Comprehensive Evaluation System and Method for Urban Green Space Soil Fertility Based on Historical Data

Abstract

The present invention discloses a comprehensive evaluation system and method for urban green space soil fertility based on historical data, which relates to the technical field of soil fertility evaluation. Historical data of sampling points are obtained; according to the historical data of the sampling points, the evaluation area is divided into several sub-areas; the comprehensive soil fertility index of each sub-area is calculated, and the comprehensive soil fertility index of the evaluation area is obtained based on the comprehensive soil fertility index of the sub-areas, providing guidance for soil treatment; various soil fertility indicators of the sampling points are obtained, considering the changes in the soil indicators, the overall soil fertility indicators of the research area are obtained from the various soil fertility indicators of the sampling points, and finally the soil fertility of the research area is evaluated to make the evaluation result more accurate; by evaluating the soil fertility indicators, the nutrient status of the soil can be understood, so as to determine appropriate fertilization and irrigation strategies, which helps to improve the green space soil environment and enhance the overall quality of the green space.

Description

Technical Field

[0001] The present invention relates to the technical field of soil fertility assessment, and in particular to a comprehensive assessment system and method for urban green space soil fertility based on historical data. Background Art

[0002] Urban green space is the only negative feedback subsystem in the urban ecosystem that "absorbs pollution and emits fresh air", and is the main body of the urban natural productivity. It plays a key role in maintaining the urban ecological balance, meeting people's recreational needs, continuing the urban historical context, and reshaping the harmonious relationship between humans and the land. It is a necessary condition for realizing the sustainable development of the city. At present, in the current stage of landscape gardening construction, attention is paid to the "quantity" of green space, while the soil environment base is the embodiment of "quality", and soil fertility assessment has become an important part of urban green space construction. At present, the grid method is mainly used to sample sampling points and obtain detailed information, but only the information at some positions can be obtained, and it is difficult to comprehensively and accurately evaluate the soil fertility of the entire research area. Summary of the Invention

[0003] The purpose of the present invention is to provide a system and method to solve the problems raised in the prior art.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A comprehensive assessment method for urban green space soil fertility based on historical data, including:

[0005] S11, obtaining the historical data of the sampling points; the historical data of the sampling points are the soil fertility index data of the sampling points and the single fertility index of the soil fertility index of the sampling points;

[0006] S12, obtaining the minimum index data of the sampling points according to the historical data of the sampling points, and dividing the evaluation area into several sub-areas based on the minimum index of the sampling points. The index corresponding to the minimum value of the single fertility index among all the indexes of the sampling points is the minimum index;

[0007] S13, calculating the comprehensive soil fertility index of each sub-area, and obtaining the comprehensive soil fertility index of the evaluation area according to the comprehensive soil fertility index of the sub-area, so as to provide guidance for soil treatment.

[0008] In step S12, the step of dividing the evaluation area into several sub-areas further includes the following steps:

[0009] S21, selecting an origin, a horizontal axis and a vertical axis on the evaluation area to establish a rectangular coordinate system;

[0010] S22, on the established rectangular coordinate system, obtaining the abscissa and ordinate of the center of the grid where each sampling point is located;

[0011] S23. Obtain the single - factor fertility index of all indicators at the sampling point, determine the minimum value of the single - factor fertility index among all indicators at each sampling point, and let the indicator corresponding to the minimum value of the single - factor fertility index be the minimum indicator; determine whether the minimum indicators of the \(i\) - th sampling point and its adjacent sampling points are the same. If they are the same, there is no boundary point between the \(i\) - th sampling point and its adjacent sampling points, and go to step S25. If they are different, go to step S24 to determine the boundary point between the \(i\) - th sampling point and its adjacent sampling points; determine the grids adjacent to the grid where the \(i\) - th sampling point is located in the vertical and horizontal axes directions, and the sampling points within the determined grids are the adjacent sampling points of the \(i\) - th sampling point.

