Quantitative evaluation method and system for soil health

Abstract

The invention relates to a soil health quantitative evaluation method and system, and the method comprises the steps: sampling a to-be-evaluated region according to a preset soil index, and obtaining index data; screening the soil indexes through a principal component analysis method, and establishing an evaluation system based on the screened soil indexes; according to the index data, linear scores of soil indexes included in the evaluation system are calculated respectively; according to the plurality of linear scores, calculating to obtain a soil health index of the to-be-evaluated region; and performing soil health evaluation on the to-be-evaluated region according to the soil health index to obtain a soil health level of the to-be-evaluated region. According to the method, the soil health can be comprehensively evaluated, the soil health conditions of different areas or different treatments are compared, and the accuracy of the evaluation result of the soil health is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil health assessment, and in particular to a soil health quantitative assessment method and system. Background Art

[0002] Soil is a holistic and dynamic life system. Soil not only provides food and fiber for human survival, but also plays an irreplaceable role in ensuring environmental and energy security, protecting biodiversity, etc. Global soil is facing threats from multiple pressures, including human activities and climate change. Soil degradation has exacerbated the contradiction between population, nature and resources.

[0003] Existing soil health assessments are mainly based on chemical indicators that represent soil productivity, with very few physical and biological indicators. At the same time, the assessment results are affected by human factors and the accuracy of the assessment results is not high. At the same time, traditional evaluation methods are often based on qualitative or semi-quantitative methods, which make it difficult to accurately and clearly reflect the actual status of soil health. Summary of the invention

[0004] The present invention provides a soil health quantitative evaluation method and system to solve the defects of the prior art.

[0005] A first aspect of the present invention provides a soil health quantitative evaluation method, comprising: S1: Sample the area to be evaluated according to the preset soil indicators to obtain indicator data; S2: screening the soil indicators by principal component analysis, and establishing an evaluation system based on the screened soil indicators; S3: Calculating the linear scores of the soil indicators included in the evaluation system according to the indicator data; S4: Calculate and obtain the soil health index of the area to be evaluated based on the multiple linear scores; S5: Perform soil health assessment on the area to be assessed according to the soil health index to obtain a soil health grade of the area to be assessed.

[0006] According to a soil health quantitative evaluation method provided by the present invention, the soil indicators in step S1 include: Physical indicators, including water content, bulk density, silt, sand, and clay; Biological indicators, the biological indicators comprising β-glucosidase, cellobiohydrolase, xylan hydrolase, N-acetylglucosaminidase, leucine aminopeptidase, acid phosphatase, microbial carbon, and carbon-nitrogen ratio; Chemical indicators, including pH, total carbon, organic carbon, total nitrogen, ammonia nitrogen, total phosphorus, available phosphorus, particulate organic carbon, particulate organic nitrogen, mineral organic carbon, mineral organic nitrogen, and dissolved organic carbon; Environmental indicators, including heavy metals and polycyclic aromatic hydrocarbons.

[0007] According to a soil health quantitative evaluation method provided by the present invention, step S2 further comprises: S21: performing variance analysis and H test on the index data obtained by sampling, and obtaining a first candidate index group from the soil indexes; S22: obtaining a second candidate indicator group from the first candidate indicator group by principal component analysis; S23: Establishing the evaluation system based on the second candidate indicator group.

[0008] According to a soil health quantitative evaluation method provided by the present invention, the p-value of each indicator of the first candidate indicator group in step S21 is less than 0.05.

[0009] According to a soil health quantitative evaluation method provided by the present invention, the characteristic value of each indicator of the second candidate indicator group in step S22 is greater than or equal to 1 and the variance is greater than or equal to 5%.

[0010] According to a soil health quantitative evaluation method provided by the present invention, the evaluation system in step S2 includes: A first dimensional indicator, wherein the first dimensional indicator is calculated by a linear scoring method, and the first dimensional indicator includes bulk density; The second dimension indicators are calculated by linear scoring using the second linear scoring method. The second dimension indicators include xylan hydrolase, acid phosphatase, and total nitrogen.

[0011] According to a soil health quantitative evaluation method provided by the present invention, the expression of the first linear scoring method is:

[0012] in, is the linear score calculated by the first linear scoring method, is the data value of the indicator data corresponding to the soil indicator belonging to the first dimension indicator, It is the maximum value in the indicator data group of a single soil indicator; The expression of the second linear scoring method is:

[0013] in, is the linear score calculated by the second linear scoring method, It is the minimum value in the indicator data group of a single soil indicator.

