked by dual indices. Normal reoxygenation is initiated when pathogens are sufficiently suppressed and root risk is controllable; anaerobic treatment continues when pathogens are insufficiently suppressed but risk is controllable; and risk reoxygenation is immediately initiated when root risk exceeds a threshold, fundamentally resolving the above contradictions.

[0079] In this embodiment of the invention, all decisions are based on the joint judgment of API and RRI, without any empirical fixed time parameters, and its control logic satisfies the following relationship: ; In the formula It is the anaerobic suppression index, used to quantify the overall suppression effect of pathogens; The seedling root risk index is used to quantify the potential risk of root damage. The preset anaerobic suppression threshold is dimensionless. The preset seedling root risk threshold is dimensionless.

[0080] The above thresholds were all determined through scientific experiments, not empirical values. Among them, the preset anaerobic suppression threshold... The value ranges from 80 to 100 and can be determined through a pathogen kill rate test. When the target pathogen kill rate is ≥90%; At that time, the kill rate is ≥95%. In practical applications, the upper limit of 100 is used for plots with continuous cropping for more than 10 years and high pathogen pressure, while 80-90 is used for general plots with continuous cropping. A preset seedling root risk threshold is also established. The value ranges from 5 to 10 and can be determined through seedling root elongation tests. At that time, the root elongation rate of the seedlings was ≥80%; when At that time, the root elongation rate of the seedlings should be ≥60%. For stone fruit trees that are sensitive to harmful substances, the lower limit of 5 should be used, such as peaches, plums, and cherries. For pome fruit trees with strong tolerance, the lower limit of 8-10 should be used, such as apples and pears.

[0081] In this embodiment of the invention, the ideal time for reoxygenation is when the reoxygenation start-up result simultaneously satisfies both "sufficient suppression of pathogens" and "low risk to roots". Under the anaerobic maintenance result, pathogen suppression has not yet reached the standard, but root risk is controllable. Continuing anaerobic treatment can further improve the bactericidal effect without significantly increasing damage. Under the risk reoxygenation result, regardless of whether pathogen suppression reaches the standard, anaerobic treatment must be terminated immediately, because continued anaerobic treatment will lead to the exponential accumulation of harmful substances, causing irreversible root damage, which is difficult to completely eliminate even if the reoxygenation time is extended subsequently.

[0082] Specifically, when a reoxygenation initiation result (normal reoxygenation) is generated, the treatment goal is to rapidly reduce the concentration of reducing metabolites in the soil, restore the soil oxidation environment, and create suitable conditions for the subsequent re-colonization of beneficial microorganisms, while ensuring that pathogens do not rebound. The corresponding standard treatment process is as follows: completely remove the covering mulch and collect and treat it to avoid white pollution; dig ventilation trenches 20-30cm deep and spaced 3-5m apart along the direction of the plot to accelerate deep soil gas exchange; till the soil to a depth of 20-30cm using a rotary tiller, tilling at least twice to break up soil compaction and increase porosity; allow natural aeration for 3-5 days after tilling, during which irrigation is prohibited to prevent the re-formation of an anaerobic environment. In addition, the process parameters can be optimized for different soil textures. For example, sandy soil has good permeability and only needs to be tilled once, followed by 3 days of natural aeration; loamy soil needs to be tilled twice, followed by 4 days of natural aeration; clay soil has poor permeability and needs to be tilled three times, followed by 5 days of natural aeration. At the same time, the density of ventilation trenches should be increased to a spacing of 2-3m.

[0083] When generating anaerobic maintenance results, the treatment objective is to continue maintaining a stable anaerobic environment until the API reaches a preset threshold, while closely monitoring RRI changes to prevent risk exceeding limits. The corresponding standard treatment process includes: keeping the mulch film intact and not performing any film removal or aeration operations; and adhering to the data collection intervals determined in step S1. Shorten the monitoring interval to half of the original interval (e.g., change the original 2-day interval to 1-day) and increase the monitoring frequency; prioritize monitoring volatile fatty acid concentrations and ammonium nitrogen concentrations. If the daily increase in RRI exceeds 0.5, prepare for risk reoxygenation in advance. To avoid irreversible soil structure damage and excessive accumulation of harmful substances, the total duration of anaerobic treatment should not exceed 60 days. If the API level still does not meet the standard after 60 days, anaerobic treatment should be terminated and risk reoxygenation should be initiated. Subsequently, the insufficient suppression of pathogens can be compensated by increasing the application of beneficial microorganisms.