[0012] S24. Let the horizontal and vertical coordinates of the center of the grid where the \(i\) - th sampling point is located be \((x_i,y_i)\), and the horizontal and vertical coordinates of the center of the grid where the adjacent sampling point is located be \((x,y)\). Let the minimum indicator of the \(i\) - th sampling point and its adjacent sampling point be the target indicator. Obtain the single - factor fertility indices \(P_1(x_i,y_i)\) and \(P_2(x_i,y_i)\) of the target indicator of the \(i\) - th sampling point. Determine the horizontal and vertical coordinates of the boundary point through the formula \(P_1(x_i,y_i)+F_1\times d = P_2(x_i,y_i)+F_2\times d\), where \(F_1\) and \(F_2\) are the change rates of the target indicator, and \(d\) is the horizontal axis distance or the vertical axis distance. When the centers of the grids where the \(i\) - th sampling point and its adjacent sampling point are adjacent in the horizontal axis direction, \(d\) is the horizontal axis distance, and the horizontal and vertical coordinates of the horizontal axis boundary point are \((x_i + d,y_i)\); when the centers of the grids where the \(i\) - th sampling point and its adjacent sampling point are adjacent in the vertical axis direction, \(d\) is the vertical axis distance, and the horizontal and vertical coordinates of the vertical axis boundary point are \((x_i,y_i + d)\).

[0013] S25. Obtain the information of all horizontal and vertical axis boundary points. Connect the horizontal axis boundary points with the adjacent horizontal or vertical axis boundary points in the vertical axis direction, and connect the vertical axis boundary points with the adjacent horizontal or vertical axis boundary points in the horizontal axis direction; if the horizontal axis boundary point is adjacent to the edge of the evaluation area, connect the horizontal axis boundary point with the edge of the evaluation area in the vertical axis direction; if the vertical axis boundary point is adjacent to the edge of the evaluation area, connect the vertical axis boundary point with the edge of the evaluation area in the horizontal axis direction; divide the evaluation area into several sub - areas according to the connection results.

[0014] The grid method is a commonly used soil sampling point selection technique. By dividing the research area into several regular grids to determine the positions of sampling points, first determine the scope of the research area, then divide the research area into grids of the same size, and take the center points of the grids or randomly sample as sampling points to achieve the uniform distribution of sampling points.

[0015] In step S24, the change rate of the target indicator is determined through the following steps:

[0016] S31. Obtain the single fertility index of the target index at the \(i\)-th sampling point and adjacent sampling points. Let the single fertility indices of the target index at the adjacent sampling points be \(P1(x, y)\) and \(P2(x, y)\), and calculate the target index change rate \(G\). i1 \((j)\) and \(G\) i2 \((j)\), , ; In this step, the value of \(j\) is taken as 0;

[0017] S32. Obtain the change direction of the target index , , obtain the target index change rate data \(G\) of the \(j\)-th historical data in the same direction as the change direction of the target index i1 \((j)\) and \(G\) i2 \((j)\). In this step, the value of \(j\) is not 0. Calculate \(F1\) and \(F2\). , , where \(W\) j is the weight and is determined by the following formula: \(W\) j = 1 / [1 + OD(j)], where OD(j) is the Euclidean distance between the \(j\)-th historical data in the same direction as the change direction of the target index and the latest historical data. The target index change rate when \(j = 0\) is the latest historical data; the Euclidean distance is calculated based on the terrain factor and environmental factor; obtain the terrain factor and environmental factor data of the latest historical data, calculate the distance between the terrain factors of other historical data and the latest historical data to get OD(j). When the sampling points corresponding to other historical data are the same as the latest historical data, the distance brought by the terrain factor is 0, and only the environmental factor has an impact.

[0018] The agricultural technical measures for green spaces are carried out in a certain direction sequence. Through the rectangular coordinates, the change of the point position data in the direction can be obtained, not limited to the currently measured point position data, and the soil fertility evaluation result in space can be obtained.

[0019] Topographic factors include, but are not limited to, altitude, slope, and soil-vegetation adjustment coefficient, etc.; altitude has an impact on the content of organic matter. As the altitude increases, the wind force and solar radiation suffered by the soil increase, making the decomposition of organic matter faster; the slope can be represented by the sine or cosine value of the slope direction. Different slope directions result in different solar radiation received by the soil, thereby affecting the organic matter content; the soil-vegetation adjustment coefficient reflects the vegetation coverage of the soil, and vegetation has an impact on soil erosion; the environmental factor data can be taken as the single fertility index of the indicator, which not only considers the differences between different data indicators but also eliminates the influence of the dimension on the indicators; other historical data only need to maintain the same change direction as the latest historical data. When the sampling points selected for other historical data are the same as those of the latest historical data, the topographic factors are also the same; calculate the topographic factor and environmental factor data at the sampling starting point of the Euclidean distance. For the latest historical data, it is recorded as the data at the point (xi, yi).