[0014] According to a soil health quantitative evaluation method provided by the present invention, the soil health index in step S4 is expressed as:

[0015] in, To calculate the soil health index, is the soil index value in the index system, is the total number of soil indicators in the indicator system, For the The linear scores of soil indicators are For the The weight value corresponding to each soil indicator.

[0016] According to a soil health quantitative evaluation method provided by the present invention, the soil health level in step S5 includes: The first health level, the soil health index range of the first health level is ; The second health level, the soil health index range of the second health level is ; The third health level, the soil health index range of the third health level is ; The fourth health level, the soil health index range of the fourth health level is 4.

[0017] A second aspect of the present invention provides a soil health quantitative evaluation system for executing a soil health quantitative evaluation method as described in any one of the above items, comprising: Sampling module: used to sample the area to be evaluated according to preset soil indicators and obtain indicator data; Screening module: used to screen the soil indicators by principal component analysis, and also used to establish an evaluation system based on the soil indicators obtained by screening; Linear score calculation module: used to calculate the linear scores of the soil indicators included in the evaluation system according to the indicator data; A health index calculation module is used to calculate the soil health index of the area to be evaluated based on the plurality of linear scores; Health grade classification module: perform soil health evaluation on the area to be evaluated according to the soil health index to obtain the soil health grade of the area to be evaluated.

[0018] The present invention provides a soil health quantitative evaluation method and system, which constructs an evaluation index system related to soil health by including evaluation indicators of physical, chemical and biological indicators, and calculates relevant weights, calculates soil health index by comprehensive index calculation method and determines soil health level, which can comprehensively evaluate soil health, and directly compare soil health conditions in different regions or different treatments, thereby improving the accuracy of soil health evaluation results. The present invention can realize quantitative evaluation of soil, especially provides a relatively comprehensive quantitative evaluation method for soil health evaluation in dryland areas, and provides a basis for comparing soil health conditions in different regions of dryland areas and under different treatment conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of a soil health quantitative evaluation method provided by the present invention; Figure 2 This is a schematic diagram of the structure of a soil health quantitative evaluation system provided by the present invention.

[0021] Reference numerals: 100. Sampling module; 200. Screening module; 300. Linear scoring calculation module; 400. Health index calculation module; 500. Health level classification module. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments, and they should not be understood as limitations on the present invention. 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. In the description of the present invention, it should be understood that the terms used are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0023] Combine the following Figure 1 to Figure 2 Embodiments of the present invention are described.

[0024] like Figure 1 As shown, the first aspect of the present invention provides a soil health quantitative evaluation method, comprising: S1: Sample the area to be evaluated according to the preset soil indicators to obtain indicator data.

[0025] Furthermore, the soil samples were collected by multi-point sampling method, and the soil from 0 to 20 cm on the soil surface was collected. Each sample was measured 3 times during sampling, and the average value was taken. The obtained data were the average values ​​of all samples.

[0026] Wherein, the soil indicators in step S1 include: Physical indicators, including water content, bulk density, silt, sand, and clay; Biological indicators, the biological indicators comprising β-glucosidase, cellobiohydrolase, xylan hydrolase, N-acetylglucosaminidase, leucine aminopeptidase, acid phosphatase, microbial carbon, and carbon-nitrogen ratio; Chemical indicators, including pH, total carbon, organic carbon, total nitrogen, ammonia nitrogen, total phosphorus, available phosphorus, particulate organic carbon, particulate organic nitrogen, mineral organic carbon, mineral organic nitrogen, and dissolved organic carbon; Environmental indicators, including heavy metals and polycyclic aromatic hydrocarbons.

[0027] In a specific embodiment, the present invention mainly explores the effects of four different tillage treatments, namely, grassland (GRL), rotary tillage without returning straw to the field (RTN), no-tillage returning straw to the field (NTS), and plowing returning straw to the field (MPS), on the soil health status of a preset area. According to the test objectives, random block sampling was performed in the soil of the four different treatment areas, and 5 sampling points were selected, with soil samples with a tillage layer thickness of 0 to 20 cm as the research object.

[0028] Subsequently, the soil water content (SWC), bulk density (BD), pH, total carbon (TC), organic carbon (SOC), total nitrogen (TN), ammonia nitrogen (NH4-N), total phosphorus (TP), available phosphorus (AvP), particulate organic carbon (POC), particulate organic nitrogen (PON), mineral organic carbon (MASOC), mineral organic nitrogen (MASON), dissolved organic carbon (DOC), nitrogen (DON), β-glucosidase (BG), cellobiohydrolase (CBH), xylan hydrolase (BXYL), N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), acid phosphatase (AP), microbial carbon (MBC), carbon-nitrogen ratio (R_CN), heavy metals (Cd, Cr, Pb), polycyclic aromatic hydrocarbons (AMFHypha) and other indicators of the soil samples were measured as indicators for soil evaluation. Each sample was measured 3 times and the average value was taken to obtain the data after sampling.

