Method for determining surplus of potato allowed phosphate fertilizer application in area

Abstract

The invention provides a method for determining the allowable phosphate fertilizer application surplus of regional potatoes, and relates to the technical field of methods for determining the allowable phosphate fertilizer application surplus, and the method comprises the steps: calculating the soil environment parameters of a whole region based on a spatial distribution diagram; constructing a phosphorus demand segmented estimation model to evaluate the phosphorus fertilizer demand of the potatoes; a soil phosphorus double-factor correction method is adopted to calculate the total effective phosphorus amount of soil, the phosphorus fertilizer surplus amount of the area is calculated, the phosphorus fertilizer surplus amount allowed to be applied is calculated, a phosphorus fertilizer accumulated surplus limit feedback method is adopted to further optimize the phosphorus fertilizer surplus amount allowed to be applied, and through regular grid point distribution and spatial interpolation, the phosphorus fertilizer surplus amount allowed to be applied is calculated. Fine differences of soil pH, humidity and phosphorus content in space can be accurately captured, growth periods are dynamically divided by introducing cumulative growth days, and dynamic feedback of fertilizer demand evaluation is realized.

Description

Technical Field

[0001] This invention relates to the technical field of methods for determining the allowable surplus of phosphate fertilizer application, specifically a method for determining the allowable surplus of phosphate fertilizer application in regional potato cultivation. Background Technology

[0002] In regional potato cultivation, the rational application of phosphate fertilizer is crucial for ensuring yield and controlling agricultural non-point source pollution. Traditional methods for determining phosphate fertilizer application rates typically rely on simple averages of soil test results combined with empirical fertilization formulas. While convenient, this approach ignores the spatial heterogeneity of soil parameters, and the average values ​​from random sampling are insufficient to represent the true regional conditions, leading to under-fertilization in some areas and over-fertilization in others. Furthermore, traditional methods often employ fixed fertilization amounts for the growing season, failing to adjust in real-time according to annual weather conditions. They also fail to adequately consider the significant impacts of soil environmental factors such as pH and humidity on phosphorus availability and crop absorption efficiency, resulting in a large discrepancy between applied and usable phosphorus. Finally, the lack of effective feedback control mechanisms fails to prevent the environmental risks caused by long-term cumulative over-fertilization.

[0003] In the prior art, patent document CN119744627A discloses a method for determining the allowable surplus range of phosphate fertilizer by controlling the amount of phosphate fertilizer applied to the apparent phosphorus balance level of the soil and plant system. However, this method does not dynamically divide the growth cycle by accumulating growth days and construct a segmented phosphorus demand model by combining the daily growth days and light duration to achieve dynamic adjustment of crop fertilizer requirements with meteorological conditions and growth process; it does not introduce pH and humidity dual factors to correct the effectiveness of soil phosphorus, nor does it use nutrient absorption efficiency to correct the application amount, so that the assessment of soil phosphorus supply capacity and fertilizer effective utilization rate is closer to the actual situation; it does not achieve dynamic optimization and total amount control of the fertilization process through a closed-loop feedback mechanism of residual amount update and cumulative surplus upper limit, thus eliminating the risk of non-point source pollution caused by long-term excessive fertilization. Therefore, there is an urgent need for a method to determine the allowable surplus of phosphate fertilizer application for potatoes in a region.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for determining the allowable surplus of phosphate fertilizer application in regional potatoes, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The method for determining the allowable surplus of phosphate fertilizer application in regional potatoes includes the following steps: S1: Divide the area into several regular grids, set up sampling points in each grid, and collect soil environmental parameters at each sampling point. The soil environmental parameters include soil moisture, soil pH value and residual phosphorus concentration. S2: Based on the soil environmental parameters of each sampling point, a spatial distribution map of the soil environmental parameters of the entire region is generated using spatial interpolation. The soil environmental parameters of each point in the spatial distribution map are evaluated to obtain the reference soil environmental parameters of the region. S3: Obtain the cumulative growth days of potatoes in the region up to the current day, determine the growth cycle of potatoes by the cumulative growth days, and construct a segmented estimation model of phosphorus demand for potatoes in different growth cycles to evaluate the amount of phosphorus fertilizer required by potatoes in the current growth cycle. S4: Soil moisture and soil pH are used as two factors to correct the residual concentration of phosphorus to obtain the total amount of available phosphorus in the soil. Based on the total amount of available phosphorus in the soil and the phosphorus fertilizer requirement of potatoes during their growth stages, the phosphorus fertilizer surplus of the region is calculated. The phosphorus fertilizer surplus represents the difference between the available phosphorus fertilizer in the soil and the requirement of potatoes. S5: Based on the regional phosphate fertilizer surplus and combined with the soil nutrient absorption efficiency, calculate the allowable phosphate fertilizer surplus and use the phosphate fertilizer cumulative surplus limit feedback method to optimize the allowable phosphate fertilizer application amount to obtain the final allowable phosphate fertilizer application surplus.

[0007] Furthermore, a spatial distribution map of the soil environmental parameters in the region is generated, and the specific steps are as follows: For any unsampled location within the region, a neighborhood of the point to be predicted is constructed with the predicted point's location as the center and a set spatial distance threshold as the radius. Soil environmental parameters of sampling points within the neighborhood are obtained. The distance between the point to be predicted and each sampling point in the neighborhood is calculated. The ratio of the reciprocal of the square of the distance between each sampling point in the neighborhood and the point to be predicted to the sum of the reciprocals of the squares of the distances between all sampling points in the neighborhood and the point to be predicted is calculated. This ratio is determined as the weighting coefficient of that sampling point relative to the point to be predicted. The soil environmental parameters of each category at all sampling points in the neighborhood are multiplied by their corresponding weighting coefficients and then summed to obtain the soil moisture, soil pH and residual phosphorus concentration at the point to be predicted. The spatial distribution map of soil environmental parameters for the region is generated by calculating the parameters for each unknown location within the region.