[0020] In step S12, the following steps are further included:

[0021] Obtain the comprehensive soil fertility index at each position within the sub-region. Let (u, v) represent the horizontal and vertical coordinates in the sub-region, and P(u, v) represent the comprehensive soil fertility index at the position (u, v). Obtain the change direction between the closest sampling point M and the position (u, v) within the same sub-region ; Obtain two non-collinear change rate data D and E generated at the sampling point M. Decompose in accordance with the change direction, , and are two non-collinear change directions generated at the sampling point M, and are coefficients. Add the change rate data D and E according to the coefficients to obtain the change rate . Obtain the single fertility index at the position (u, v) according to the change rate in the manner of step S24.

[0022] In step S13, the calculation of the comprehensive soil fertility index for each sub-region further includes the following steps:

[0023] Obtain the single fertility index for each sub-region, and calculate the comprehensive soil fertility index P(r) of the sub-region according to the single fertility index, , , where A(r) represents the area of the r-th sub-region, P(r) is the comprehensive soil fertility index of the r-th sub-region, P min represents the minimum value of the single fertility index at the position (u, v) in the r-th sub-region, and P ave represents the average value of the single fertility index at the position (u, v) in the r-th sub-region.

[0024] Within the same sub-region, the minimum values of the unidirectional fertility index all come from the same indicator, that is, the indicators with the lowest content are the same. The indicators with too low content will become the main factors restricting plant growth and thus the main factors affecting the green space. Therefore, within the same sub-region, the properties of soil fertility are similar. There is at least one sampling point in a sub-region. When two adjacent sampling points have different minimum indicators, these two sampling points belong to different sub-regions. At this time, there is at least one sampling point in each sub-region. When two adjacent sampling points have the same minimum indicator, the number of sampling points in each sub-region is still not less than one.

[0025] In step S13, the obtaining of the soil fertility comprehensive index of the evaluation region based on the soil fertility comprehensive index of the sub-region further includes the following steps:

[0026] Calculate the soil fertility comprehensive index P of the evaluation region according to the formula, , where (a, b) represents the abscissa and ordinate in the rectangular coordinate system, and P(a, b) represents the soil fertility comprehensive index at the position (a, b); simplify the formula according to the sub-region according to the actual situation to obtain the soil fertility comprehensive index P of the evaluation region: .

[0027] To achieve the above object, the present invention provides the following technical solution: A comprehensive soil fertility evaluation system for urban green spaces based on historical data, including: a soil index data acquisition module, a data storage module, a soil fertility analysis module, and an output module; the output end of the soil index data acquisition module is connected to the input ends of the data storage module and the soil fertility analysis module, and is used to obtain various index data of the soil; the output end of the data storage module is connected to the input end of the soil fertility analysis module, and is used to store various index data of the soil in the research area; the output end of the soil fertility analysis module is connected to the input end of the output module, and obtains the comprehensive soil fertility index of the entire research area according to the index data of the sampling points; the output module is used to output the comprehensive soil fertility evaluation result.

[0028] The soil index data acquisition module further includes a sampling unit, an index analysis unit, and a sensing unit; the sampling unit is used to divide the research area into grids and determine sampling points; the index analysis unit is used to experimentally analyze the index data of soil samples; the sensing unit is used to perform field measurements on soil fertility indicators. The soil fertility analysis module further includes a regional division unit, a change rate analysis unit, and a soil fertility comprehensive index calculation unit. The regional division unit is used to divide the research area into several sub-areas; the change rate analysis unit is used to obtain the change rate of soil fertility indicators in a fixed direction; the soil fertility comprehensive index calculation unit is used to calculate the soil fertility comprehensive index of the research area. The soil fertility comprehensive index calculation unit calculates the soil fertility comprehensive index P(r) of the sub-region according to the single fertility index, where P(r) is the soil fertility comprehensive index of the r-th sub-region; calculates the soil fertility comprehensive index P of the evaluation area according to the formula, , where (a, b) represents the abscissa and ordinate in the rectangular coordinate system, and P(a, b) represents the soil fertility comprehensive index at the position (a, b); simplifies the formula according to the sub-region according to the actual situation to obtain the soil fertility comprehensive index P of the evaluation area: P = ∑P(r).