[0084] When generating risky reoxygenation results, the treatment objective is to reduce the concentration of harmful substances in the soil as quickly as possible, control the risk of root damage, and minimize pathogen rebound. The process differs significantly from normal reoxygenation. Firstly, it is necessary to detect... Completely remove the film within 2 hours after the initial exposure; do not delay. Secondly, adopt an intermittent ventilation pattern of "4 hours of ventilation + 2 hours of sealing" for 3 consecutive days to avoid a rapid rebound of pathogens caused by a single large-scale ventilation (sudden reoxygenation can cause facultative anaerobic pathogens to multiply more than 10 times within 24 hours). Tillage should combine shallow tillage with multiple tillages, initially tilling to a depth of 10-15cm, once a day for 3 consecutive days, gradually increasing to 20-30cm. For severe cases of excessive levels, auxiliary measures can be taken to reduce harm. If the concentration of volatile fatty acids is >200mg / L, a 0.1% hydrogen peroxide solution (100L / acre) can be sprayed to accelerate its oxidation and decomposition. If the concentration of ammonium nitrogen is >300mg / kg, nitrifying bacteria inoculant (1kg / acre) can be applied to promote the conversion of ammonium nitrogen to nitrate nitrogen.

[0085] It should also be noted that continuous monitoring is required during the reoxygenation process. Soil samples should be collected every 1-2 days to measure soil redox potential, volatile fatty acid concentration, pathogen abundance, soil pH, and soil moisture content during the reoxygenation stage. After reoxygenation, the following standards must be met before proceeding to step S5 for the phased re-inoculation of beneficial microorganisms: soil redox potential rises to ≥0mV; volatile fatty acid concentration decreases to ≤50mg / L; pathogen rebound rate ≤20% (i.e., pathogen abundance after reoxygenation does not exceed 1.2 times that at the end of anaerobic treatment); soil pH stabilizes between 6.0 and 7.5, with a coefficient of variation ≤5% for 3 consecutive days; and soil moisture content decreases to 60%-70% of field capacity.

[0086] Furthermore, if pathogens rebound rapidly after reoxygenation (rebound rate >50%), it is usually caused by insufficient anaerobic treatment, excessively rapid reoxygenation, or insufficient beneficial microorganisms. In such cases, reoxygenation should be stopped immediately, and the mulch should be re-covered for 5-7 days of supplementary anaerobic treatment, while simultaneously applying 0.5-1 t / hm² of fertilizer. 2 Molasses enhances the bactericidal effect; after reoxygenation, apply a hypoxia-resistant antagonistic bacterium to inhibit pathogen proliferation. If volatile fatty acids decrease slowly (still >100mg / L after 5 days of reoxygenation), increase tillage frequency to twice daily and deepen to 30cm. Use a blower to force airflow into the ventilation trenches; if necessary, spray with a 0.2% hydrogen peroxide solution. If soil pH fluctuates drastically after reoxygenation (coefficient of variation >10%), apply 50-100kg / mu of quicklime to adjust pH to 6.0-7.0, extend intermittent aeration time to 5-7 days, and apply humic acid substances to improve soil buffering capacity. If ammonium nitrogen conversion is slow (still >200mg / kg after 7 days of reoxygenation), first adjust soil pH to the optimal range of 7.0-7.5 for nitrifying bacteria, then apply 1-2kg / mu of nitrifying bacteria inoculant and appropriately increase aeration to raise the oxidation-reduction potential to ≥100mV.

[0087] Step S5: Obtain the reoxygenation status data of the reoxygenated soil, generate a basic repopulation window index based on the reoxygenation status data, correct the basic repopulation window index based on the soil moisture content of the reoxygenation stage in the reoxygenation status data to obtain the corrected repopulation window index, and generate the batch repopulation results of beneficial microorganisms based on the corrected repopulation window index.

[0088] It should be understood that anaerobic treatment completely alters the soil microbial community structure, leading to the death of a large number of native beneficial microorganisms. The reoxygenated soil then enters a microbial niche vacuum. If fruit tree seedlings are planted directly at this time, residual pathogens will quickly seize the niche, causing recurrence of continuous cropping problems. If all beneficial microbial agents are applied blindly at once, most aerobic beneficial microorganisms will die due to environmental unsuitability, as the soil redox potential is low, volatile fatty acid residues are high, and pH fluctuations are large in the early stages of reoxygenation. The colonization rate is typically only 10%–30%. To address these issues, this step uses precise window index judgment, batch functional matching, and feedback-based dynamic adjustment to achieve quantitative control of the timing of beneficial microbial application. First, hypoxia-tolerant antagonistic bacteria are applied during the low repopulation window to quickly occupy the niche and inhibit pathogen rebound. After the soil environment has further improved, growth-promoting bacteria, autotoxic substance-degrading bacteria, and mycorrhizal fungi, which have higher environmental requirements, are then applied, ultimately increasing the beneficial microbial colonization rate to over 60% and constructing a stable disease-suppressing soil micro-ecosystem.

[0089] In one embodiment of the present invention, step S5 specifically includes: The data on soil redox potential rise, volatile fatty acid decline rate, pH stability, pathogen rebound rate, and soil moisture content during the reoxygenation stage were obtained to form reoxygenation status data.

[0090] The basic repopulation window index is generated based on the soil redox potential rise during the reoxygenation stage, the volatile fatty acid decline rate during the reoxygenation stage, the pH stability during the reoxygenation stage, and the pathogen rebound rate during the reoxygenation stage.

[0091] The moisture content correction coefficient is determined based on the soil moisture content during the reoxygenation stage, and the basic repopulation window index is corrected based on the moisture content correction coefficient to obtain the corrected repopulation window index. The results of the batch repopulation of beneficial microorganisms were generated based on the modified repopulation window index.