[0008] Furthermore, the reference soil environmental parameters for the region are obtained through the following steps: For each type of soil environmental parameter, including soil moisture, soil pH, and residual phosphorus concentration, the K-means clustering algorithm was used to cluster the spatial distribution map of the entire region according to the type of soil environmental parameter, dividing it into different categories. The clustering results are converted into vector maps, the actual geographic area occupied by each category is calculated, and the average parameter within each category is calculated as the representative parameter of that category. By using the actual geographical area of ​​each category as the weight, a weighted average of representative parameters for each category is calculated to obtain reference values ​​for soil environmental parameters for each type. Reference values ​​for all types of soil environmental parameters are statistically analyzed and used as reference soil environmental parameters for the region.

[0009] Furthermore, the cumulative growth days of potatoes up to that day are calculated based on the temperature in the region. The specific steps are as follows: Obtain the daily maximum and minimum temperatures in the region from potato planting to the current day. Add the daily maximum and minimum temperatures together and divide by 2 to calculate the daily average temperature. Subtract the baseline temperature at which the potatoes began to grow from the daily average temperature to obtain the daily growth days of the potatoes. The daily growth days are accumulated to obtain the cumulative growth days up to that day. Based on a preset cumulative growth day threshold range, the current growth cycle of the potato is determined, specifically: When the cumulative growth days are not greater than the preset first cumulative growth days, the potato is determined to be in the seedling stage; when the cumulative growth days are greater than the preset first cumulative growth days but not greater than the preset second cumulative growth days, the potato is determined to be in the tuber formation stage; when the cumulative growth days are greater than the preset second cumulative growth days, the potato is determined to be in the tuber enlargement stage.

[0010] Furthermore, assess the phosphate fertilizer requirements of potatoes at their current growth stage. The specific steps are as follows: ; in, This indicates the remaining unmet phosphorus requirement for potatoes in the current cycle; This indicates the actual amount of sunlight the potatoes received on that day; This indicates the duration of light saturation during the tuber formation period of potatoes; This indicates the index number of the potato's growth cycle. This indicates that the potatoes are in the seedling stage; This indicates that the potato is in the tuber formation stage; This indicates that the potato is in the tuber enlargement stage; This indicates the potato's growth period on that day; This indicates the number of days that the potato has been in its current growth cycle. This represents the theoretical total length of days during the potato seedling stage. This represents the theoretical total growth days during the potato tuber formation period; This represents the theoretical total growth days during the tuber enlargement period of potatoes; This represents the total theoretical phosphorus requirement during the potato seedling stage; This represents the total theoretical phosphorus requirement during the potato tuber formation period; This represents the total theoretical phosphorus requirement during the tuber enlargement period of potatoes; This represents the theoretical total number of days in the potato seedling stage; This represents the theoretical total number of days during the potato tuber enlargement period; This indicates that the current cycle is from day 1 to day 2. The sum of the actual amount of phosphorus applied each day.

[0011] Further, the total available phosphorus in the soil of the area is calculated, specifically through the following steps: Soil moisture and soil pH were used as two factors to calculate the total available phosphorus in the soil using the soil phosphorus two-factor correction method. ; in, This indicates the total available phosphorus in the soil within the region on that day. This indicates the soil pH level in the area on that day. This indicates the soil moisture level in the area on that day. This indicates the residual concentration of phosphorus in the soil within the region on that day. This indicates the dry weight of soil per unit volume; Indicates the root depth of the potato; Indicates the area of ​​the region.

[0012] Further, the surplus of phosphate fertilizer in the region is calculated, specifically through the following steps: Based on the total available phosphorus in the soil and the phosphorus fertilizer requirement during the potato growth stage, the phosphorus fertilizer surplus in the region is calculated. This phosphorus fertilizer surplus represents the difference between the available phosphorus fertilizer in the soil and the potato's requirement. Specifically: ; in, ; in, Indicates the region's phosphate fertilizer surplus; The potato in the region is the first The theoretical number of days during a growth cycle when phosphorus demand reaches its peak. This indicates that the potato is in the [number]th stage of its growth cycle. The daily demand weight parameter.

[0013] Furthermore, the allowable surplus of phosphate fertilizer was calculated, specifically as follows: Based on the surplus of phosphate fertilizer and the soil's nutrient absorption efficiency, the allowable surplus of phosphate fertilizer to be applied is calculated: ; in, ; This indicates the soil's nutrient absorption efficiency; This indicates the rated maximum absorption efficiency of the soil; This indicates the maximum permissible daily application rate of phosphate fertilizer; This indicates the amount of phosphate fertilizer surplus that is permitted to be applied. express Sensitivity coefficient; This represents the humidity sensitivity coefficient.

[0014] Furthermore, the permitted amount of phosphate fertilizer to be applied is optimized, specifically as follows: The formula used to update the residual amount of phosphate fertilizer in the soil on the day of the update is as follows: ; in, This indicates the residual amount of phosphate fertilizer in the regenerated soil. This indicates the amount of residual phosphate fertilizer in the soil before fertilization. The historical phosphate fertilizer surplus of the region up to the current day is accumulated to calculate the cumulative value of the phosphate fertilizer surplus. The cumulative value of the phosphate fertilizer surplus is compared with the preset upper limit of the total cumulative phosphate surplus of the region. If the cumulative value of the phosphate fertilizer surplus is not less than the upper limit of the total cumulative phosphate surplus, the allowable phosphate fertilizer surplus for the current day is set to 0. When the cumulative value of the phosphate fertilizer surplus is less than the upper limit of the total cumulative phosphate surplus, the phosphate fertilizer surplus of the region is recalculated, and the allowable phosphate fertilizer surplus for potatoes is further updated.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This scheme dynamically divides the growth cycle by accumulating growth days and constructs a segmented phosphorus demand model by combining daily growth days and light duration, enabling dynamic adjustment of crop fertilizer requirements according to meteorological conditions and growth process. It introduces pH and humidity as dual factors to correct soil phosphorus availability and uses nutrient absorption efficiency to adjust application rates, making the assessment of soil phosphorus supply capacity and fertilizer utilization efficiency closer to reality and significantly improving the accuracy of supply and demand balance calculations. Finally, through a closed-loop feedback mechanism of residual amount updates and the upper limit of accumulated surplus, it achieves dynamic optimization and total amount control of the fertilization process, eliminating the risk of non-point source pollution caused by long-term excessive fertilization. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall method flow of the present invention; Figure 2 This is a graph showing the relationship between the number of days in the growth cycle and the surplus of phosphate fertilizer in the corresponding region. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0018] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0019] Example: Please see Figures 1-2 The present invention provides a technical solution: The method for determining the allowable surplus of phosphate fertilizer application in regional potatoes includes the following steps: S1: Divide the area into several regular grids, set up sampling points in each grid, and collect soil environmental parameters at each sampling point. The soil environmental parameters include soil moisture, soil pH value, and residual phosphorus concentration.