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: obtaining various soil fertility indicators of the sampling points, considering the change situation of soil indicators, obtaining the overall soil fertility indicators of the research area from the various soil fertility indicators of the sampling points, and finally evaluating the soil fertility of the research area, making the evaluation result more accurate; evaluating the soil fertility indicators can understand the nutrient status of the soil, so as to determine appropriate fertilization and irrigation strategies, which helps to improve the green space soil environment and enhance the overall quality of the green space; can understand the health status and development trend of the green space, provide a scientific basis for green space management, help to formulate reasonable green space management strategies, and improve management efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic structural diagram of a comprehensive evaluation system for urban green space soil fertility based on historical data of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] Example: As Figure 1As shown in the figure, the present invention provides a technical solution, a comprehensive evaluation system for urban green space soil fertility based on historical data, including: a soil index data acquisition module, a data storage module, a soil fertility analysis module, and an output module; the output end of the soil index data acquisition module is connected to the input ends of the data storage module and the soil fertility analysis module, and is used to obtain various index data of the soil; the output end of the data storage module is connected to the input end of the soil fertility analysis module, and is used to store various index data of the soil in the research area; the output end of the soil fertility analysis module is connected to the input end of the output module, and obtains the comprehensive soil fertility index of the entire research area according to the index data of the sampling points; the output module is used to output the comprehensive evaluation result of the soil fertility.

[0033] The soil index data acquisition module further includes a sampling unit, an index analysis unit, and a sensing unit; the sampling unit is used to divide the research area into grids and determine the sampling points; the index analysis unit is used to experimentally analyze the index data of the soil samples; the sensing unit is used to perform field measurements on the soil fertility indicators. The soil fertility analysis module further includes a region division unit, a change rate analysis unit, and a comprehensive soil fertility index calculation unit. The region division unit is used to divide the research area into several sub-regions; the change rate analysis unit is used to obtain the change rate of the soil fertility indicators in a fixed direction; the comprehensive soil fertility index calculation unit is used to calculate the comprehensive soil fertility index of the research area. The comprehensive soil fertility index calculation unit calculates the comprehensive soil fertility index P(r) of the sub-region according to the single fertility index, where P(r) is the comprehensive soil fertility index of the r-th sub-region; calculates the comprehensive soil fertility index P of the evaluation area according to the formula, , where (a, b) represents the abscissa and ordinate in the rectangular coordinate system, and P(a, b) represents the comprehensive soil fertility index at the position (a, b); simplifies the formula according to the sub-region according to the actual situation to obtain the comprehensive soil fertility index P of the evaluation area: P = ∑P(r).

[0034] Embodiment: The present invention provides a technical solution, a comprehensive evaluation method for urban green space soil fertility based on historical data, including:

[0035] S11, obtaining the historical data of the sampling points; the historical data of the sampling points are the soil fertility index data of the sampling points and the single fertility index of the soil fertility indicators of the sampling points;

[0036] S12, according to the historical data of the sampling points, obtaining the minimum index data of the sampling points, and dividing the evaluation area into several sub-regions based on the minimum index of the sampling points. The index corresponding to the minimum value of the single fertility index among all the indicators of the sampling points is the minimum index; including steps S21 to S25:

[0037] S21. Establish a rectangular coordinate system by selecting an origin, a horizontal axis, and a vertical axis on the evaluation area;

[0038] S22. On the established rectangular coordinate system, obtain the abscissa and ordinate of the center of the grid where each sampling point is located;

[0039] S23. Obtain the single - fertility index of all indicators of the sampling point, determine the minimum value of the single - fertility index among all indicators of each sampling point, and let the indicator corresponding to the minimum value of the single - fertility index be the minimum indicator; Determine whether the minimum indicators of the i - th sampling point and its adjacent sampling points are the same. If they are the same, there is no boundary point between the i - th sampling point and its adjacent sampling points, and go to step S25. If they are different, go to step S24 to determine the boundary point between the i - th sampling point and its adjacent sampling points; Determine the grids adjacent to the grid where the i - th sampling point is located in the vertical and horizontal directions, and the sampling points within the determined grids are the adjacent sampling points of the i - th sampling point;