[0092] Specifically, the basic recolonization window index RWI satisfies the following relationship: ; in, This represents the increase in soil redox potential during the reoxygenation phase. The rate of decrease in volatile fatty acids during the reoxygenation phase. pH stability during the reoxygenation phase. The pathogen rebound rate during the reoxygenation phase. , , , The pre-defined repopulation window weight coefficient; Corrected Repopulation Window Index The following relationship must be satisfied: ; in, This is the moisture content correction factor; When adjusting the repopulation window index When the first repopulation threshold is reached, the first beneficial microbial agent is applied; When adjusting the repopulation window index When the second repopulation threshold is reached, a second beneficial microbial agent is applied to obtain the result of batch repopulation of beneficial microorganisms. Among them, the second repopulation threshold is greater than the first repopulation threshold.

[0093] In one embodiment of the present invention, the first beneficial microbial agent includes hypoxia-resistant antagonistic bacteria, and the second beneficial microbial agent includes growth-promoting bacteria, autotoxic substance-degrading bacteria, or mycorrhizal fungi. After the first beneficial microbial agent is applied, the first recolonization monitoring data is obtained, which includes the colonization rate of the first beneficial microorganism, the abundance of the first pathogenic bacteria, and the residual value of the first volatile fatty acid. A repopulation feedback coefficient is generated based on the colonization rate of the first beneficial microorganism, the residual abundance of the first pathogen, and the residual value of the first volatile fatty acid. The repopulation window index is then adjusted based on this feedback coefficient. The update is performed to obtain the updated and corrected repopulation window index; The timing of application of the second beneficial microbial agent is determined based on the updated and revised repopulation window index; After the second beneficial microbial agent is applied, second recolonization monitoring data is obtained, and the batch recolonization results of beneficial microorganisms are generated based on the second recolonization monitoring data. The second recolonization monitoring data includes the colonization rate of the second beneficial microorganisms and the abundance of residual second pathogens.

[0094] In this invention, reoxygenation status data are collected from the start of the reoxygenation treatment until the beneficial microorganisms have re-colonized in batches. All samples are collected from the 0-30cm topsoil layer using a five-point mixed sampling method. The routine sampling frequency is once every 2-3 days, and when the corrected recolonization window index approaches a preset threshold, the frequency is increased to once a day. The collected indicators include soil redox potential, volatile fatty acid concentration, soil pH, pathogen abundance, and soil moisture content during the reoxygenation stage. Soil redox potential and moisture content are measured in situ using an in-situ method. Volatile fatty acids, pathogen abundance, and pH are analyzed in the laboratory within 24 hours of collection. Three parallel samples are set for all indicators, and the relative deviation of parallel samples is controlled within 10%. The above indicators comprehensively characterize the dynamic changes of the soil microenvironment during the reoxygenation process from five dimensions: the degree of oxidative environment recovery, residual harmful substances, acid-base stability, pathogen rebound risk, and moisture conditions.

[0095] The basal recolonization window index is used to quantify the basic suitability of the soil environment for the colonization of beneficial microorganisms during the reoxygenation stage; a higher value indicates a more suitable soil environment for the growth of beneficial microorganisms. This model comprehensively considers four dimensions: oxidative environment recovery, degradation of harmful substances, pH stability, and pathogen rebound. Its model formula is: ; In the formula, , , , The pre-defined repopulation window weight coefficients have values ​​ranging from 0.005 to 0.02, 0.5 to 2, 1 to 5, and 0.01 to 0.05, respectively, and can be optimized through orthogonal experiments on microbial colonization rates. This represents the rise in soil redox potential during the reoxygenation stage, expressed in mV. It is calculated as the [value] during the reoxygenation [stage]. The difference between the redox potential at the end of the first day and the redox potential at the end of the anaerobic period, i.e. ,in For reoxygenation The redox potential of the day, This represents the redox potential at the end of anaerobic digestion.

[0096] The percentage decrease in volatile fatty acid concentration during the reoxygenation stage reflects the degree of degradation of residual microbial inhibitory substances in the soil. ,in This represents the concentration of volatile fatty acids at the end of anaerobic digestion. This represents the stability of pH during the reoxygenation phase; a higher value indicates smaller pH fluctuations. , The coefficient of variation of pH over the past 3 days after reoxygenation. This is the average value. The standard deviation is denoted as . The rebound rate of pathogens during the reoxygenation stage is expressed as a percentage, reflecting the risk of pathogens competing for ecological niches with beneficial microorganisms. , This represents the abundance of pathogens at the end of anaerobic conditions.

[0097] This model comprehensively considers four dimensions: oxidative environment recovery, degradation of harmful substances, pH stability, and pathogen rebound. It can accurately characterize the friendliness of the soil microenvironment to beneficial microorganisms. When RWI≥60, the colonization rate of most aerobic beneficial microorganisms can reach more than 50%.