[0020] In this embodiment, the area refers to the target potato planting plot that requires precise management of phosphate fertilizer, which is usually a farmland area with clear geographical boundaries, such as a farm, an experimental field, or a contiguous planting area of ​​an agricultural cooperative. The grid division method is a regular grid method, which means that a fixed grid size, such as 50 meters × 50 meters or 100 meters × 100 meters, is set according to the actual area of ​​the region and the required sampling density, and the entire region is divided into several rectangular grids of equal size; the sampling point is set by the grid center point sampling method, that is, the geometric center of each grid is used as a fixed sampling point.

[0021] S2: Based on the soil environmental parameters of each sampling point, a spatial distribution map of the soil environmental parameters of the entire region is generated using spatial interpolation. The soil environmental parameters of each point in the spatial distribution map are evaluated to obtain the reference soil environmental parameters of the region.

[0022] The steps to generate a spatial distribution map of soil environmental parameters in the region are as follows: For any unsampled location within the region, a neighborhood of the point to be predicted is constructed with the predicted point's location as the center and a set spatial distance threshold as the radius. Soil environmental parameters of sampling points within the neighborhood are obtained. The distance between the point to be predicted and each sampling point in the neighborhood is calculated. The ratio of the reciprocal of the square of the distance between each sampling point in the neighborhood and the point to be predicted to the sum of the reciprocals of the squares of the distances between all sampling points in the neighborhood and the point to be predicted is calculated. This ratio is determined as the weighting coefficient of that sampling point relative to the point to be predicted. The soil environmental parameters of each category at all sampling points in the neighborhood are multiplied by their corresponding weighting coefficients and then summed to obtain the soil moisture, soil pH and residual phosphorus concentration at the point to be predicted. The spatial distribution map of soil environmental parameters for the region is generated by calculating the parameters for each unknown location within the region.

[0023] In the above process, the reciprocal of the square of the distance is used to assign a higher weight coefficient to the neighboring sampling points, so that the interpolation results can truly reflect the continuous and gradual change of soil properties in space and avoid local information distortion caused by the discretization of sampling points. At the same time, by setting the radius of the circular neighborhood for local interpolation, it is ensured that the calculation of each point to be predicted is only affected by the most representative sampling points around it, and the calculation efficiency is greatly improved. It is suitable for the needs of high-resolution mapping of large areas, and finally achieves synchronous and accurate interpolation of soil moisture, pH value and residual phosphorus concentration. Determining the spatial distance threshold requires comprehensive consideration of the grid size. An empirical formula based on the grid size is typically used, where the spatial distance threshold is set to 1.5 to 2 times the grid side length. For example, if the grid side length is 50 meters, the threshold radius can be set to 75 to 100 meters. This setting ensures that regardless of the location of the point to be predicted within the grid, its circular neighborhood covers at least 3 to 5 adjacent known sampling points.

[0024] Furthermore, the reference soil environmental parameters for the region are obtained through the following steps: The K-means clustering algorithm was used to cluster the entire region into different categories. The clustering results were converted into vector maps in GIS software. The actual geographical area occupied by each category was calculated. The average parameter of all points in each category was calculated as the representative parameter of that category. Finally, the representative parameters of each category were weighted by the actual geographical area of ​​each category to obtain the reference soil environmental parameters of the region.

[0025] In the above process, the K-means clustering algorithm specifically involves: constructing a multi-dimensional feature vector from the soil moisture, soil pH, and residual phosphorus concentration at each point in the spatial distribution map, which serves as the input data for the K-means clustering algorithm; then, presetting the number of clusters K and randomly initializing... The algorithm iteratively calculates the Euclidean distance from each point to each cluster center, assigning it to the nearest cluster. After each round of assignment, the center point of each cluster is recalculated, where the center point is the mean of all parameters of all points in that cluster. This is used as the basis for the next round of assignment until the cluster centers no longer change significantly or the preset number of iterations is reached. Finally, points with similar attributes throughout the entire region are aggregated into clusters. A category with distinct soil characteristics; The K-means clustering algorithm can be illustrated with the following examples: Suppose we obtain a soil distribution map containing 100 points through spatial interpolation. Each point has two key attributes: soil moisture value and soil pH value. Now we want to divide these points into three regions with different soil characteristics through clustering. At the beginning of the algorithm, three points are randomly selected on the entire spatial distribution map as the initial "cluster centers". These three center points are equivalent to the "cores" of three temporary regions, and their positions are completely randomly determined. The second step involves the algorithm traversing every point on the spatial distribution map and calculating the distance from that point to the three random center points. The distance calculation considers both humidity and pH values, taking into account the proximity of the values. Each point is assigned to the category of the nearest center point. After this round of calculation, the entire area is initially divided into three "spheres of influence" surrounding the random center points. The third step is that after the initial division is completed, the algorithm will recalculate the average humidity and average pH value of all points in each category, and take the position of this average value as the new cluster center. For example, if the average humidity of all points in the first category is 58% and the average pH is 6.8, then this average value point will replace the original random point and become the new center. The algorithm repeats steps two and three: based on the new center points, it recalculates the distance from each point to the three new centers and reassigns them; after the assignment is complete, it updates the center point positions again. In each iteration, the center points move, and the class boundaries are adjusted accordingly. As the number of iterations increases, the movement of the center points becomes smaller and smaller, and the class assignments become more and more stable. Finally, when the positions of the center points hardly change anymore, the algorithm reaches convergence. After multiple iterations, the initial 100 points were stably divided into three categories with distinct characteristics: the first category may be concentrated in areas with high humidity and neutral pH, representing fertile soil areas; the second category may be concentrated in areas with moderate humidity and slightly acidic pH, representing areas that need acidity adjustment; and the third category may be concentrated in areas with low humidity and slightly alkaline pH, representing areas that need improved irrigation. These three categories each form contiguous areas in space, providing a scientific basis for subsequent conversion into vector plots, statistical area calculations, and weighted average calculations.

