Rapid evaluation method for stability of soil organic carbon library

Abstract

The invention discloses a method for rapidly evaluating the stability of a soil organic carbon library. The method comprises the following steps: firstly, carrying out standard pretreatment on a soil sample; carrying out particle size grading on the pretreated standardized sample through a physical method, separating out organic carbon components fPOM, cPOM and MAOM, respectively collecting each component and removing inorganic carbon in each component; all the components are dried and ground; standard sample packaging is conducted on all the components, the components are sent into an element analyzer to be detected and analyzed, and the organic carbon content measured by all the components is obtained; calculating the stability index of the organic carbon library, and evaluating the stability. According to the method, a quantitative carbon library stability evaluation model is constructed, the operation is simple, the cost is low, a closed loop is formed by separation-detection-evaluation, and a powerful technical tool is provided for rapid and accurate evaluation of the soil carbon sink function under the carbon neutralization background.

Description

Technical Field

[0001] This invention belongs to the technical field of soil organic carbon pool stability evaluation, and particularly relates to a rapid evaluation method for soil organic carbon pool stability. Background Technology

[0002] Under the national strategy of "carbon neutrality," accurately assessing the stability of the soil organic carbon pool is crucial for measuring soil health, predicting climate change feedback, and evaluating the carbon sequestration potential of agricultural management practices. Soil organic matter (SOM) is not homogeneous; the turnover times of its different components can range from several years to thousands of years. The current international consensus classifies SOM into particulate organic matter (POM) and mineral-bound organic matter (MAOM). POM can be further divided into coarse particulate organic matter (cPOM) and light free particulate organic matter (fPOM). POM is mainly composed of incompletely decomposed plant residues, with a relatively rapid turnover time, generally several years to several decades, and is the main source of soil carbon input. MAOM, on the other hand, is tightly bound to soil minerals, with a slow turnover time of hundreds to thousands of years, and is the core of the long-term stable carbon pool. Current methods for assessing the stability of soil organic carbon pools often employ biological and chemical component separation, which are complex, inefficient, and difficult to guarantee the accuracy of the assessment results. This has become a bottleneck restricting large-scale, standardized soil carbon pool research. More importantly, existing technologies are mostly focused on the separation operation itself and have failed to form a closed-loop assessment system of "separation-detection-evaluation". Summary of the Invention

[0003] Based on the above background, the present invention aims to provide a rapid evaluation method for the stability of soil organic carbon pools, providing strong technical support for the rapid and accurate assessment of soil carbon sink function under carbon neutrality.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A rapid evaluation method for the stability of soil organic carbon pools includes the following steps: S1. Standard pretreatment of soil samples; S2. The pretreated standardized samples are subjected to particle size fractionation by physical methods to separate the organic carbon components fPOM, cPOM and MAOM. Each component is collected and the inorganic carbon is removed. S3. Dry and grind each component; S4. Standardize and package each component, and send it into an elemental analyzer for detection and analysis to obtain the machine-measured organic carbon content of each component; S5. Calculate the stability index of the organic carbon library and assess its stability. Specific steps include: Calculate the organic carbon reserves of each component: ; ; Among them, is the organic carbon storage in the th component, is the dry weight of the th component, is the optimized organic carbon content of the th component, is the machine-measured organic carbon content of the th component; Calculate the proportion of organic carbon in each component: : Among them, is the proportion of organic carbon in the th component; Calculate the stability index of the organic carbon pool: ; Among them, is the stability index of the organic carbon pool, , , are respectively the proportions of organic carbon in the components fPOM, cPOM, and MAOM, , , are respectively the average turnover times of fPOM, cPOM, and MAOM; Stability evaluation: Stable if 50 < CSI ≤ 100, moderately stable if 10 < CSI ≤ 50, and unstable if CSI ≤ 10.

[0005] Preferably, the specific steps of step S2 include: S21: Add a heavy liquid to the standardized sample to make a sample suspension, and place it in an ultrasonic chamber for water bath ultrasonic treatment to disperse the aggregates; S22: Place the sample suspension after water bath ultrasonic treatment in a centrifuge for accelerated centrifugation to make it stratified. The floating free component on the upper layer after stratification is fPOM, and collect it; S23. Put the remaining precipitated soil sample into a vibrating screening device. The vibrating motor drives the 53 μm sieve mesh to vibrate, and at the same time, rinse the soil sample with circulating pure water. Place a collection container for the MAOM component at the bottom of the sieve mesh. After rinsing with pure water for 2 minutes, the collection of the MAOM component is completed; S24. The remaining soil sample in the sieve mesh is the cPOM component. Rotate the sieve mesh 180°, and use circulating pure water to rinse and collect the cPOM component in a container; S24: Inject dilute hydrochloric acid into the collection containers of the three components respectively to remove the inorganic carbon inside.

[0006] Preferably, in step S1, the standard pretreatment of the soil sample includes coarse grinding, air drying, fine grinding, and sieving.

