Jujube wood compost quality grading method based on fuzzy comprehensive evaluation

Abstract

The invention provides a jujube wood compost quality grading method based on fuzzy comprehensive evaluation, and belongs to the technical field of compost quality evaluation and agricultural resource utilization. The jujube wood compost quality grading method comprises the following steps: (1) collecting jujube wood compost samples to be evaluated, and measuring the measured values of various indexes of the jujube wood compost samples; (2) adopting a membership function model, and converting the measured value of each index into a membership value between 0 and 1; (3) grading by adopting an analytic hierarchy process in combination with a 1-9 scaling method to determine the weight of each index; (4) calculating a comprehensive evaluation value of the compost quality according to a formula 1 according to the membership degree value and the weight of each index; and (5) grading the compost quality according to the comprehensive evaluation value. According to the jujube wood compost quality grading method, a scientific, systematic and operable evaluation system is formed, and rapid, objective and quantitative evaluation of the jujube wood compost quality is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of compost quality evaluation and agricultural resource utilization, and particularly relates to a jujube tree compost quality grading method based on fuzzy comprehensive evaluation. BACKGROUND

[0002] As a common agricultural waste, jujube tree has high lignin and cellulose content and dense structure, and thus has problems such as slow degradation, long composting period, and uneven product quality in the composting process. At present, the evaluation of compost quality mainly depends on experience or a few physical and chemical indexes, and lacks a systematic, quantifiable and comprehensive evaluation system. The existing method cannot comprehensively and objectively reflect the composting degree, nutrient availability, stability and agricultural safety of jujube tree compost, which is not conducive to the standardized production and scientific utilization of jujube tree compost.

[0003] Therefore, it is of great significance to develop a comprehensive evaluation method suitable for jujube tree compost, which is multi-index integrated and quantifiable, for promoting the resourceization, standardization and high-value utilization of jujube tree compost. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a jujube tree compost quality grading method based on fuzzy comprehensive evaluation. The present application builds a multi-dimensional index system including physical and chemical indexes, nutrients, maturity and structure, and adopts membership function to standardize the indexes based on fuzzy comprehensive evaluation theory, and combines weight to perform fuzzy synthesis calculation, so as to form a scientific, systematic and operable evaluation system, and realize rapid, objective and quantitative evaluation of jujube tree compost quality.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical solution: The present application provides a jujube tree compost quality grading method based on fuzzy comprehensive evaluation, which comprises the following steps: (1) Collecting jujube tree compost samples to be evaluated, and measuring the measured values of various indexes; (2) Using a membership function model to convert the measured values of various indexes into membership degree values between 0 and 1; (3) Using analytic hierarchy process combined with 1-9 scale method to determine the weight of each index; (4) According to the membership degree values and weights of various indexes, calculating the comprehensive evaluation value of compost quality according to formula 1; (5) Grading the compost quality according to the comprehensive evaluation value; (Formula 1), wherein, S is the comprehensive evaluation value of compost quality, U i is the membership degree value of the i th index, WiLet be the overall weight of the i-th indicator, and n be the total number of all indicators.

[0006] Preferably, the indicators include physicochemical properties, nutrient indicators, decomposition indicators, and structural components.

[0007] Preferably, the physicochemical properties include pH value, electrical conductivity, and moisture content; the nutrient indicators include organic matter, total nitrogen, total phosphorus, total potassium, and available phosphorus; the decomposition indicators include carbon-nitrogen ratio, nitrate nitrogen, ammonium nitrogen, and seed germination index; and the structural components include humic acid content, humic acid content, cellulose content, and lignin content.

[0008] Preferably, the membership function model includes positive indicators, negative indicators, and moderate indicators.

[0009] Preferably, the positive index is as shown in Equation 2: (Equation 2); Where U(x) is the membership degree value of indicator x; x is the measured value of the indicator; X min X is the lower limit of the indicator x; max This represents the upper limit of the indicator x; The negative index is shown in Equation 3: (Equation 3); The appropriateness index is shown in Equation 4: (Equation 4); in, X O The optimal value of index x X L Let X be the lower limit threshold of indicator x. H This represents the upper limit threshold of the indicator x.

[0010] Preferably, the positive index is applicable to GI, organic matter, humic acid, available phosphorus, total nitrogen, total phosphorus, total potassium, and nitrate nitrogen; the negative index is applicable to C / N, lignin, cellulose, EC, and ammonium nitrogen; and the moderate index is applicable to pH and moisture content.