[0026] The spatial distribution map processed by the K-means clustering algorithm is exported as a raster image with category attribute labels. Each pixel in the image is assigned a category number. Then, the raster-to-vector tool in the GIS software is used to convert this categorized raster image into vector polygon features. During the conversion process, the software automatically identifies pixels with the same category number and spatially adjacent pixels, merges them into an independent vector polygon, and generates a corresponding category attribute field for each polygon. After the conversion, each vector polygon represents a continuous geographic area with the same soil attribute characteristics. Its boundary is formed by the aggregated outline of adjacent pixels. The actual geographic area of ​​each category of vector polygon is calculated using the area calculation function of the GIS software. By performing K-means clustering analysis on a massive number of points in the spatial distribution map, regions with similar soil properties are grouped into the same category and transformed into vector plots. Clustering reveals the inherent differentiation patterns of soil parameters within the region, enabling the representative parameters of each category to truly reflect the typical characteristics of that type of soil. At the same time, a weighted average is performed using the actual geographical area of ​​each category as the weight, so that the final regional reference value not only retains the numerical characteristics of soil properties but also accurately reflects the spatial area proportion of different attribute categories, effectively avoiding the result bias caused by uneven sampling density or extreme value interference.

[0027] S3: Obtain the cumulative growth days of potatoes in the region up to the current day, determine the growth cycle of potatoes by the cumulative growth days, and construct a segmented estimation model of phosphorus demand for potatoes in different growth cycles to evaluate the amount of phosphorus fertilizer required by potatoes in the current growth cycle.

[0028] In this embodiment, the cumulative growth degree-days of potatoes up to the current day are calculated based on the temperature in the region. The specific steps are as follows: Obtain the daily maximum and minimum temperatures in the region from potato planting to the current day. Add the daily maximum and minimum temperatures together and divide by 2 to calculate the daily average temperature. Subtract the baseline temperature at which the potatoes began to grow from the daily average temperature to obtain the daily growth days of the potatoes. The daily growth days are accumulated to obtain the cumulative growth days up to that day. Based on a preset cumulative growth day threshold range, the current growth cycle of the potato is determined, specifically: When the cumulative growth days are not greater than the preset first cumulative growth days, the potato is determined to be in the seedling stage; when the cumulative growth days are greater than the preset first cumulative growth days but not greater than the preset second cumulative growth days, the potato is determined to be in the tuber formation stage; when the cumulative growth days are greater than the preset second cumulative growth days, the potato is determined to be in the tuber enlargement stage.

[0029] In the above process, by continuously monitoring the daily maximum and minimum temperatures to calculate and accumulate the daily growth days, the actual impact of interannual temperature fluctuations on potato growth and development can be accurately reflected, avoiding misjudgments such as "the date has arrived but the accumulated temperature is insufficient" or "the accumulated temperature is sufficient but the date has not arrived" caused by abnormal temperatures. By discretizing the continuous accumulated growth days into three key growth stages—seedling stage, tuber formation stage, and tuber enlargement stage—the assessment of phosphorus fertilizer demand is kept highly synchronized with the actual physiological processes of the crop. Obtaining the daily maximum and minimum temperatures within a region from the potato planting date up to the current day typically relies on regional meteorological monitoring networks or publicly available meteorological data services. In practice, the geographical coordinates of the target area must first be determined. Then, access is provided to nearby national benchmark meteorological stations, automatic weather stations, or gridded meteorological forecasting data platforms. The actual daily maximum and minimum temperatures can be obtained through the daily recorded data from these facilities. The determination of the first and second cumulative growth days was achieved by consulting local agricultural technology extension manuals or variety cultivation data to obtain the physiological duration or effective accumulated temperature range required for the tested potato varieties from emergence to tuber formation and from tuber formation to tuber enlargement. Subsequently, combined with long-term historical meteorological data of the region, the average cumulative growth days with daily average temperatures higher than the benchmark temperature during the corresponding period were statistically calculated, and appropriate corrections were made considering the interannual fluctuation range. Finally, the thresholds for the first and second cumulative growth days that can accurately divide the potato growth cycle in this region were determined.

[0030] The specific steps to assess the phosphate fertilizer requirements of potatoes at their current growth stage are as follows: Based on different growth stages of potatoes and the daily growth days of potatoes, a segmented estimation model for phosphorus requirement is constructed to assess the phosphorus fertilizer demand of potatoes. Specifically: ; in, This indicates the remaining unmet phosphorus requirement for potatoes in the current cycle; This indicates the actual amount of sunlight the potatoes received on that day; This indicates the duration of light saturation during the tuber formation period of potatoes; This indicates the index number of the potato's growth cycle. This indicates that the potatoes are in the seedling stage; This indicates that the potato is in the tuber formation stage; This indicates that the potato is in the tuber enlargement stage; This indicates the potato's growth period on that day; This indicates the number of days that the potato has been in its current growth cycle. This represents the theoretical total length of days during the potato seedling stage. This represents the theoretical total growth days during the potato tuber formation period; This represents the theoretical total growth days during the tuber enlargement period of potatoes; This represents the total theoretical phosphorus requirement during the potato seedling stage; This represents the total theoretical phosphorus requirement during the potato tuber formation period; This represents the total theoretical phosphorus requirement during the tuber enlargement period of potatoes; This represents the theoretical total number of days in the potato seedling stage; This represents the theoretical total number of days during the potato tuber enlargement period; This indicates that the current cycle is from day 1 to day 2. The sum of the actual amount of phosphorus applied each day.