[0007] The present invention has the following advantages over the prior art: This invention provides a rapid evaluation method for the stability of soil organic carbon pools. It separates organic carbon components in soil using physical methods, which is simple to operate and low in cost. Furthermore, it adopts an optimized organic carbon pool stability evaluation index to ensure the reliability of the stability evaluation. This invention also forms a closed loop of "separation-detection-evaluation" and constructs a quantitative carbon pool stability evaluation model, providing a powerful technical tool for the rapid and accurate assessment of soil carbon sink function under carbon neutrality. Detailed Implementation

[0008] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0009] A rapid evaluation method for the stability of soil organic carbon pools includes the following steps: S1. Standard pretreatment of soil samples, including coarse grinding, air drying, fine grinding and sieving; S2. The pretreated standardized samples are subjected to particle size fractionation using physical methods to separate the organic carbon components fPOM, cPOM, and MAOM. Each component is collected separately, and the inorganic carbon is removed. The specific steps are as follows: Heavy liquid was added to the standardized sample to prepare a sample suspension, which was then placed in an ultrasonic chamber for water bath sonication to disperse the aggregates. The sample suspension after water bath sonication was then centrifuged to accelerate the separation into layers. The free component floating on the upper layer after separation was fPOM, which was collected. The remaining precipitated soil sample was placed in a vibrating sieve device, where a vibrating motor drove a 53μm sieve to vibrate. At the same time, the soil sample was rinsed with circulating pure water. A MAOM component collection container was placed at the bottom of the sieve. After rinsing with pure water for 2 minutes, the MAOM component was collected. The remaining soil sample in the sieve was component cPOM. The sieve was rotated 180°, and component cPOM was collected in a container using circulating pure water. Dilute hydrochloric acid was injected into the collection containers of the three components to remove the inorganic carbon. S3. Dry and grind each component; S4. Standardize and package each component, and send it into an elemental analyzer for detection and analysis to obtain the machine-measured organic carbon content of each component; S5. Calculate the stability index of the organic carbon pool and evaluate its stability. The specific steps include: Calculate the organic carbon storage of each component: ; ; Among them, is the organic carbon storage of the th component, is the dry weight of the th component, is the optimized organic carbon content of the th component, is the measured organic carbon content of the th component; Calculate the proportion of organic carbon in each component: ; Among them, is the proportion of organic carbon in the th component; Calculate the stability index of the organic carbon pool: ; Among them, is the stability index of the organic carbon pool, , , are the proportions of organic carbon in fPOM, cPOM, and MAOM respectively, , , are the average turnover times of fPOM, cPOM, and MAOM respectively; the average turnover time reference value can be adjusted according to the research consensus of different soil types and climate zones; in this embodiment, takes 1 year, takes 10 years, [[ID=|63]] takes 100 years; Stability evaluation: Stable when 50 < CSI ≤ 100, moderately stable when 10 < CSI ≤ 50, and unstable when CSI ≤ 10.

[0010] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A rapid evaluation method for the stability of soil organic carbon pools, characterized in that, It includes the following steps: S1. Conduct standard pretreatment on the soil sample; S2. The pretreated standardized sample is subjected to particle size grading by physical methods to separate the organic carbon components fPOM, cPOM, and MAOM, collect each component respectively and remove the inorganic carbon therein; S3. Dry and grind each component; S4. Package each component in a standardized manner and send it into an elemental analyzer for detection and analysis to obtain the measured organic carbon content of each component; S5. Calculate the stability index of the organic carbon pool and evaluate its stability. The specific steps include: Calculate the organic carbon reserves of each component: ； ； in, For the first Component organic carbon reserves For the first dry weight of components For the first The optimized organic carbon content of the components For the first The organic carbon content of the components was determined by mechanical analysis. Calculate the proportion of organic carbon in each component: ； in, For the first The percentage of organic carbon in the components; Calculate the stability index of the organic carbon pool: ； in, This is the stability index of the organic carbon pool. , , These represent the percentage of organic carbon in components fPOM, cPOM, and MAOM, respectively. , , These are the average turnaround times for fPOM, cPOM, and MAOM, respectively. Stability evaluation: Stable when 50 < CSI ≤ 100, moderately stable when 10 < CSI ≤ 50, and unstable when CSI ≤ 10.

2. The rapid evaluation method for soil organic carbon pool stability according to claim 1, characterized in that, The specific steps of step S2 include: S21: Add heavy liquid to the standardized sample to make a sample suspension, put it into an ultrasonic chamber for water bath ultrasonic treatment to disperse the aggregates; S22: Put the sample suspension after water bath ultrasonic treatment into a centrifuge for accelerated centrifugation to make it stratified. The floating free component on the upper layer after stratification is fPOM, and collect it; S23. Put the remaining precipitated soil sample into a vibrating screening device. The vibrating motor drives the 53μm sieve mesh to vibrate, and at the same time, use circulating pure water to scour the soil sample. A collection container for the MAOM component is placed at the bottom of the sieve mesh. After 2 minutes of pure water scouring, the collection of the MAOM component is completed; S24. The remaining soil sample in the sieve mesh is the cPOM component. Rotate the sieve mesh 180°, and use circulating pure water to scour and collect the cPOM component in a container; S24: Inject dilute hydrochloric acid into the collection containers of the three components respectively to remove the inorganic carbon therein.

3. The rapid evaluation method for soil organic carbon pool stability according to claim 1, characterized in that, In step S1, the standard pretreatment of the soil sample includes coarse grinding, air drying, fine grinding, and sieving.

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