[0098] Soil moisture content is a key environmental factor affecting the respiration and nutrient absorption of beneficial microorganisms. When the moisture content deviates from the range of 60%–70% of field capacity, the colonization rate of microorganisms decreases significantly. This invention utilizes a moisture content correction coefficient... The basic repopulation window index RWI is corrected to obtain a more accurate corrected repopulation window index CRWI, further improving the accuracy of inoculant application timing. The model formula is as follows: ; In the formula This is a moisture content correction factor; when the soil moisture content is 60%–70% of field capacity, Take 1.0; when the moisture content is below 60%, It equals the ratio of the current moisture content to 0.6; when the moisture content is higher than 70%, It equals the ratio of 0.7 to the current moisture content. The modified recombination window index is the ultimate basis for determining the timing of beneficial microorganism application. This invention presets a first recombination threshold of 30-50 and a second recombination threshold of 60-80, which correspond to the suitable application windows for hypoxia-resistant antagonistic bacteria and functional microorganisms, respectively.

[0099] Based on the modified recombination window index (CRWI), this invention employs a two-stage, batch recombination strategy, precisely matching the application timing according to the varying environmental adaptability of different functional microorganisms. Specifically, when the CRWI reaches the first recombination threshold, a first beneficial microbial agent is applied. This agent primarily consists of hypoxia-resistant antagonistic bacteria, including Bacillus subtilis, Bacillus amyloliquefaciens, and Pseudomonas fluorescens, which can survive and rapidly multiply in low redox potential environments. They inhibit pathogen rebound by occupying ecological niches and secreting antimicrobial substances, while simultaneously decomposing residual volatile fatty acids. The application rate of the first beneficial microbial agent is 2-5 kg / mu (effective viable count ≥ 10). 9 (CFU / g) can be applied by spreading and then tilling to evenly mix it into the 0-20cm soil layer. After application, spray water appropriately to maintain the soil moisture content at 60%~70%.

[0100] To dynamically evaluate the colonization effect of the first beneficial microbial agent and optimize the application timing of the second beneficial microbial agent, this invention introduces a recolonization feedback mechanism. Three days after applying the first beneficial microbial agent, first recolonization monitoring data is collected, including the colonization rate of the first beneficial microorganism, the abundance of the first pathogenic bacteria, and the residual value of the first volatile fatty acid. Based on this, a recolonization feedback coefficient is calculated. The calculation formula is as follows: ; In the formula The colonization rate of the first beneficial microorganism (unit: %) can be determined by plate counting or qPCR. The target colonization rate for the primary beneficial microbial inoculant is typically 60%. The abundance of the primary pathogen. The initial abundance of pathogens determined in step S1; This is the residual value of the first volatile fatty acid; The threshold for volatile fatty acids for microbial safety is typically 20 mg / L. Recolonization feedback coefficient. The value range is 0-1.5, when This indicates that the first beneficial microbial agent has a good colonization effect, and the second beneficial microbial agent can be applied in advance; when The time indicates poor colonization results, requiring delayed application and remedial measures. The revised repopulation window index is updated based on the repopulation feedback coefficient, resulting in the updated revised repopulation window index. This serves as a basis for determining the timing of the application of the second beneficial microbial agent.

[0101] When the updated and corrected repopulation window index reaches the second repopulation threshold, a second beneficial microbial agent is applied. This agent is a functional microbial compound agent, mainly comprising three categories: growth-promoting bacteria, autotoxin-degrading bacteria, and mycorrhizal fungi. Growth-promoting bacteria promote root growth and nutrient absorption in fruit trees; autotoxin-degrading bacteria decompose phenolic acids and organic acids accumulated in the soil; and mycorrhizal fungi form a symbiotic system with the fruit tree roots, enhancing the fruit tree's resistance to adverse conditions and its nutrient absorption capacity. The application rate of the second beneficial microbial agent is 3-6 kg / mu (effective viable count ≥ 10). 8 (CFU / g) can be applied by trenching or hole application to a depth of 15-20cm in the future planting row of fruit trees. After application, cover with soil and water. Five days after application of the second beneficial microbial agent, collect monitoring data on the second repopulation. When the colonization rate of the second beneficial microorganism is ≥50% and the residual abundance of the second pathogen is ≤10% of the initial abundance, the phased repopulation of beneficial microorganisms is confirmed to be complete.

[0102] This step must meet the following requirements: the timing of the first inoculant application must be accurate and the colonization rate ≥60%; the repopulation feedback coefficient must be calculated correctly; the timing of the second batch of inoculant application must meet the requirements; the final pathogen residual abundance must be controlled within 10% of the initial abundance; and the residual value of volatile fatty acids in the soil must be ≤20mg / L. If the colonization rate of the first inoculant is lower than 40% during implementation, 1-2 kg / mu of the first beneficial microbial inoculant must be applied again, and the soil moisture content must be adjusted to the optimal range. If the pathogen rebound rate exceeds 50%, a broad-spectrum antagonistic inoculant must be applied again, and the reoxygenation time must be extended. Subsequent operations can only be carried out after the pathogen abundance decreases.