[0031] In the above process, the formula is jointly determined by multiple factors. The value of . Total demand according to periodic theory. , , As a total quantity constraint, this determines the upper limit of fertilizer requirement at this stage; the amount already applied... This reflects the cumulative effect of historical fertilization, and the two together constitute the basis of surplus demand. , , Daily heat factor This characterizes the proportion of daily heat accumulation to the total heat of the cycle, reflecting the positive correlation between fertilizer requirement and developmental progress; the morphological coefficients are designed according to the differences in the growth cycle, with a linearly increasing function used in the seedling stage. Simulating the process of gradually increasing nutrient demand during root development, a parabolic function was used to describe the inverted U-shaped relationship of nutrient demand intensity, which first increases and then decreases, during the tuber enlargement stage. The influence of light was introduced during the tuber formation stage. This reflects the promoting effect of photosynthesis on phosphorus absorption; ultimately, it is achieved by minimizing the theoretical demand and the remaining demand. Ensure that the recommended quantity for the day does not exceed the total limit; Growth day of the day and There is a positive correlation, meaning that the greater the daily heat contribution, the greater the fertilizer requirement. (This is related to) duration of sunlight. During the tuber formation period and There is a positive correlation: the more abundant the sunlight, the greater the theoretical fertilizer requirement. During the seedling stage, the number of growth days... and There is a positive correlation, reflecting the pattern that the fertilizer requirement gradually increases as the seedlings grow. During the tuber enlargement period, the number of growth days... and It exhibits an inverted U-shaped relationship of initial positive correlation followed by negative correlation, meaning that the fertilizer requirement peaks in the middle of the cycle and then gradually decreases, accurately simulating the physiological process of slow-fast-slow tuber enlargement rate. During the seedling stage, the segmented estimation model of phosphorus demand uses a morphological coefficient that increases linearly with the number of days of growth, accurately simulating the biological process of gradually increasing phosphorus demand as the root system develops during the seedling stage. During the tuber formation stage, the duration of light is introduced as a regulating factor, scientifically demonstrating the significant promoting effect of photosynthetic product supply capacity on phosphorus absorption efficiency at this stage. During the tuber enlargement stage, a parabolic function is used to describe the slow-fast-slow growth pattern of fertilizer demand intensity, which first increases and then decreases with the number of days, highly consistent with the actual physiological process of tuber enlargement.

[0032] S4: The residual concentration of phosphorus is corrected by soil moisture and soil pH as two factors to obtain the total amount of available phosphorus in the soil. Based on the total amount of available phosphorus in the soil and the phosphorus fertilizer requirement of potatoes at different growth stages, the phosphorus fertilizer surplus of the region is calculated. The phosphorus fertilizer surplus represents the difference between the available phosphorus fertilizer in the soil and the requirement of potatoes.

[0033] In this embodiment, the total available phosphorus in the soil of the area is calculated through the following steps: Soil moisture and soil pH were used as two factors to calculate the total available phosphorus in the soil using the soil phosphorus two-factor correction method. ; in, This indicates the total available phosphorus in the soil within the region on that day. This indicates the soil pH level in the area on that day. This indicates the soil moisture level in the area on that day. This indicates the residual concentration of phosphorus in the soil within the region on that day. This indicates the dry weight of soil per unit volume; Indicates the root depth of the potato; Indicates the area of ​​the region.

[0034] In the above process, the residual phosphorus concentration measured in the laboratory is converted into the total amount of phosphorus actually available in the field. At the same time, the interference of pH and humidity on phosphorus availability is eliminated through environmental factor correction, providing accurate supply-side data for subsequent calculation of phosphate fertilizer surplus. pH correction factor This reflects the inhibitory effect of pH deviation from the optimum on phosphorus availability, and the humidity correction factor. This reflects the impact of humidity deviations from optimal conditions on phosphorus availability. Soil bulk density. Root depth and area product Convert the concentration unit to the total mass in the specified soil mass, with a constant of 10 as the unit conversion factor to ensure that the units of each physical quantity are consistent. Soil phosphorus residual concentration and There is a positive correlation, meaning that the higher the phosphorus content in the soil, the greater the total available phosphorus. (The pH correction factor...) and There is a negative correlation, meaning the further the pH deviates from neutral, the greater the decrease in phosphorus availability; the humidity correction factor... and There is a negative correlation, meaning that the further the humidity deviates from the optimal conditions, the greater the decrease in phosphorus availability; soil bulk density Root depth and area All with There is a positive correlation, that is, the denser the soil, the deeper the root system, and the larger the area, the greater the total available phosphorus. A value of 6.5 is the critical point for the highest soil phosphorus availability for most crops, including potatoes. When the pH is around 6.5, phosphorus in the soil mainly exists in the forms of H2PO4⁻ and HPO4²⁻, which are most easily absorbed by crop roots. The coefficient 0.02 indicates that for every unit of pH value deviating from the optimum value of 6.5, the availability of phosphorus decreases by an average of 2%. This is an empirical coefficient based on statistics from a large number of soil chemical experiments, reflecting the intensity of pH's regulation of phosphorus availability by affecting the phosphorus precipitation-dissolution balance and microbial activity. Soil moisture of 60% usually corresponds to the suitable range of field water holding capacity. At this level, the soil moisture meets the crop's absorption needs while ensuring soil aeration, which is conducive to phosphorus diffusion and root absorption. A coefficient of 0.05 indicates that for every ten percentage points that soil moisture deviates from the optimal value of 60%, the availability of phosphorus decreases by an average of 5%. This is because excessively low humidity will inhibit the diffusion and migration of phosphorus, while excessively high humidity will lead to poor aeration and reduce root activity. This coefficient was obtained by fitting field humidity gradient experiments. 10 is a comprehensive result of unit conversion, stemming from the need to convert soil phosphorus residue concentration from milligrams per kilogram to kilograms per hectare; specifically, when Units are , The unit is g / cm³, and D is in meters. Units are hour, Therefore, multiplying by 10 yields the total available phosphorus in the soil in kilograms, ensuring that the units of all physical quantities in the formula are consistent and that the calculation results have practical agronomic significance.

[0035] The specific steps for calculating the phosphate fertilizer surplus in the region are as follows: Based on the total available phosphorus in the soil and the phosphorus fertilizer requirement during the potato growth stage, the phosphorus fertilizer surplus in the region is calculated. This phosphorus fertilizer surplus represents the difference between the available phosphorus fertilizer in the soil and the potato's requirement. Specifically: ; in, ; in, Indicates the region's phosphate fertilizer surplus; The potato in the region is the first The theoretical number of days during a growth cycle when phosphorus demand reaches its peak. This indicates that the potato is in the [number]th stage of its growth cycle. The daily demand weight parameter.