[0011] As a preferred embodiment, the membership values ​​of each indicator are shown in Table 1; Table 1. Parameters of Membership Functions for Each Indicator

[0012] As a preferred option, the weights of each indicator are shown in Table 2; Table 2 Weighting System for Each Indicator

[0013] Preferably, the grading criteria are as follows: when S≥0.80, the compost quality is excellent; when 0.70≤S<0.80, the compost quality is good; when 0.60≤S<0.70, the compost quality is medium; and when S<0.60, the compost quality is poor.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) Comprehensive evaluation system: This invention constructs a comprehensive evaluation system covering 16 indicators in four major categories: physicochemical, nutrient, decomposition and structure, specifically targeting the characteristics of jujube wood composting, overcoming the limitation of single indicators in existing technologies; (2) The method is scientific and objective with a high degree of quantification: This invention introduces a fuzzy comprehensive evaluation model, which standardizes the heterogeneous indicators through membership functions and determines the weights by combining qualitative and quantitative (AHP) methods, thereby minimizing subjective arbitrariness and realizing the objective quantification of the evaluation results; (3) The model structure is clear and the operability is strong: This invention decomposes the complex multi-index evaluation problem into clear steps such as index fuzzification, weight determination, fuzzy synthesis, and grade decision-making. The calculation formula and parameters are public, which makes it easy to apply and promote in actual production, quality inspection and scientific research. (4) Wide applicability: Applicable to the quality evaluation of jujube wood compost produced from different raw materials and with different processes; (5) Clear and practical guidance: It can provide direct basis for compost production regulation, product quality grading and safe application. Attached Figure Description

[0015] Figure 1 This is a flowchart of the quality grading of jujube wood compost based on fuzzy comprehensive evaluation. Detailed Implementation

[0016] This invention provides a method for quality grading of jujube wood compost based on fuzzy comprehensive evaluation, comprising the following steps: (1) Collect jujube wood compost samples to be evaluated and determine the measured values ​​of various indicators; (2) The membership function model is used to convert the measured values ​​of each indicator into membership values ​​between 0 and 1; (3) The weights of each indicator are determined by using the analytic hierarchy process combined with the 1-9 scale method for scoring; (4) Calculate the comprehensive evaluation value of compost quality according to Formula 1 based on the membership degree value and weight of each indicator; (5) The compost quality is graded according to the comprehensive evaluation value; (Equation 1) in, S This is a comprehensive evaluation value for compost quality. U iLet be the membership value of the i-th indicator. Wi Let be the overall weight of the i-th indicator, and n be the total number of all indicators.

[0017] In this invention, jujube wood compost samples to be evaluated are collected, and the measured values ​​of various indicators are determined. An evaluation system is constructed for the collected jujube wood compost samples, comprising 16 secondary indicators in 4 primary categories: physicochemical properties, nutrient indicators, decomposition indicators, and structural components. The physicochemical properties include pH value, electrical conductivity, and moisture content. The nutrient indicators include organic matter, total nitrogen, total phosphorus, total potassium, and available phosphorus. The decomposition indicators include carbon-nitrogen ratio, nitrate nitrogen, ammonium nitrogen, and seed germination index. The structural components include humic acid content, humic acid content, cellulose content, and lignin content.

[0018] In this invention, a membership function model is used to transform the measured values ​​of each indicator into membership values ​​between 0 and 1, thereby achieving dimensionless and standardized representation of indicators with different dimensions. The membership function model includes positive indicators, negative indicators, and moderate indicators. The positive indicators are shown in Equation 2. (Equation 2); Where U(x) is the membership degree value of indicator x; x is the measured value of the indicator; X min X is the lower limit of the indicator x; max This represents the upper limit of the indicator x; The negative index is shown in Equation 3: (Equation 3); The appropriateness index is shown in Equation 4: (Equation 4); in, X O The optimal value of index x X L Let X be the lower limit threshold of indicator x. H This represents the upper limit threshold of the indicator x.

[0019] In this invention, the positive index is applicable to GI, organic matter, humic acid, available phosphorus, total nitrogen, total phosphorus, total potassium, and nitrate nitrogen; the negative index is applicable to C / N, lignin, cellulose, EC, and ammonium nitrogen; and the moderate index is applicable to pH and moisture content.