[0103] Step S6: Obtain rhizosphere safety data after the completion of the batch repopulation of beneficial microorganisms, generate a rhizosphere safety index based on the rhizosphere safety data, and generate the planting control results based on the rhizosphere safety index.

[0104] The essence of replanting obstacles in fruit trees lies in the imbalance of the "soil-microorganism-root" interaction system. Simply suppressing pathogens and re-introducing beneficial microorganisms is insufficient to guarantee successful seedling establishment. Soil physicochemical properties (oxidation-reduction potential, pH, EC, ammonium-nitrate ratio), microbial activity (soil respiration rate), and direct biotoxicity to roots (residual autotoxic substances) collectively constitute the core elements of rhizosphere safety. Current technologies generally rely on empirical judgments such as "planting several days after reoxygenation," lacking a comprehensive quantitative assessment of the rhizosphere environment. This results in approximately 20% of plots experiencing "improved conditions but failed planting," manifested as slow seedling establishment, fewer white roots, root tip browning, and even seedling death. This step constructs a three-in-one rhizosphere safety index (RSI) model integrating physicochemical indicators, microbiological indicators, and bioassays, achieving a quantitative assessment of fruit tree planting safety and improving planting survival rates.

[0105] In one embodiment of the present invention, step S6 specifically includes: After the completion of the batch repopulation of beneficial microorganisms, the soil redox potential, residual value of volatile fatty acids, soil EC, pH, ratio of ammonium nitrogen to nitrate nitrogen, soil respiration rate and seedling root elongation were obtained to form rhizosphere safety data.

[0106] A root security index is generated based on root security data.

[0107] When the rhizosphere safety index reaches the preset planting safety threshold, a planting permit result is generated.

[0108] When the rhizosphere safety index does not reach the preset planting safety threshold, a temporary planting delay result is generated, and reoxygenation correction parameters are generated based on the rhizosphere safety data.

[0109] Rhizosphere safety data were collected 3 days after the beneficial microorganisms had completed their repopulation and stabilized. All data were collected from the 0-30cm topsoil layer using a five-point mixed sampling method, representing the main root distribution layer after seedling transplanting. The rhizosphere safety data included seven indicators: soil redox potential after repopulation, residual volatile fatty acid value after repopulation, soil EC after repopulation, soil pH after repopulation, ammonium nitrogen to nitrate nitrogen ratio after repopulation, soil respiration rate after repopulation, and seedling root elongation rate. Root elongation rate is the gold standard reflecting the comprehensive biotoxicity of soil to fruit tree roots. It was determined using a standardized seedling root elongation bioassay. Soil samples were sieved through a 2mm sieve and placed in sterile petri dishes. Plump, uniform target fruit tree seeds were disinfected, germinated, and placed on the soil surface. The seeds were cultured at 25℃ in the dark for 7 days. The length of the taproot was measured, and the root elongation rate was calculated using the following formula: ; In the formula The average taproot length of seedlings in the soil being tested. The average taproot length of seedlings in the sterile quartz sand control group is shown.

[0110] The Rhizosphere Safety Index (RSI) is used to quantify the overall safety of soil for fruit tree seedlings. A higher RSI value indicates a safer rhizosphere environment and a higher survival rate after planting. The mathematical expression for the RSI is: ; In the formula, RSI is the root zone safety index (dimensionless). , , , , , , To predetermine the rhizosphere safety weight coefficients, all of which are dimensionless, they can be optimized through orthogonal experiments with "seedling survival rate ≥ 95%" as the objective function. The values ​​range as follows: e = 0.001~0.005, f = 0.1~0.3, g = 0.1~0.3, h = 0.2~0.5, i = 0.1~0.3, j = 0.005~0.02, k = 0.005~0.02. The weight allocation follows the principle of "prioritizing biological toxicity and secondarily considering physicochemical properties." The residual value of volatile fatty acids... The weights of root elongation rate (G) and seedling root elongation rate (G) are each 20%, followed by soil pH. and EC Each accounts for 15%, and the remaining indicators each account for 10%.

[0111] The soil redox potential (unit: mV) after replanting reflects the final oxidative environment of the soil and is the basis for root aerobic respiration. The residual value of volatile fatty acids after replanting (unit: mg / L) reflects the final residual amount of toxic substances in the root system; The threshold for safe volatile fatty acids for roots (unit: mg / L) is usually 20 mg / L. Exceeding this value will significantly inhibit root growth. The soil EC (unit: mS / cm) after reclamation reflects the total soil salt content; excessively high levels can lead to root osmotic stress. The optimal soil EC value (unit: mS / cm) for the target fruit trees is usually 0.5-1.0 mS / cm; The soil pH (dimensionless) after replanting affects root nutrient absorption and enzyme activity; The optimal soil pH value (dimensionless) for the target fruit trees is usually 6.0-7.0; The ratio of ammonium nitrogen to nitrate nitrogen after reclamation (dimensionless) reflects the nitrogen form balance in the soil. The optimal ammonium-nitrate ratio (dimensionless) for the target fruit trees is typically 0.5-1.0. Soil respiration rate after replanting (unit: mg CO2·kg) -1 ・h -1 This reflects the total activity of soil microorganisms; Root elongation rate (unit: %).

