Soil pH value distribution diagram compiling method based on soil-planting mountain tobacco-growing area

Abstract

The invention provides a soil pH value distribution diagram compiling method based on a soil-planting mountain tobacco-growing area, which comprises the following steps of: compiling a geographic space distribution diagram according to different soil types, counting a mean value of pH values according to the different soil types, and then compiling the soil pH value distribution diagram by performing Kriging interpolation in different soil type areas. And finally, splicing the soil pH value distribution diagrams woven in different soil type regions into a distribution diagram of the whole tobacco region. According to the method, special knowledge of soil taxonomy is organically fused with technologies such as a geographic information system and a geostatistics model, and technical modules such as layer superposition, mask extraction and reclassification in an ArcGIS platform are adopted for'classification ', 'interpolation' and'splicing ', so that mutability of pH values of soil among different soil parent materials can be overcome; and compiling a high-accuracy spatial distribution diagram of the soil pH value of the tobacco-growing area in the mountain land.

Description

Technical Field

[0001] The present invention belongs to the technical field of digital soil mapping, and particularly relates to a method for compiling a soil pH value distribution map of mountainous tobacco-growing areas based on soil types. Background Art

[0002] Soil pH value is a form of expression of acidity and alkalinity. If the soil is too acidic or too alkaline, crops cannot grow normally, resulting in reduced yields and lower quality. Relevant research shows that the suitable soil pH value for growing tobacco is 5.5 - 7.0. Too acidic or too alkaline soil will affect the quality of tobacco leaves. The incidence of tobacco bacterial wilt and black shank is very closely related to the degree of soil acidification. The higher the degree of soil acidification, the more serious the disease. Existing research shows that in tobacco-growing areas with relatively abundant annual precipitation (≥1200 mm), the incidence of tobacco bacterial wilt and black shank in extremely acidic soil (pH ≤ 4.5) is 100%, and the tobacco-growing areas almost have no harvest every year; the incidence of tobacco bacterial wilt and black shank in strongly acidic soil (4.5 < pH ≤ 5.0) is 30 - 50%, and the yield of tobacco leaves decreases significantly; while when the soil pH ≥ 6.5, the disease rarely occurs.

[0003] Due to the influence of soil parent material on the soil pH value in hilly and mountainous areas, in areas with different soil parent materials, sometimes the spatial variation is very large within a very short distance, showing a "mutation" controlled by the soil parent material. Currently, the Kriging interpolation method is usually used to compile the spatial distribution map of regional soil pH value. This method summarizes the soil pH value between two sampling points as a continuous change curve following a certain regularity. The result of the Kriging interpolation method is often that a high pH value point will raise the values of surrounding low pH value points, resulting in the homogenization of soil pH value within a certain range, thus covering some strongly acidic or extremely acidic areas. For hilly and mountainous tobacco-growing areas, these strongly acidic or extremely acidic areas are often high-incidence areas for inducing tobacco bacterial wilt and black shank. Therefore, the current method of predicting the soil pH value distribution map by Kriging interpolation has insufficient accuracy for hilly and mountainous areas and cannot meet the actual needs of guiding tobacco planting in hilly and mountainous areas. Compiling a soil pH value distribution map of tobacco-growing areas with higher accuracy has become very important for guiding the production of high-quality flue-cured tobacco. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for compiling a soil pH distribution map of a mountain tobacco area based on soil type, in view of the deficiencies of the above-mentioned prior art. The method is based on soil type units and uses a spatial prediction method of Kriging interpolation. It can be briefly characterized as first "classification", then "interpolation", and finally "splicing". "Classification" refers to using the most detailed classification unit soil type in soil taxonomy as the basic classification unit, and its meaning includes two aspects. First, compile its geographical spatial distribution map according to different soil types, and count the mean of its pH value according to different soil types; "interpolation" refers to compiling a soil pH distribution map by Kriging interpolation in different soil type areas; "splicing" is to finally splice the soil pH distribution maps compiled in different soil type areas into a distribution map of the entire tobacco area. The method can significantly improve the prediction accuracy of the spatial distribution map of soil pH in mountain tobacco areas.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for compiling a soil pH distribution map in a mountain tobacco-growing area based on soil types, the method comprising the following steps:

[0007] S1. Establish soil type spatial database

[0008] S101, obtaining pH values, geographic coordinates and elevation data of soil sample points to obtain a spatial distribution map of soil sample points;

[0009] S102, establishing a soil type vector database with soil type as a basic unit;

[0010] S103, using ArcGIS spatial overlay technology, overlaying the soil sample point spatial distribution map with the soil vector database to establish a soil type spatial database;

[0011] S2. Data classification interpolation

[0012] The mean of the measured pH value of each soil type was calculated according to the soil type, and the soil sample points were divided according to the local tobacco-growing soil pH classification standard. Then, the pH values ​​of the classified soil sample points were interpolated by Kriging to obtain the Kriging interpolation distribution map of the soil sample points.