[0029] S2: The soil indicators are screened by principal component analysis, and an evaluation system is established based on the screened soil indicators.

[0030] Wherein, step S2 further comprises: S21: performing variance analysis and H test on the index data obtained by sampling, and obtaining a first candidate index group from the soil indexes.

[0031] Wherein, the p-value of each indicator of the first candidate indicator group in step S21 is less than 0.05.

[0032] In a specific embodiment, after using R software analysis of variance and H test, the above-mentioned 9 soil indicators (BD, POC, MASON, BG, CBH, BXYL, LAP, AP, DON) between the 4 different treatment groups can be obtained, and the evaluation indicators obtained by the screening are significantly different, that is, p<0.05.

[0033] Furthermore, the probability that the observed data are inconsistent with the null hypothesis (i.e., no significant differences among the treatment groups) is less than 5%, which can be considered statistically as sufficient evidence to reject the null hypothesis that there are significant differences among the treatment groups in these soil indices.

[0034] In addition, the above-mentioned H test, namely the Kruskal-Wallis test, is mainly used to compare whether there is a significant difference between the medians of two or more independent samples. This method is a non-parametric test, which means that it does not assume that the data comes from a specific probability distribution, such as a normal distribution. Therefore, it is suitable for situations where the sample size is small and the data does not conform to a normal distribution.

[0035] S22: Using the principal component analysis method, a second candidate indicator group is obtained by selecting the first candidate indicator group.

[0036] Among them, the characteristic value of each indicator of the second candidate indicator group in step S22 is greater than or equal to 1 and the variance is greater than or equal to 5%.

[0037] After the indicators in step S21 are normalized, in step S22, principal component analysis is performed on these normalized indicators to select evaluation indicators and calculate indicator weights to construct a soil health evaluation indicator system.

[0038] Specifically, Table 1 shows the principal component analysis of the soil indicators with significant differences. PC1 and PC3 are the three principal components. These coefficients reflect the strength and direction of the linear relationship between the indicators and the principal components. Positive values ​​indicate positive correlation, and negative values ​​indicate negative correlation. The eigenvalue indicates the importance of each principal component, and the weight further illustrates the relative importance of each principal component in the analysis. The cumulative variance percentage (Cumulative Var(%)) reveals the amount of variation explained by the first few principal components, indicating that these principal components can well summarize the main characteristics of the original data. As shown in Table 1, the eigenvalues ​​of the first three PCs are >1.0 and the variance is >5%. These factors jointly explain 83% of the variance in the original data. For the indicators with high correlation, only one indicator with the highest load is selected. Therefore, the four indicators BXYL, DON, BD and AP are finally selected to construct the soil health evaluation index system, and the indicators are ranked by weight as follows: BXYL (0.52)>DON (0.27)>BD (0.10) =AP(0.10).

[0039] Table 1 Results of principal component analysis of indicators in the first candidate indicator group Soil indicator PC1 PC2 PC3 BD -0.16 0.35 0.58 POC 0.55 0.68 0.14 MASON 0.31 0.81 0.24 BG 0.95 0.07 0.26 CBH 0.80 -0.08 0.44 BYZ 0.97 0.08 -0.11 LAP 0.92 0.07 -0.25 AP 0.17 0.09 0.91 DON -0.29 0.87 0.01 Eigenvalue 3.87 2.04 1.60 Variance(%) 43 23 18 Weighting 0.52 0.27 0.21 Cumulative Var(%) 43 66 83 S23: Establishing the evaluation system based on the second candidate indicator group.

[0040] Wherein, the evaluation system in step S2 includes: A first dimensional indicator, wherein the first dimensional indicator is calculated by a linear scoring method, and the first dimensional indicator includes bulk density; The second dimension indicators are calculated by linear scoring using the second linear scoring method. The second dimension indicators include xylan hydrolase, acid phosphatase, and total nitrogen.

[0041] Furthermore, after obtaining the indicators in the final evaluation system, the present invention distinguishes the indicators in the soil health evaluation index system and calculates the indicator scores through different linear scoring methods, wherein the first dimension indicator, namely BD, uses a "less is better" scoring function, and the second dimension indicators, including BXYL, DON, and AP, all use a "more is better" scoring function.