[0036] In the above process, by quantifying the supply and demand balance between soil phosphorus supply and crop phosphorus requirements, a direct basis is provided for subsequent decisions on whether and how much fertilizer to apply: when This indicates that the soil is deficient in phosphorus and needs supplemental fertilization. This indicates that the soil has sufficient phosphorus supply and no additional fertilization is needed, realizing the transformation of fertilization decisions from experience-based judgment to quantitative assessment; Total available phosphorus in soil As a phosphorus-supplying input, it represents the total amount of phosphorus that the soil can actually provide after adjusting for environmental factors; the higher the value, the greater the phosphorus fertilizer surplus. The larger the amount; the greater the daily phosphorus requirement of potatoes As the phosphorus-demanding input, among which This is a dynamic phosphorus demand index. Demand weighting parameters For the area, This is a unit conversion factor; this part reflects the actual phosphorus requirement of crops under the current growth stage, daily environmental conditions, and physiological processes. The higher the value, the greater the phosphorus fertilizer surplus. The smaller; demand weight parameter Using a piecewise function definition, when the number of growth days... In When within range, Follow The changes exhibit a parabolic shape, first increasing and then decreasing, simulating the slow-fast-slow variation pattern of crop fertilizer requirement intensity during its growth cycle; when When outside this range This indicates that the growth cycle has not yet begun or has already ended. Total available phosphorus in soil and There is a positive correlation, meaning the stronger the soil's phosphorus supply capacity, the greater the phosphorus fertilizer surplus. The total daily phosphorus requirement of potatoes and There is a negative correlation, meaning that the higher the crop's phosphorus requirement, the smaller the phosphorus fertilizer surplus; demand weighting parameter and There is a negative correlation, meaning that during periods of higher fertilizer demand in the growth cycle, the daily phosphorus requirement is greater, leading to a surplus. Decrease accordingly; With growth days The changes exhibit an inverted U-shaped relationship, initially positively correlated and then negatively correlated, reflecting the impact of fertilizer demand intensity on the period around its peak in the middle of the cycle. The impact of differentiation.

[0037] In the above embodiments, 15 sets of data on the number of days in the growth cycle and the corresponding phosphate fertilizer surplus in the region are provided to reflect the change in the phosphate fertilizer surplus in the region as the number of days in the growth cycle changes, as shown in Table 1: Table 1: Relationship between the number of days in the growth cycle and the corresponding phosphate fertilizer surplus in the region

[0038] In Table 1 above, it is determined that the potato is currently in the tuber formation stage, and the following information is provided: , , , You can see With growth days The changes exhibit an inverted U-shaped relationship, initially positively correlated and then negatively correlated, reflecting the impact of fertilizer demand intensity on the period around its peak in the middle of the cycle. The impact of differentiation.

[0039] S5: Based on the regional phosphate fertilizer surplus and combined with the soil nutrient absorption efficiency, calculate the allowable phosphate fertilizer surplus and use the phosphate fertilizer cumulative surplus limit feedback method to optimize the allowable phosphate fertilizer application amount to obtain the final allowable phosphate fertilizer application surplus.

[0040] In this embodiment, the allowable surplus of phosphate fertilizer is calculated as follows: Based on the surplus of phosphate fertilizer and the soil's nutrient absorption efficiency, the allowable surplus of phosphate fertilizer to be applied is calculated: ; in, ; This indicates the soil's nutrient absorption efficiency; This indicates the rated maximum absorption efficiency of the soil; This indicates the maximum permissible daily application rate of phosphate fertilizer; This indicates the amount of phosphate fertilizer surplus that is permitted to be applied. express Sensitivity coefficient; This represents the humidity sensitivity coefficient.

[0041] In the above process, the phosphorus deficiency was corrected by introducing soil nutrient absorption efficiency and constrained by the daily safety limit, thus achieving precise quantification and risk control of fertilizer application: when the soil is deficient in phosphorus, the application amount is calculated according to the principle of "supplementing as much as is lacking but not exceeding the absorption capacity and safety threshold", and when the soil is not deficient in phosphorus, fertilization is prohibited, which effectively avoids the waste of resources and environmental risks caused by excessive fertilization. Phosphate fertilizer surplus As a basis for decision-making, when This indicates that the soil is not supplying enough phosphorus and needs to be supplemented. Only with sufficient phosphorus can the crop's needs be met; when This indicates sufficient phosphorus supply, requiring no fertilization; soil nutrient absorption efficiency Phosphorus deficiency Make corrections. This indicates the actual amount of phosphate fertilizer that needs to be applied, taking into account the possibility that the fertilizer cannot be completely absorbed. The higher the value, the greater the allowable application rate; the maximum allowable daily application rate of phosphate fertilizer. As a safety threshold, take and The smaller the value, the more ensure that the amount of fertilizer applied in a single application does not exceed the environmental safety or crop tolerance limit; soil nutrient absorption efficiency It is itself rated by maximum absorption efficiency. through Sensitivity coefficient Humidity sensitivity coefficient The corrections reflect the real-time impact of the soil environment on fertilizer utilization. Phosphate fertilizer surplus absolute value and There is a positive correlation; that is, the more severe the phosphorus deficiency in the soil, the higher the allowable application rate. Soil nutrient uptake efficiency. and There is a negative correlation, meaning that the lower the fertilizer utilization rate, the more phosphorus needs to be applied to make up for the same amount of phosphorus deficiency. Degree of deviation and It shows a negative correlation, and thus indirectly with They are positively correlated, that is The further the deviation from the optimal value, the lower the absorption efficiency, requiring more phosphate fertilizer to be applied. Degree of humidity deviation and It shows a negative correlation, and thus indirectly with There is a positive correlation; that is, the further the humidity deviates from the optimal conditions, the lower the absorption efficiency, and the more phosphate fertilizer is needed. Maximum permissible daily application rate. As an upper limit constraint, when When the threshold is exceeded, Pick The decision not to increase further reflects the principle of prioritizing safety.