[0013] S3. Obtain soil range boundary distribution map

[0014] Extract the range boundaries of each soil type, and after superimposing it with the soil type map, obtain a soil range boundary distribution map based on the soil type;

[0015] S4. Splicing

[0016] Based on the soil sample point Kriging interpolation map obtained by S2 and the soil range boundary distribution map obtained by S3, the layer overlay and mask extraction technology of the geographic information system are used to "splice" and form a soil pH distribution map of the mountain tobacco area based on soil type.

[0017] Preferably, the data acquisition method in S101 includes obtaining the pH value of soil samples through existing information, databases, or through field soil surveys and laboratory analysis, and obtaining the geographic coordinates and elevation data of soil samples through GPS, DEM or remote sensing analysis.

[0018] Preferably, the kriging interpolation in S2 is to firstly perform accuracy evaluation on the ArcGIS platform using the ordinary kriging interpolation method, select the optimal geostatistical interpolation model, and then perform kriging interpolation. The accuracy evaluation method is: using the standard mean value, root mean square prediction error, average standard error and standard root mean square prediction error as evaluation parameters, wherein the calculation formula of the evaluation parameters is as follows:

[0019]

[0020] In the formula, n is the number of soil samples, and Z(S i ) is the Sth i The predicted and measured soil pH values ​​for each soil sample point. and σ(S i ) is the Sth i The predicted and measured standard deviations of soil pH at each soil sample point;

[0021] Among the accuracy evaluation parameters, the standard mean value is closest to 0, the root mean square prediction error is the smallest, the average standard error is closest to the root mean square prediction error, and the standard root mean square prediction error is closest to 1, which is the optimal model for Kriging interpolation.

[0022] Preferably, the soil pH distribution map of the mountain tobacco area based on soil type obtained in S4 can use the area tabulation technology of ArcGIS geographic information system to evaluate the distribution characteristics of the pH level distribution of the soil tobacco area in the target area, or use the reclassification technology to reclassify the soil pH level in the target area.

[0023] The present invention has significant technical effects due to the adoption of the above technical solution:

[0024] 1. The present invention provides a method for compiling a soil pH distribution map of a mountain tobacco area based on soil types. First, a geographical spatial distribution map is compiled according to different soil types, and the mean pH value of the different soil types is statistically calculated. Then, a soil pH distribution map is compiled by Kriging interpolation in different soil type areas. Finally, the soil pH distribution maps compiled in different soil type areas are spliced ​​into a distribution map of the entire tobacco area. Based on a large amount of soil survey data, the present invention uses geographic information systems, geostatistical models, quantitative soil science and other technologies to develop a method for compiling a mountain tobacco area distribution map based on soil types as basic units and using Kriging interpolation to predict the spatial distribution of soil pH. The method can significantly improve the prediction accuracy of the spatial distribution map of soil pH in mountain tobacco areas, and has the characteristics of high accuracy, fast mapping speed, and easy updating.

[0025] 2. In hilly and mountainous tobacco-growing areas, the soil parent materials have a strong influence on the soil pH value, and the soil pH value between different soil parent materials often "mutates". The widely used Kriging interpolation mapping method leads to homogenization, which conceals this mutation and causes inconsistency with the actual situation. The method of the present invention overcomes this defect, utilizes the specialized knowledge of soil taxonomy and organically integrates the technologies such as geographic information system and geostatistical model, and adopts the layer overlay, mask extraction, reclassification and other technical modules in the ArcGIS platform to perform "classification", "interpolation" and "splicing", so as to compile a spatial distribution map of soil pH value in mountainous tobacco-growing areas with high accuracy.

