Method for evaluating carbon sequestration and sink increase of farmland soil carbon reservoirs with different planting systems in coastal saline-alkali soil

Abstract

The invention provides a method for evaluating carbon sequestration and sink increase of farmland soil carbon reservoirs with different planting systems in coastal saline-alkali soil. A coastal saline-alkali land farmland soil carbon reservoir carbon sequestration and sink increase evaluation method comprises the following steps: S1, early-stage preparation: S11, sampling area delimiting; s12, preparing a tool; s13, sampling the soil; s14, obtaining soil attribute data; s15, obtaining soil carbon component data; s2, evaluation process: S21, establishment of an evaluation index system; s22, determining a weight; s23, determining a membership degree; s24, calculating a soil carbon library grade comprehensive index; s25, determining a grade division index; s26, re-checking is carried out; s27, performing field verification; and S28, optimizing the evaluation method. The method provided by the invention has the advantages that a multi-dimensional index system and a dynamic optimization mechanism are provided, the soil carbon sequestration capability is scientifically quantified, and a standardized and verifiable technical support can be provided for precise carbon sequestration management of the farmland.

Description

Technical Field

[0001] The present invention relates to the technical field of soil carbon pools, and in particular to a method for evaluating carbon sequestration and carbon sink enhancement in farmland soil carbon pools with different planting systems in coastal saline-alkali land. Background Art

[0002] As global climate change intensifies, coastal saline-alkali lands, as a critical marginal land resource, possess significant potential for carbon sequestration through their soil carbon pools. However, due to high salinity, high pH, ​​and frequent tidal influences, coastal saline-alkali lands exhibit poor soil carbon stability, rapid organic carbon decomposition, and significantly lower carbon sequestration capacity than conventional farmland. Existing evaluation methods are often designed for conventional farmland and fail to fully consider the unique soil properties of saline-alkali lands (e.g., salinization degree, sodium adsorption ratio) and carbon cycle characteristics (e.g., carbon retention mechanisms caused by salt inhibition of microbial activity). Traditional methods typically focus only on the surface soil (0-20 cm). However, deep soil layers (20-60 cm) in coastal saline-alkali lands may serve as potential carbon sinks due to salt leaching, but this lacks systematic sampling and evaluation. Furthermore, existing technologies inadequately quantify dynamic carbon processes in saline-alkali lands (e.g., tidal-driven carbon inputs and outputs), rely on generalized models for weighting, and fail to adjust indicator sensitivity for saline-alkali environments (e.g., salt content requires a higher weight than conventional farmland). This results in significant deviations from actual carbon sequestration capacity.

[0003] Therefore, it is necessary to provide a method for evaluating carbon sequestration and carbon sink enhancement in farmland soils under different cropping systems in coastal saline-alkali land to solve the above technical problems. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a multi-dimensional indicator system and dynamic optimization mechanism to scientifically quantify the soil carbon sequestration capacity, and to provide a method for evaluating the carbon sequestration and increase in soil carbon pools in farmland with different planting systems in coastal saline-alkali land, which can provide standardized and verifiable technical support for precise carbon sequestration management in farmland.

[0005] To solve the above technical problems, the present invention provides a method for evaluating carbon sequestration and carbon sink enhancement in farmland soils with different cropping systems in coastal saline-alkali land, comprising the following steps:

[0006] S1: Preliminary preparation, including:

[0007] S11: Delineation of sampling area;

[0008] S12: tool preparation;

[0009] S13: soil sampling;

[0010] S14: soil property data;

[0011] S15: soil carbon fraction data;

[0012] S2: Evaluation process, including:

[0013] S21: Establishment of evaluation index system;

[0014] S22: Determine weight;

[0015] S23: Determine the degree of membership;

[0016] S24: Calculate the comprehensive index of soil carbon pool level;

[0017] S25: Determine the grading index;

[0018] S26: Review;

[0019] S27: Field verification;

[0020] S28: Optimization of evaluation methods.

[0021] Preferably, in S13, 12-15 sampling points are randomly selected in the demonstration area according to the chessboard method in the sampling area, and 3 drills are randomly selected and mixed in each sampling point as 1 sample. The soil is divided into 3 layers, and the depths of the 3 layers are 0-20 cm, 20-40 cm and 40-60 cm respectively, and a total of 36-45 soil samples are obtained.

[0022] Preferably, in S23, each evaluation indicator is graded, and the evaluation level of each indicator is divided using the degree of membership.

[0023] Preferably, in S24, the soil carbon pool grade comprehensive index is calculated using the accumulation method:

[0024] P=∑(C i ×F i )

[0025] Among them, P is the comprehensive index of soil carbon pool level; C i is the weight of the i-th evaluation index; F i is the membership degree of the i-th evaluation index.

[0026] Preferably, in S26, the entire evaluation process is sorted out to ensure that the entire process is accurate and there are no operational errors or missing data.