[0112] This model eliminates the dimensional differences between different indicators through normalization, directly weighting positive indicators, converting negative indicators into positive contributions, and calculating the contribution of interval-type indicators based on their deviation from the optimal value, ensuring that the index accurately reflects the overall safety of the rhizosphere environment. Based on the RSI value, the rhizosphere safety level can be divided into four levels: For maximum safety, the survival rate after transplanting is ≥98%. For safety, the survival rate after transplanting should be 90%-98%. For low-risk individuals, the survival rate after transplanting is 70% to 90%. This is considered high-risk, with a survival rate of less than 70% after transplanting.

[0113] Based on the rhizosphere safety index, this step employs quantitative planting control logic, when... When the allowed colonization result is generated, The results of delayed planting are generated at that time, among which The preset planting safety threshold (dimensionless) is typically 70-90. For fruit trees sensitive to the rhizosphere environment, such as peaches and cherries, the upper limit of 90 is used, while for more tolerant fruit trees, such as apples and pears, 70-80 is used. After generating a result indicating that planting is permissible, the fruit tree seedlings can be planted. However, it should be noted that planting should be done on cloudy days or in the evening to avoid direct sunlight causing dehydration. The planting depth should be consistent with the original nursery depth, with the grafting point 5-10cm above the ground to prevent disease infection at the grafting point. Immediately after planting, water thoroughly to maintain a soil moisture content of 60%-70%, providing suitable water conditions for root growth. Avoid fertilizing within one week after planting to prevent root burn and hinder seedling establishment.

[0114] After generating the results of the temporary planting delay, targeted improvement measures should be taken based on the indicators that do not meet the standards in the rhizosphere safety data to avoid losses caused by blind planting. Specifically, if the residual value of volatile fatty acids... mg / L can be treated by increasing aeration through daily tilling for 3 consecutive days, spraying with 0.1% hydrogen peroxide solution (100L / mu) to accelerate oxidation, and supplementing with Bacillus subtilis inoculant (1kg / mu) to promote decomposition, until... mg / L; if soil EC mS / cm, can be washed away by flood irrigation, with each irrigation volume being 30-40m³. 3 / acre, while simultaneously digging drainage ditches to drain the leachate, repeating the rinsing process 2-3 times until... mS / cm; If the soil pH deviates from the range of 6.0-7.5, if the pH is too low, quicklime (50-100 kg / mu) can be applied to adjust it; if the pH is too high, sulfur powder (20-30 kg / mu) or humic acid can be applied to adjust it. After tilling and mixing evenly, the pH should be measured again after 7 days; if the ammonium-nitrate ratio Soil redox potential can be adjusted to a range of 0.5-1.0 by increasing aeration to raise soil redox potential, applying nitrifying bacteria inoculants (1-2 kg / mu) to promote ammonium nitrogen conversion, and appropriately supplementing nitrate nitrogen fertilizer; if the soil respiration rate Well-rotted organic fertilizer (500-1000 kg / mu) and compound microbial agents (2-3 kg / mu) can be applied to improve soil microbial activity until... If the root elongation rate The presence of undetected autotoxic substances indicates the presence of residual autotoxic substances. This can be addressed by supplementing with autotoxic substance degrading bacteria (2-3 kg / mu), applying activated carbon (100-200 kg / mu) for adsorption, or planting fast-growing green manure and then turning it over after 20 days of growth. The test should be repeated after 30 days.

[0115] It is important to emphasize that after step S6 is completed, all of the following criteria must be met simultaneously for formal planting to proceed: Rhizosphere safety index volatile fatty acid residue value mg / L, soil EC mS / cm, soil pH between 6.0 and 7.5, ammonium-nitrate ratio between 0.5 and 1.0, and seedling root elongation rate. The residual abundance of pathogens should not exceed 10% of the initial abundance. To ensure successful planting, continuous monitoring is required for one week after planting. Observe the condition of the seedling leaves daily for any abnormalities such as wilting or yellowing. Measure the soil moisture content every 3 days, maintaining it within the suitable range of 60% to 70%. Seven days after planting, randomly select 10 seedlings and gently pull them out to observe root growth; the number of white roots should be ≥5 per seedling. If any abnormalities occur, take timely measures such as shading, watering with a 500-fold diluted humic acid solution to promote root growth, and foliar spraying with a 0.2% potassium dihydrogen phosphate solution to enhance the seedlings' resistance.

[0116] In specific embodiments of the present invention, to address special problems that may arise in practical applications, if multiple indicators exceed the standard simultaneously, resulting in a low RSI, it is usually caused by excessive anaerobic treatment, insufficient reoxygenation, or poor colonization of beneficial microorganisms. In this case, the soil should be thoroughly tilled to a depth of 30cm, ventilated and sun-dried for 5-7 days, and 1000kg / mu of well-rotted organic fertilizer and 3kg / mu of compound microbial agent should be applied to adjust the soil pH and EC to a suitable range. The rhizosphere safety index should be re-measured after 10 days. If all physicochemical indicators meet the standards but the seedling root elongation rate is low, it indicates the presence of autotoxic substances in the soil that have not been detected by conventional testing methods. 200kg / mu of activated carbon can be applied to adsorb the autotoxic substances, and 3kg / mu of compound microbial agent of Pseudomonas and Bacillus can be applied at the same time. The seedling root elongation rate should be re-measured after 30 days.