[0040] S24. Let the abscissa and ordinate of the center of the grid where the i - th sampling point is located be (xi, yi), and the abscissa and ordinate of the center of the grid where the adjacent sampling point is located be (x, y). Let the minimum indicator of the i - th sampling point and its adjacent sampling point be the target indicator. Obtain the single - fertility indices P1(xi, yi) and P2(xi, yi) of the target indicator of the i - th sampling point. Determine the abscissa and ordinate of the boundary point through the formula P1(xi, yi)+F1×d = P2(xi, yi)+F2×d, where F1 and F2 are the change rates of the target indicator, and d is the horizontal - axis distance or vertical - axis distance. When the centers of the grids where the i - th sampling point and its adjacent sampling point are located are adjacent in the horizontal - axis direction, d is the horizontal - axis distance, and the abscissa and ordinate of the horizontal - axis boundary point are (xi + d, yi); When the centers of the grids where the i - th sampling point and its adjacent sampling point are located are adjacent in the vertical - axis direction, d is the vertical - axis distance, and the abscissa and ordinate of the vertical - axis boundary point are (xi, yi + d);

[0041] The data of the sampling points are obtained through the following methods:

[0042] Determine the boundary and scope of the research area;

[0043] Divide the research area into grids of equal size using a map or GIS software according to the scope of the research area;

[0044] Select sampling points inside each grid to ensure that each grid has a sampling point selected;

[0045] Number the sampling points and conduct soil sampling according to the numbers;

[0046] Record the information of the sampling points, including sampling time, location, etc.;

[0047] Bring the soil samples back to the laboratory for analysis;

[0048] Organize the laboratory analysis results together with the recorded sampling point information to obtain the data of the sampling points.

[0049] The origin of the coordinate system can be set as the center point of the research area. The horizontal axis is selected as the straight line within the research area with the longest length passing through the center point, and the vertical axis is perpendicular to the horizontal axis; obtain the coordinate information of the sampling points according to the recorded position information of the sampling points.

[0050] The change rate of the target index is determined through the following steps:

[0051] Obtain the single fertility index of the target index at the i-th sampling point and the adjacent sampling points. Let the single fertility index of the target index at the adjacent sampling points be P1(x, y) and P2(x, y), and calculate the target index change rate G i1 (j) and G i2 (j), , ; in this step, the value of j is taken as 0;

[0052] Obtain the change direction of the target index , , obtain the target index change rate data G i1 (j) and G i2 (j) of the j-th historical data in the same direction as the change direction of the target index. In this step, the value of j is not 0, and calculate F1 and F2, , , where W j is the weight and is determined through the following formula: W j = 1 / [1 + OD(j)], where OD(j) is the Euclidean distance between the j-th historical data in the same direction as the change direction of the target index and the latest historical data. The target index change rate when j is 0 is the latest historical data; the Euclidean distance is calculated based on the terrain factor and the environmental factor; obtain the terrain factor and environmental factor data of the latest historical data, calculate the distance between the terrain factors of other historical data and the latest historical data to obtain OD(j). When the sampling points corresponding to other historical data are the same as the latest historical data, the distance brought by the terrain factor is 0, and only the environmental factor has an impact;

[0053] For example, when the soil fertility indicators are soil bulk density, organic matter, and soil vegetation regulation coefficient, the topographic factors affecting soil bulk density include slope, height, and land type, etc.; land types include production green spaces, public green spaces, protection green spaces, etc., which are distinguished after assignment; if the sampling locations do not change each time, that is, the first sampling locations are CY1, CY2, and CY3, and the second sampling locations are also CY1, CY2, and CY3, then the influence of topographic factors is 0, and only environmental factors have an impact. The environmental factors are the soil indicators measured in the experiment, which are soil bulk density, organic matter, and soil vegetation regulation coefficient. Under different sampling times, the data of soil bulk density, organic matter, and soil vegetation regulation coefficient are different, resulting in different impacts on the index change rate; for the soil vegetation regulation coefficient, it is less affected by height, so height may not be included in the topographic factors.