[0042] S3: Calculate the linear scores of the soil indicators included in the evaluation system according to the indicator data.

[0043] The expression of the first linear scoring method is:

[0044] in, is the linear score calculated by the first linear scoring method, is the data value of the indicator data corresponding to the soil indicator belonging to the first dimension indicator, It is the maximum value in the indicator data group of a single soil indicator; The expression of the second linear scoring method is:

[0045] in, is the linear score calculated by the second linear scoring method, It is the minimum value in the indicator data group of a single soil indicator.

[0046] For other selected indicators, the soil moisture content uses the "more, the better" scoring function. For dry farming areas, soil moisture is one of the factors restricting soil health, directly affecting the soil structure and affecting soil microorganisms and nutrient cycles; the bulk density uses the "less, the better" scoring function. The greater the soil bulk density, the more compact the soil layer, and the air permeability, water permeability, water retention, and fertilizer retention are all poor; the content of silt and clay particles is conducive to soil water and fertilizer retention, and the "more, the better" scoring function is generally used. The sand content generally affects the soil's fertilizer retention capacity, and the "less, the better" scoring function is generally used; pH affects the activity of microorganisms and soil enzymes, and 6.6-7.5 is generally the best, so acidic soil uses the "more, the better" scoring function, and alkaline soil uses the "less, the better" scoring function; Heavy metals are one of the main factors restricting soil health, and the "less the better" scoring function is used; polycyclic aromatic hydrocarbons are important indicators of pesticide residues in the soil, and the "less the better" scoring function is used; total carbon, organic carbon, total nitrogen, ammonia nitrogen, total phosphorus, available phosphorus, particulate organic carbon, particulate organic nitrogen, mineral organic carbon, mineral organic nitrogen, dissolved organic carbon, and nitrogen are soil nutrient indicators, which are related to the size of soil productivity, and the "more the better" scoring function is used; β-glucosidase, cellobiohydrolase, xylan hydrolase, N-acetylglucosaminidase, leucine aminopeptidase, acid phosphatase, microbial carbon, carbon-nitrogen ratio, etc. are related to soil biological activity, and play an important role in soil ecosystem services and biodiversity, and the "more the better" scoring function is used.

[0047] S4: Calculate and obtain the soil health index of the area to be evaluated based on the multiple linear scores.

[0048] The soil health index in step S4 is expressed as:

[0049] in, To calculate the soil health index, is the soil index value in the index system, is the total number of soil indicators in the indicator system, For the The linear scores of soil indicators are For the The weight value corresponding to each soil indicator.

[0050] S5: Perform soil health assessment on the area to be assessed according to the soil health index to obtain a soil health grade of the area to be assessed.

[0051] The soil health level in step S5 includes: The first health level, the soil health index range of the first health level is ; The second health level, the soil health index range of the second health level is ; The third health level, the soil health index range of the third health level is ; The fourth health level, the soil health index range of the fourth health level is 4.

[0052] Furthermore, the above-mentioned level division is divided according to the soil health index calculated in step S4, the first health level is extremely healthy, the second health level is healthy, the third health level is sub-healthy, and the fourth health level is unhealthy.

[0053] In a specific embodiment, the soil health index SHI is calculated using a soil health evaluation index system, and the soil health conditions under different treatments are compared. The preset overall soil health conditions studied in the present invention show a sub-healthy to healthy state. By comparing the soil health conditions under different tillage treatments, it can be found that the soil health condition under the rotary tillage straw not returned to the field treatment is the best, which is healthy soil, and the grassland soil health level is between sub-healthy and healthy. The soil health condition under the tillage straw returning to the field treatment is the worst, which is sub-healthy soil. It can be concluded that conservation tillage straw not returned to the field can improve the soil health level in the preset area studied in the present invention.

[0054] like Figure 2 As shown, the second aspect of the present invention provides a soil health quantitative evaluation system, comprising: Sampling module 100: used to sample the area to be evaluated according to preset soil indicators to obtain indicator data; Screening module 200: used to screen the soil indicators by principal component analysis, and also used to establish an evaluation system based on the soil indicators obtained by screening; Linear score calculation module 300: used to calculate the linear scores of the soil indicators included in the evaluation system according to the indicator data; The health index calculation module 400 is used to calculate the soil health index of the area to be evaluated according to the plurality of linear scores; The health grade classification module 500 performs soil health assessment on the area to be assessed according to the soil health index to obtain the soil health grade of the area to be assessed.