[0117] According to embodiments of the present invention, this method for soil improvement to overcome the obstacle of continuous cropping of fruit trees generates anaerobic treatment parameters based on basic soil data. During the anaerobic treatment process, an anaerobic suppression index and a seedling root risk index are introduced to achieve quantitative control over the timing of anaerobic termination, avoiding pathogen rebound due to insufficient treatment or seedling root damage due to excessive treatment. Simultaneously, a re-colonization window index is generated and corrected using reoxygenation status data to control the phased application of beneficial microbial agents, improving the colonization stability of beneficial microorganisms. Furthermore, a rhizosphere safety index is used to determine planting conditions, reducing the impact of volatile fatty acid residues, salt risk, and ammonium nitrogen accumulation on fruit tree seedlings, thereby improving the stability of soil improvement for continuous cropping, seedling survival rate, and orchard establishment consistency.

[0118] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A soil improvement method for overcoming the obstacle of continuous cropping of fruit trees, characterized in that, The method includes: S1. Obtain basic soil data of the replanted soil to be improved, and generate anaerobic treatment parameters based on the basic soil data; S2. Apply carbon source, adjust moisture content and cover the replanted soil to be improved according to the anaerobic treatment parameters to obtain anaerobic treated soil. S3. Obtain anaerobic state data of the anaerobic treated soil, and generate anaerobic suppression index and seedling root risk index based on the anaerobic state data. S4. Generate anaerobic stage control results based on the anaerobic suppression index and the seedling root risk index, and when the anaerobic stage control results meet the reoxygenation start-up conditions, perform reoxygenation treatment on the anaerobic soil to obtain reoxygenated soil. S5. Obtain the reoxygenation status data of the soil treated with reoxygenation, generate a basic repopulation window index based on the reoxygenation status data, correct the basic repopulation window index based on the soil moisture content of the reoxygenation stage in the reoxygenation status data to obtain a corrected repopulation window index, and generate the batch repopulation results of beneficial microorganisms based on the corrected repopulation window index. S6. Obtain rhizosphere safety data after the completion of the batch repopulation results of the beneficial microorganisms, generate a rhizosphere safety index based on the rhizosphere safety data, and generate planting control results based on the rhizosphere safety index.

2. The soil improvement method for overcoming the obstacle of continuous cropping of fruit trees according to claim 1, characterized in that, S1 includes: The soil redox potential, soil moisture content, soil temperature, soil pH, soil EC, soil organic matter content, initial abundance of pathogens, initial concentration of volatile fatty acids, initial concentration of ammonium nitrogen, initial concentration of nitrate nitrogen, and target fruit tree type of the soil to be improved are obtained to form the basic soil data. Based on the soil organic matter content, soil moisture content, soil temperature, initial abundance of pathogens, and initial concentration of volatile fatty acids, the amount of easily degradable carbon source to be applied, the target moisture content, the initial value of the mulch treatment duration, and the data collection interval are generated. The anaerobic treatment parameters are formed by combining the amount of readily degradable carbon source applied, the target moisture content, the initial value of the coverage treatment duration, and the data acquisition interval.

3. The soil improvement method for overcoming the obstacle of continuous cropping of fruit trees according to claim 2, characterized in that, S2 includes: The readily degradable carbon source is applied to the replanted soil to be improved according to the specified amount of readily degradable carbon source to obtain carbon source-treated soil. The carbon source-treated soil is irrigated or replenished with water according to the target moisture content to obtain moisture-conditioned soil. The moisture-conditioning soil is covered and sealed according to the initial value of the covering treatment time to obtain the anaerobic soil. The readily biodegradable carbon source includes at least one of rice bran, molasses, crushed green manure, and fermented fruit tree waste.

4. The soil improvement method for overcoming the obstacle of continuous cropping of fruit trees according to claim 2, characterized in that, S3 includes: According to the data acquisition interval, the soil redox potential, volatile fatty acid concentration, soil temperature, pathogen abundance, soil EC, ammonium nitrogen concentration, and pH of the anaerobic soil in the anaerobic stage are acquired to form the anaerobic state data. The anaerobic suppression index is generated based on the soil redox potential, volatile fatty acid concentration, soil temperature, and pathogen abundance during the anaerobic stage. The seedling root risk index is generated based on the volatile fatty acid concentration, soil EC, ammonium nitrogen concentration, and pH of the anaerobic stage.