[0054] S25. Obtain the information of all horizontal and vertical axis boundary points, connect the horizontal axis boundary points with adjacent horizontal or vertical axis boundary points in the vertical axis direction, and connect the vertical axis boundary points with adjacent horizontal or vertical axis boundary points in the horizontal axis direction; if the horizontal axis boundary point is adjacent to the edge of the evaluation area, then connect the horizontal axis boundary point with the edge of the evaluation area in the vertical axis direction; if the vertical axis boundary point is adjacent to the edge of the evaluation area, then connect the vertical axis boundary point with the edge of the evaluation area in the horizontal axis direction; divide the evaluation area into several sub-areas according to the connection results.

[0055] Obtain the comprehensive soil fertility index at each position inside the sub-area. Let (u, v) represent the horizontal and vertical coordinates in the sub-area, and P(u, v) represent the comprehensive soil fertility index at the position (u, v). Obtain the change direction between the closest sampling point M and the position (u, v) within the same sub-area. ; Obtain the change rate data D and E of two non-collinear change directions generated at the sampling point M, and decompose according to the change direction ; ; and are two non-collinear change directions generated at the sampling point M, and are coefficients, and add the change rate D and E data according to the coefficients to obtain the change rate . Obtain the single fertility index at the position (u, v) according to the change rate in the manner of step S24.

[0056] A change direction information can be formed between every two sampling points. For sampling points CY1, CY2, and CY3 with coordinates (4, 6), (8, 2), and (8, 10) respectively, two change directions (4, -4) and (4, 4) are obtained. For the position (u, v) in the same sub-region as sampling point CY1, if CY1, CY2, and CY3 are not collinear, the change direction between sampling point M and the position (u, v) can be obtained through vector synthesis of (4, -4) and (4, 4). , and at the same time, coefficients and are obtained. There is an index change rate for the soil fertility index of sampling point CY1 in each of the change directions (4, -4) and (4, 4). According to the coefficients and , the two change rates are synthesized to obtain the change rate in the change direction , and then the soil fertility index at the position (u, v) is obtained.

[0057] S13. Calculate the comprehensive soil fertility index of each sub-region, and obtain the comprehensive soil fertility index of the evaluation region based on the comprehensive soil fertility index of the sub-region:

[0058] Obtain the single fertility index of each sub-region, and calculate the comprehensive soil fertility index P(r) of the sub-region according to the single fertility index, , , where A(r) represents the area of the r-th sub-region, P(r) in the formula is the comprehensive soil fertility index of the r-th sub-region, P min represents the minimum value of the single fertility index at the position (u, v) in the r-th sub-region, and P ave represents the average value of the single fertility index at the position (u, v) in the r-th sub-region.

[0059] Calculate the comprehensive soil fertility index P of the evaluation region according to the formula, , where (a, b) represents the abscissa and ordinate in the rectangular coordinate system, and P(a, b) represents the comprehensive soil fertility index at the position (a, b); simplify the formula according to the sub-region according to the actual situation to obtain the comprehensive soil fertility index P of the evaluation region: P = ∑P(r); provide guidance for soil treatment based on the comprehensive soil fertility index of the evaluation region.

[0060] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims concerned.