[0020] In this invention, the membership values ​​of each indicator are shown in Table 1; Table 1. Parameters of Membership Functions for Each Indicator

[0021] In this invention, the weights of each indicator are determined by combining the analytic hierarchy process (AHP) with a 1-9 scale. The method for determining the weights of each indicator is as follows: five experts in composting and soil fertility are invited to conduct pairwise comparisons of each indicator and its internal indicators, scoring them using a 1-9 scale; the eigenvalue method is used to calculate the relative weights of each indicator; then a consistency test is performed; the final weight is the geometric mean of the weights assigned by the five experts. The weights of each indicator are shown in Table 2; the consistency test requires a consistency ratio (CR) < 0.10. Table 2 Weighting System for Each Indicator

[0022] In this invention, the comprehensive evaluation value of compost quality is calculated according to Formula 1 based on the membership degree value and weight of each indicator. (Equation 1) in, S This is a comprehensive evaluation value for compost quality. U i Let be the membership value of the i-th indicator. Wi Let be the comprehensive weight of the i-th indicator, and n be the total number of indicators. This formula essentially uses a weighted average fuzzy synthesis operator M( , +) are used for composition operations.

[0023] In this invention, compost quality is graded based on a comprehensive evaluation value to determine the intended use of the compost. The grading criteria are as follows: when S ≥ 0.80, the compost quality is excellent; when 0.70 ≤ S < 0.80, the compost quality is good; when 0.60 ≤ S < 0.70, the compost quality is medium; and when S < 0.60, the compost quality is poor.

[0024] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0025] Example 1: Preparation method of jujube wood compost

[0026] (1) The collected jujube branches were mechanically crushed using a pulverizer to obtain jujube wood chips with a particle size range of 0.5~5cm.

[0027] (2) Add 0.5% of the dry weight of the jujube wood chips (purchased from Renyuan Biotechnology Development Co., Ltd.) of compound microbial agent to the jujube wood chips obtained in step (1) to obtain a mixture. Adjust the moisture content of the mixture to 60% by spraying water to maintain the microbial activity.

[0028] (3) The prepared compost materials are piled up for aerobic fermentation. A temperature-triggered system is used to check the core temperature of the pile. When the pile temperature reaches its peak for the first time and begins to drop naturally, the first turning of the pile is performed. Thereafter, whenever the pile temperature rises above 55℃ again and begins to drop, the next turning is performed. The pile is turned a total of 5 times until the pile temperature no longer rises sharply, at which point fermentation is complete (fermentation time is 55 days), and fermented material is obtained. The pile height is 1.5 meters, and a layer of straw about 5 cm thick is laid at the bottom of the pile to facilitate aeration.

[0029] (4) The fermented materials are piled up for post-maturation and aging. During this period, proper ventilation is maintained, and the aging time is 25 days to obtain fully decomposed compost products.

[0030] Example 2

[0031] A method for quality grading of jujube wood compost based on fuzzy comprehensive evaluation, the specific process is as follows: Figure 1 .

[0032] (1) The jujube wood compost obtained by the method in Example 1 was collected as a sample, and the measured values ​​of the evaluation system of 16 secondary indicators in 4 primary categories and 4 primary categories of physicochemical properties, nutrient indicators, decomposition indicators and structural components were tested. The test methods and results are shown in Table 3. Table 3. Methods and Results of Jujube Wood Compost Index Measurement

[0033] (2) The membership function model (Equations 2 to 4) is adopted to convert the measured values ​​of each index into membership values ​​between 0 and 1, so as to realize the dimensionless and standardized nature of the indexes with different dimensions. The membership function parameters of each index are shown in Table 1. Among them, GI, organic matter, humic acid, available phosphorus, total nitrogen, total phosphorus, total potassium, and nitrate nitrogen use the positive index model (Equation 2), C / N, lignin, cellulose, EC (when the salt content is too high), and ammonium nitrogen use the negative index model (Equation 3), and pH (suitable range 6.5 to 8.0) and moisture content (suitable range 50% to 65%) use the moderate index model (Equation 4). (Equation 2); (Equation 3); (Equation 4); (3) Determine the indicator weight system: The weight of each indicator is determined by using the analytic hierarchy process combined with expert consultation, as shown in Table 2; (4) Fuzzy comprehensive score calculation: The membership values ​​of each index obtained in step (2) and the corresponding weights obtained in step (3) are combined using a weighted average fuzzy synthesis operator to calculate the comprehensive evaluation value S of compost quality (Equation 1). (Equation 1); According to Equation 1, the comprehensive evaluation value of the compost quality is 0.596.

