Urban green land soil fertility comprehensive evaluation system and method based on historical data

Abstract

The invention discloses an urban green land soil fertility comprehensive evaluation system and method based on historical data, and relates to the technical field of soil fertility evaluation. Dividing the evaluation area into a plurality of sub-areas according to the historical data of the sampling points; calculating a soil fertility comprehensive index of each sub-region, and obtaining a soil fertility comprehensive index of the evaluation region according to the soil fertility comprehensive indexes of the sub-regions to provide guidance for soil treatment; all soil fertility indexes of the sampling points are obtained, the change condition of the soil indexes is considered, the overall soil fertility index of the research area is obtained from all the soil fertility indexes of the sampling points, finally, the soil fertility of the research area is evaluated, and the evaluation result is more accurate; by evaluating the soil fertility index, the nutrient condition of the soil can be known, so that a proper fertilization and irrigation strategy is determined, the improvement of the green land soil environment is facilitated, and the overall quality of the green land is improved.

Description

Technical Field

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

[0002] Urban green space is the only negative feedback subsystem in the urban ecosystem that implements "taking in pollution and spitting out new things". It is the main body of the city's natural productivity. It plays a key role in maintaining the ecological balance of the city, satisfying people's recreation and leisure, continuing the historical context of the city, and reshaping the harmonious relationship between people and land. It is a necessary condition for achieving sustainable urban development. At present, urban green space attaches importance to the "quantity" of green space in the current stage of garden greening construction, while the soil environmental base is the embodiment of "quality". Soil fertility assessment has become an important part of urban green space construction; at present, the grid method is mainly used to conduct and obtain detailed information on sampling points, and only information at some locations can be obtained, making it difficult to comprehensively and accurately assess the soil fertility of the entire study area. Summary of the invention

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

[0004] To achieve the above object, the present invention provides the following technical solution: a method for comprehensive evaluation of urban green space soil fertility based on historical data, comprising: 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, obtaining minimum index data of the sampling point according to historical data of the sampling point, dividing the evaluation area 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; 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.

[0005] In step S12, dividing the evaluation area into a plurality of sub-areas further comprises the following steps: 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), 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 index of 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 by the formula, P1 (xi, yi) + F1 × d = P2 (xi, yi) + F2 × d, where F1 and F2 are the change rates of the target index, d is the horizontal axis distance or the vertical axis distance, when the i-th sampling point and the 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 (xi + d, yi); when the i-th sampling point and the 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 (xi, yi + d); S25, obtain the information of all the horizontal and vertical boundary points, connect the horizontal boundary points with the adjacent horizontal or vertical boundary points in the vertical direction along the vertical direction, and connect the vertical boundary points with the adjacent horizontal or vertical boundary points in the horizontal direction along the horizontal direction; if the horizontal boundary points are adjacent to the edge of the evaluation area, connect the horizontal boundary points with the edge of the evaluation area along the vertical direction; if the vertical boundary points are adjacent to the edge of the evaluation area, connect the vertical boundary points with the edge of the evaluation area along the horizontal direction; divide the evaluation area into several sub-areas according to the connection results.

[0006] The grid method is a commonly used soil sampling point selection technology. The location of the sampling point is determined by dividing the study area into several regular grids. First, the scope of the study area is determined, and then the study area is divided into grids of the same size. The center point of the grid is taken or randomly sampled as the sampling point to achieve a uniform distribution of the sampling points.

[0007] In step S24, 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), , ; In this step, the value of j 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.

[0008] Agricultural technical measures for green spaces are carried out in a certain directional order. The directional changes of point data can be obtained through rectangular coordinates. It is not limited to the currently measured point data, and the spatial soil fertility evaluation results can be obtained.

[0009] Topographic factors include but are not limited to altitude, slope and soil vegetation adjustment coefficient; altitude has an impact on the content of organic matter. As the altitude increases, the wind and solar radiation to which the soil is exposed increases, causing the organic matter to decompose faster; the slope can be represented by the sine or cosine value of the slope direction. Different slope directions cause the soil to be exposed to different solar radiation, which in turn affects the organic matter content; the soil vegetation adjustment coefficient reflects the vegetation coverage of the soil, and vegetation has an impact on soil loss; the environmental factor data can be taken as a single fertility index of the indicator, which not only takes into account the differences in indicators between different data, but also eliminates the impact of the dimension on the indicator; other historical data only need to keep the change direction the same as the latest historical data. When the sampling points selected for other historical data and the latest historical data are the same, the terrain factors are also the same; calculate the terrain factor and environmental factor data at the starting point of the Euclidean distance sampling. For the latest historical data, it is recorded as the data at the point (xi, yi).