Claims

1. A comprehensive evaluation method for urban green space soil fertility based on historical data, characterized in that: The following steps are involved: S11, obtaining historical data of the sampling point; the historical data of the sampling point is soil fertility index data of the sampling point and a single fertility index of the soil fertility index of the sampling point; S12, according to the historical data of the sampling point, the minimum index data of the sampling point is obtained, and the evaluation area is divided into several sub-areas based on the minimum index of the sampling point, and the index corresponding to the minimum value of the single fertility index among all the indexes of the sampling point is the minimum index; specifically including steps S21 to S25: S21, selecting an origin, a horizontal axis, and a vertical axis on the evaluation area to establish a rectangular coordinate system; S22, obtaining the horizontal coordinate and the vertical coordinate of the center of the grid where each sampling point is located in the established rectangular coordinate system; S23, obtaining the single fertility index of all indicators of the sampling point, determining the minimum value of the single fertility index among all indicators of each sampling point, and setting the indicator corresponding to the minimum value of the single fertility index as the minimum indicator; judging whether the minimum indicators of the i-th sampling point and the adjacent sampling point are the same, if they are the same, there is no boundary point between the i-th sampling point and the adjacent sampling point, and entering step S25; if they are not the same, entering step S24, determining the boundary point between the i-th sampling point and the adjacent sampling point; determining the grids adjacent to the grid where the i-th sampling point is located in the vertical and horizontal directions, and the sampling points in the determined grids are the adjacent sampling points of the i-th sampling point; S24, let the horizontal and vertical coordinates of the center of the grid where the i-th sampling point is located be (xi, yi), let the horizontal and vertical coordinates of the center of the grid where the adjacent sampling point is located be (x, y), let the minimum index between the i-th sampling point and the adjacent sampling point be the target index, obtain the single fertility index P1 (xi, yi) and P2 (xi, yi) of the target index of the i-th sampling point, and determine the horizontal and vertical coordinates of the boundary point according to the single fertility index P1 (xi, yi) and P2 (xi, yi) of the target index of the i-th sampling point; S25, obtaining information of all horizontal and vertical axis boundary points, connecting the horizontal axis boundary point with the horizontal axis or vertical axis boundary point adjacent to the vertical axis along the vertical axis direction, and connecting the vertical axis boundary point with the horizontal axis or vertical axis boundary point adjacent to the horizontal axis along the horizontal axis direction; if the horizontal axis boundary point is adjacent to the edge of the evaluation area, connecting the horizontal axis boundary point with the edge of the evaluation area along the vertical axis direction; if the vertical axis boundary point is adjacent to the edge of the evaluation area, connecting the vertical axis boundary point with the edge of the evaluation area along the horizontal axis direction; dividing the evaluation area into a plurality of sub-areas according to the connection results; In step S12, the following steps are also included: Get the soil fertility comprehensive index at each position in the sub-region, let (u, v) represent the horizontal and vertical coordinates in the sub-region, P(u, v) represents the soil fertility comprehensive index at the position (u, v), and get the change direction between the closest sampling point M and the position (u, v) in the same sub-region ; Obtain the two non-collinear change rate data D and E generated at the sampling point M, and convert them according to the change direction. To decompose, , and are the two non-collinear change directions generated at the sampling point M, and The coefficient is the change rate D and E data are added according to the coefficient to get the change rate , according to the change rate, obtain the single fertility index at the position (u, v) in the manner of step S24; S13, calculate the comprehensive soil fertility index of each sub-region, and obtain the comprehensive soil fertility index of the assessment area based on the comprehensive soil fertility index of the sub-region, to provide guidance for soil management.

2. The method for comprehensive evaluation of urban green space soil fertility based on historical data according to claim 1 is characterized in that: In step S24, the following steps are also included: The horizontal and vertical coordinates of the boundary point are determined by the formula: P1 (xi, yi) + F1×d = P2 (xi, yi) + F2×d, where F1 and F2 are the change rates of the target indicators, d is the horizontal axis distance or the vertical axis distance, when the i-th sampling point is adjacent to the grid center of the adjacent sampling point in the horizontal direction, d is the horizontal axis distance, and the horizontal and vertical coordinates of the horizontal axis boundary point are (xi+d, yi); when the i-th sampling point is adjacent to the grid center of the adjacent sampling point in the vertical direction, d is the vertical axis distance, and the horizontal and vertical coordinates of the vertical axis boundary point are (xi, yi+d).

3. The method for comprehensive evaluation of urban green space soil fertility based on historical data according to claim 2 is characterized in that: The rate of change of the target indicator is determined by the following steps: S31, obtain the single fertility index of the target indicator at the i-th sampling point and the adjacent sampling points, let the single fertility index of the target indicator at the adjacent sampling points be P1 (x, y) and P2 (x, y), and calculate the target indicator change rate G i1 (j) and G i2 (j), , ; The value of j in this step is taken as 0; S32, obtain the change direction of the target indicator , , obtain the target indicator change rate data G of the jth historical data with the same change direction as the target indicator i1 (j) and G i2 (j), the value of j in this step is not 0, calculate F1 and F2, , , where W j is the weight, which is determined by the following formula: j =1 / [1+OD(j)], where OD(j) is the Euclidean distance between the jth historical data with the same change direction as the target indicator and the latest historical data. The target indicator change rate when j is 0 is the latest historical data. The Euclidean distance is calculated based on the terrain factor and the environmental factor. The terrain factor and environmental factor data of the latest historical data are obtained, and the distance between other historical data and the terrain factor of the latest historical data is calculated to obtain OD(j). When the sampling points corresponding to other historical data are the same as the latest historical data, the distance brought by the terrain factor is 0, and only the environmental factor has an impact.