[0027] Compared with related technologies, the method for evaluating carbon sequestration and carbon sink enhancement in farmland soils with different cropping systems in coastal saline-alkali land provided by the present invention has the following beneficial effects:

[0028] The present invention provides a method for evaluating carbon sequestration and carbon sink enhancement in farmland soils with different cropping systems in coastal saline-alkali land. By establishing an evaluation index system covering multiple dimensions such as soil carbon component content, organic matter, and structure, combining the analytic hierarchy process to determine weights, and using membership to divide evaluation levels, a scientific and quantitative evaluation of the carbon sequestration capacity of the soil carbon pool is achieved, avoiding subjectivity and one-sidedness. Standardized processes are provided from sampling area demarcation, tool preparation to soil stratification sampling (0-60cm), and laboratory testing (salt content, pH value, organic carbon, etc.) to ensure data comparability. At the same time, random sampling using the chessboard method (12-15 sample points, 36-45 samples) and field verification are used to significantly improve data reliability. The implementation of steps S27-S28 Through on-site verification and feedback optimization, the indicator weights and membership classification can be adjusted according to the soil characteristics of different regions, so that the evaluation system has both universality and regional adaptability. For example, the pH value weights can be set differently for saline-alkali land and black soil areas; based on the comprehensive index (P value), the carbon pool level is refined into 6 levels (excellent to poor) and associated with specific thresholds (such as excellent ≥ 0.9), which makes it easier for agricultural managers to quickly identify the soil carbon sequestration potential and provide an accurate basis for formulating differentiated farmland management measures (such as straw return and crop rotation system); the indicator system is compatible with traditional indicators (organic carbon content) and dynamic process indicators (soil respiration rate), which can not only reflect the current carbon reserves, but also evaluate the carbon cycle process, providing comprehensive technical support for the assessment of farmland carbon sequestration potential under the carbon neutrality goal. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the embodiments.

[0030] The evaluation methods for carbon sequestration and carbon sink enhancement in farmland soils under different cropping systems in coastal saline-alkali land include:

[0031] S1: Preliminary preparation:

[0032] S11: Delineation of sampling area: Determine the farmland soil area to be evaluated and collect farmland cropping system information and soil data within the sampling area;

[0033] S12: Tools: camera, earth drill, shovel, ring cutter (including ring cutter holder), rubber hammer, ruler, scissors, envelope, ziplock bag, marker, signature pen, label, survey record sheet, etc.

[0034] S13: Soil sampling: 12-15 sampling points were randomly selected from the demonstration area according to the chessboard method. Three drills were randomly selected and mixed at each sampling point as one sample. The soil was divided into three layers (0-20 cm, 20-40 cm, and 40-60 cm). A total of 36-45 soil samples were obtained.

[0035] S14: Soil attribute data: soil samples are tested to obtain soil attribute data such as salinity and pH value, which provide a basis for establishing an evaluation index system;

[0036] S15: Soil carbon component data: Detect indicators such as organic carbon, soluble organic carbon and microbial carbon in soil samples, and quantitatively analyze their content distribution;

[0037] S2: Evaluation process:

[0038] S21: Establishment of an evaluation index system: Based on the characteristics of different components of the soil carbon pool, an index system covering carbon component content, soil organic matter, soil structure and other factors will be established to evaluate the carbon sequestration and emission reduction effects of soils in multiple dimensions;

[0039] S22: Determine weights: The weights reflect the degree of influence of the evaluation indicators on the soil carbon pool. They can be obtained using the analytic hierarchy process (AHP) or expert experience method, with the analytic hierarchy process (AHP) being given priority.

[0040] S23: Determine the membership degree: Classify each evaluation indicator and use the membership degree to divide the evaluation level of each indicator. For example, the carbon pool level can be divided according to the organic carbon content to ensure the scientific nature of the evaluation results.

[0041] S24: Calculate the comprehensive index of soil carbon pool level: Use the accumulation method to calculate the comprehensive index of soil carbon pool level:

[0042] P=∑(C i ×F i )

[0043] Among them, P is the comprehensive index of soil carbon pool level; C i is the weight of the i-th evaluation index; F i is the membership degree of the i-th evaluation index.

[0044] S25: Determine the grading index: Based on the comprehensive index, the farmland soil carbon pool expansion and emission reduction levels of different cropping systems are divided into three levels, such as excellent level (>=0.9), good level (0.7-0.9), and poor level (<0.7);

[0045] S26: Review: Review the entire evaluation process to ensure that the entire process is accurate and there are no operational errors, missing data, etc.

[0046] S27: Field verification: After the grades are calculated, field verification is carried out to verify the accuracy of the comprehensive index on the effect of soil carbon pool expansion and emission reduction through sampling and monitoring;

[0047] S28: Optimization of evaluation methods: Based on field feedback, optimize the weights and membership classification of indicators in the evaluation system to better adapt to the soil conditions in specific areas, and then conduct evaluations until the evaluation results are reasonable.