[0026] The present invention is further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of a method for compiling a soil pH distribution map in a mountain tobacco-growing area based on soil type of the present invention;

[0028] Figure 2 It is the soil sample points and soil pH distribution map of Yuxi City in Example 1 of the present invention;

[0029] Figure 3 It is a Kriging interpolation map of five types of soil samples in Yuxi City in Example 1 of the present invention; wherein, soil samples 1 to 5 respectively represent acidic pH <5.0, slightly acidic pH 5.0-5.5, moderate pH 5.5-7.0, alkaline pH 7.0-7.5, and alkaline pH>7.5;

[0030] Figure 4 It is a boundary map of the range of five soil types in Yuxi City in Example 1 of the present invention; wherein soil type boundaries 1 to 5 respectively represent acidic pH <5.0, slightly acidic pH 5.0 to 5.5, moderate pH 5.5 to 7.0, alkaline pH 7.0 to 7.5, and alkaline pH>7.5;

[0031] Figure 5 This is a pH level distribution map of the Yuxi tobacco area based on the soil type interpolation boundary of Example 1 of the present invention. DETAILED DESCRIPTION

[0032] Example 1

[0033] This embodiment is a method for compiling a soil pH distribution map based on soil types in mountain tobacco-growing areas, with the soil in the tobacco-growing area of ​​Yuxi City, Yunnan Province as the target area. The method includes the following steps:

[0034] S1. Establish soil spatial database

[0035] S101. Field soil survey: Obtain soil survey data in Yuxi City, Yunnan Province. There are 2335 soil survey points in total, and each soil type has at least one survey point. The physical and chemical property data of the 2335 cultivated surface soil sample points are derived from the soil analysis data of the Yuxi Tobacco Company in 2021 (2020-2021), including soil pH value, longitude and latitude, elevation and other data. According to the longitude and latitude coordinates of the soil sample points and the physical and chemical analysis data such as soil pH value, a soil sample point database was established in ArcGIS10.8.1 software, and the longitude and latitude coordinates of the sampling points were projected into the CGCS2000 plane coordinate system to obtain the spatial distribution map of the 2335 soil sample points in Yuxi City;

[0036] S102. Establish a 1:50,000 digital soil type vector spatial database in Yuxi City, Yunnan Province, with soil type as the basic unit;

[0037] S103, using ArcGIS spatial overlay technology, the spatial distribution map of soil samples in Yuxi City was overlaid with the 1:50,000 digital soil vector map of Yuxi City to generate a new map ( Figure 2 ), after smoothing and trimming, a spatial database of soil type information of 2335 soil sampling points in Yuxi City was obtained. The spatial database contains geographic coordinate information, soil pH value and effective characteristic data information, and the characteristic data are the soil physical and chemical properties and soil types, subtypes, soil genera and soil species that affect pH value.

[0038] S2. Data classification and interpolation to obtain the Kriging interpolation distribution map of soil sample points

[0039] The measured pH values ​​of 2335 soil sampling points in Yuxi City were divided into five categories: acidic, slightly acidic, moderate, alkaline, and alkaline according to the common tobacco-growing soil pH classification standards (Table 1). The soil pH values ​​of these five types of sampling points were spatially interpolated and predicted, and the Kriging interpolation maps of the five types of soil sampling points in Yuxi City were obtained.

[0040] Table 1 Common soil pH classification standards for tobacco planting

[0041] Acidic Slightly acidic Moderate Alkaline Alkaline <5.0 5.0～5.5 5.5～7.0 7.0～7.5 >7.5

[0042] S201. First, the sampling points were “classified”. According to the statistical requirements, the mean pH value of each soil type was calculated according to the soil type. Combined with the tobacco-growing soil pH grade classification standard (5 categories), the 2335 soil sampling points in Yuxi City were divided into 5 categories. The classification results are shown in Table 2.

[0043] Table 2 Classification standards for pH levels of tobacco-growing soils in Yuxi City (5 categories)

[0044] Acidic Slightly acidic Moderate Alkaline Alkaline pH level classification standard <5.0 5.0～5.5 5.5～7.0 7.0～7.5 >7.5 Number of sample points 26 857 573 112 767

[0045] S202. Perform spatial interpolation prediction on pH values ​​of five types of sampling points. In ArcGIS software, use the geostatistical wizard function to select the optimal geostatistical interpolation model for the 2335 soil sample points in Yuxi City corresponding to the five types. The accuracy evaluation method of the interpolation model is as follows: The accuracy evaluation of the Kriging interpolation model is performed on the ArcGIS platform. The accuracy evaluation parameters of the interpolation model are the standardized mean value (mean standardized), root mean square prediction error (root mean square), average standard error (average standard error), and standardized root mean square prediction error (root mean square standardized). Among them, the calculation formula of the evaluation parameters is as follows:

[0046]

[0047] In the formula, n is the number of soil samples, and Z(S i ) is the Sth i The predicted and measured soil pH values ​​for each soil sample point. and σ(S i ) is the Sth i The predicted standard deviation and measured standard deviation of soil pH at each soil sample point are shown in Table 1. Among the accuracy evaluation parameters of the interpolation model, the standard mean value is closest to 0, the root mean square prediction error is the smallest, the average standard error is closest to the root mean square prediction error, and the standard root mean square prediction error is closest to 1, which is the optimal model for Kriging interpolation.

[0048] The accuracy evaluation indexes and parameter distribution of the Kriging optimal interpolation model for five types of soil pH levels in Yuxi City in this embodiment are listed in Table 3.

[0049] Table 3 Differences in interpolation accuracy of soil pH values ​​at different levels in mountain tobacco-growing areas of Yuxi City based on soil types

[0050]

[0051] S203, according to the optimal model corresponding to the five types of soil acidity and alkalinity obtained in S202, Kriging interpolation is performed respectively to obtain the Kriging interpolation distribution map of the pH value of the five types of soil sample points (see Figure 3 ).

[0052] S3. Obtain soil range boundary distribution map

[0053] Based on the above steps, the range boundaries of each soil type are extracted and superimposed with the soil type map to obtain the range boundary maps of the five types of soil types in Yuxi City, such as Figure 4 .

[0054] S4. Splicing

[0055] According to the kriging interpolation map of the five types of soil sample points in Yuxi obtained in step S2 and the boundary map of the five types of soil types in Yuxi obtained in step S3, the layer overlay and mask extraction technology of the geographic information system are used to "splice" to form the pH grade distribution map of the five types of soil tobacco areas in Yuxi based on the soil type interpolation boundary ( Figure 5 ).

[0056] In this embodiment, the area proportion statistics of five types of soil acidity and alkalinity are also conducted for typical tobacco-growing areas in Yuxi City, Xinping County, Yuanjiang County and Eshan County. According to the statistical requirements, the mean pH value of each soil type is counted according to the soil type, and the 1:50,000 digital soil map of Yuxi City is divided into five categories. According to the distribution area of ​​these five categories, the statistical wizard function is used to conduct the area proportion statistics of five types of soil acidity and alkalinity in typical tobacco-growing areas in Yuxi City, Xinping County, Yuanjiang County and Eshan County. The results are shown in Table 4.

[0057] Table 4 Distribution of pH levels in soil tobacco-producing areas in Yuxi City

[0058] area Strong acid Acidic Moderate Alkaline Alkaline pH Level ＜5.0 5.0～5.5 5.5～7.0 7.0～7.5 ＞7.5 Yuxi City (%) 10.0 17.6 51.2 11.3 9.9 Xinping County (%) 56.1 26.3 17.6 0.0 0.0 Yuanjiang County (%) 12.3 42.7 34.8 5.7 4.5 Eshan County (%) 0.5 33.3 42.3 9.4 14.5

[0059] Example 2

[0060] This embodiment is a method for compiling a soil pH distribution map of a mountain tobacco-growing area based on soil type. The soil of the tobacco-growing area of ​​Yuanjiang County, Yuxi City, Yunnan Province is taken as the target area. The method is the same as that of Example 1, and a soil pH grade distribution map of the tobacco-growing area of ​​Yuanjiang County, Yuxi City, Yunnan Province based on soil type is obtained. Then, according to statistical requirements, the reclassification technology and area tabulation technology in the ArcGIS platform are used to reclassify the obtained soil pH grade distribution map of the tobacco-growing area of ​​Yuanjiang County, Yuxi City, Yunnan Province into 7 categories (see Table 5) according to the pH value classification standard in Table 5, and the spatial distribution area of ​​each type is classified and counted, and the results are shown in Table 6.