[0042] use The optimal baseline values ​​of 6.5 and 65% humidity are based on scientific principles of soil chemistry and crop physiology. A phosphorus content of 6.5 is the critical point for the highest availability of soil phosphorus for most crops, including potatoes. At this value, soil phosphorus exists mainly in the forms of H₂PO₄⁻ and HPO₄²⁻, is not easily fixed by calcium, iron, aluminum, or other ions, and is most easily absorbed by crop roots. Therefore, it is considered a critical value. The baseline for the influence of humidity is 65%. A humidity level of 65% usually corresponds to the suitable range of field water holding capacity. At this level, the soil moisture meets the crop's absorption needs and ensures soil aeration, which is conducive to the diffusion and migration of phosphorus and root respiration and metabolism. It can maximize the absorption activity of the root system, so it is used as the baseline value for the influence of humidity.

[0043] The permitted amount of phosphate fertilizer to be applied has been optimized, specifically as follows: The formula used to update the residual amount of phosphate fertilizer in the soil on the day of the update is as follows: ; in, This indicates the residual amount of phosphate fertilizer in the regenerated soil. This indicates the amount of residual phosphate fertilizer in the soil before fertilization. In the above process, real-time tracking of dynamic changes in soil phosphorus was achieved. By quantifying the residual accumulation after each fertilization, an updated initial state was provided for subsequent recalculation of surplus and fertilization decisions, enabling the entire system to form a closed-loop control. The formula is determined by the principle of conservation of mass. The value of . The residual amount of soil phosphate fertilizer before fertilization on that day. This initial state determines the baseline level of residual phosphorus. The permissible amount of phosphate fertilizer to be applied that day. As an input, it represents the total amount of newly applied phosphate fertilizer to the soil; soil nutrient uptake efficiency. This determines the proportion of newly applied phosphate fertilizer that is absorbed by the crop, and This indicates the proportion of substances that were not absorbed and remained; the three are... The relationship coupling reflects the cumulative pattern of original soil phosphorus residues plus newly added residues; Residual amount of phosphate fertilizer in the soil before fertilization and There is a positive correlation, meaning the greater the original residue, the greater the residue after renewal. Daily application rate. and There is a positive correlation, meaning that the more fertilizer applied, the more residues are added; nutrient absorption efficiency and There is a negative correlation, meaning that the higher the fertilizer utilization rate, the less residue there is; The historical phosphate fertilizer surplus of the region up to the current day is accumulated to calculate the cumulative value of the phosphate fertilizer surplus. The cumulative value of the phosphate fertilizer surplus is compared with the preset upper limit of the total cumulative phosphate surplus of the region. If the cumulative value of the phosphate fertilizer surplus is not less than the upper limit of the total cumulative phosphate surplus, the allowable phosphate fertilizer surplus for the current day is set to 0. When the cumulative value of the phosphate fertilizer surplus is less than the upper limit of the total cumulative phosphate surplus, the phosphate fertilizer surplus of the region is recalculated, and the allowable phosphate fertilizer surplus for potatoes is further updated.

[0044] In the above process, the cumulative total control process dynamically tracks the total amount of phosphorus remaining in the regional soil by accumulating the historical surplus of phosphate fertilizer and comparing it with the preset environmental safety limit. When the cumulative value reaches or exceeds the environmental carrying capacity threshold, subsequent fertilization is automatically prohibited, thus eliminating the risk of soil phosphorus saturation and non-point source pollution caused by years of continuous excessive fertilization. When the cumulative value is lower than the safety limit, the application amount is allowed to be recalculated and updated, forming a closed-loop control system of "monitoring-comparison-decision-feedback".

[0045] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0046] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0047] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0048] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for determining the allowable surplus of phosphate fertilizer application in regional potatoes, characterized by the following steps: include: S1: Divide the area into several regular grids, set up sampling points in each grid, and collect soil environmental parameters at each sampling point. The soil environmental parameters include soil moisture, soil pH value and residual phosphorus concentration. S2: Based on the soil environmental parameters of each sampling point, a spatial distribution map of the soil environmental parameters of the entire region is generated using spatial interpolation. The soil environmental parameters of each point in the spatial distribution map are evaluated to obtain the reference soil environmental parameters of the region. S3: Obtain the cumulative growth days of potatoes in the region up to the current day, determine the growth cycle of potatoes by the cumulative growth days, and construct a segmented estimation model of phosphorus demand for potatoes in different growth cycles to evaluate the amount of phosphorus fertilizer required by potatoes in the current growth cycle. S4: Soil moisture and soil pH are used as two factors to correct the residual concentration of phosphorus to obtain the total amount of available phosphorus in the soil. Based on the total amount of available phosphorus in the soil and the phosphorus fertilizer requirement of potatoes during their growth stages, the phosphorus fertilizer surplus of the region is calculated. The phosphorus fertilizer surplus represents the difference between the available phosphorus fertilizer in the soil and the requirement of potatoes. S5: Based on the regional phosphate fertilizer surplus and combined with the soil nutrient absorption efficiency, calculate the allowable phosphate fertilizer surplus and use the phosphate fertilizer cumulative surplus limit feedback method to optimize the allowable phosphate fertilizer application amount to obtain the final allowable phosphate fertilizer application surplus.

2. The method for determining the regional allowable surplus of phosphate fertilizer application for potatoes according to claim 1, characterized in that, The steps to generate a spatial distribution map of soil environmental parameters in the region are as follows: For any unsampled location within the region, a neighborhood of the point to be predicted is constructed with the predicted point's location as the center and a set spatial distance threshold as the radius. Obtain the soil environmental parameters of the sampling points in the neighborhood, calculate the distance between the point to be predicted and each sampling point in the neighborhood, and calculate the ratio of the reciprocal of the square of the distance between each sampling point in the neighborhood and the point to be predicted to the sum of the reciprocals of the squares of the distances between all sampling points in the neighborhood and the point to be predicted. Determine this ratio as the weight coefficient of the sampling point relative to the point to be predicted. The soil environmental parameters of each category at all sampling points in the neighborhood are multiplied by their corresponding weighting coefficients and then summed to obtain the soil moisture, soil pH and residual phosphorus concentration at the point to be predicted. The spatial distribution map of soil environmental parameters for the region is generated by calculating the parameters for each unknown location within the region.