[0034] (5) Quality grade classification and decision: According to the comprehensive evaluation value S, the compost quality is "medium" grade, indicating that the compost has been initially decomposed, but some indicators (low available phosphorus content and low humic acid content) lower the overall score. It is recommended to further optimize the composting process or extend the post-maturation process to improve the compost quality to "good" or "excellent" grade.

[0035] Example 3: Optimized Process for the Preparation of Jujube Wood Compost

[0036] (1) The collected jujube branches were mechanically crushed using a pulverizer to obtain jujube wood chips with a particle size range of 0.5~5cm.

[0037] (2) Add 0.5% of the dry weight of jujube wood chips and sheep manure (the amount of sheep manure is obtained by calculating the carbon-nitrogen ratio in the mixture, which is 30:1) to the jujube wood chips obtained in step (1) to obtain the mixture. Adjust the moisture content of the mixture to 60% by spraying water to maintain the microbial activity.

[0038] (3) The prepared compost materials are piled up for aerobic fermentation. A temperature-triggered system is used to check the core temperature of the pile. When the pile temperature reaches its peak for the first time and begins to drop naturally, the pile is turned over for the first time. Thereafter, whenever the pile temperature rises above 55°C again and begins to drop, the pile is turned over again. The pile is turned over a total of 5 times until the pile temperature no longer rises sharply, at which point fermentation is complete (fermentation time is 45 days), and the fermented material is obtained. The pile height is 1.5 meters, and a layer of straw about 5 cm thick is laid at the bottom of the pile to facilitate aeration.

[0039] (4) The fermented materials are piled up for post-maturation and aging. During this period, proper ventilation is maintained, and the aging time is 25 days to obtain fully decomposed compost products.

[0040] Example 4

[0041] A method for quality grading of jujube wood compost based on fuzzy comprehensive evaluation, the specific process is the same as... Figure 1 .

[0042] (1) Jujube wood compost prepared by the method in Example 3 was collected as a sample and its various indicators were tested. The test methods and results are shown in Table 4. Table 4. Methods and Results for Determining Jujube Wood Composting Indicators in Optimized Processes

[0043] (2) Using the membership function model (Equations 2 to 4), the measured values ​​of each index are converted into membership degree values ​​(U). The calculation process is the same as in Example 2, and the results are shown in Table 4. (3) The weighting system shown in Table 2 shall be adopted; (4) Calculate the comprehensive evaluation value S (Equation 1) based on the membership value and weight of each indicator.

[0044] According to Equation 1, the comprehensive evaluation value of the compost quality is 0.812.

[0045] (5) Quality grade classification and decision: Based on the comprehensive evaluation value S=0.812, the quality grade of this compost is "excellent". This indicates that by optimizing the process (co-fermentation with sheep manure), the maturity, nutrient balance and stability of jujube wood compost have been significantly improved, and the product can be directly used as a seedling substrate or high-quality organic fertilizer.

[0046] Verification Example

[0047] To verify the scientific validity, effectiveness, and advantages of the method of this invention compared with traditional methods, the following comparative verification experiment was designed.

[0048] (1) Sample and data sources

[0049] Jujube wood compost prepared using the two processes in Examples 1 and 3 was selected as the evaluation subjects: Sample A: Prepared using conventional process (with only the addition of basic compound microbial agent) (Example 1). The measured data, calculation process and evaluation results of its various indicators are shown in Example 2 (corresponding to Table 3 and calculation result S=0.596).

[0050] Sample B: Prepared using an optimized process (addition of compound microbial agent and co-fermentation of sheep manure) (Example 3). The measured data, calculation process and evaluation results of its various indicators are shown in Example 4 (corresponding to Table 4 and calculation result S=0.812).

[0051] (2) Comparison of evaluation methods: Comparison Method (Traditional Standard Judgment Method): Based on the requirements for organic fertilizer products in the current national standard "Organic Fertilizer" (NY / T 525-2021), the main limit indicators such as organic matter, total nitrogen, moisture, and pH of the two samples were tested and their compliance was determined. This standard does not include core indicators reflecting compost maturity and safety, such as seed germination index (GI) and carbon-to-nitrogen ratio (C / N), in mandatory quality requirements.

[0052] The method of this invention: according to the method of this invention and the process demonstrated in Examples 2 and 4, multi-index fuzzy comprehensive evaluation and classification are performed.