5. The soil improvement method for overcoming the obstacle of continuous cropping of fruit trees according to claim 4, characterized in that, The anaerobic suppression index API satisfies the following relationship: ； in, This represents the cumulative decrease in soil redox potential during the anaerobic stage. This represents the effective cumulative value of the volatile fatty acid concentration during the anaerobic phase. The percentage decrease in pathogen abundance during the anaerobic phase. The temperature-time product of the soil temperature during the anaerobic stage. , , , Preset anaerobic suppression weighting coefficients; The seedling root risk index RRI satisfies the following relationship: ； in, This represents the residual value of the volatile fatty acid concentration during the anaerobic stage. For the anaerobic stage soil EC, The concentration of ammonium nitrogen during the anaerobic stage. The pH stability during the anaerobic phase. , , , The seedling root risk weight coefficient is preset.

6. The soil improvement method for overcoming the obstacle of continuous cropping of fruit trees according to claim 5, characterized in that, S4 includes: When the anaerobic suppression index The preset anaerobic suppression threshold is reached and the seedling root risk index is... When the risk level is below the preset seedling root risk threshold, a reoxygenation initiation result is generated; When the anaerobic suppression index The preset anaerobic suppression threshold was not reached and the seedling root risk index was not met. When the risk level is below the preset seedling root risk threshold, an anaerobic maintenance result is generated, and the anaerobic soil is covered and sealed according to the anaerobic maintenance result. When the seedling risk index When the risk threshold for seedling roots is reached or exceeded, a risk reoxygenation result is generated. Based on the reoxygenation initiation results or the risk reoxygenation results, the anaerobic soil is subjected to methods such as removing the film, opening and ventilating, tilling and ventilating, or intermittent aeration to obtain the reoxygenated soil.

7. The soil improvement method for overcoming the obstacle of continuous cropping of fruit trees according to claim 1, characterized in that, S5 includes: The soil redox potential rise value, volatile fatty acid decrease rate, pH stability, pathogen rebound rate, and soil moisture content during the reoxygenation stage of the soil under reoxygenation treatment were obtained to form the reoxygenation status data. The basic repopulation window index is generated based on the soil redox potential rise during the reoxygenation stage, the volatile fatty acid decline rate during the reoxygenation stage, the pH stability during the reoxygenation stage, and the pathogen rebound rate during the reoxygenation stage. A moisture content correction coefficient is determined based on the soil moisture content during the reoxygenation stage, and the basic repopulation window index is corrected based on the moisture content correction coefficient to obtain the corrected repopulation window index. The beneficial microorganisms were repopulated in batches based on the modified repopulation window index.

8. The soil improvement method for overcoming the obstacle of continuous cropping of fruit trees according to claim 7, characterized in that, The basic repopulation window index RWI satisfies the following relationship: ； in, This refers to the increase in soil redox potential during the reoxygenation stage. The rate of decrease in volatile fatty acids during the reoxygenation phase. This refers to the pH stability during the reoxygenation phase. The pathogen rebound rate during the reoxygenation phase. , , , The pre-set repopulation window weight coefficient; The modified repopulation window index The following relationship must be satisfied: ； in, This is the moisture content correction factor; When the modified repopulation window index When the first repopulation threshold is reached, the first beneficial microbial agent is applied; When the modified repopulation window index When the second repopulation threshold is reached, a second beneficial microbial agent is applied to obtain the batch repopulation results of the beneficial microorganisms. Wherein, the second repopulation threshold is greater than the first repopulation threshold.

9. The soil improvement method for overcoming the obstacle of continuous cropping of fruit trees according to claim 8, characterized in that, The first beneficial microbial agent includes hypoxia-resistant antagonistic bacteria, and the second beneficial microbial agent includes growth-promoting bacteria, autotoxic substance-degrading bacteria, or mycorrhizal fungi; After the first beneficial microbial agent is applied, first repopulation monitoring data is obtained, which includes the colonization rate of the first beneficial microorganism, the abundance of the first pathogenic bacteria, and the residual value of the first volatile fatty acid. A repopulation feedback coefficient is generated based on the colonization rate of the first beneficial microorganism, the residual abundance of the first pathogen, and the residual value of the first volatile fatty acid. The modified repopulation window index is then adjusted based on the repopulation feedback coefficient. The update is performed to obtain the updated and corrected repopulation window index; The timing of application of the second beneficial microbial agent is determined based on the updated and corrected repopulation window index; After the second beneficial microbial agent is applied, second recolonization monitoring data is obtained, and the batch recolonization results of the beneficial microorganisms are generated based on the second recolonization monitoring data. The second recolonization monitoring data includes the colonization rate of the second beneficial microorganisms and the abundance of residual pathogens.

10. The soil improvement method for overcoming the obstacle of continuous cropping of fruit trees according to claim 1, characterized in that, S6 includes: The following data were obtained after the completion of the batch reclamation of the beneficial microorganisms: soil redox potential, residual value of volatile fatty acids, soil EC, pH, ratio of ammonium nitrogen to nitrate nitrogen, soil respiration rate and seedling root elongation rate, to form the rhizosphere safety data. The root zone security index is generated based on the root zone security data; When the rhizosphere safety index reaches the preset planting safety threshold, a planting permission result is generated; When the rhizosphere safety index does not reach the preset planting safety threshold, a temporary planting delay result is generated, and a reoxygenation correction parameter is generated based on the rhizosphere safety data.

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