[0010] 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 is the coefficient, add the change rate D and E data according to the coefficient to get the change rate According to the change rate, the single fertility index at the position (u, v) is obtained in step S24.

[0011] 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 soil fertility index of 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 rth sub-region position (u, v).

[0012] In the same sub-region, the minimum values ​​of the one-way fertility index all come from the same indicator, that is, the indicators that the soil lacks the most are the same. Indicators with too low content will become the main factor restricting plant growth, and then become the main factor affecting green space. Therefore, in the same sub-region, the nature of soil fertility is similar. A sub-region includes at least one sampling point. When two sampling points are adjacent and the minimum indicators are different, the two sampling points belong to different sub-regions. At this time, there is at least one sampling point in each sub-region. When two sampling points are adjacent and the minimum indicators are the same, the number of sampling points in each sub-region is still not less than one.

[0013] 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 index of soil fertility at the position (a, b). According to the actual situation, the formula is simplified according to the sub-region to obtain the comprehensive index of soil fertility P in the evaluation area: .

[0014] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a comprehensive evaluation system for urban green space soil fertility based on historical data, comprising: 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 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 soil fertility evaluation result.

[0015] 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; the sensing unit is used to perform field measurements of soil fertility indicators. The soil fertility analysis module also includes a regional segmentation unit, a change rate analysis unit and a soil fertility comprehensive index calculation unit. The regional segmentation unit is used to divide the study area into several sub-areas; the change rate analysis unit is used to obtain the change rate of the soil fertility index in a fixed direction; the soil fertility comprehensive index calculation unit is used to calculate the soil fertility comprehensive index of the study area. The soil fertility comprehensive index calculation unit calculates the soil fertility comprehensive index P (r) of the sub-area based on the single fertility index, and P (r) is the soil fertility comprehensive index of the rth sub-area; the soil fertility comprehensive index P of the evaluation 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).

[0016] Compared with the prior art, the beneficial effects of the present invention are: obtaining various soil fertility indicators of the sampling points, considering the changes in soil indicators, obtaining the overall soil fertility indicators of the study area from the various soil fertility indicators of the sampling points, and finally evaluating the soil fertility of the study area to make the evaluation results more accurate; the evaluation of soil fertility indicators can understand the nutrient status of the soil, so as to determine appropriate fertilization and irrigation strategies, which is helpful to improve the soil environment of green spaces and enhance the overall quality of green spaces; the health status and development trend of green spaces can be understood, providing a scientific basis for green space management, helping to formulate reasonable green space management strategies and improve management efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a schematic structural diagram of a comprehensive urban green space soil fertility assessment system based on historical data. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example: Figure 1As shown, the present invention provides a technical solution, a comprehensive evaluation system for urban green space soil fertility based on historical data, comprising: 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 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 soil fertility evaluation result.

[0020] 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; the sensing unit is used to perform field measurements of soil fertility indicators. The soil fertility analysis module also includes a regional segmentation unit, a change rate analysis unit and a soil fertility comprehensive index calculation unit. The regional segmentation unit is used to divide the study area into several sub-areas; the change rate analysis unit is used to obtain the change rate of the soil fertility index in a fixed direction; the soil fertility comprehensive index calculation unit is used to calculate the soil fertility comprehensive index of the study area. The soil fertility comprehensive index calculation unit calculates the soil fertility comprehensive index P (r) of the sub-area based on the single fertility index, and P (r) is the soil fertility comprehensive index of the rth sub-area; the soil fertility comprehensive index P of the evaluation 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).

[0021] Embodiment: The present invention provides a technical solution, a method for comprehensive evaluation of urban green space soil fertility based on historical data, comprising: 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; 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), 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 index of 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 by the formula, P1 (xi, yi) + F1 × d = P2 (xi, yi) + F2 × d, where F1 and F2 are the change rates of the target index, d is the horizontal axis distance or the vertical axis distance, when the i-th sampling point and the 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 (xi + d, yi); when the i-th sampling point and the 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 (xi, yi + d); The data of the sampling points are obtained in the following ways: Determine the boundaries and extent of the study area; Divide the study area into grids of equal size using a map or GIS software according to the scope of the study area; Select sampling points inside each grid, making sure that each grid has sampling points selected; Number the sampling points and conduct soil sampling according to the numbers; Record the information of the sampling point, including sampling time, location, etc.; Take soil samples back to the lab for analysis; The laboratory analysis results are collated together with the recorded sampling point information to obtain the data of the sampling point.