[0055] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0056] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0057] The present invention provides a soil health quantitative evaluation method and system, which integrates soil physical, chemical and biological indicators, introduces environmental stress indicators, constructs a soil health evaluation index system and calculates weights, avoids the subjective influence of human factors, improves the comprehensiveness and accuracy of soil health evaluation in the evaluation area, especially in dry farming areas, and uses the soil health index method to calculate the soil health status, which can realize the comparison of soil health status in different treatments or different regions, and has important significance for soil health status research and soil health management.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A soil health quantitative evaluation method, characterized in that: include: S1: Sample the area to be evaluated according to the preset soil indicators to obtain indicator data; S2: screening the soil indicators by principal component analysis, and establishing an evaluation system based on the screened soil indicators; S3: Calculating the linear scores of the soil indicators included in the evaluation system according to the indicator data; S4: Calculate and obtain the soil health index of the area to be evaluated based on the multiple linear scores; S5: Perform soil health assessment on the area to be assessed according to the soil health index to obtain a soil health grade of the area to be assessed.

2. A soil health quantitative evaluation method according to claim 1, characterized in that: The soil indicators in step S1 include: Physical indicators, including water content, bulk density, silt, sand, and clay; Biological indicators, the biological indicators comprising β-glucosidase, cellobiohydrolase, xylan hydrolase, N-acetylglucosaminidase, leucine aminopeptidase, acid phosphatase, microbial carbon, and carbon-nitrogen ratio; Chemical indicators, including pH, total carbon, organic carbon, total nitrogen, ammonia nitrogen, total phosphorus, available phosphorus, particulate organic carbon, particulate organic nitrogen, mineral organic carbon, mineral organic nitrogen, and dissolved organic carbon; Environmental indicators, including heavy metals and polycyclic aromatic hydrocarbons.

3. A soil health quantitative evaluation method according to claim 1, characterized in that: Step S2 further comprises: S21: performing variance analysis and H test on the index data obtained by sampling, and obtaining a first candidate index group from the soil indexes; S22: obtaining a second candidate indicator group from the first candidate indicator group by principal component analysis; S23: Establishing the evaluation system based on the second candidate indicator group.

4. A soil health quantitative evaluation method according to claim 3, characterized in that: The p-value of each indicator of the first candidate indicator group in step S21 is less than 0.

05.

5. A soil health quantitative evaluation method according to claim 3, characterized in that: In step S21, the characteristic value of each indicator of the second candidate indicator group is greater than or equal to 1 and the variance is greater than or equal to 5%.

6. A soil health quantitative evaluation method according to claim 1, characterized in that: The evaluation system in step S2 includes: A first dimensional indicator, wherein the first dimensional indicator is calculated by a linear scoring method, and the first dimensional indicator includes bulk density; The second dimension indicators are calculated by linear scoring using the second linear scoring method. The second dimension indicators include xylan hydrolase, acid phosphatase, and total nitrogen.

7. A soil health quantitative evaluation method according to claim 6, characterized in that: The expression of the first linear scoring method is: in, is the linear score calculated by the first linear scoring method, is the data value of the indicator data corresponding to the soil indicator belonging to the first dimension indicator, It is the maximum value in the indicator data group of a single soil indicator; The expression of the second linear scoring method is: in, is the linear score calculated by the second linear scoring method, It is the minimum value in the indicator data group of a single soil indicator.

8. A soil health quantitative evaluation method according to claim 1, characterized in that: The expression of the soil health index in step S4 is: in, To calculate the soil health index, is the soil index value in the index system, is the total number of soil indicators in the indicator system, For the The linear scores of soil indicators are For the The weight value corresponding to each soil indicator.

9. A soil health quantitative evaluation method according to claim 1, characterized in that: The soil health level in step S5 includes: The first health level, the soil health index range of the first health level is ; The second health level, the soil health index range of the second health level is ; The third health level, the soil health index range of the third health level is ; The fourth health level, the soil health index range of the fourth health level is 4.

10. A soil health quantitative evaluation system, used to implement a soil health quantitative evaluation method as claimed in any one of claims 1 to 9, characterized in that: include: Sampling module: used to sample the area to be evaluated according to preset soil indicators and obtain indicator data; Screening module: used to screen the soil indicators by principal component analysis, and also used to establish an evaluation system based on the soil indicators obtained by screening; Linear score calculation module: used to calculate the linear scores of the soil indicators included in the evaluation system according to the indicator data; A health index calculation module is used to calculate the soil health index of the area to be evaluated based on the plurality of linear scores; Health grade classification module: perform soil health evaluation on the area to be evaluated according to the soil health index to obtain the soil health grade of the area to be evaluated.

Images