[0061] Table 5 Classification standards of tobacco-growing soil pH based on soil type in counties and districts of Yuxi City

[0062] Very acidic Strong acid Acidic Slightly acidic Deeply acidified soil Acidic soil Suitable soil <4.5 4.5～5.0 5.0～5.5 5.5～6.5 ≤5.5 ≤6.5 5.5～7.0

[0063] Table 6 Differences in soil pH level in tobacco-growing areas of Yuanjiang County, Yuxi City

[0064]

[0065]

[0066] Example 3

[0067] This embodiment is a method for compiling a soil pH distribution map of a mountain tobacco-growing area based on soil type. The soil of the tobacco-growing area in Eshan County, Yuxi City, Yunnan Province is taken as the target area. The method is the same as that in Example 1, and a soil pH grade distribution map of the tobacco-growing area in Eshan County, Yuxi City, Yunnan Province based on soil type is obtained. Then, according to statistical requirements, the reclassification technology and area tabulation technology in the ArcGIS platform are used to reclassify the obtained soil pH grade distribution map of the tobacco-growing area in Eshan County, Yuxi City, Yunnan Province into 7 categories (see Table 5) according to the pH value classification standard in Table 5, and the spatial distribution area of ​​each type is classified and counted, and the results are shown in Table 7.

[0068] Table 7 Differences in the proportion of soil pH values ​​at different levels in tobacco-growing areas of Eshan County, Yuxi City

[0069]

[0070]

[0071] The present invention provides a method for compiling a soil pH distribution map of a mountain tobacco area based on soil type. Based on a large amount of soil survey data, a method for compiling a mountain tobacco area distribution map based on soil type as a basic unit and using Kriging interpolation to predict the spatial distribution of soil pH is developed using geographic information systems, geostatistical models, quantitative soil science and other technologies. The method can significantly improve the prediction accuracy of the spatial distribution map of soil pH in mountain tobacco areas. The method solves the defect that individual high pH points affect the results in the process of compiling a regional soil pH spatial distribution map, and has the characteristics of high accuracy, fast mapping speed and easy updating.

[0072] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for compiling a soil pH distribution map based on soil types in mountain tobacco areas, characterized in that: The following steps are involved: S1. Establish soil type spatial database S101, obtaining pH values, geographic coordinates and elevation data of soil sample points to obtain a spatial distribution map of soil sample points; S102, establishing a soil type vector database with soil type as a basic unit; S103, using ArcGIS spatial overlay technology, overlaying the soil sample point spatial distribution map with the soil vector database to establish a soil type spatial database; S2. Data classification interpolation The mean of the measured pH value of each soil type was calculated according to the soil type, and the soil sample points were divided according to the local tobacco-growing soil pH classification standard. Then, the pH values ​​of the classified soil sample points were interpolated by Kriging to obtain the Kriging interpolation distribution map of the soil sample points. S3. Obtain soil range boundary distribution map Extract the range boundaries of each soil type, and after superimposing it with the soil type map, obtain a soil range boundary distribution map based on the soil type; S4. Splicing According to the soil sample point Kriging interpolation map obtained by S2 and the soil range boundary distribution map obtained by S3, the layer overlay and mask extraction technology of the geographic information system are used to "splice" and form a soil pH distribution map of the mountain tobacco area based on soil type.

2. The method according to claim 1, characterized in that The data acquisition method described in S101 includes obtaining the pH value of the soil sample point through existing information, database, or through field soil survey and laboratory analysis, and obtaining the geographic coordinates and elevation data of the soil sample point through GPS, DEM or remote sensing analysis.

3. The method according to claim 1, characterized in that The Kriging interpolation described in S2 is to first use the ordinary Kriging interpolation method on the ArcGIS platform to evaluate the accuracy, select the optimal geostatistical interpolation model, and then perform Kriging interpolation.

4. The method according to claim 3, characterized in that The accuracy evaluation method is: using the standard mean value, root mean square prediction error, average standard error and standard root mean square prediction error as evaluation parameters, wherein the calculation formula of the evaluation parameters is as follows: In the formula, n is the number of soil samples, and Z(S i ) is the Sth i The predicted and measured soil pH values ​​for each soil sample point. and σ(S i ) is the Sth i The predicted and measured standard deviations of soil pH at each soil sample point; Among the accuracy evaluation parameters, the standard mean value is closest to 0, the root mean square prediction error is the smallest, the average standard error is closest to the root mean square prediction error, and the standard root mean square prediction error is closest to 1, which is the optimal model for Kriging interpolation.

5. The method according to claim 1, characterized in that The soil pH distribution map of mountain tobacco areas based on soil type obtained by S4 can be used to evaluate the distribution characteristics of soil pH levels in the target area using the area tabulation technology of the ArcGIS geographic information system, or to reclassify the soil pH levels in the target area using the reclassification technology.

Images