[0022] The origin of the coordinate system can be set as the center point of the study area, the horizontal axis selects the straight line in the study area with the longest length passing through the center point, and the vertical axis is perpendicular to the horizontal axis; the coordinate information of the sampling point is obtained according to the recorded location information of the sampling point; The rate of change of the target indicator is determined by the following steps: Get 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; Get 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. For example, when the soil fertility indicators are soil bulk density, organic matter and soil vegetation adjustment coefficient, the terrain factors that affect soil bulk density include slope, height and land type; land types include production green space, public green space, protective green space, etc., which are distinguished by assignment; if the sampling location does not change each time, that is, the first sampling location is CY1, CY2 and CY3, and the second sampling location is also CY1, CY2 and CY3, then the influence of the terrain factor is 0, and only the environmental factor has an impact. The environmental factor is the soil indicator measured experimentally, which is soil bulk density, organic matter and soil vegetation adjustment coefficient. At different sampling times, the data of soil bulk density, organic matter and soil vegetation adjustment coefficient are different, which have different impacts on the indicator change rate; for the soil vegetation adjustment coefficient, it is less affected by the height, so there can be no height in the terrain factor.

[0023] S25, obtain the information of all the horizontal and vertical boundary points, connect the horizontal boundary points with the adjacent horizontal or vertical boundary points in the vertical direction along the vertical direction, and connect the vertical boundary points with the adjacent horizontal or vertical boundary points in the horizontal direction along the horizontal direction; if the horizontal boundary points are adjacent to the edge of the evaluation area, connect the horizontal boundary points with the edge of the evaluation area along the vertical direction; if the vertical boundary points are adjacent to the edge of the evaluation area, connect the vertical boundary points with the edge of the evaluation area along the horizontal direction; divide the evaluation area into several sub-areas according to the connection results.

[0024] 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 is the coefficient, add the change rate D and E data according to the coefficient to get the change rate According to the change rate, the single fertility index at the position (u, v) is obtained in step S24.

[0025] A change direction information can be formed between every two sampling points. For the sampling points CY1, CY2 and CY3, the coordinates are: (4, 6), (8, 2) and (8, 10), respectively, and two change directions (4, -4) and (4, 4) are obtained. For the position (u, v) in the same sub-area as the sampling point CY1, if CY1, CY2 and CY3 are not collinear, the change direction between the sampling point M and the position (u, v) can be obtained by vector synthesis of (4, -4) and (4, 4). , and get the coefficient and The soil fertility index of sampling point CY1 has an index change rate in the change direction (4, -4) and (4, 4), according to the coefficient and The direction of change is obtained by synthesizing the two change rates The rate of change on the soil can then be used to obtain the soil fertility index at the position (u, v).

[0026] S13, calculating the soil fertility comprehensive index of each sub-region, and obtaining the soil fertility comprehensive index of the evaluation region according to the soil fertility comprehensive index of the sub-region: 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 soil fertility index of 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 rth sub-region position (u, v).

[0027] 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 assessment area: P = ∑P (r); based on the comprehensive soil fertility index of the assessment area, guidance is provided for soil management.

[0028] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

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; 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), , ; In this step, the value of j 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 S12, the following steps are also included: Get the comprehensive index of soil fertility 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 comprehensive index of soil fertility at position (u, v), and get the change direction between the closest sampling point M and 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 is the coefficient, add the change rate D and E data according to the coefficient to get the change rate According to the change rate, the single fertility index at the position (u, v) is obtained in step S24.

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, 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 soil fertility index of 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 rth sub-region position (u, v).

6. The method for comprehensive evaluation of urban green space soil fertility based on historical data according to claim 5 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 index of soil fertility at the position (a, b). According to the actual situation, the formula is simplified according to the sub-region to obtain the comprehensive index of soil fertility P in the evaluation area: .

7. A comprehensive evaluation system for urban green space soil fertility based on historical data, characterized in that: include: 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 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 soil fertility comprehensive 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.

8. The urban green space soil fertility comprehensive evaluation system based on historical data according to claim 7 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.

9. The urban green space soil fertility comprehensive evaluation system based on historical data according to claim 7 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.

10. The urban green space soil fertility comprehensive evaluation system based on historical data according to claim 9 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 index of soil fertility at the position (a, b). According to the actual situation, the formula is simplified according to the sub-region to obtain the comprehensive index of soil fertility P in the evaluation area: .

Images