4. The method for comprehensive evaluation of urban green space soil fertility based on historical data according to claim 3 is characterized in that: In step S13, the step of calculating the comprehensive soil fertility index of each sub-region further includes the following steps: Obtain the individual fertility index of each sub-region, and calculate the comprehensive soil fertility index P (r) of the sub-region based on the individual fertility index. , , where A(r) represents the area of ​​the rth sub-region, P(r) is the comprehensive index of soil fertility in the rth sub-region, and P min represents the minimum value of the single fertility index at the rth sub-region position (u, v), P ave Represents the average value of the single fertility index at the position (u, v) of the rth sub-region.

5. The method for comprehensive evaluation of urban green space soil fertility based on historical data according to claim 4 is characterized in that: In step S13, obtaining the comprehensive soil fertility index of the evaluation area according to the comprehensive soil fertility index of the sub-area further comprises the following steps: The comprehensive soil fertility index P of the assessment area is calculated according to the formula: , where (a, b) represents the horizontal and vertical coordinates in the rectangular coordinate system, and P (a, b) represents the comprehensive soil fertility index at the position (a, b); based on the actual situation, the formula is simplified according to the sub-region to obtain the comprehensive soil fertility index P of the evaluation area: P = ∑P (r).

6. A system for comprehensively evaluating soil fertility of urban green spaces based on historical data, using a method for comprehensively evaluating soil fertility of urban green spaces based on historical data as claimed in any one of claims 1 to 5, characterized in that: include: Soil index data acquisition module, data storage module, soil fertility analysis module and output module; The output end of the soil index data acquisition module is connected to the input end of the data storage module and the soil fertility analysis module, and is used to obtain various index data of the soil; the output end of the data storage module is connected to the input end of the soil fertility analysis module, and is used to store various index data of the soil in the study area; the output end of the soil fertility analysis module is connected to the input end of the output module, and the comprehensive soil fertility index of the entire study area is obtained according to the index data of the sampling points; the output module is used to output the comprehensive evaluation result of soil fertility.

7. The urban green space soil fertility comprehensive evaluation system based on historical data according to claim 6 is characterized by: The soil index data acquisition module also includes a sampling unit, an index analysis unit and a sensing unit; the sampling unit is used to divide the study area into grids and determine sampling points; the index analysis unit is used to experimentally analyze the index data of soil samples; and the sensing unit is used to perform field measurements of soil fertility indicators.

8. The urban green space soil fertility comprehensive evaluation system based on historical data according to claim 6 is characterized in that: The soil fertility analysis module also includes a region segmentation unit, a change rate analysis unit and a soil fertility comprehensive index calculation unit. The region segmentation unit is used to divide the study area into a plurality of sub-areas; the change rate analysis unit is used to obtain the change rate of the soil fertility index in a fixed direction; and the soil fertility comprehensive index calculation unit is used to calculate the soil fertility comprehensive index of the study area.

9. The urban green space soil fertility comprehensive evaluation system based on historical data according to claim 8 is characterized in that: The soil fertility comprehensive index calculation unit calculates the soil fertility comprehensive index P(r) of the sub-region according to the single fertility index, where P(r) is the soil fertility comprehensive index of the r-th sub-region; the soil fertility comprehensive index P of the evaluation region is calculated according to the formula, , where (a, b) represents the horizontal and vertical coordinates in the rectangular coordinate system, and P (a, b) represents the comprehensive soil fertility index at the position (a, b); based on the actual situation, the formula is simplified according to the sub-region to obtain the comprehensive soil fertility index P of the evaluation area: P = ∑P (r).

Images