[0048] The evaluation index system provided by the present invention includes:

[0049] 1. Soil suitability classification indicators are shown in the following table:

[0050] Soil properties Soil carbon storage capacity Soil carbon pool dynamics Salt content Organic carbon content Carbon input and output ratio pH Soluble organic carbon content Soil carbon sequestration efficiency Microbial biomass carbon Organic matter decomposition rate Soil respiration rate

[0051] 2. Indicator weights are as shown in the following table:

[0052] Indicator name Indicator weight Salt content 20 pH 15 Organic carbon content 20 Soluble organic carbon content 10 Microbial biomass carbon 10 Carbon input and output ratio 10 Soil carbon sequestration efficiency 5 Organic matter decomposition rate 5 Soil respiration rate 5

[0053] 3. Indicator membership, as shown in the following table:

[0054]

[0055]

[0056] 4. The grading index is as shown in the following table:

[0057]

[0058] Compared with related technologies, the method for evaluating carbon sequestration and carbon sink enhancement in farmland soils with different cropping systems in coastal saline-alkali land provided by the present invention has the following beneficial effects:

[0059] The present invention provides a method for evaluating carbon sequestration and carbon sink enhancement in farmland soils with different cropping systems in coastal saline-alkali land. By establishing an evaluation index system covering multiple dimensions such as soil carbon component content, organic matter, and structure, combining the analytic hierarchy process to determine weights, and using membership to divide evaluation levels, a scientific and quantitative evaluation of the carbon sequestration capacity of the soil carbon pool is achieved, avoiding subjectivity and one-sidedness. Standardized processes are provided from sampling area demarcation, tool preparation to soil stratification sampling (0-60cm), and laboratory testing (salt content, pH value, organic carbon, etc.) to ensure data comparability. At the same time, random sampling using the chessboard method (12-15 sample points, 36-45 samples) and field verification are used to significantly improve data reliability. The implementation of steps S27-S28 Through on-site verification and feedback optimization, the indicator weights and membership classification can be adjusted according to the soil characteristics of different regions, so that the evaluation system has both universality and regional adaptability. For example, the pH value weights can be set differently for saline-alkali land and black soil areas; based on the comprehensive index (P value), the carbon pool level is refined into 6 levels (excellent to poor) and associated with specific thresholds (such as excellent ≥ 0.9), which makes it easier for agricultural managers to quickly identify the soil carbon sequestration potential and provide an accurate basis for formulating differentiated farmland management measures (such as straw return and crop rotation system); the indicator system is compatible with traditional indicators (organic carbon content) and dynamic process indicators (soil respiration rate), which can not only reflect the current carbon reserves, but also evaluate the carbon cycle process, providing comprehensive technical support for the assessment of farmland carbon sequestration potential under the carbon neutrality goal.

[0060] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for evaluating carbon sequestration and carbon sink enhancement in farmland soils with different cropping systems in coastal saline-alkali land, characterized in that: The following steps are involved: S1: Preliminary preparation, including: S11: Delineation of sampling area; S12: tool preparation; S13: soil sampling; S14: soil property data; S15: soil carbon fraction data; S2: Evaluation process, including: S21: Establishment of evaluation index system; S22: Determine weight; S23: Determine the degree of membership; S24: Calculate the comprehensive index of soil carbon pool level; S25: Determine the grading index; S26: Review; S27: Field verification; S28: Optimization of evaluation methods.

2. The method for evaluating carbon sequestration and carbon sink enhancement in farmland soils with different cropping systems in coastal saline-alkali land according to claim 1, characterized in that: In S13, 12-15 sampling points are randomly selected from the demonstration area according to the chessboard method in the sampling area, and 3 drills are randomly selected and mixed in each sampling point as 1 sample. The soil is divided into 3 layers, and the depths of the 3 layers are 0-20 cm, 20-40 cm and 40-60 cm respectively. A total of 36-45 soil samples are obtained.

3. The method for evaluating carbon sequestration and carbon sink enhancement in farmland soils with different cropping systems in coastal saline-alkali land according to claim 1, characterized in that: In S23, each evaluation indicator is graded, and the evaluation level of each indicator is divided using the degree of membership.

4. The method for evaluating carbon sequestration and carbon sink enhancement in farmland soils with different cropping systems in coastal saline-alkali land according to claim 1, characterized in that: In S24, the soil carbon pool grade comprehensive index is calculated using the accumulation method: P=∑(C i ×F i ) Among them, P is the comprehensive index of soil carbon pool level; C i is the weight of the i-th evaluation index; F i is the membership degree of the i-th evaluation index.

5. The method for evaluating carbon sequestration and carbon sink enhancement in farmland soils with different cropping systems in coastal saline-alkali land according to claim 1, characterized in that: In S26, the entire evaluation process is sorted out to ensure that the entire process is accurate and there are no operational errors or erroneous data.

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