3. The method for determining the regional allowable surplus of phosphate fertilizer application for potatoes according to claim 2, characterized in that, The steps for determining the reference soil environmental parameters for the region are as follows: For each type of soil environmental parameter, including soil moisture, soil pH, and residual phosphorus concentration, the K-means clustering algorithm was used to cluster the spatial distribution map of the entire region according to the type of soil environmental parameter, dividing it into different categories. The clustering results are converted into vector maps, the actual geographic area occupied by each category is calculated, and the average parameter within each category is calculated as the representative parameter of that category. By using the actual geographical area of ​​each category as the weight, a weighted average of representative parameters for each category is calculated to obtain reference values ​​for soil environmental parameters for each type. Reference values ​​for all types of soil environmental parameters are statistically analyzed and used as reference soil environmental parameters for the region.

4. The method for determining the regional allowable surplus of phosphate fertilizer application for potatoes according to claim 1, characterized in that, The cumulative growth days of potatoes up to the current day are calculated based on the temperature in the region. The specific steps are as follows: Obtain the daily maximum and minimum temperatures in the region from potato planting to the current day. Add the daily maximum and minimum temperatures together and divide by 2 to calculate the daily average temperature. Subtract the baseline temperature at which the potatoes began to grow from the daily average temperature to obtain the daily growth days of the potatoes. The daily growth days are accumulated to obtain the cumulative growth days up to that day. Based on a preset cumulative growth day threshold range, the current growth cycle of the potato is determined, specifically: When the cumulative growth days are not greater than the preset first cumulative growth days, the potato is determined to be in the seedling stage; when the cumulative growth days are greater than the preset first cumulative growth days but not greater than the preset second cumulative growth days, the potato is determined to be in the tuber formation stage; when the cumulative growth days are greater than the preset second cumulative growth days, the potato is determined to be in the tuber enlargement stage.

5. The method for determining the regional allowable phosphate fertilizer application surplus for potatoes according to claim 4, characterized in that, The specific steps to assess the phosphate fertilizer requirements of potatoes at their current growth stage are as follows: Based on different growth stages of potatoes and the daily growth days of potatoes, a segmented estimation model for phosphorus requirement is constructed to assess the phosphorus fertilizer demand of potatoes. Specifically: in, This indicates the remaining unmet phosphorus requirement for potatoes in the current cycle; This indicates the actual amount of sunlight the potatoes received on that day; This indicates the duration of light saturation during the tuber formation period of potatoes; This indicates the index number of the potato's growth cycle. This indicates that the potatoes are in the seedling stage; This indicates that the potato is in the tuber formation stage; This indicates that the potato is in the tuber enlargement stage; This indicates the potato's growth period on that day; This indicates the number of days that the potato has been in its current growth cycle; it indicates the theoretical total length of days in the potato seedling stage; and it indicates the theoretical total growth days in the potato tuber formation stage. This represents the theoretical total growth days during the tuber enlargement period of potatoes; This represents the total theoretical phosphorus requirement during the potato seedling stage; This represents the total theoretical phosphorus requirement during the potato tuber formation period; This represents the total theoretical phosphorus requirement during the tuber enlargement period of potatoes; This represents the theoretical total number of days in the potato seedling stage; This represents the theoretical total number of days during the potato tuber enlargement period; This represents the sum of phosphorus amounts actually applied from day 1 to day 2 in the current cycle.

6. The method for determining the regional allowable phosphate fertilizer application surplus for potatoes according to claim 5, characterized in that, The specific steps for calculating the total available phosphorus in the soil of the area are as follows: Soil moisture and soil pH were used as two factors to calculate the total available phosphorus in the soil using the soil phosphorus two-factor correction method. in, This indicates the total available phosphorus in the soil within the region on that day. This indicates the soil pH level in the area on that day. This indicates the soil moisture level in the area on that day. This indicates the residual concentration of phosphorus in the soil within the region on that day. This indicates the dry weight of soil per unit volume; Indicates the root depth of the potato; Indicates the area of ​​the region.

7. The method for determining the regional allowable phosphate fertilizer application surplus for potatoes according to claim 6, characterized in that, The specific steps for calculating the phosphate fertilizer surplus in the region are as follows: Based on the total available phosphorus in the soil and the phosphorus fertilizer requirement during the potato growth stage, the phosphorus fertilizer surplus in the region is calculated. This phosphorus fertilizer surplus represents the difference between the available phosphorus fertilizer in the soil and the potato's requirement. Specifically: in, in, Indicates the region's phosphate fertilizer surplus; The potato in the region is the first The theoretical number of days during a growth cycle when phosphorus demand reaches its peak. This indicates that the potato is in the [number]th stage of its growth cycle. The daily demand weight parameter.

8. The method for determining the regional allowable phosphate fertilizer application surplus for potatoes according to claim 7, characterized in that, The allowable surplus of phosphate fertilizer is calculated as follows: Based on the surplus of phosphate fertilizer and the soil's nutrient absorption efficiency, the allowable surplus of phosphate fertilizer to be applied is calculated: in, This indicates the soil's nutrient absorption efficiency; This indicates the rated maximum absorption efficiency of the soil; This indicates the maximum permissible daily application rate of phosphate fertilizer; This indicates the amount of phosphate fertilizer surplus that is permitted to be applied. express Sensitivity coefficient; This represents the humidity sensitivity coefficient.

9. The method for determining the regional allowable surplus of phosphate fertilizer application for potatoes according to claim 8, characterized in that, The permitted amount of phosphate fertilizer to be applied has been optimized, specifically as follows: The formula used to update the residual amount of phosphate fertilizer in the soil on the day of the update is as follows: in, This indicates the residual amount of phosphate fertilizer in the regenerated soil. This indicates the amount of residual phosphate fertilizer in the soil before fertilization. The historical phosphate fertilizer surplus of the region up to the current day is accumulated to calculate the cumulative value of the phosphate fertilizer surplus. The cumulative value of the phosphate fertilizer surplus is compared with the preset upper limit of the total cumulative phosphate surplus of the region. If the cumulative value of the phosphate fertilizer surplus is not less than the upper limit of the total cumulative phosphate surplus, the allowable phosphate fertilizer surplus for the current day is set to 0. When the cumulative value of the phosphate fertilizer surplus is less than the upper limit of the total cumulative phosphate surplus, the phosphate fertilizer surplus of the region is recalculated, and the allowable phosphate fertilizer surplus for potatoes is further updated.

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