[0053] (3) Results Comparison and Analysis: The two methods described above were used to evaluate samples A and B, and the results are compared below: Table 5 Comparison of evaluation results between the method of this invention and the traditional standard method.

[0054] (4) Verification conclusion

[0055] By directly comparing the specific evaluation results of the samples obtained in Example 1 (Sample A) and Example 3 (Sample B) with the judgment conclusions of the current national standards, the results show that: ① The method of this invention can effectively distinguish the quality differences of jujube wood compost produced under different process conditions. The evaluation results are highly consistent with the complexity of the production process and the expected quality target, which proves the effectiveness and sensitivity of the method.

[0056] ② Traditional standard methods can only make a binary judgment of "qualified" and "unqualified", and the evaluation indicators are not comprehensive enough for jujube wood compost, a specific material. The method of this invention establishes a multi-index fuzzy comprehensive evaluation system, which realizes a precise and quantitative grading of the quality of jujube wood compost, and also has a production diagnostic function, showing significant advantages in terms of the comprehensiveness, accuracy and practicality of the evaluation.

[0057] ③ Clear practical guidance value: The "excellent, good, medium, poor" quality grades and potential indicator shortcomings information output by the method of this invention can directly serve the quality grading, market pricing, precision agricultural use of compost products, and process optimization of production processes, which has important practical guidance significance for promoting the high-value resource utilization of jujube wood waste.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for quality grading of jujube wood compost based on fuzzy comprehensive evaluation, characterized in that, Includes the following steps: (1) Collect jujube wood compost samples to be evaluated and determine the measured values ​​of various indicators; (2) The membership function model is used to convert the measured values ​​of each indicator into membership values ​​between 0 and 1; (3) The weights of each indicator are determined by using the analytic hierarchy process combined with the 1-9 scale method for scoring; (4) Calculate the comprehensive evaluation value of compost quality according to Formula 1 based on the membership degree value and weight of each indicator; (5) The compost quality is graded according to the comprehensive evaluation value; (Equation 1) in, S This is a comprehensive evaluation value for compost quality. U i Let be the membership value of the i-th indicator. Wi Let be the overall weight of the i-th indicator, and n be the total number of all indicators.

2. The method for quality grading of jujube wood compost according to claim 1, characterized in that, The indicators include physicochemical properties, nutrient indicators, decomposition indicators, and structural components.

3. The method for quality grading of jujube wood compost according to claim 2, characterized in that, The physicochemical properties include pH value, electrical conductivity, and moisture content; the nutrient indicators include organic matter, total nitrogen, total phosphorus, total potassium, and available phosphorus; the decomposition indicators include carbon-nitrogen ratio, nitrate nitrogen, ammonium nitrogen, and seed germination index; and the structural components include humic acid content, humic acid content, cellulose content, and lignin content.

4. The method for quality grading of jujube wood compost according to claim 1, characterized in that, The membership function model includes positive indicators, negative indicators, and moderate indicators.

5. The method for quality grading of jujube wood compost according to claim 4, characterized in that, The positive index is shown in Equation 2: (Equation 2); Where U(x) is the membership degree value of indicator x; x is the measured value of the indicator; X min X is the lower limit of the indicator x; max This represents the upper limit of the indicator x; The negative index is shown in Equation 3: (Equation 3); The appropriateness index is shown in Equation 4: (Equation 4); in, X O The optimal value of index x X L Let X be the lower limit threshold of indicator x. H This represents the upper limit threshold of the indicator x.

6. The method for quality grading of jujube wood compost according to claim 5, characterized in that, The positive index applies to GI, organic matter, humic acid, available phosphorus, total nitrogen, total phosphorus, total potassium, and nitrate nitrogen; the negative index applies to C / N ratio, lignin, cellulose, EC, and ammonium nitrogen; and the moderate index applies to pH and moisture content.

7. The method for quality grading of jujube wood compost according to claim 1, characterized in that, The membership values ​​of each indicator are shown in Table 1; Table 1. Parameters of Membership Functions for Each Indicator 8. The method for quality grading of jujube wood compost according to claim 1, characterized in that, The weights of each indicator are shown in Table 2; Table 2 Weighting System for Each Indicator 9. The method for quality grading of jujube wood compost according to claim 1, characterized in that, The grading criteria are as follows: when S≥0.80, the compost quality is excellent; when 0.70≤S<0.80, the compost quality is good; when 0.60≤S<0.70, the compost quality is medium; and when S<0.60, the compost quality is poor.

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